P E O P L E A N D T H E C O A S T: C O M M E R C I A L A C T I V I T I E S
Fishing Industry 2B
S
outh Africans have been utilizing their
rock lobster. The warm waters of the east coast support
abundant marine resources for food since
fewer fish of commercial importance, although the number
the Strandlopers first lived along our shores some
6 000 years ago.
of species that occur on this coast is much higher.
The South African fisheries
• The demersal (deep water) sector is South Africa’s most
Commercial fishing, or fishing for profit, began shortly after
the arrival of Europeans and developed rapidly in the
twentieth century. Total harvests from South African waters
remained relatively small until 1950 when technological
advances led to a rapid increase in the quantity of fish
caught. Catches from the south east Atlantic peaked at
over 3 million tons in 1968 and then declined sharply as
fishing companies began to experience the effects of overfishing. Today, South Africa’s fisheries contribute approximately
valuable commercial fishery and is worth over R1 billion
annually. The mainstay of the fishery is the Cape hakes,
Merluccius capensis (shallow water hake) and Merluccius
paradoxus (deep-water hake). However, as in trawl fisheries
around the world, other species are caught, either as bycatch or as targeted species. Many of these, including
sole, kingklip and monkfish, are highly prized by consumers
and their unit price is often greater than that of hake.
• The South African pelagic fishery is the country’s second
R2 billion to the national economy. Some 28 000 people living
most valuable fishery. In 1996 the pelagic fishery netted
in the coastal provinces are directly employed by the fishing
approximately 214 000 tons of anchovy and pilchard with a
industry, while another 60 000 people find employment in
value of R366 million. Although pelagic catches far out-
related sectors. South Africa’s fisheries are managed by the
weigh demersal catches, pelagic fish have a lower unit
Department of Environmental Affairs and Tourism, according
price, being used for canning, fishmeal and oil. (Fishmeal is
to the principles that are contained in the 1996 White Paper
an important constituent in certain animal feeds). Pelagic
on Marine Fisheries Policy. The Marine Living Resources Act
catches fluctuate from year to year and are largely dependent
of 1998 provides the legal foundation for the management
on environmental conditions. When catches are bad – as
of commercial fisheries in South Africa. The Act seeks to
they were in 1996, owing to a strong El Niño event –
facilitate a fisheries management ethos that is based on
a larger share of the pelagic catch is used for human
the principle of sustainable utilization; meaning that future
consumption. Purse seine nets are used to encircle large
generations of South Africans will enjoy similar catch levels
shoals of pelagic fish: the top of the net is buoyed by floats
to those of today.
and the net hangs like a curtain. Once the shoal has been
South Africa’s fisheries zone extends seawards from the
coastline for 200 nautical miles. The cold waters on the
western side of the country are highly productive and support
encircled the net is pulled in, closing the bottom of the net
like a purse.
• South Africa’s commercial rock lobster fishery is based on
enormous numbers of commercially important fish; including
two species, one on the south coast and one on the west
shoaling fish such as pilchard and anchovy, deepsea species
coast. The latter is caught inshore by traps and hoopnets
such as hake, sole and kingklip, as well as healthy stocks of
deployed from small vessels and the former is a deep
Hake – South Africa’s most important commercial fish species
water species caught by means of long lines of traps set
to be the greatest. Fishing disrupts marine biodiversity by
by larger vessels. Approximately 2 000 tons of rock lobster
removing fish and disturbing the biological and physical
are caught and marketed by South Africa every year. The
environments. Some examples follow.
majority are exported live to markets in Europe and Asia
where they are highly prized as a seafood delicacy.
• The squid-jigging fishery is based in the Eastern Cape
• Trawling equipment impacts the benthic environment by
scraping and ploughing the substratum. The affects of
these impacts vary according to the fragility of the habitat
Province where between 2 000 and 10 000 t of the chokka
and severity of natural disturbance. Coral reefs and deep
squid, Loligo vulgaris reynaudii are harvested annually.
sea environments have been severely impacted. There is
Some 2 500 people are directly employed by this labour-
concern that bobbin-gear and tickler chains, which were
intensive fishery.
once used extensively to catch panga and flatfish, have
damaged temperate reef habitat on the Agulhas Bank, an
• Catches in the commercial linefishery peaked at 20 000
important fishing ground off the south coast.
tons in the late 1960s but then declined steadily. Today
approximately 13 000 t of linefish species, such as yellowtail, snoek, kob and reef fish are harvested. Linefish
species are protected by a variety of management
measures, but catches have declined to dangerously low
levels due to increasing pressure from commercial and
recreational fishers.
• Fishing methods are seldom selective. Many species are
caught despite the fact that they are not wanted, not allowed
to be caught or damage the gear. Bycatch rates in South
Africa vary between 5% and 70%. The effect of fishing on
‘bycatch’ species is seldom known because these species
are mostly not recorded in catches and not regulated by
quotas. A serious bycatch issue is currently the mortality of
• The commercial abalone fishery is one of South Africa’s
most valuable fisheries. It is based on the south coast,
around the coastal town of Hermanus. Approximately 500 t
of abalone are harvested every year, but an escalation in
illegal fishing is having a detrimental affect on the resource.
• Mariculture accounts for less than one percent of South
Africa’s seafood production, but a recent surge in the
sea-birds inflicted by long-line operations.
• Fisheries are size- and species-selective and the tendency
of fisheries to deplete large top predators first and then
target the next largest species has substantially altered
marine community structures. A comparison of contemporary and historical records of South African linefish catches
show that large piscivorous fish species have declined
cultivation of abalone has shown that the industry has a
relative to smaller species over the course of the twentieth
high growth potential. South Africa also farms oysters and
century.
mussels mostly for local markets.
• "Harder" is the common name for the southern mullet, Liza
• The primary objective of fisheries management has been to
ensure the sustained yield of fisheries, with less attention
richardsonii, which forms the basis of the trek-net or
being paid to the effects of fishing on non-targeted species
beach-seine fishing industry in South Africa. This sector of
and the environment. The process of fishery management
the fishing industry, which is active predominantly on the
reduces fisheries to their component parts and assesses
West Coast, relies on traditional methods to net large
and controls each independently. Fisheries managers almost
shoals of fish from the beach.
always ignore the fact that fish populations are dependent
on other components of the ecosystem for maintaining their
Environmental considerations
productivity. This oversight creates serious consequences if
The South African marine environment is showing symptoms
the ecological structure and processes that support stock
of over-exploitation and degradation, and the pressures that
production are impacted by the fishing activity itself, or by
bear on marine resources are likely to increase in the future.
other human activities or natural phenomena.
Of all the threats to the marine environment, fishing is thought
Author: Claire Attwood September 2000
FURTHER INFORMATION: • Payne, A.I.L. and Crawford, R.J. (Eds) 1989. Oceans of Life off South Africa . Vlaeberg Publishers, Cape Town.
• Branch, G. and Branch, M. 1981. The Living Shores of Southern Africa . Struik Publishers, Cape Town.
RELATED FACTSHEETS: • West Coast • Recreational Angling • Sustainable use of Coastal Resources • Mariculture • Abalone • Food Value of Fish
• Rock Lobster • Demersal Fishing • Squid Fishery • Bivalves • Cephalopods • Pelagic Fishing • Seaweed and their Uses
For more information, please contact: The Coastal Management Office, Marine and Coastal Management, Department of Environmental Affairs and Tourism, Private Bag X2,
Roggebaai 8012, Cape Town, South Africa. Tel: +27 (0)21 402-3208 Fax: +27 (0)21 418-2582 e-mail: czm@mcm.wcape.gov.za Website: http://sacoast.wcape.gov.za
P E O P L E A ND T HE C O A ST: C O MM E R CI AL A C T I V I T I ES
Harder Industry 2B
O
ne of the most colourful sectors of the South
are set either from a boat or by walking them out from the
African fishery is the harder industry, a
shore in the hope that a shoal of fish will swim into them and
sector that relies on traditional methods to net large
shoals of fish from the beach. Visitors to the west
become entangled. These nets either drift or they are staked
or anchored. The size of the mesh determines the minimum
size of the fish that are caught.
coast, where harder fishing is most intensive, are
often fascinated by the activities of the "trek" fishers
Trek nets
who set their nets from small, brightly painted
Beach-seining or trek-netting is another method used to
boats and then patiently haul in their catch as
catch harders. Woven nylon nets are rowed out into the surf
onlookers rush to their assistance.
zone to encircle a shoal of fish. Sometimes the nets are set
blindly, but on most occasions a fish spotter, who stands on
high ground adjacent to the beach, guides the netters
"Harder" is the common name for the southern mullet, Liza
towards a clearly visible shoal of fish. A single man holds the
richardsonii, which forms the basis of the harder industry in
long headrope on the
The Southern
Mullet
South Africa. Liza richardsonii is by far the
most abundant of the 15
beach while the net is
payed out from the
species of mullet that occur
boat. Both ends of the
in our waters and is
headrope are then
endemic to our shores. It is an
pulled by hand towards
elongated, silver-grey fish which grows
the shore by a group of
quickly, reaching a length of 200 mm in about three years.
between eight and thirty fishers. The net gradually folds
Estuaries and intertidal rock pools are important nursery
around the fish and they are brought ashore in the bag at the
grounds for harders, many of which will remain in these
end of the net.
sheltered waters until they reach adulthood. Harders are most
commonly eaten in a cured form. Salted and dried harders
Until the late 1960s the only restriction imposed on harder
are called "bokkoms" on the west coast where they form an
fishers was the requirement that a minimum mesh size of
important part of the diet of many rural communities.
44 mm be used to limit the capture of juvenile fish. In 1974
the practice of purse seining harders from boats was phased
Harder fishing dates back to the seventeenth century, when
out, largely in response to complaints by anglers that the
Dutch settlers began using beach-seine nets to catch shoals
netting was having a detrimental effect on stocks of popular
of mullet in Table Bay. Today harders are caught by licensed
angling fish. A range of management measures was intro-
fishers who use gill nets and beach seine nets to snare their
duced around this time and by the early 1980s a permit
catch. On the west coast fishing is intensive; in St Helena
system was in place. The number of permits issued to net
Bay and the Berg River estuary some 600 nets are used.
fishers dropped during the 1980s and it is estimated that
approximately 7 000 fishers take part in the fishery today.
Gill nets
Many of these fishers are involved in the harder fishery on a
The most common method for catching harders is the setting
part time basis, switching to other forms of fishing when
of gill nets. This is a passive form of fishing whereby gill nets
opportunities arise.
Gill Net
Trek net
Bycatch concerns
been established that some fishers are involved in targeting
prohibited species, particularly galjoen, for which a large but
Conflict between net fishers and other users of the sea is not
illicit fishery exists.
a new phenomenon. As early as 1966 a commission of
enquiry was appointed to investigate the catching of linefish
The future management of this fishery depends to a large
species by net fishers. Since then, the problem of linefish
extent on improved monitoring and control of the net fishery.
bycatch has continued to plague this fishery and remains a
Scientists have recommended that, in future, the harder fish-
bone of contention, especially amongst recreational fishers.
ery should not be managed in isolation from the recreational
and commercial linefisheries.
“Bycatch” is a term used by fisheries managers to describe
incidental catch. “Netting” is an unselective method of fishing
Author: Claire Attwood September 2000
and a large number of fish species, besides harders, are
trapped and killed by the nets used in this industry. In the
Western Cape, St Joseph sharks comprise about 25% of the
Throw-nets may be used in
estuaries to catch harders
bycatch. Other species that are commonly caught in harder
nets are yellowtail, white steenbras, elf (shad), grunter and
galjoen. Harders are sold for about R2 per kg while linefish
species fetch much higher prices (R6 – R10 per kg). This
price discrepancy offers major incentives for harder fishers to
target prohibited, but more valuable, species.
Recent surveys of the harder fishery have shown that,
although permit holders are compelled to submit details of
their catches to fisheries authorities, in many cases catches,
and specifically bycatches, are under-reported. As a result,
it is likely that an important component of the South African
linefish catch is not accurately recorded. Furthermore, it has
FURTHER INFORMATION: • Payne, A.I.L. and Crawford, R.J. (Eds). 1989. Oceans of Life off Southern Africa . Vlaeberg Publishers, Cape Town.
• Lamberth, S.J., et al. 1997. The Status of the South African Beach Seine and Gill-net Fisheries. South African Journal of Marine Science 18:195-202
RELATED FACTSHEETS: • Fishing Industry • Recreational Angling along our Coast • Traditional Fishing Methods • Food Value of Fish
For more information, please contact: The Coastal Management Office, Marine and Coastal Management, Department of Environmental Affairs and Tourism, Private Bag X2,
Roggebaai 8012, Cape Town, South Africa. Tel: +27 (0)21 402-3208 Fax: +27 (0)21 418-2582 e-mail: czm@mcm.wcape.gov.za Website: http://sacoast.wcape.gov.za
P EO P L E A ND T HE C O A ST: C O MM E R C I A L A C T I V I T I E S
Mariculture 2B
M
ariculture is often referred to as sea
Mariculture in South Africa
farming or marine aquaculture.
Mariculture accounts for less than one percent of South Africa’s
Mariculturists, or fish farmers, grow marine
seafood production, but a recent surge in the cultivation of
organisms, such as fish, shellfish and even
abalone has shown that the industry has a high growth potential.
seaweed, for harvest and use by human beings.
It is predicted that cultivated abalone production will overtake the
wild harvest over the next few years.
South Africa does not have a coastline suited to mariculture,
Mariculture has been practised by people in the Indo-Pacific and
and the few enterprises that have flourished are located in
Mediterranean for centuries. In its present form, however,
physically protected bays and estuaries (eg. Mediterranean
mariculture is a relatively new industry that is generating a
mussels, Mytilus galloprovincialis, in Saldanha Bay and
great deal of commercial interest. For instance, world catches
Pacific oysters, Crassostrea gigas, in Knysna Lagoon). Land-
and landings of aquatic organisms increased by about one
based impoundments with a pumped seawater supply are used
million tons in 1997. However, all of this increase was due to
to grow abalone, Haliotus midae, mainly in Walker Bay,
a continued growth in aquaculture, while capture fisheries
Hermanus, but also on the west and east coasts.
showed a decline in production. China’s fisheries production
grew at a rapid pace, thanks to aquaculture, and for the first
Oysters The cultivation of oysters takes place mainly in the
time in history, the production of cultured salmon outstripped
Eastern Cape Province, most notably in the shelter of the
production from capture fisheries. As wild stocks become
Knysna lagoon. The Pacific oyster, Crassostrea gigas, is
depleted by pollution and over-fishing, mariculture is expected
grown in mesh bags that are suspended from racks. The
to fill an ever-increasing global demand for seafood products.
oysters are provided with a rich source of food in the form of
plankton and other microscopic forms of sealife which wash
Mariculture practices are many and varied and mariculturists
into the lagoon with the tides. C. gigas is the most commonly
may use experimental laboratories, shore-based systems or
cultivated oyster species in the world; it is favoured because it
farms in sheltered bays and estuaries to produce seafood
grows relatively quickly, reaching an edible size within two
products such as oysters, mussels, abalone, fish, prawns
years. Approximately four million cultivated oysters are sold
and seaweed. Fish ranchers in the United States and Great
fresh on the local market every year.
Britain rear some fish species under controlled conditions and
then release them to grow in the wild, knowing that they will
Mussels The Mediterranean mussel, Mytilus galloprovincialis,
return to the site where they were born, to breed. The adult
is cultivated on the west coast, at Saldanha Bay. The mussels
fish are harvested when they return to the hatchery.
are grown on ropes which are suspended from wooden frames.
Almost all fish farms have a fundamental requirement – the
by South African shellfish farmers in 1997.
Approximately 2 000 tons of cultivated mussels were produced
need to contain the animal or plant that is to be cultured
(grown) in a prescribed aquatic environment. To farm fish
Abalone/Perlemoen The first shipment of cultured abalone
successfully, mariculturists must ensure that the basic
from South Africa took place during September 1994 and
requirements for supporting marine life are efficiently supplied
since then interest in abalone farming has burgeoned. On the
on the fish farm. Suitable water temperatures and a supply of
south coast, near Hermanus, approximately eight abalone farms
food and oxygen are some of the most basic requirements
have been developed. Some of these have started exporting
for growing fish.
their product to markets in the Far East, and most farms are
expected to produce 100 tons of abalone per year when they
are running at full capacity. Interestingly, cultured abalone may be
marketed after three years as “cocktail abalone”. Wild abalone
Pacific oyster
Cocktail-sized abalone is
farmed in Walker Bay
may only be harvested when they are sexually mature – at
following are some of the most critical environmental concerns
between nine and 12 years of age – so that they have an
associated with mariculture industries around the world.
opportunity to reproduce. Live abalone fetch between R180
and R240 per kg on Eastern markets. It is likely that most
South African abalone farms will export their product in a live
form, sealed in oxygenated polystyrene containers.
• In recent years the increasing demand for fish and shrimp
farming in wetland habitats has intensified concerns around
the destruction or alteration of such habitats. For instance,
it is estimated that the Philippines has lost approximately
Prawns The Indian white prawn, Penaeus indicus, is cultivated
75% of its mangroves due to wetland clearing for land-
at Mtunzini and Amatikulu in KwaZulu-Natal, the southern
based mariculture practices.
limit of the distribution of this species. Large open ponds
supplied with pumped water from neighbouring estuaries are
stocked with juvenile prawns reared in the hatchery at
Mtunzini. Artificial food manufactured at Amatikulu, is provided
until harvest. One harvest a year is possible with a fallow period
of about three months during which the ponds are drained
and cleaned. Present production is about 100 tons, destined
mainly for European markets.
Seaweeds There is increasing commercial interest in the
cultivation of the red seaweed, Gracilaria gracilis, on the west
coast. Feasibility studies undertaken at Saldanha Bay have
shown that the seaweed grows well on horizontal, suspended
• Water-based mariculture practices, such as oyster
cultivation on racks, have also caused habitat transformation by obstructing the natural flow of water in
estuarine environments, increasing sediment accumulation
and smothering the benthos underneath the racks.
• Some mariculture operations are known to discharge high
levels of organic carbon and nitrogen compounds. Effluent
from fish farms generally consists of faeces and uneaten
food – pollutants which may lead to oxygen depletion in
natural systems.
• Toxic chemicals, such as water treatment compounds,
rope or netting lines. Growth is optimised by keeping the
disinfectants, antibiotics and vitamins, are used by fish
plants close to the surface where water motion caused by
farms and may have an impact on the environment if they
wind chop results in better nutrient uptake by the seaweed.
are released into natural systems.
Agar, the jelly found in G. gracilis, is irreplaceable as a
medium on which to culture fungi and bacteria for medical
testing and research in microbiology.
Environmental concerns
• The introduction of exotic species for mariculture purposes
is common practice worldwide. The most important ecological concern is that some of these species might escape
into the natural environment where they might out-compete
natural species and introduce foreign parasites. For instance,
Mariculture is a well established industry in many parts of the
the Mediterranean mussel, M. galloprovincialis, was
world and offers some advantages over capture fisheries. For
introduced to South Africa for cultivation purposes and is
instance, mariculturists are able to supply superior quality
rapidly displacing indigenous black mussels along the
seafoods according to pre-determined market preferences. In
western and southern Cape coasts.
addition, mariculture practices can enhance commercial and
recreational fisheries through the release of juvenile fish.
Author: Claire Attwood September 2000
Mariculture offers the additional benefit of creating
employment opportunities in remote areas.
Despite the apparent advantages of mariculture development,
the practice of fish farming has important impacts on the
natural environment. The impacts and hazards associated
with mariculture practices vary significantly, depending on the
species grown, the methods used and the siting of farms. The
The Mediterranean
mussel is grown in
Saldanha Bay
FURTHER INFORMATION:
• Mariculture Association of South Africa. Tel: (021) 6503631 Fax: (021) 6503301 e-mail: pcook@botzoo.uct.ac.za
RELATED FACTSHEETS:
• Abalone • Oyster Harvesting • Sustainable Use of Coastal Resources
• Bivalves – Mussels, Oysters and Clams • Seaweed and their Uses • Mussel Harvesting • Seafood Delicacies
For more information, please contact: The Coastal Management Office, Marine and Coastal Management, Department of Environmental Affairs and Tourism, Private Bag X2,
Roggebaai 8012, Cape Town, South Africa. Tel: +27 (0)21 402-3208 Fax: +27 (0)21 418-2582 e-mail: czm@mcm.wcape.gov.za Website: http://sacoast.wcape.gov.za
P E O P L E A N D T H E C O A S T: C O M M E R C I A L A C T I V I T I E S
Sardine Run 2B
T
he sardine run creates great excitement in
KwaZulu-Natal during winter, when large
shoals of pilchards migrate into the shallows and
even wash ashore. The sight of gannets and
cormorants diving into the shimmering shoals of
are usually associated with areas of upwelling, where deep,
cool, nutrient-rich water moves into shallow coastal areas.
Enormous shoals of pilchards are commonly found on the west
coasts of California, Peru, Chile, Japan, Australia and, of course,
South Africa. In Southern Africa, pilchards live in temperate
coastal and shelf waters, ranging from northern Namibia to
sardines, while gamefish, sharks and dolphins
KwaZulu-Natal (KZN). It is their movement into the waters of
attack them from below, is an amazing spectacle.
KZN that results in the well-known “sardine run”.
Certain wind and current conditions force the
sardines, also known as pilchards, very close to
Biology
the beach, where they can easily be caught using
Pilchards are short lived, fast growing fish that reach a length
baskets, hand-nets or even skirts! In fact, when
of about 23 cm in two years. Most pilchards do not live for
sardines are beaching ‘anything goes’ and it is not
uncommon to see grandmothers competing with
more than three years and may grow up to 0.6 mm per day.
Pilchards are sequential spawners with a prolonged breeding
season from September to February, and most reach sexual
teenagers for a share of the feast. Sardines are an
maturity when about 19 cm long. Pilchards are highly fecund,
integral component of the marine ecosystems along
producing many thousands of eggs per female. These eggs
the whole coast of South Africa and are of
are simply released into the water, fertilised and the larvae
considerable economic and social importance.
abandoned to an almost certain death. Only two larvae (one
male and one female) need to reach maturity for the pilchard
population to remain stable; all the others become part of the
Sardines / Pilchards
food web of the ocean. The movement of the larvae has been
well researched and it appears that, after spawning takes place
The South African sardine, also known as the pilchard,
on the Agulhas Banks, the larvae are transported northwards,
Sardinops sagax, is usually found in huge shoals in the upper
along the West Coast. Although conditions are very harsh for
layers of the ocean. Pilchards, like anchovies and herrings,
the larvae, which can barely swim, the currents enable them
are small, primitive fish belonging to the group of fish known
to aggregate into small groups which gradually expand as
as the clupeoids. Although each fish is small, they collectively
more and more larvae are attracted. After metamorphosing
make up about 23% of the world’s fish catch and are very
into juvenile fish, pilchards are ready to return south to their
important economically. Pilchards are cold water species and
spawning grounds, thereby completing their life cycle.
The sardine run along the KwaZulu-Natal shore causes much excitement annually
The sardine –
also known as the pilchard
Pilchards are primarily filter feeders, straining plankton from
the water as it flows between their gills, using their modified
gill rakers as sieves. Juvenile pilchards feed primarily on
copepods (minute crustaceans), while adults are
opportunistic, omnivorous feeders. Pilchards
are eaten, in turn, by many larger predators.
From gamefish to birds, marine mammals to humans,
all want their share.
The sardine run is known to attract a large number of piscivo-
Sardine fisheries
rous predators, including gamefish such as geelbek, shad (elf)
In the large pelagic fishery off the Western Cape coast, about
and garrick (leervis), and sharks, such as copper, dusky,
100 000 t of pilchards are caught annually. Each night,
blacktip and spinner sharks. Cape gannets, cormorants, the
depending on the weather and season, a fleet of purse-seiners
occasional penguin and marine mammals, such as Cape fur
sets out from harbours along the south and west coasts. Once
seals and dolphins, all pursue the pilchards into KZN. In fact,
a shoal of pilchards has been located, huge purse-seine nets
the appearance of common dolphins usually indicates the
are used to encircle it. The fish are then drawn up alongside
arrival of the sardine run. It has even been suggested that the
the vessel before being pumped on board. Depending on the
female dolphins use the plentiful food supply to wean their
quality of the fish, the catch may be canned or reduced to
calves and replenish their depleted fat stores.
fishmeal. This fishery employs thousands of people in the
During the sardine run pilchards are caught using beach seine
Western Cape and sustains many coastal communities. In
nets. While one group of fishers on the shore holds a rope at
the Eastern Cape, about 4000 t are caught annually while the
one end of the net, the other end is cast around the shoal of
catch is about 700 t in KZN waters.
fish using a small boat. The encircled fish are then dragged
The sardine run
The sardine run is an annual phenomenon that occurs during
the winter months when large shoals of pilchards enter KZN
waters from the cooler Cape waters. The great bulk of South
Africa’s pilchard stock is found distributed between the Agulhas
ashore, where they are quickly scooped into baskets both by
the fishers and many eager helpers. These fish are usually
sold for human consumption or bait.
The sardine run is a spectacular, natural, annual phenomenon
that visitors to the KZN south coast in winter may be fortunate
to witness.
Bank (off the Cape south coast) and the west coast. Each
winter, however, a small proportion of the stock expands its
Author: Judy Mann-Lang September 2000
range eastwards, attracted into southern KZN waters by a
narrow band of cooler water between the coast and the warm
Classification:
Agulhas Current. Although some of the pilchards are in a
spawning condition and do spawn in KZN waters, it is unlikely
that the "sardine run" represents a spawning migration. And,
although higher concentrations of copepods occur off KZN
during the winter months, it also does not appear to be a
feeding migration. Conditions for both spawning and feeding
probably remain more favourable on the Agulhas Bank. The
migration seems to be related to an extension of the cool
environmental conditions that are suitable for pilchards.
PHYLUM:
Chordata
SUBPHYLUM:
Vertebrata
CLASS:
Osteichthyes
ORDER:
Clupeiformes
FAMILY:
Clupeidae
GENUS:
Sardinops
SPECIES:
sagax
COMMON NAME:
pilchard / South African sardine
FURTHER INFORMATION:
• KwaZulu-Natal Wildlife (formerly KZN Nature Conservation Service), P.O. Box 13053, Cascades, Pietermaritzburg, 3200. Tel: (0331) 8451999
• Oceanographic Research Institute, P.O. Box 10712, MarineParade 4056. Tel: (031) 3373536, Fax: (031) 3372132
• Natal Sharks Board Private Bag X2, Umhlanga Rocks 4320. Tel: (031) 566 1001
• Payne, A.I.L., Crawford, R.J.M. & van Dalsen, A.P. 1989. Oceans of Life off Southern Africa. Vlaeberg Publishers, Cape Town.
RELATED FACTSHEETS: • Shad • Pelagic Fishery • Fishing Industry • Upwelling • Ocean Currents • Food Value of Fish
For more information, please contact: The Coastal Management Office, Marine and Coastal Management, Department of Environmental Affairs and Tourism, Private Bag X2,
Roggebaai 8012, Cape Town, South Africa. Tel: +27 (0)21 402-3208 Fax: +27 (0)21 418-2582 e-mail: czm@mcm.wcape.gov.za Website: http://sacoast.wcape.gov.za
P E O P L E A N D T H E C O A S T: C O M M E R C I A L A C T I V I T I E S
Mussel Harvesting 2B
M
ussels are the most accessible and easily
collected intertidal resource on the South
African coast but the level of harvesting and the
abundance of mussels differ dramatically between
different regions. On the west coast mussels are
abundant where there were once ‘wall-to-wall’
limpet beds on some wave-battered rocky platforms,
the invasive alien Mediterranean mussel is rapidly
displacing the local intertidal community. On the
south and east coasts, where the brown mussel
occurs, the abundance of mussels is patchy and
there is evidence of heavy exploitation by
commercial enterprises, recreational gatherers
and subsistence harvesters.
Introduction
Mussels are marine bivalve molluscs that use their large gills
for respiration and to filter feed. Most of the body consists of
gonad making them extraordinary prolific. They release eggs
and sperm into the water, yielding numerous planktonic larvae
that settle to form tiny mussels, known as ‘spat’. Once the
mussels attach themselves to the rocks by means of byssus
threads, they will remain sessile for the rest of their lives. Four
important mussel species are found on rocky shores in South
Africa. The ribbed mussel, Aulacomya ater, the black mussel
Choromytilus meridionalis, and the introduced Mediterranean
mussel Mytilus galloprovincialis are common along the west
and south coasts whereas the brown mussel, Perna perna,
occurs on the south and east coasts.
Pollution and red tide
The major drawback to mussel harvesting on the west coast
is the prevalence of toxic red tides along this coast. Mussels
filter out the red tide organisms and concentrate and retain
the poison in their bodies for about 4 months. As few as two
contaminated mussels can prove fatal if eaten by humans.
The human population is low on the west coast and there is
very limited harvesting of mussels there.
Conflicting interests
On the south and east coasts red tides hardly ever occur and
the human population is enormous so mussels are collected
intensively. This has often resulted in conflict between the
different user groups and conservation authorities. In KwaZuluNatal, nature conservation officials spent long nights sitting in
the bush waiting to catch poachers that stripped the shore
using pangas. In 1994 in the former Transkei people living
around Dwesa nature reserve compared the rich potential
harvest within the reserve to the denuded surrounding coast
and tried to obtain collecting rights within the reserve. When
negotiations failed they swept into the reserve and stripped
the rocks of mussels and other sea creatures and left them to
rot at the entrance to Dwesa. This highly publicised protest
action focused the attention of conservation authorities,
scientists and the media on the problems facing the management of marine resources and the needs of subsistence
gatherers. Being unemployed, subsistence gatherers could
not afford the R35 recreational permit, and the restriction of
50 mussels per day meant that they could not collect enough
to feed a family.
The national mussel research project
A national five-year mussel project was initiated in 1995 to:
• find out the effects of utilisation of mussels
• determine the regeneration capabilities of mussel beds
different number of bags of mussels can be removed. Mussel
• predict the optimal sustainable levels of utilisation
monitors are stationed on the beach during spring tides to
oversee the harvesting and weigh each bag of mussels to
of mussels
• find ways for all stakeholders to work together for the
benefit of all.
obtain accurate records. As the experiment progresses the
effects of different amounts of harvesting and the recovery
within the zones will be clear for all to see.
This project involved scientists from the University of Cape Town,
Rhodes University, University of Transkei, University of Port
Elizabeth, KwaZulu-Natal Wildlife (KZN Wildlife), Oceanographic
Research Institute, Namibian Fisheries Institute, conservationists
and local communities of subsistence gatherers. At 8 sites
around the coast mussel beds were rigorously monitored every
three months. The composition and size structure of the mussels
Another experiment, in which local women participated,
resulted in a unanimous decision to allow the use of only
screwdrivers for collecting mussels. They found that bush
knives remove too many small mussels and thus affected
future harvests.
There is great pride and excitement among the women
and the other marine organisms at the sites were recorded, and
participating in the project and on the first day of harvesting
the recruitment of juveniles and the recolonisation of cleared
after the negotiations an 80-year-old who had walked five
areas studied. Experiments were designed to test whether
kilometres to the beach said “I used to collect mussels with
more larvae settle among adult mussels, in totally cleared
my grandmother. But after my mother-in-law was arrested
areas or areas where byssus threads remain after the removal
and we had to sell the cow to get her from jail, we stopped
of adult mussels. Because there are different species of
getting mussels. Now we work with Jean to look after the
mussels in the different regions, the experiment also provides
mussels. Now when I die, I will be happy.”
comparisons between species and between warm and cold
water communities.
Sharing the spoils
Future management plans
It is hoped that this promising project will pave the way for a
scientifically based plan for the sustainable utilisation of mussels
In KwaZulu-Natal where subsistence harvesting and poaching
that will be implemented by co-operative management. In this
were rife, a research team led by Dr Jean Harris (KZN Wildlife),
way all stakeholders share the responsibility and ownership
held workshops and community meetings on the beach, and
for the resource and as a result the need for harsh controls
interviewed Sokhulu residents to assess local knowledge about
over poaching should be reduced.
mussels. One old woman told researchers “We come to collect
the mussels when the moon is full (indicating spring tides) and
Author: Margo Branch September 2000
it is best when the Msinsi tree is flowering.” Msinsi is the coral
tree, which flowers in winter. The mussels spawn in early spring
and so are fat and succulent during winter. Unemployment in
the Sokhulu area is estimated at close to 90%, so mussels are
an important source of food for this impoverished community.
In a joint agreement between KZN Wildlife and the Sokhulu
people, a two-kilometre stretch between Mapelane and
Richards Bay, known as Flat Ledges, was identified as a
study site and set aside for exclusive use by subsistence
gatherers. Two hundred harvesters have registered but only
one permit is allowed per household. The area has been
divided into colour-coded zones and from each sub-zone a
Brown mussel
FURTHER INFORMATION:
• Derwent, S. 1997. Sharing the spoils. African Wildlife, Vol. 52 (2): 30-31
• KwaZulu-Natal Wildlife (formerly KZN Nature Conservation Services), P O Box 662, Pietermaritzburg, 3200. Tel. (0331) 471961
RELATED FACTSHEETS:
• Sustainable Use of Coastal Resources • Bivalves • Oyster Harvesting • Mariculture • Dwesa and Cwebe Nature Reserves
For more information, please contact: The Coastal Management Office, Marine and Coastal Management, Department of Environmental Affairs and Tourism, Private Bag X2,
Roggebaai 8012, Cape Town, South Africa. Tel: +27 (0)21 402-3208 Fax: +27 (0)21 418-2582 e-mail: czm@mcm.wcape.gov.za Website: http://sacoast.wcape.gov.za
P E O P L E A N D T H E C O A S T: C O M M E R C I A L A C T I V I T I E S
Seaweeds and their Uses 2B
A
lgae are simple plants that live in water and
include microscopic, free-floating phyto -
plankton as well as large seaweeds, usually
attached to a substrate. The term “weeds” can be
misleading because these plants, which grow almost
placed in the Plant Kingdom but, because they are much
simpler than higher plants.
Seaweed diversity in S. Africa
Of the 8 500 species of seaweed that occur around the
world, about 850 have been recorded on the coast of South
exclusively in the shallow waters at the edge of the
Africa. The red algae have by far the most species, but the
world’s oceans, are essential to the marine environ -
brown algae grow to enormous sizes and form extensive kelp
ment and are of immense value to humans.
forests. The diversity of our seaweed flora is high, largely due
to the fact that some algae are adapted to the warm, subtropical waters of KwaZulu-Natal, while others thrive in the
A primary source of food and shelter
cold, temperate waters off the west coast or the warm,
temperate waters of the south coast. Many are endemic and
Together, phytoplankton and seaweeds form the basis of the
occur only on S. African shores.
food chain in the oceans. Seaweeds are eaten by grazing
animals, limpets and urchins as well as herbivorous fish. Tiny
The west coast is dominated by large luxuriant seaweeds
particles provide food for filter-feeders such as mussels and
that thrive in the cold nutrient rich water that upwells there.
barnacles. Predators feed on seaweed-eaters.
The brown kelps are among the fastest-growing algae in the
world and form extensive forests. In the shade of their
Not only are seaweeds the primary source of food for marine
animals, but they also create unique habitats. They buffer the
effects of wave action and provide a haven for animals seeking
to escape predators. In the intertidal zone, which is exposed
to air during low tide, seaweeds offer protection from drying
out. Unbelievable though it may seem, a single tuft of seaweed
was found to support a community of nearly 1 500 tiny animals!
The seaweeds themselves are adapted to withstand drying
out and those that are pounded by waves, are firmly attached
and have a tough branching structure. Seaweeds in calmer
water are usually large and flat. Some are covered with knobs
or leaflets to increase the surface area for the absorption of
sunlight and nutrients. Others are flat forming crusts.
Like land plants, seaweeds use green chlorophyll to absorb
the sun’s energy and produce carbohydrates from carbon
dioxide and water. This process is called photosynthesis and
it is vital to life on earth. Oxygen is a by-product of photosynthesis, and plants and seaweeds play an important role in
maintaining the delicate balance between carbon dioxide and
oxygen in the earth’s atmosphere. All sea-
canopy, flat red algae grow. They have a large surface area to
absorb nutrients and have special blue and red pigments to
increase the uptake of light energy for photosynthesis. They
are flexible and allow the easy flow of water over them.
Epiphytic algae grow, like ferns and creepers on the kelps.
Another notable feature of the algae on the west coast is
that, because the kelp breaks the force of the waves hitting
the shore, many flat and leaf-like forms can survive in the
intertidal. These may be interspersed by tough branching
forms in the most exposed areas. A common seasonal, high
shore alga is the purple laver, Porphyra, which is membranous and slippery when wet, but resembles crumpled black
plastic when dry. It is able to withstand severe drying.
Visitors to the east coast are enchanted by the iridescent
small algae in the tide pools. There is no kelp to break the
force of the waves so the algae have to be tough and flexible.
Branching jelly weeds are firmly attached to the rocks to withstand the crash of the waves. Many of the seaweeds contain
chemicals to deter herbivores. The deposition of lime
(calcium carbonate) is increased in high temperatures
weeds contain chlorophyll and one would
and in the warm waters of the east coast there
expect them to be green, but the majority
are a large number of upright, jointed,
of seaweeds are brown or red. Their
coralline algae and others, such as the
chlorophyll is masked by other coloured
turkey tail, Padina, and the wedge weed,
pigments that enable them to absorb light
Halimeda, with lime-impregnated skins.
of different wavelengths, particularly in
Crust-like coralline algae are well adapted
deeper water.
to withstand grazing and wave action
because they are low growing and firmly
Seaweeds are classified into green algae
cemented to the substrate.
(Chlorophyta), brown algae (Phaeophyta)
and red algae (Rhodophyta) according to
their pigments. At one time algae were
Sea lettuce –
a green alga
Fertilizers
A MULTITUDE OF USES
Seaweeds have been used as
Despite the abundance of seaweed along
fertilizers for centuries and in
our shores, South Africans do not utilize
South Africa today fresh kelp
seaweeds to the extent that other cultures
extracts are widely valued as a
do. For instance, in the Far East sea
lettuce (Ulva and Monostroma species)
growth stimulant for crops
and purple laver (Porphyra species) are a
such as wheat. Freshly cut
kelp is taken at Kommetjie on the
valued source of food, and in Chile, there is
a thriving trade in these “sea vegetables”.
Cape Peninsula. Mariculturists on
as vegetables, seaweed extracts are used as stabilizers in a
Kelp,
Ecklonia maxima –
a brown alga
variety of foods. Salad dressings, flavoured milk, pizza
on the ecological effects of kelp harvesting at Danger
toppings and pet food all contain seaweed extracts. Gelling
Point showed that harvesting kelps with stipes longer
Although most South Africans do not eat seaweeds
the south coast utilize fresh kelp to
feed abalone. A research project
agents and emulsifiers manufactured from seaweeds, are
than 50 cm had no significant effects on understorey
used in thousands of everyday products like dental moulds,
algae and animals. As long as kelp fronds are not sheared
clothing dyes, toothpaste and welding rods.
too close to the primary blade, they continue to grow.
Kelps produce millions of spores and grow very quickly
Agar from red seaweeds
Agar, the jelly found in many of the red seaweeds, is used in
so are easily replaced after harvesting.
Although the South African seaweed industry is
confectionery and is irreplaceable as a medium on which to
small when compared to similar industries
culture fungi and bacteria for medical testing and research in
in the Far East, it generates approxi-
microbiology. The main sources of agar in S. Africa are jelly
mately R15 million per year. To date the
weeds, Gelidium species, collected in the Eastern Cape, and
commercial exploitation of seaweed
the agar weed, Gracilaria verrucosa, harvested in Saldanha
has had a negligible impact on South
Bay. Agar can be extracted from many other red algae as
Africa’s natural environment but there is a
well, by simply boiling the seaweed in water. It sets to make a
danger of overexploiting the jelly weeds in the
nutritious jelly to which flavouring should be added. There is
former Transkei. Monitoring and control of the
increasing commercial interest in the cultivation of Gracilaria
seaweed industry is the responsibility of the
on the west coast. Feasibility studies have shown that it
Department of Environmental Affairs and
grows well on horizontal rope or netting lines suspended near
Tourism. New seaweed ventures are only
the surface, where water motion, caused by wind chop,
introduced if research has shown that har-
results in better nutrient uptake.
vesting is sustainable and the environment
Alginic acid from kelps
Beach cast kelp, Ecklonia maxima or sea bamboo, is collected
will not be harmed.
Agarweed –
a red alga
Author: Claire Attwood September 2000
on the west coast and exported for the extraction of alginic
acid, a gel and an important ingredient in a variety of food
Classification:
products. Alginic acid has the additional property of forming
salts with metals such as calcium, sodium, copper and iron,
KINGDOM:
which have different solubilities. They can be used in an
PHYLUM:
Protoctista
Chlorophyta: Green Algae
insoluble form to bind materials together and then dissolved
Phaeophyta: Brown Algae
out at a later stage if needed.
Rhodophyta: Red Algae
FURTHER INFORMATION: • Botany Department , University of the Western Cape, Tel (021) 959 2301.
• Branch, G. and Branch, M. 1985. The Living Shores of Southern Africa . Struik, Cape Town.
• Branch, G.M., Griffiths, C.L., Branch, M.L. and Beckley, L.E. 1994. Two Oceans: A Guide to Marine Life of Southern Africa. David Phillip, Cape Town.
• Stegenga, H., Bolton, J.J. and Anderson, R.J. 1997. Seaweeds of the South African West Coast. Contributions from the Bolus Herbarium No.18.
RELATED FACTSHEETS: • Kelp Forests • Red Algae • Green Algae • Brown Algae • Rocky Shores • Classification of Marine Species.
For more information, please contact: The Coastal Management Office, Marine and Coastal Management, Department of Environmental Affairs and Tourism, Private Bag X2,
Roggebaai 8012, Cape Town, South Africa. Tel: +27 (0)21 402-3208 Fax: +27 (0)21 418-2582 e-mail: czm@mcm.wcape.gov.za Website: http://sacoast.wcape.gov.za
P E O P L E A N D T H E C O A S T: C O M M E R C I A L A C T I V I T I E S
Mining the Sea 2B
M
ining the ocean bed is a daunting task
marine geologists with important information. Each layer of
because the oceans cover 3.63 million
sediment contains distinctive species and because warm-
square kilometres and average 3660 m in depth.
Finding diamonds or prospecting for oil in this
water species are distinct from cold-water species they
convey information about ancient climates as well.
dark, deep world is like searching for a needle in a
Prospecting and mapping the ocean bed
haystack with your eyes closed. In recent years South
The first step to mining is to map the mountains and valleys
Africa has successfully mined diamonds from the
of the oceans floor and the different layers within it. Forams
ocean bed, Soekor discovered and exploited gasfields
enable the geologist to identify different sedimentary layers
off the south coast and Mossgas pipes natural gas
85 kilometres to its onshore refinery at Mossel Bay.
within sample cores drilled through the ocean bed and to
map the folded, faulted and eroded sedimentary layers of
earlier eras. Diamond-bearing gravels can be identified. Oil is
formed by the bacterial decomposition of marine organisms.
Normally it diffuses away and is lost, but if it is trapped in a
Fossils point the way
dome under impermeable rocks it may form an exploitable
Surprisingly tiny fossil animals known as Foraminifera (forams)
reserve. In this way micro-fossils were used to pinpoint the
have helped point the way and provided clues as to where to
gas deposits off Mossel Bay.
search in the vast ocean for both diamond-bearing rocks and
petroleum. Forams are single-celled planktonic animals that
build tests (shells) of various materials. The majority of fossil
Diamond mining at sea
DeBeers Marine have spent nearly 30 years of research,
forams range from 0.2 mm to 2 mm but a few long-extinct
working out how to find diamonds in this sea of water and sand.
giants exceeded 15 mm. Thousands of different species have
Today they can claim to have one of the most advanced marine
come and gone during the past 500 million years and they
mining operations in the world. Their sampling ships follow a
constitute 99% of the fossils found in ocean sediments.
pre-determined grid pattern taking sediment samples that
Because of the rapid succession of distinctive species
provide information about the extent of the diamond-ore
throughout successive geological ages, Foraminifera provide
reserves and the undersea terrain. Two mining processes are
used. Vertical mining is best suited for rugged terrain – a
petroleum gas (LPG) produced daily by Mossgas is far more
huge 7-metre wide drill is used to scour the ocean floor and
friendly to the environment than fuels produced from crude oil.
suck up rocks, gravel and sand. The ship, controlled by
By replacing the equivalent of 45 barrels of crude oil imports
computers, can compensate for the effect of a 6-metre swell
daily and exporting more than 100 000 t of alcohols annually,
on the drill shaft while applying a constant pressure of 20 tons.
Mossgas has a positive impact of more than R1,4 billion
Every 10 minutes the drill is lifted and moved. The ‘crawler’ is
annually on South Africa’s Balance of Payments. 45 000
used for mining more level terrain. It is like a military tank with
South Africans were involved during the production phase of
wide tracks that are stable against undersea currents, and is
the project. Today Mossgas employs over 1 000 people
guided, by remote control, along specific lanes. It cuts up the
directly and a further 7 000 owe their livelihood indirectly to the
rocks and sucks the sediment through a sorting screen, sending
project. Mossgas is at present developing another gasfield
it up slurry pipes into the ship. On board the ship, ultra-secure
49 km west of its present production platform. This will extend
recovery and treatment plants extract the diamonds. The
the life of the proven reserves available to Mossgas to the
diamonds appear luminous as they pass in front of an X-ray
year 2007.
machine. They are picked up by a photometer linked to a
compressor that emits a squirt of air that jets the diamonds
into a tin can, which is hermetically sealed. No one ever sees
the diamond treasure that one of these ‘Neptune’s Cans’
holds, until it arrives at the prospecting laboratory or diamond
sorting house.
In 1988 and 1990 Soekor and its partner Energy Africa
Bredasdorp discovered the Oryx and Oribi oilfields 140 km
south-west of Mossel Bay. Since 1960 this gas has been
exploited from depths of about 2.5 km and pumped via the
Orca offshore production platform into a tanker moored at a
‘calm’ buoy nearby. Oribi produces 16 500 and Oryx 10 000
Mining petroleum gas
barrels a day. A new oilfield, Sable, with a higher proportion
of gas and a potential 40 000 barrels a day is expected to
The search for crude oil by Soekor, the fully state-owned oil
come on line in 2003.
and gas exploration and production company, led to the
discovery of petroleum gas deposits in the continental shelf
off the southern Cape coast in 1969. In 1987 the massive
Mossgas project began and went into full production in 1993.
The offshore operation consists of a production platform in
the Indian Ocean 85 km southwest of Mossel Bay. Towering
114 m above sea level and extending 105 m below the
Environmental impacts
Mossgas is regarded by many as one of the cleanest refinery
operations in the world. Various measures to protect the
environment, such as smokeless flare stacks, high technology
seals and water treatment facilities, have been installed.
production platform is one of the largest structures ever
With regard to diamond mining at sea, mined areas have been
constructed in South Africa. It is supported by a steel lattice
compared against unmined areas on a regular basis and it
structure 124 m in height and weighing nearly 14 500 t and is
has been shown that mined areas can regain their biological
firmly fixed to the ocean bed by 24 piles 12 m into the sea bed.
composition over a period of a few years. Given that only a
The giant drill penetrates the sea bed to a depth of 2 500 m
few square kilometres are worked per year, the overall effects
to recover the gas and condensate. Satellite gas fields are
at the present level of mining are not considered damaging.
linked to the platform by sub-sea systems.
There are several companies mining the Namibian coastline,
The offshore process consists of cooling the hot gas,
so it is important that the area be managed as a whole.
condensate and water mixture and separating them in a high-
Both Mossgas and De Beers Marine have received the
pressure separator. The gas and condensate are dehydrated
International Standards Organisation ISO14001 accreditation
and further refined and piped ashore for processing at the
for environmental management.
onshore operation 11 km west of Mossel Bay. The natural
gas has a sulphur content of less than 5%. As a result the
nearly 5 million litres of petrol, diesel, kerosene and liquid
Author: Margo Branch September 2000
FURTHER INFORMATION: • De Beers Marine Communications Department Tel (021) 410 4444, Fax (021) 410 4403
• Mossgas, Communications Department, Mossel Bay.
RELATED FACTSHEETS: • Salt and the Sea • Marine Fossils • Future use of the Sea • Diamond Mining on the West Coast
For more information, please contact: The Coastal Management Office, Marine and Coastal Management, Department of Environmental Affairs and Tourism, Private Bag X2,
Roggebaai 8012, Cape Town, South Africa. Tel: +27 (0)21 402-3208 Fax: +27 (0)21 418-2582 e-mail: czm@mcm.wcape.gov.za Website: http://sacoast.wcape.gov.za
P E O P L E A N D T HE C O A ST: C O MM E R CI AL A C T I V I T I ES
Future Use of the Sea 2B
T
he ocean is no longer an unknown expanse,
with endless resources in unplummable depths
Mining for the future
The ocean has been an expensive and difficult place in which
and able to absorb everything that is dumped into
to mine. In the future the development of improved technology
it. Now, for humans, the ocean is a finite entity in
is likely to lead to more mining in the sea. A natural gas deposit
which the movements of the tectonic plates of the
has been located off Honderklip Bay near Port Nolloth on the
earth’s crust are being monitored, the temperatures
and climate systems are mapped and the changing
west coast and could be brought into production within the
next decade. Prospecting for manganese nodules has been
carried out and these may be exploited sometime in the future.
sea levels can be predicted. Most of the marine
Gold is being mined from the sea off New Zealand. At present
species have been described and there is extensive
common salt, sodium chloride, is the main salt extracted from
knowledge of their population dynamics and the
seawater but there are many other salts, admittedly in smaller
ecosystems of the coast. Human use of the sea has
quantities, which could be recovered from the sea. The de-
shifted from one of exploration and uncontrolled
salination of salt water is likely to be considered more seriously
as a solution to fresh water shortages, particularly along the
exploitation to a need for responsible custodianship,
west coast. Several heavy metals occur in the dunes around
sustainable use and international co-operation.
the coast and there is increasing interest in mining these.
However dune mining has to be undertaken with care so as
not to irreversibly damage the natural ecosystems.
To meet these challenges S. Africa needs to build information
in marine science, engineering and technology, to strengthen the
Undersea exploration
capacity for the management of marine and coastal resources
and to conserve the biodiversity of its rich coastal life. There
is also a need to address ecological, social and economic
challenges, and to promote sustainable development.
The deep sea is becoming less of an unknown and there is
likely to be more exploration in the future, using increasingly
sophisticated submersibles. The understanding of the geology
of the ocean bed and the movements of the tectonic plates
Sustainable use of living resources
provides valuable information about the earth’s history and
can be used for predicting the future.
South Africa has a wealth of marine living resources, many of
which are being optimally harvested. The future use of these
Antarctic exploration and exploitation
resources will depend on careful monitoring, population studies
and the setting and maintaining of quotas. In the past, improved
technology led to over-exploitation, but in the future new
technology should focus on efficiency and reducing costs. The
by-catch from many fisheries could be better used and the
careful handling of the catch to minimise damage, loss and
spoilage will add to the value, without further depleting stocks.
The Antarctic is one of the last areas for exploration and
exploitation. The vast swarms of krill are likely to be harvested
in increasing numbers and the challenge will be to find some
more efficient use for them than merely as fertiliser and fish
feed. Whales are being monitored and their population
dynamics studied. With the use of predictive models the
future management and protection of both krill and whales in
Genetic manipulation of certain stocks could lead to
the Antarctic will be a focus for international control.
improved productivity and disease resistant populations. This
Patagonian tooth fish occur in the region and the problems
is particularly relevant in the field of mariculture where disease
associated with the control of this lucrative fishery will have to
can be a major problem. The farming of abalone may
be addressed.
become the only way of saving this vulnerable species from
rampant poaching. Mariculture in general, is likely to become
increasingly important with the farming of oysters, mussels,
prawns and mullet being increased and improved and other
species being added. Seaweed cultivation is likely to increase
with work being done on their uses and marketing.
Transport
Ships are the most economical way of transporting large and
heavy loads over great distances. Containerisation is likely to
continue as the main form of cargo transport. Over half of the
world’s total oil production is carried by sea each year and is
Bioprospecting for marine organisms that can be exploited for
bound to lead to some pollution. New tankers have to comply
their medical properties is becoming increasingly important.
with ‘environmental friendly’ designs, such as double hulls.
The extracts from certain sponges and bryozoans are being
Old tankers have to upgrade once they reach 25 years of
tested for the treatment of cancer. Seaweed extracts have
age. Oil pollution is likely to be an ongoing concern for the
many medicinal uses.
future.
Control of pollution
creatures also become entangled in the nets and die. Other
types of shark repellent are being investigated and the number
Other forms of pollution besides oil pollution are likely to
of nets is being reduced.
increase and time and effort will need to be spent in minimising
pollutants, and enforcing pollution control measures world-
Tourism development and management
wide. Air pollution is likely to become an increasing problem
and the use and disposal of plastic products will have to be
The coast is a tremendous draw card for tourism. There is
addressed. The disposal of untreated sewerage directly into
scope for a wide range of tourism opportunities in South
the sea will have to be stopped and the recycling of waste-
Africa and resultant economic advantages. The “Blue Flag” is
water practised. Sound waves can travel under water for
an international organisation that recognises the quality of
hundreds of kilometres. Since many marine creatures (such
coastal resorts. Those that adhere to certain standards of
as dolphins) have highly-developed acoustic systems, noise
cleanliness, ecological protection and safety are awarded
pollution from ships, seabed drilling and weapons testing is
blue flag status. A wider range of tourist attractions is likely to
likely to be invasive and even painful to them. Research
be developed in the future.
needs to be done on this type of pollution.
Computers and satellites
Preventing the introduction of alien
invasive species
Computers and modern information systems will enable better
Marine species are often carried to new areas as larvae in the
data capture and predictions. The use of satellites to gain
bilges of ships or as adults attached to their hulls. They can also
information on climate, currents, and sea temperature and for
be introduced by aquaria or for mariculture. The European
navigation and rescue operations will continue to increase
crab has caused enormous damage to the shellfish industry
and develop.
in America and has already been introduced to S. Africa. So
far it has not caused a lot of damage as it is confined to calm
Biodiversity and marine protected areas
water. The Mediterranean mussel was introduced some time
in the 1970s and has spread hundreds of kilometres up the
Protecting biodiversity has been identified as a priority for the
future. The protection of ecosystems to maintain biodiversity is
a focus and marine protected areas will need to be carefully
assessed, set aside and maintained. At present there are many
west coast where it is ousting the natural populations of
limpets and indigenous mussels. The prevention of the introduction of further invasive species and the control of existing
alien species is essential.
single species reserves, such as crayfish sanctuaries. These
are being reassessed and are likely to be upgraded into larger
totally protected areas and reduced in number to make
Policy development especially with regard
to international laws and compliance
protection of these areas more practical and effective. There
is not a single marine reserve on the west coast to protect
The future use of the sea is likely to become more and more
this unique eco-region. The coast between Groen River and
regulated with the need for international co-operation and
Spoeg River in Namaqualand has been set aside and it is
compliance, as well as national and regional management.
hoped that it will be afforded protection in the near future.
There is a continual need for scientific and technological infor-
Anti-shark measures
whole population in a huge awareness drive is a priority, as is
mation and regular monitoring programmes. Education of the
The use of shark nets to prevent shark attack along the east
coast has been successful, from the point of view of reducing
attacks on humans, but there is increasing concern about the
affects that killing so many of the large sharks has had on the
ecosystem of the region. Many dolphins, skates and other
the need for the training and empowerment of management
and enforcement officials. Sufficient and sustainable funding
must be generated if our valuable coast is to be protected
and used to the full.
Author: Margo Branch September 2000
FURTHER INFORMATION: • SANCOR secretariat: Tel (021) 402 3172, Fax: (021) 695 3937 • Our Coast Our Future 1998. Coastal policy Green Paper.
Department of Environment Affairs and Tourism.
RELATED FACTSHEETS: • Mining the Sea • Fishing Industry • Penguins • Mariculture • Mussel Harvesting • Sustainable Use of Coastal Resources
• Tourism along the Coast • Whale Watching • Oil Pollution • Plastic Pollution • Beach Clean-ups • SANCOR
For more information, please contact: The Coastal Management Office, Marine and Coastal Management, Department of Environmental Affairs and Tourism, Private Bag X2,
Roggebaai 8012, Cape Town, South Africa. Tel: +27 (0)21 402-3208 Fax: +27 (0)21 418-2582 e-mail: czm@mcm.wcape.gov.za Website: http://sacoast.wcape.gov.za
P E O P L E A N D T H E C O A S T: C O M M E R C I A L A C T I V I T I E S
Oyster Harvesting 2B
O
ysters, together with clams, cockles and
no care of the eggs or the larvae. The portuguese oyster
mussels, belong to the class Bivalvia, the
(Crassostrea angulata) and the Cape oyster (Striostrea
second largest molluscan class which contains
margaritacea) are examples of these oviparous oysters.
about 8 000 species. As the name Bivalvia implies,
Oysters are extraordinarily prolific; one animal may produce at
all species in this class have a bivalved shell which
least a million eggs in a season. Spawning is stimulated by
encases the body. The two shell valves are held
together by a ligament which is made of a protein
warm sea temperatures or by the eggs and sperm of other
oysters being released in the water. The larvae of both groups
of oysters pass through a short free-swimming phase before
called resilin. The ligament is elastic and stretches
they become baby oysters, or ‘spat’. During this stage of their
when the animal clamps the shell shut, but springs
lifecycle, baby oysters sink to the bottom, but only those that
the valves apart when the animal relaxes.
settle on a clean surface manage to cement themselves and
continue to grow. Consequently, where oysters are cultivated,
slates and tiles are often laid down to catch the spat which
Oysters are marine and estuarine bivalve molluscs which occur
are later transferred to the permanent oyster beds. Oysters
throughout the world, except in cold regions. They live a
grow rapidly and attain sexual maturity within a year, although
sedentary life, cemented to rocks by the lower, more deeply
they may live for as many as 25 years.
hollowed valve; the upper valve is usually smaller and forms a
flat plate that can be tightly sealed over the body. Oysters pump
large volumes of sea water through sieve-like gills which extract
oxygen and food particles.
Harvesting the Cape oyster
Oysters are prized for their salty, succulent flesh and many
South African restaurants, particularly those that are located on
Oyster shells are very variable and irregular in shape and, as a
or near the coast, serve oysters as a seafood delicacy. Most
result, oyster species are difficult to classify according to their
of the Pacific oysters are supplied by oyster farms in Knysna or
shells alone. There are, however, two groups of species which
Saldanha Bay, but small quantities of the common Cape oyster,
are physiologically separated by their method of reproduction.
Striostrea margaritacea, are harvested on the South Coast,
In the first group the animals are hermaphroditic, but the two
between Witsand and Port Elizabeth, or along the KwaZulu-
sexes may not be simultaneously functional; in one season an
Natal coast.
individual may be male, in the next season female, and again
male in the following season. The sperm is carried to the
female by currents and the eggs are fertilised within the
female’s gills, where they remain until they hatch. This group
of oysters, of which the European oyster (Ostrea edulis) is a
typical example, is thus incubatory (or larviparous).
In the second group the sexes are separate, each oyster being
Early records show that there was a commercial fishery for the
Cape oyster as long ago as 1894. Today the wild oyster fishery
is one of South Africa’s smallest fisheries, with approximately
160 participants. The annual commercial catch is around
600 000 oysters for the South Coast and 300 000 in KwaZuluNatal. Harvesting takes place on rocky shores, from the intertidal zone to the shallow subtidal zone. Oyster pickers may not
either male or female throughout its life. The eggs are shed
use dive gear such as fins or underwater breathing apparatus.
into the sea, where they are fertilised, and the mother takes
This regulation ensures that a large sub-tidal spawning stock is
Natal rock oysters form a distinct band
at mid-tide level
Cape oyster harvested on the south coast
conserved which provides future generations of oysters for
according to a rotational system, which allows certain areas to
exploited inter-tidal areas. A second regulation stipulates that
remain fallow for a few years to promote sustainable harvesting
oysters may only be collected by hand or with a lever that has
of the stock.
a flat surface that is no wider than 40 mm. This regulation is
aimed at preventing unnecessary destruction to other parts of
the marine ecosystem. There is no size limit for oysters due to
the inherent difficulties in estimating the size. Oyster pickers
often collect undersized oysters that have been dislodged by
wave action. They sell these to oyster farms where the oysters
are kept in holding tubes until they reach a marketable size.
Subsistence fishers, particularly in northern KwaZulu-Natal
and the Eastern Cape, often harvest intertidal organisms
such as oysters for food or for sale to restaurants to supply
their basic nutritional needs. In the past these fishers were
subject to regulations that governed recreational fishers and,
as a result, often resorted to fishing illegally in an effort to feed
their families. However, new fisheries regulations, contained
In 2 000 new permit conditions were introduced to encourage
in the Marine Living Resources Act of 1998, recognise that
free market practices in the fishery and pickers can now sell
subsistence fishers represent a formal fishing sector that is
direct to hotels and restaurants instead of to an oyster mar-
entitled to a share of South Africa’s marine resources. It is
keter. As a result on the south coast pickers can earn three
likely that, in the future, the subsistence fishers’ licence will
times what they did in the past but unfortunately this has also
be subject to a different set of regulations.
made poaching more lucrative and oyster poaching is on the
increase. Due to socio-economic conditions in KwaZulu-Natal
Farming oysters
pickers have not been able to sell their harvest for good prices.
World supplies of oysters are largely provided by mariculture.
Other pertinent issues in the management of the fishery are
In South Africa the cultivation of oysters takes place mainly in
the constant pressures to gain access to all fishing areas and
the Knysna lagoon where the Pacific oyster, Crassostrea gigas,
to harvest the subtidal stocks that help to seed the intertidal
is grown in mesh bags that are suspended from wooden
zone. However changes to the fishery will not be implement-
racks. C. gigas is the most commonly cultivated oyster
ed until more information on the biology and existing stocks
species in the world; it is favoured because it grows relatively
of the Cape oyster, as well as the ecology of the harvesting
quickly, reaching an edible size within two years.
zones, is gathered.
Authors: Claire Attwood and Craig Smith May 2001
With so few participants, the wild oyster industry provides
relatively few employment opportunities when compared to
other sectors of the fishing industry which are prominent in
the south coast region – squid and linefishing for instance.
But the oyster fishery generally provides a sole source of
income for these licensed pickers.
Recreational and subsistence oyster fisheries
Permits are required to gather oysters in South Africa.
Licensed recreational fishers are limited to 25 oysters per
person, per day. In KwaZulu-Natal the Natal rock oyster
Saccostrea cuccullata (previously Crassostria cucculata) and
the Cape oyster Striostria margaritacea are harvested
Pacific oyster, an imported species, is cultivated at Knysna.
FURTHER INFORMATION: • Chief Directorate: Marine and Coastal Management
Private Bag X2, Roggebaai 8012 Tel: (021) 402-3025 / 402-3043 / 430-7000 Fax: (021) 425-2920
RELATED FACTSHEETS: • Ocean Delicacies • Understanding Fishing Regulations • Mussels • The South African Fishing Industry.
For more information, please contact: The Coastal Management Office, Marine and Coastal Management, Department of Environmental Affairs and Tourism, Private Bag X2,
Roggebaai 8012, Cape Town, South Africa. Tel: +27 (0)21 402-3208 Fax: +27 (0)21 418-2582 e-mail: czm@mcm.wcape.gov.za Website: http://sacoast.wcape.gov.za
P E O P L E A ND T HE C O A ST: C O MM E R CI AL A C T I V I T I ES
Dune Mining 2B
T
he inland regions of South Africa have a
long legacy of mining for gold, coal and
diamonds. However, in recent decades our coastal
zone has become a new focus for mining activities.
manufacture of paints, coatings and plastics, and is also
converted to titanium metal, which is found in jet aircraft,
spectacle frames, artificial limbs and other modern
applications. Zircon is used in the ceramic industry for the
white glazing of wall tiles and bathroom fittings. It is also
Along the northern parts of the west coast, beaches
used in the construction, steel, glass, abrasive and metal
and dunes are subject to strip-mining for diamond
industries as a refactory – a substance that is able to resist
extraction, but the sand in dunes can be a valuable
high temperatures and corrosion.
resource in itself.
South Africa is second only to Australia as a world leader in
the mineral sands industry, accounting for about 23 per cent
of the world’s titanium ore. Namakwa Sands is proceeding
Mining for heavy minerals
Two companies in South Africa currently mine coastal dunes to
exploit their heavy mineral sands – Richards Bay Minerals (RBM)
and Namakwa Sands, a subsidiary of the Anglo American
Corporation. While RBM operates in the dunes north and
south of Richards Bay on the northern KwaZulu-Natal coast,
Namakwa Sands mines at Brand se Baai on the west coast.
Both companies mine the heavy sands to extract and separate
with a second phase expansion programme that will increase
its production of titanium slag to 230 000 t by 2001, while RBM
maintains an annual slag output of 1 million t. In 1988, RBM
applied for a lease to mine the eastern shores of Lake St Lucia
in an effort to increase production. Following a large number
of objections on environmental grounds, the government
instructed that an environmental impact assessment be
undertaken to investigate two alternative land uses for the
area, namely nature conservation and tourism only, or mining
the minerals ilmenite, rutile and zircon. Ilmenite is used for
in conjuction with nature conservation and tourism. The
downstream processing to titanium slag, which is an important
recommendation of the independent Review Panel appointed
source of titanium dioxide pigment. The pig iron that is a by-
by the government to reach a decision was that there should
product of this process has wide application in the automobile
be no mining anywhere in the Greater St Lucia Area, and this
manufacturing industry. Rutile is used as the base for the
decision was ratified by Parliament on 6 March 1996.
RBM uses a dredging operation to mine the sand. In the
the largest in South Africa and a provincial nature reserve that
dunes, a large artificial pond is created, on the surface of
would be included in the proposed Greater Addo National Park.
which floats a dredger and concentrator plant. The dredger
cuts into the mining face of the dune, advancing 2-3 metres
Environmental management and rehabilitation
per day depending on the height of the dune. As the sand
The Minerals Act (Act 50 of 1991) requires that an Environmental
face is undermined it collapses into the pond, forming a slurry
Management Programme Report (EMPR), incorporating plans
that is sucked up and pumped to the concentrator. In the
for post-mining rehabilitation, is submitted for all mining
area mined by Namakwa Sands, the upper portion of the ore
applications and existing operations. However, while the EMPRs
is embedded in a hard silcrete layer, necessitating a stripping
for large mining concerns are usually comprehensive, those
operation by front-end loaders.
for small-scale sand mining are often woefully inadequate, and
In both operations, the heavy minerals are separated from the
are frequently prepared by the landowners without the benefit
sand in the concentrator through a gravity process. The heavy
of expert advice. The Department of Minerals & Energy is
mineral concentrate is then transported to the separation
empowered by legislation to close down mining operations
plant, where it is re-slurried (mixed with water) before being
with unsatisfactory EMPRs, but staff capacity problems mean
passed over successive stages of magnets. In this way, the
that monitoring and enforcement is often neglected.
magnetic ilmenite is separated out and set aside for smelting.
During post-mining rehabilitation, land may either be reclaimed
The non-magnetic zircon and rutile that remain are then dried
so that it can be re-used for some other purpose, (such as
and separated using an electrostatic process, which takes
planting crops or woodlots), or restored to its original state.
advantage of the difference in conductivity of the minerals.
Richard Bay Minerals’ commendable efforts at restoration are
The rutile and zircon are exported in their raw form as mineral
promising, but have not yet been proven in the long term.
sands, although some zircon is upgraded by removing iron
Ahead of the slowly advancing mining plant, the vegetation
oxide staining to produce a high-grade product.
is cleared and the topsoil removed for later use. Behind the
artificial pond, the tailings (remaining sand) are shaped and
At the smelter, the ilmenite is mixed with anthracite and melted
in electric furnaces to reduce most of the iron oxides to
metallic iron, thereby producing titanium dioxide-rich slag and
high-purity pig iron.
contoured to resemble the original topography. The topsoil,
which contains seeds and plant nutrients, is then placed
over the shaped tailings, after which a mixture of cereal and
indigenous seeds is sown. The fast-germinating cereal plants
Mining sand for construction
help stabilize the rehabilitated areas, and form a cover crop that
provides protection for the slower germinating indigenous
Dunes are, in places, also exploited as a source of sand for
seeds. After about a year the cereal plants die off, leaving the
construction purposes, or simply for levelling or raising land.
indigenous species behind. The natural process of succession
For example, the Macassar dunefield on the northern shore of
then occurs, and within a few months the area is covered with
Cape Town’s False Bay is being extensively mined to supply
Acacia karoo pioneer trees. After only ten years, the Acacia
sand for infill. The dunefield has been recognised as a con-
karoo has formed a canopy under which the trees of a
servation-worthy area with cultural significance for the local
mature coastal forest begin to appear. At fifteen years, the
community, and there are concerns that sand mining may
rehabilitating forests contain a wide diversity of plant and
adversely affect its ecological functioning and future use.
animal species. However, it will be another few decades before
In the Eastern Cape, on the northern shore of Port Elizabeth’s
Algoa Bay, the cement manufacturing company PPC has
purchased the Schelmhoek dunefield, after prospecting
the success of re-establishing a natural climax community will
be evident. The average cost of rehabilitation to RBM in 1999
was between R25 000 and 30 000 per hectare.
indicated its potential for lime (calcium carbonate) extraction.
The dunefield is adjacent to the Alexandria dunefield, at 50 km2
Author: Sue Matthews September 2000
FURTHER INFORMATION: • Department of Minerals & Energy Affairs website: www.dme.gov.za/minerals
• Richards Bay Minerals website: www.rbm.co.za
RELATED FACTSHEETS: • Mining the Sea • Diamond Mining on the West Coast • Sea Sand • St Lucia
For more information, please contact: The Coastal Management Office, Marine and Coastal Management, Department of Environmental Affairs and Tourism, Private Bag X2,
Roggebaai 8012, Cape Town, South Africa. Tel: +27 (0)21 402-3208 Fax: +27 (0)21 418-2582 e-mail: czm@mcm.wcape.gov.za Website: http://sacoast.wcape.gov.za
P E O P L E A N D T H E C O A S T: C O M M E R C I A L A C T I V I T I E S
Diamond Mining on the West Coast 2B
T
he west coast of southern Africa is a harsh,
barren environment that can support little
human habitation or agriculture. However, it is
well-endowed with riches of another kind – it is the
largest known economic source of alluvial diamonds
considerations. The mining involves removing tons of sand
and calcrete, known as overburden, to reach the underlying
diamond-bearing gravel. The overburden, which is up to 35 m
deep, is removed using draglines, giant scrapers and bulldozers, and is then dumped in areas that have already been
worked. Some-times the diamond bearing gravel is locked up
in the world. More than 90% of the diamonds
in concrete-like conglomerates, requiring drilling and blasting.
recovered are of gem quality, having a colour,
The remaining bedrock is then cleaned and meticulously
clarity and size most desired by consumers in the
swept by hand. Some of the richest concentrations of gems
retail jewellery industry. Strict security is
lie in gullies and potholes where the machines cannot reach.
necessary for all diamond-mining operations, as
In the recovery plant, the gravel is crushed and scrubbed to
the gems are easy to conceal and steal.
remove sand and clay, after which the material is passed
through a dense media separation process, where the gravel
and diamonds sink out. Magnetic separation is then used to
Geological history
separate magnetic gravels from the non-magnetic diamonds.
Diamonds were originally formed at high temperatures and
This is followed by X-ray separation to isolate diamonds from
pressures at depths of 150-250 km below the earth’s surface.
the accompanying minerals. During this process, the dia-
About 90-120 million years ago, the diamonds were brought
mond fluoresces as it passes under the X-ray beam, and an
to the surface by volcanic eruptions. The resulting geological
air-operated ejector deflects it from the main stream of gravel.
features are known as diamondiferous kimberlite pipes, and
The final sorting is done by hand.
are concentrated in the interior of the country (Kimberley’s
‘Big Hole’ was formed by blasting one such pipe to gain
access to its diamonds). Over time, the top layers of the
Marine diamond-mining
South Africa’s coastal waters between the Orange River mouth
kimberlite pipes were eroded away and transported by the
and Cape Columbine are divided into 20 mining concession
Orange River and its tributaries to the coast. Here the soft,
areas, which are further sub-divided into four zones according
light material was destroyed and removed by wave action, in
to depth and distance from the shore:
the process concentrating the heavier and harder material,
A : shore to 1 km offshore
such as diamonds, on the beach terraces.
Over the last 80 million years, the sea level has retreated and
advanced several times due to global cooling or warming. At
various times, it was as much as 500 m lower and 200 m
higher than it is today. For this reason, diamonds can be found
both on land, buried in the sands of the ancient beaches,
and underwater, in the sediments of the continental shelf.
History of mining
In 1908, the first diamonds on the west coast of southern
Africa were discovered near the coastal town of Luderitz in
Namibia. By the 1950s, land-based mining of the exposed
marine terraces was well established, especially at the major
deposits at Alexander Bay and Oranjemond and around
Kleinsee. In 1957, the first diamonds were recovered from the
sea, and a few years later the marine diamond-mining industry
was initiated by a Texan entrepreneur named Sam Collins.
Land-based diamond mining
Diamond mining concessions cover much of the coastal land
between Groenrivier in the south and Luderitz in the north,
and access is restricted to these areas because of security
B : 1 – 5 km offshore
C : 5 km – 200 m depth isobath
D : 200 – 500 m depth isobath.
Not all of these areas are being mined, but the divisions are
consulting firm OLRAC. The study revealed that diver-operated
useful for administrative purposes.
air-lift dredging resulted in only a localised and short-term
impact. The biological community quickly recovered and within
Methods used for mining diamonds from
the sea
be detected. The consultants nevertheless recommended that
1. In the shallow inshore zones, to depths of down to 30 m,
the diamond divers should minimise kelp-cutting and avoid
mining is by diver-operated air-lift dredging. This entails
revisiting mining sites. More problematic than the environmental
divers using a suction hose to vacuum up alluvial gravel,
impact was the user-conflict between the diamond and rock-
which is sorted and screened at the surface. Divers working
lobster sectors. Both operate in protected gullies, but fishermen
in gullies close to the shore operate from a shore-based unit,
are prohibited from entering areas where mining is taking
while those in deeper water work from a small vessel.
a year no difference between mined and unmined sites could
place. Similar environmental impact assessments have also
been carried out for Consolidated Diamonds Mines at
2. At depths of 30-80 m , most mining is by dredges
Elizabeth Bay, south of Luderitz, in Namibia.
operated directly from larger vessels.
An environmental impact assessment was also commissioned
3. Deep-sea mining, currently limited to waters less than
by De Beers Marine – the major roleplayer in the deep-sea
130 m deep, makes use of two techniques. Vertical mining
mining sector – when the company began mining in 1990.
involves using 7 m-diameter drill bits that maintain a force of
There were concerns that the seafloor communities would be
up to 20 tons. The mining ships work according to a planned
irreversibly altered by the disturbance, and that the sediment
grid, covering the seafloor in overlapping circles to maximise
cast overboard would smother them as it settled. The study,
yield. The other technique, known as horizontal mining, uses
conducted by a team of scientists from the University of
a remotely operated vehicle called a crawler. The crawler
Cape Town, revealed that it takes a number of years for the
advances down specific lanes according to a mapped grid,
seafloor community to recover. However, since only a few
mining gravel and mechanically transporting it onto a screen.
square kilometres are worked each year, the overall impact is
Oversized material is discarded, and the rest is transported
minimal. The effects of the plume of sediment are limited to a
as a slurry via flexible hoses to the ship. The slurry is then
small area around the ship.
processed on board, being passed through various sorting
screens. The oversize material is returned overboard, while
Much of the insight gained from this study has been used to
the fluorescent material containing diamonds is separated out
develop a Generic Environmental Management Programme
automatically, using sophisticated X-ray and robotics equipment.
for the Marine Diamond Mines Association, made up of nine
member companies. The programme is in accordance with the
Before a deep-sea area is mined, intensive surveys are
internationally recognised environmental standard ISO 14001,
conducted to locate economically viable diamond deposits.
which incorporates clearly defined implementation and auditing
Diamonds are known to be concentrated in underwater
procedures.
topographical features such as depressions, gullies, potholes,
and along offshore ridges and ancient submerged bays and
The environmental impacts of diamond-mining are more obvious
headlands. High-precision bathometry, side-scan sonar and
on land, where open cast strip-mining has destroyed large
seismics are used to identify these features, which are then
areas of Namaqualand’s sandveld succulent vegetation. The
sampled to estimate the area’s potential diamond yield.
overburden sand is bulldozed into enormous mounds on this
otherwise generally flat landscape. Although it is unlikely that
Environmental impacts
the communities of flora and fauna will ever resemble the premining scenario, steps are being taken to rehabilitate the
In response to concerns that the inshore diamond-mining
overburden dumps as far as possible.
industry was negatively impacting the West Coast rock lobster
fishery, an environmental assessment was conducted by the
Author: Sue Matthews September 2000
FURTHER INFORMATION: • Marine Diamond Mines Association, tel. (021) 92 1105
RELATED FACTSHEETS: • Dune Mining • Mining the Sea • Orange/Gariep River Mouth
For more information, please contact: The Coastal Management Office, Marine and Coastal Management, Department of Environmental Affairs and Tourism, Private Bag X2,
Roggebaai 8012, Cape Town, South Africa. Tel: +27 (0)21 402-3208 Fax: +27 (0)21 418-2582 e-mail: czm@mcm.wcape.gov.za Website: http://sacoast.wcape.gov.za
P E O P L E A N D T H E C O A S T: C O M M E R C I A L A C T I V I T I E S
Guano 2B
F
our centuries ago, in their voyages along the
west coast of South America, the Spanish had
The later years
In 1895 the newly-formed Government Guano Islands
contact with ancient tribes who used the excrement
Department took control of all the coastal islands off southern
of seabirds as a fertiliser for their crops. This
Africa. From that time the guano was harvested on a more
“huano” – a Spanish word for seabird droppings –
rational basis, with only about 700 tons scraped annually.
was rich in nitrogen and phosphorus, and was so
Headmen were placed on the islands to manage and super-
highly prized that the tribes would attack anyone
found disturbing or killing the birds. Later, in the
vise the guano operations, which were only permitted after
the annual gannet breeding season to minimise disturbance
of the seabirds.
19th century, guano became a valued commodity
on the international market, and was known as
“white gold”.
In the early days of the industry, forks, brooms and shovels
were used to dig the guano up, spread it out to dry and pile it
up for bagging. Stones, feathers and bones were usually
removed with large sieves, although during World War II there
was a shortage of fertilisers and the scrapers were instructed
The “guano rush”
to include the riddlings (feathers and bones) in the guano
bags. Once bagged, the guano was rowed out to the ships in
The southern African resource of guano was first noted by
Captain Benjamin Morrel, the master of an American sealing
vessel, who in 1828 visited Ichaboe Island (off the coast of
present-day Namibia). In his voyage journal, published in the
early 1940s, he mentioned that the island was covered in
large flat-bottomed longboats called “skuits”. Mules and carts
were initially brought in to help transport bags and equipment
back and forth, but as technology advanced rail tracks were
constructed for trolleys, and later tractors were brought in to
expedite the collection process.
a layer of guano 25 feet deep. Several astute merchants
immediately started preparing for expeditions to investigate
Between 1930 and 1963, guano platforms were constructed
the island’s commercial potential, the first ships arriving in
north of Walvis Bay, outside Swakopmund and in the Cape
1843. They discovered to their joy that Captain Morrel had
Cross lagoon. Some of these platforms replaced islets that had
underestimated the island’s guano resource, which was in
become joined to the mainland by siltation and other factors,
fact 23 metres deep!
exposing the seabirds to terrestrial predators. The platforms
were designed to be accessible only to flying seabirds such
News of the bounty quickly spread, prompting a “guano rush”
to the island. By 1844, more than 400 vessels were anchored
off Ichaboe, and within a year they had removed 90 000 tons,
representing half of the guano. With the supply expected to
be exhausted in another six months, attention turned to other
guano-producing islands. Malgas Island, at the entrance to
Saldanha Bay, was found to be almost as rich in guano as
Ichaboe. The eight-hectare island was covered in a layer of
guano nine to ten metres thick, but in a matter of months it
had been scraped down to bare rock.
At the height of the guano rush in 1845 the Cape Governor
attempted to annex certain islands as property of the Queen.
A legal battle ensued until 1874, when “The Annexation of
Ichaboe and Penguin Islands Act” was finally passed (this
excluded Bird Island in Algoa Bay). In the meantime, operators
eager to harvest the guano before the government gained
control targeted other islands. Mercury Island, Possession
Island, Bird Island in Lambert’s Bay and Bird Island in Algoa
Bay were the most profitable after Ichaboe and Malgas had
been scraped clean.
as gannets and cormorants, rather than seals and penguins.
On coastal islands seals compete with seabirds for space
season. The resulting human disturbance and egg-collecting
and penguins build their nests under boulders or bushes,
activities exacted a heavy toll on the penguin and cormorant
making collection of their guano difficult. In addition, penguins
population. In addition, fossil guano deposits were often
prefer to nest in burrows in sandy soils, so the guano is soon
scraped from penguin breeding areas to provide nesting
mixed with sand and is therefore of inferior quality and value.
material for gannets in the following season. Normally penguins
The guano yield remained constant from 1895 to the mid1960s and then drastically declined. In 1977, for example,
only 152 tons were harvested. The decline was a reflection of
the collapse of the pilchard stock because of overfishing.
Pilchard is a small pelagic fish that shoals near the surface in
large schools, and is the primary food of seabirds.
The decline in yield, combined with the fact that synthetic
fertilisers were becoming a cheaper substitute, prompted the
halt to guano scraping in 1972. However, in the late 1970s Atlas
Organic Fertilisers obtained a concession to scrape some of
the islands off the West Coast, as well as Bird Island in Algoa
Bay. Scraping of the South African islands was finally discontinued altogether in 1986, and the last stored guano was
build their nests on well-drained guano, but removal of the
fossil deposits forced them to nest in depressions on bare rock,
which rapidly filled with water, drowning the nest contents.
These nests were also fully exposed to the elements, the rock
surface becoming unbearably hot on sunny days. The penguins
were forced to leave their nests regularly to cool off in the sea,
allowing gulls to prey on the unguarded eggs and chicks.
One positive impact of the guano industry was the formal
protection of the islands, and hence the seabirds. Today the
South African islands are protected by the provincial nature
conservation authorities in the Western and Eastern Cape,
while Malgas Island forms part of the West Coast National Park.
Guano fertilises the sea
removed and sold in the mid-1990s. The most recent wholesale value for the guano was R779/ton but the value would have
Guano is not only a useful fertiliser for land grown crops but it
been increased greatly by mixing it with synthetic fertilisers.
also provides nutrients for marine food webs. Comparisons
between island and mainland sites show the influence of guano
With the growing popularity of “enviro-friendly” organic
gardening, it is possible that the demand for guano-based
fertilisers could increase, but it is unlikely that guano-scraping
would ever resume at the South African islands. Today the
entire guano yield from southern Africa is taken from the
platforms in Namibia.
on intertidal communities. Researchers have demonstrated the
fertilising effect of guano runoff from islands: algal productivity
was elevated 2-5 fold and limpets on islands grew faster and
reached twice the size of those on mainland sites. The
combined effects of increased productivity (due to guano) and
decreased grazing (due to oystercatcher predation on limpets)
Impacts of guano collection
leads to large algal beds in the mid- and high-shore of the
islands. These algal beds support many small crustaceans,
Cape Gannets construct their nests on mounds made from
worms and molluscs. As a consequence smaller birds, such
guano and mud. Guano scraping often created a shortage of
as Curlew Sandpipers and Turnstones, which feed on these
nest-building material, resulting in the nests being lower than
invertebrates, are 2-4 times more common on the islands than
the surrounding terrain. This made them prone to flooding
on the mainland. Guano runoff also elevates phytoplankton
during heavy rain, increasing the mortality of eggs and chicks.
productivity and has a ripple effect on the pelagic food web.
Gannet colonies were unable to breed during the guano rush
of 1845 and many relocated to unexploited islands.
Although scraping was later permitted only after the gannet
breeding season, it coincided with the penguin breeding
Authors: Sue Matthews & Meredith Thornton September 2000
FURTHER INFORMATION:
• Burman, J & Levine, S. 1974. The Saldanha Bay stor y. Human and Rousseau, Cape Town.
• Green, L. 1950. At daybreak for the isles . Rustica Press, Wynberg.
• Payne, A.I.L., Crawford, R.J.M. & Van Dalsen, A. 1989. Oceans of Life off Southern Africa . Vlaeberg Publishers, Cape Town.
• Urquart, C. & Klages, N. 1996. East to the Isles. Bluecliff Publishing, Bridgemead.
RELATED FACTSHEETS:
• Gannets • Penguins • Islands around South Africa • Pelagic Fishing • Seals • Cormorants
For more information, please contact: The Coastal Management Office, Marine and Coastal Management, Department of Environmental Affairs and Tourism, Private Bag X2,
Roggebaai 8012, Cape Town, South Africa. Tel: +27 (0)21 402-3208 Fax: +27 (0)21 418-2582 e-mail: czm@mcm.wcape.gov.za Website: http://sacoast.wcape.gov.za
P E O P L E A N D T H E C O A S T: C O M M E R C I A L A C T I V I T I E S
Squid Fishery 2B
S
quid are free-swimming predators, related to
the octopus and cuttlefish, belonging to the
phylum Mollusca. They form large shoals, so they
are an important fishery resource. Most of the
catch is bound for the export market, where it
fetches such high prices that the squid resource has
shadow of the boats. Because they attract squid away from
their mating activity, there are concerns that the jig fishery
may disturb the spawning process and cause a decline in
subsequent recruitment. Furthermore, jigging mainly removes
males, which may impact the population structure. As is typical
of squid fisheries worldwide, catches have fluctuated widely,
with annual landings ranging from 2 500 to almost 10 000 t.
been dubbed ‘white gold’ by local fishers.
Management of the fishery
Trawling
In the early days of its existence the fishery grew rapidly, until
a permit system for vessels was introduced in 1987. Initially
Before the mid-1980s, almost all of the squid catch in South
the fleet comprised small vessels such as skiboats and cata-
African waters was by trawlers, their landings peaking at
marans, but more recently there has been a trend towards
about 5 000 tons per year in the mid-1970s. Much of the
larger vessels with blast freezers and many crew.
catch was by foreign vessels, which targeted the chokka
squid Loligo vulgaris reynaudi, but these were gradually
The jig-fishery is managed on the basis of effort limitation –
phased out and in 1993 were excluded altogether. The South
by restricting the number of vessels and crew operating in the
African trawlers caught squid mainly as a by-catch, landing
fishery, it was hoped that fishing pressure would be reduced.
the chokka squid as well as the red squid Todaropsis eblanae
However, because monitoring and enforcement is poor, many
and T. angolensis along with their demersal fish catch. Today
vessels carry more than the legally permitted number of fishers.
the annual catches of trawled squid are usually less than
For example, freezer vessels were entitled to carry extra crew
several hundred tons.
for packing purposes, but these crew members frequently
also jigged for squid, thereby elevating the total fishing effort.
Jig-fishery
The jig-fishery, in which squid are line-caught on a large spiny
hook that is ‘jigged’ up and down, was initiated in 1983. The
If this extra effort is not taken into account during stock
assessment, the sustainability of the chokka resource may be
compromised.
fishery targets chokka squid when they aggregate in protected
Other measures to manage the fishery are a closed area at
bays along the south coast to breed. The jiggers fish both at
the Tsitsikamma National Park, which straddles the main
day and at night and use bright lights to attract squid to the
spawning grounds, and a closed season in November-
Jiggers fish at night for squid
December each year, when squid spawning is at a peak.
jig-fishery, which targets these spawning aggregations, are
Fisheries managers use the results of trawl surveys conducted
likely to be caused by environmental influences on breeding
by Marine & Coastal Management to determine squid biomass.
behaviour. Laboratory studies have shown that optimal egg
By comparing the results of the spring and autumn biomass
hatching occurs in the temperature range 12-18°C, which
surveys, together with the catch per unit effort of the trawl
explains why the warmer inshore areas are the preferred
and jig fisheries, they can determine the status of the stock.
spawning grounds. However, it is known that some spawning
Some uncertainty exists because the by-catch from trawlers
also occurs in mid-shelf waters, at depths of up to 120 m.
shows a steep decline in abundance, while biomass surveys
indicate an increase. The reason for these conflicting results
has yet to be clarified, but it is generally accepted that any
increase in fishing effort would have a negative effect on the
long-term viability of the squid resource. Fisheries managers
have the difficult task of reducing fishing effort while also
allowing new entrants from previously disadvantaged
communities into the fishery, according to the principles of
the Marine Living Resources Act.
Good catches of squid correspond to low temperatures of
coastal waters, while poor catches occur when turbidity is
high on the spawning grounds. It is therefore believed that
the squid move inshore to spawn at the start of a windinduced upwelling event, when temperatures are low and the
water column is relatively clear. Chokka squid have large,
well-developed eyes and visual communication and water
clarity is important during mating. The chromatophores in the
skin enable them to change colour rapidly and their bodies
Biology and behaviour of squid
sparkle with iridescent colours and ripple with dark stripes
Squid are molluscs belonging to the class Cephalopoda that
the sea floor and increase turbidity, the squid are forced to
during the mating display. When storms stir up sediment on
includes the octopus and cuttlefish. Chokka squid move into
spawn on the deeper mid-shelf area, where waters are colder
shallow inshore waters to mate, forming spawning aggregations
but clearer. Here the squid are unavailable to the jig-fishery,
of males and females. After mating, the females lay their egg
resulting in poor catches.
capsules in gelatinous masses on
the seabed. It is thought that, like
other cephalopods, the squid dis perse and die shortly after spawning.
Chokka squid, a swimming mollusc,
The eggs hatch about three weeks
feeding on small fish
after being laid. The paralarvae initially drift with the currents, feeding
on zooplankton. At about six months
of age they include small fish in their
diet. Some move up the West
Coast, but when they are almost a
year old they begin to mature, and
start the migration inshore to breed.
The widely fluctuating catches in the
Long diamond shaped fins.
8 short arms and 2 long
retractile tentacles
FURTHER INFORMATION:
• Payne, A.I.L., Crawford, R.J.M. & Van Dalsen, A. 1989. Oceans of Life off Southern Africa . Vlaeberg Publishers, Cape Town.
• Dr Marek R. Lipinski, MCM, Tel. 082 830 9041 E-mail lipinski@mcm.wcape.gov.za
• Mike Roberts, Marine & Coastal Management, Private Bag X2, Roggebaai 8012, tel. (021) 402-3911.
RELATED FACTSHEETS:
• Cephalopods • Fishing Industry • Seafood Delicacies
For more information, please contact: The Coastal Management Office, Marine and Coastal Management, Department of Environmental Affairs and Tourism, Private Bag X2,
Roggebaai 8012, Cape Town, South Africa. Tel: +27 (0)21 402-3208 Fax: +27 (0)21 418-2582 e-mail: czm@mcm.wcape.gov.za Website: http://sacoast.wcape.gov.za
P E O P L E A N D T H E C O A S T: C O M M E R C I A L A C T I V I T I E S
Value of the Coast 2B
T
he coast a special place to live, work and
relax. South Africa’s coast is a rich and
diverse national asset extending 3 000 km from
the border with Mozambique in the east to the
Orange River, the border with Namibia in the
west. It is of strategic importance on a national
and global scales. Its position at the tip of Africa
has made it a regular port of call on shipping
routes through the ages, including the tea and
Examples of direct benefits are the fishing industry, tourism,
mining and shipping.
• The fishing industry is worth R2.4 billion and employs
27 000 people directly while secondary industries such as
fish processing, transporting of fish products and boat
building employ a further 60 000.
• Coastal tourism is estimated to generate R13.5 billion for
the economy every year.
• South African’s ports and harbours provide links to
world economies and markets and the shipping industry
spice sailing ships plying between Europe and the
transports R140 billion worth of cargo which generates
East, modern tankers transporting oil or sleek
R4.2 billion in revenue per year.
racing yachts circumnavigating the globe. The
coast has been a focal point for the development of
• Mining There are also significant mineral resources in the
form of diamonds, heavy minerals (titanium and zirconium),
industries within the country such as fisheries,
oil and gas, as well as sand and pebbles for building
agriculture, mining, trade and tourism. It has
material and salt from sea water.
been identified as one of the most important
Indirect benefits obtained from the coast are coastal services
areas for future economic development, poverty
such as the protection offered by dunes to roads, buildings and
reduction and job creation.
the hinterland from the flooding, corrosive salt spray and windblown sand. The beauty and dynamic setting provided by the
ocean adds value to property - about 40% of the building
The economic value of South Africa’s coast
The coast provides important economic benefits to the people
activity in South Africa is conducted at the coast. The fastest
economic growth at present is in the four major coastal cities
– Cape Town, Port Elizabeth, Durban and East London. The
of South Africa. It is estimated that the direct benefits obtained
Department of Trade and Industry has identified areas for
from coastal goods and services amount to R168 billion each
development and 80% of these are linked to the coast with a
year. Indirect benefits contribute a further R134 billion annually.
potential value of R90 billion and employment for 90 000 people.
The economic opportunities that are offered by the coast
water and moist climate and as a result development and
depend on a high-quality coastal environment, healthy
population pressure are more evident there than on the arid
ecosystems and sound planning and management.
west coast with its cold water and dry climate.
The biophysical value of the coast
Tourism, recreation and leisure activities have grown into a
burgeoning global industry and South Africa’s coast has
Our coast is rich in diversity, being influenced by the warm
particular value in this regard. Together these sectors generate
Indian Ocean on the south and east coasts and the cold
more than R15.2 billion, with over 20 million international and
Atlantic Ocean on the west coast. These different currents,
local visitors annually. The recreational fishery alone attracts
and related factors such as water temperature, climate and
600 000 anglers and employs 131 000 people and is worth
geographic location, influence the distribution of marine life,
R1.3 billion annually. The small areas of coral reefs in northern
which is particularly diverse and rich due to the variety of
KwaZulu-Natal attract many thousands of recreational divers
conditions and habitats. Productivity on the west coast is
annually to places like Sodwana and Aliwal shoals.
exceptionally high, fuelled by the upwelling of nutrients from
deep water. Here, large kelp forests flourish and, together
with plankton, nourish vast shoals of pilchards and anchovy.
These in turn are the food of larger economically-important
fish and huge colonies of sea birds and seals. The intertidal
life consists of dense stands of limpets, mussels and Cape
reef worms which produce more flesh mass per square metre
than the most productive farms. Some of these resources
such as the fish and kelp are already being harvested in vast
quantities but the potential of others is still to be realised. By
contrast the warm waters of the east coast support fewer
numbers but many more species of marine life and a high
proportion of endemic species,
More than 11 000 species have been recorded around South
Africa, 5% of the total number of marine species worldwide.
Approximately 17% of South African species are believed to be
endemic; they occur nowhere else on earth. This rich biodiversity
of species, communities, ecosystems and genes is difficult to
express in monetary terms but the potential for yielding products of commercial value is great.
It is important to recognise that human activities impact on
coastal ecosystems and affect the flow of goods and services.
To sustain the economic and social benefits of the coast it is
vital that the health and productivity of coastal ecosystems is
maintained. There is plenty of evidence to show how human
development and mining have changed the coast. Some
estuaries, coastal dunes and even beaches have been altered
beyond recognition. Many species have become endangered.
Management
The government recognises the enormous value of the coast
and has produced a policy document for coastal management
so that all South Africans can benefit. It does however require
a dedicated, co-ordinated and integrated management
approach to sustain the coastal ecosystems and attractive
features on which coastal benefits depend and we all must
accept the responsibility to help maintain the diversity, health
and productivity of coastal ecosystems.
The importance of compliance with legislation aimed at protecting the coastal environment, and enforcement thereof, has
The social value of the coast
Although for many South Africans the coast is a place of
employment for others it is of cultural and spiritual significance
been recognised. In order to protect our fish resources, a
number of fast effective patrol vessels have been ordered to
police South Africa’s national waters.
or is a place for recreation and refreshment. More people have
been attracted to the east and south coasts due to the warm
Authors: Margo Branch and Claire Attwood November 2000
FURTHER INFORMATION: • Branch, G. M. & Branch M. L. 1981. The Living Shores of Southern Africa . Struik, Cape Town.
• Payne, A. I. L. Crawford, J.M. 1995. 2nd edition. Oceans of Life off Southern Africa . Vlaeberg Publishers, Cape Town.
• Our Coast Our Future 1998. Coastal Policy Green Paper.
• Our coast for Life, 2000. National Marine Week booklet, Marine and Coastal Management, Department of Environment Affairs and Tourism.
RELATED FACTSHEETS:
• National Coastal Policy • Fishing Industry • Tourism along the Coast • Biodiversity • Mining the Sea • Ecosystems in the Sea • Coast – what is it?
For more information, please contact: The Coastal Management Office, Marine and Coastal Management, Department of Environmental Affairs and Tourism, Private Bag X2,
Roggebaai 8012, Cape Town, South Africa. Tel: +27 (0)21 402-3208 Fax: +27 (0)21 418-2582 e-mail: czm@mcm.wcape.gov.za Website: http://sacoast.wcape.gov.za
P E O P L E A N D T H E C O A S T: C O M M E R C I A L A C T I V I T I E S
Pelagic Fishing 2B
T
he pelagic fishery is the largest South
African fishery in terms of volume landed,
although it is only the second most valuable, worth
Anchovy
The Cape anchovy, Engraulis capensis (called Engraulis
japonicus by some authorities), has a distribution stretching from
about R300 million annually. This is because most
Kwazulu-Natal to the Orange River, but most of the population
of the fish are used to make fish meal and oil, which
is concentrated over the shallow Agulhas Bank on the south
does not fetch high prices. The fishery targets small
coast and in the inshore areas of the west coast. Anchovy is the
fish that form large shoals in the surface layers of
the sea, i.e. the pelagic zone. Here, where light is
sufficient for photosynthesis, the tiny plant life of
the sea, known as phytoplankton, forms the basis
of the pelagic food chain. The most productive
areas for phytoplankton are the shallow nutrient-
smallest of the three targeted fish species, reaching a maximum
length of about 15 cm by the end of its three-year life-span.
Anchovies feed mostly on copepods, which are tiny phytoplankton-eating crustaceans. The young fish grow rapidly and
are ready to breed when they reach an age of one year, by
which time they are 12 cm long. Most breeding takes place
on the main spawning grounds on the Agulhas Bank between
rich waters over the world’s continental shelves,
October and February. Many of the fertilised eggs are eaten
particularly in the upwelling areas off California,
by adult fish, but the rest hatch after three days into larvae,
Peru, north-west Africa and the west coast of
which float about in the plankton. Those that have not been
South Africa. Consequently, this is also where the
born into an area of abundant food die of starvation once
largest populations of pelagic fish occur.
they have absorbed the nutritious egg yolk.
A jet current transports the surviving larvae from the Agulhas
Pelagic fish, which belong to the order Clupeiformes, can be
divided into:
• Clupeids – pilchard, herring, round herring and sardinella
• Engraulids – anchovy.
Bank past the Cape Peninsula to the west coast. Here the
larvae are able to grow rapidly in the food-rich upwelling
areas, which are known as nursery grounds. Many of the
young fish, called “recruits”, are caught by the pelagic fishery
before they are a year old. Those that escape being caught,
In South Africa the main pelagic fish caught are anchovy,
or eaten by predators such as seabirds and seals, migrate
pilchard and round herring, while juvenile horse mackerel and
back to the Agulhas Bank by the end of their first year in
lanternfish make up a small portion of the total catch.
order to breed.
A shoal of pilchards is encircled by a purse-seine net.
Pilchard
or winds, which might transport the larvae far offshore where
food is scarce. Anchovy catches have ranged from 595 000
The South African pilchard, Sardinops sagax, better known as
sardine, lives to an age of 6-8 years, by which time it is about
tons in 1987 – the highest on record – to an all-time low of
41 000 tons in 1996.
30 cm long. Sexual maturity is reached at 2-3 years of age,
at a length of 20 cm. The main spawning grounds are off the
The anchovy fishery only began after the collapse of pilchard
south-west Cape coast, although some spawning takes
stocks because of overfishing in the early 1960s, when
place on the east coast. Pilchard are serial spawners, which
catches peaked at 400 000 tons. Today, in order to prevent
means they spawn several times during the lengthy spawning
overfishing, an annual Total Allowable Catch, or TAC, is set
season, lasting from August until the following May. The well
for each species. TACs are based on catch statistics together
known “sardine run” on the Kwazulu-Natal coast is thought
with the results of hydroacoustic surveys conducted during
to be a result of pockets of warm water, at temperatures too
research cruises. These involve using calibrated echosounders
high for the fish to tolerate, forcing the shoals close inshore.
to find and estimate the density of fish shoals. The
echosounders send pulses of sound into the ocean and
Round herring
measure the amount of sound reflected from the fish, called
The Cape round herring, Etrumeus whiteheadi, also known as
red eye, is widely distributed off the South African coast, but
the backscatter. This is processed with other data to estimate
the biomass of fish.
forms a small part of the total pelagic harvest. Spawning takes
Two hydroacoustic surveys are conducted by Marine and
place offshore between July and November, but mostly from
Coastal Management each year: the spawner biomass survey
August to October. Currents transport the larvae inshore,
in November is used to estimate the number of adult fish,
where conditions are more favourable for their survival, so the
while the mid-year recruitment survey targets fish in their first
juveniles are often caught as a by-catch with anchovy and
year of life which will “recruit” to the pelagic fishery. Fisheries
pilchard. The fish migrate into deeper water as they grow. The
scientists use an Operational Management Procedure, or
adults undertake daily vertical migrations, forming dense shoals
OMP, to set initial TACs for anchovy and pilchard based on
near the bottom during the day and moving up to disperse in
results from the November spawner biomass survey. These
surface waters at night.
TACs are later revised according to industry catches and the
results of the mid-year recruitment survey.
Fishing and fisheries management
During the last decade, the spawner biomass surveys have
The pelagic fishery relies on the purse-seine method of fishing.
Once a large shoal of pelagic fish has been located, the fishing
boat drops one end of a very large net and steams round the
shoal in a circle, paying out the net behind it. The net is
suspended by floats and weighted at the bottom so that it
hangs from the surface. The bottom of the net is then drawn
in under the shoal until the fish are packed together in a small
shown a clear recovery of pilchard stocks, from about 30 000
tons of adult fish in 1984 to over one million tons in 1999.
This is good news for the pelagic fishery, as pilchard is a
more valuable resource than anchovy because it is canned
for human consumption. In 1999, directed catches for
pilchard totalled 132 000 tons, with 14 000 tons taken as
by-catch with anchovy and round herring.
corner of the net. Finally, a suction pump is lowered into the
net and the fish are sucked into the hold of the fishing boat.
Since the hydroacaustic surveys began in 1984, anchovy
About 85 purse-seine vessels operate out of harbours in
spawner biomass has peaked twice, in 1986 and 1991, and
Lambert’s Bay, St Helena Bay, Saldanha Bay, Hout Bay, Gans
reached an all-time low in 1996, which corresponded to the
lowest catch on record. In 1999 the anchovy spawner biomass
Bay and Algoa Bay.
was estimated at 1.3 million tons, while catches totalled
Catches in the pelagic fishery fluctuate widely, mainly
because of the reliance on anchovy. Anchovy is a short-lived
180 000 tons. Round herring was estimated at 2 million tons
in 1999, but only about 59 000 tons were caught.
species and its numbers can vary significantly from year to year
because of environmental changes such as unusual currents
Author: Sue Matthews, September 2000
FURTHER INFORMATION: • Payne, A. I. L., Crawford, R. J. M. & Van Dalsen, A. 1989. Oceans of Life off Southern Africa . Vlaeberg Publishers, Cape Town.
RELATED FACTSHEETS: • Fishing Industry • Upwelling • Sardine Run
For more information, please contact: The Coastal Management Office, Marine and Coastal Management, Department of Environmental Affairs and Tourism, Private Bag X2,
Roggebaai 8012, Cape Town, South Africa. Tel: +27 (0)21 402-3208 Fax: +27 (0)21 418-2582 e-mail: czm@mcm.wcape.gov.za Website: http://sacoast.wcape.gov.za
P E O P L E A N D T H E C O A S T: C O M M E R C I A L A C T I V I T I E S
Demersal Fishing 2B
T
he demersal fishery, which uses trawl gear to
exploit bottom-living fish, is South Africa’s
most valuable fishery. Hake makes up most of
at night to search for food, but also move in response to
changes in temperature or oxygen content of the water.
Both species spawn along the entire coast throughout the
the catch, but sole and horse mackerel are also
year, with minor peaks in autumn and spring. Young hake may
targeted, and these resources are the only ones for
form schools near the surface, but they become bottom-living
which catch limits are imposed. A variety of other
and solitary at a size of 7-8 cm. The largest fish grow to over
species, including kingklip, snoek, ribbonfish
(buttersnoek), monk, panga, carpenter, kob,
1.2 m long and weigh almost 20 kg at an age of 15 years, but
the bulk of the catch is made up of 3-4 year old fish between
30 and 50 cm in length.
gurnards, angelfish and various sharks and skates,
are caught as by-catch, although some of the more
Sole
valuable species are targeted on a seasonal basis.
Sole is by far the most valuable fish per unit mass caught in
In recent years, a small exploratory deep-water
South Africa, although it contributes less than one percent of
trawl fishery targeting oreo dories and orange
the total demersal catch. Two commercially exploitable
roughy has also been established.
species occur in our waters – the Agulhas sole Austroglossus
pectoralis, with a distribution from Cape Agulhas to East
London, and the West Coast sole Austroglossus microlepis,
Hake
occurring from False Bay to Angola. The latter supports only a
small experimental fishery off Port Nolloth, so almost the entire
Two species of hake are caught in South Africa’s waters – the
catch is made up of Agulhas sole, mainly from a shallow area
shallow-water hake Merluccius capensis and the deep-water
off the south coast known as the Agulhas Bank.
hake Merluccius paradoxus. As their names suggest, the two
species have different distributions, shallow-water hake
occurring from close inshore to about 400 m depth, and deepwater hake ranging from depths of 150 m to over 600 m.
Soles have an unusual life history. The larva looks and swims
like a normal fish, but at about 8 mm long the left eye gradually
moves over the top of the head to the right side. The young
sole then takes up a bottom-living lifestyle, lying on its side on
The two species have different life histories and behaviours, but
the seafloor and feeding on small benthic invertebrates such
both hunt or scavenge individually, feeding on small schooling
as polychaetes, crustaceans, bivalves and brittle stars. The
fish, squid and crustaceans. They generally leave the bottom
upper side becomes a mottled brown, which can change
shade to blend into the surroundings for effective camouflage,
number of vessels, and certain closed areas (mainly in areas
imparting some protection from predators. The sole can also
where Agulhas sole or pelagic fish are targeted). While deep-
hide by flipping sediment over itself with the fins, leaving only
sea stern trawlers on the west coast are restricted to nets of
the eyes and upper part of the mouth at the surface.
110 mm mesh, those fishing east of 20 E are permitted to
Juvenile fish remain close inshore, but are believed to take
shelter in deeper water during winter storms. Older fish occur
progressively deeper to a depth of about 125 m. Agulhas
use nets of 75 mm mesh. However, the latter may not fish
shallower than 110 m (a further measure to protect the sole
resource).
sole grow slowly, reaching a maximum length of about 50 cm
The hake TAC has remained in the region of 150 000 tons
when the fish is more than 12 years old. The West Coast sole
since, but part of this is allocated to a relatively new method
grows a little longer and faster, and fish of up to 75 cm,
of catching hake, known as longlining. Hake longlining is
weighing almost 4 kg, are not uncommon. It also reaches
concentrated in two areas - off the south-west coast in the
sexual maturity slightly faster, but both species start breeding
vicinity of Cape Point, where deep-water hake is targeted,
at 3-4 years of age.
and off the south coast between Cape St Francis and Mossel
Bay, where the shallow-water species is targeted. Fisheries
Horse mackerel
The Cape horse mackerel Trachurus trachurus, also known
as maasbanker, occurs off Namibia and the Cape coast. The
young fish form large shoals near the surface on the West
managers have recommended that the longline allocation
should not exceed 10 % of the hake TAC until the ecological
and socio-economic impacts of this method have been more
thoroughly researched.
Coast, where they are caught by purse-seiners in the pelagic
Another growing sector is the hake handline fishery, which
fishing sector. As the fish grow larger, they spend the day
has been poorly studied to date. However, it is known that
close to the seabed in deep water, where they are caught by
hake caught by handline are on average smaller than those
bottom-trawl as a by-catch in the hake fishery. At night,
caught by longline, but larger than those caught by trawl.
schools of horse mackerel rise through the water to feed on
zooplankton; these fish are targeted by specialised mid-water
trawl vessels.
The inshore trawl fishery operates along the south coast and
comprises mostly small side trawlers working in waters
shallower than 110 m on the Agulhas bank. This fishery lands
Cape horse mackerel can live longer than 10 years, growing
less than 10 % of the hake catch but almost all of the sole
to more than 50 cm in length and in excess of 1,3 kg in
catch. In assessing the size of the sole resource, scientists
weight. They reach sexual maturity at 3-4 years, and at a size
use the same type of data as they do for hake – commercial
of 32-40 cm they move inshore to spawn. Spawning occurs
catch rates and the results of research surveys. However,
all year round, but with a major peak season from May to
because of inconsistencies in the data a cautious approach
August and a minor peak from October to January.
Fishing and fisheries management
has been adopted, and the TAC has therefore remained at
872 t since 1993.
Owing to difficulties in assessing the size of the horse mackerel
During the 1960s and ‘70s, hake stocks were decimated by
heavy exploitation, mostly by foreign vessels. Fisheries
managers advocated a conservative strategy, based on
stock, largely because of its horizontal and vertical migrations,
a precautionary maximum catch limit rather than a TAC is set
for this species. In 1999 the catch limit was 34 000 t.
analyses of commercial catch rates and the results of research
surveys, to rebuild the hake resource. The fishery is therefore
controlled by a Total Allowable Catch (TAC), limitations on the
Author: Sue Matthews September 2000
FURTHER INFORMATION:
• Payne, A. I. L., Crawford, R. J. M. & Van Dalsen, A. 1989. Oceans of Life off Southern Africa . Vlaeberg Publishers, Cape Town.
• Research Highlights, annual booklet issued free of charge by Marine & Coastal Management, Private Bag X2, Roggebaai 8012.
RELATED FACTSHEETS:
• Fishing Industry • Value of the Coast • Snoek • Pelagic Fishing • Sustainable Use of Coastal Resources • SANCOR • Food Value of Fish
For more information, please contact: The Coastal Management Office, Marine and Coastal Management, Department of Environmental Affairs and Tourism, Private Bag X2,
Roggebaai 8012, Cape Town, South Africa. Tel: +27 (0)21 402-3208 Fax: +27 (0)21 418-2582 e-mail: czm@mcm.wcape.gov.za Website: http://sacoast.wcape.gov.za