LECTURE NOTES:
OCEANOGRAPHY (MARSC 100),
SNYDER, L.
CH. 17 Marine Resources
Economic Resources of the Ocean
 Non-renewable: Present in fixed amount, can’t be replenished (geologic time)
o Minerals: fossil fuels (petroleum, natural gas) sand & gravel, sea salts
o Freshwater: Total amount of Earth’s water is fixed (only cycles from sea-airground....)
 Desalinization of seawater is expensive & damages coastal ecosystems
 Renewable: Naturally replaced by organisms or physical processes
o Food (animals & algae)
o Renewable Energy (wind, waves, heat)
 Wind energy – clean & can’t be used up
 Wave energy – experimental right now
Petroleum & Natural Gas
 ~25% of world supply from from seabed (continental margins, slopes)
 Known supply: 33% on continental margin
 Formation Process (Millions of years):
o Plankton & benthic organisms accumulate on seabed
o Anaerobic bacteria breakdown tissue
o Rapidly buried
o Converted to hydrocarbons by high temperature & pressure
Offshore Oil Drilling
As demand increases, price increases
More platforms, deeper, far offshore
Supply will ultimately run out
Conservation can decrease demand, lower prices, & save supplies
Renewable Resources: Fish & Invertebrates
What World region/nation harvests the most fish from the ocean (in millions of metric tons)?
1.
China: 16.5 MMT (human population = 1.3 billion)  #1 world population
2.
Peru: 8 MMT (hum pop = 27 million)
3.
USA: 5 MMT (hum pop = 295 million)  #3 world pop.
4.
Japan: 4.7 MMT (hum pop = 127 million)
5.
India: 3.8 MMT (hum pop = 1 billion)  #2 world pop.
Top 5 ocean fishing regions:
1.
2.
3.
4.
Northwestern Pacific (Near China & Japan)
Southeastern Pacific (Near Peru)
Northeastern Atlantic (Near Europe)
Western Central Pacific (Near China & Japan)
As fishing areas near nations with a high demand for fish (often large populations & wealthy
nations) become depleted by overfishing/harvest, these nations move to new regions to
exploit fish populations in less utilized areas
EX: South Atlantic Ocean off coast of Africa:
 As fish stocks decrease in the North Atlantic, the European Union has increased
fishing off of Africa’s Western Coast.
 Excessive European fishing decreases available fish for Africans, which leads to a
cascade effect of other problems.
o Many Coastal African fishermen/women can no longer support themselves or
feed their families by fishing due to depleted fish stocks, so they are forced to
hunt for “Bush Meat” in the forests.
 Bush meat: meat of terrestrial wild animals, killed for subsistence or
commercial purposes throughout the humid tropics (especially Africa).
o Bush Meat includes: primates & great Apes (monkeys, chimps, gorillas) as
well as many other types of species.
 This type of hunting has increased so much that many of these species
are now at risk of extinction (up to 70% of these species have been
depleted in last 30 yrs).
Marine Species in Food Supply
4% of protein from marine animals, algae
18% total animal protein from ocean
Fishing: big business (worldwide):
15 million employed , $90 billion industry (2001)
Dangerous job
Fishing fleets
75% of harvest by huge commercial fleets that Work year-round
Scouting vessels locate fish
Factory ships follow fleet: Process, can, freeze at sea
Commercial Fishing Technology
1950-1997: Marine catch has increased more than (five-fold) 5X
Due to improvements to & increased use of fishing gear technology


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HUGE Nets: Can hold up to 12 747 airplanes
o Gigantic trawl nets (as big as statue of liberty) that drag on seafloor & also
catch mid-water fish & invertebrates
 Shrimp trawls are especially damaging to seafloor
Purse Seines – slowly enclose around surface & mid-water species
Satellite Technology:
o Tracks plankton blooms (help locate fish) & fish schools
Maximum sustainable yield (MST): Maximum amount of a population that can be
harvested without impairing future populations.
World MST Estimate: 110-135 million metric tons
2001 world harvest = 130.2 MMT
We’re at limit or have exceeded it
Exceeding Maximum Sustainable Yield
 Properly managed fisheries can be renewable resources, however
 Despite a major increase in fishing effort, yield has decreased since 1980’s
 ~70% of marine fisheries are out-fished or over-fished
o Not enough breeders left to replenish the population
 Money (not science) drives the fishing industry
o Greatly impacted by consumer demand
Georges Bank Cod Fishery
 North Atlantic (Maine)
 Landings decreased ~91% from 1990-1999
 Industry response: increase use of technology & increase the number of fishing boats
 Over-fishing became so severe that the Cod population crashed (nearly no fish left)
 Regulations had to be implemented to save the Cod from extinction:
 Daily catch limits
o Increased Minimum size requirements (so more young could survive to
adulthood for breeding)
 Increased Trawl mesh size (so small, young fish could escape)
 Permit restrictions (fewer permits)
 Rolling area closures
Other Mismanaged Fisheries
 Orange Roughy (New Zealand)
o 1980’s “favorite fish”
o Take 25-30 yrs. to sexually mature
o Commercially extinct in 13 years (so few left = not profitable to catch)
 Chilean Seabass (Tootfish)
o High Demand causing severe overfishing
o Unless demand decreases, it may be commercially extinct in 5 yrs.
o A large percentage are caught illegally
Consumer Choices
 You, the consumer, have an impact on the health & survival of marine species
o Choose well-managed, harvested & farmed species
o Monterey Bay Aquarium’s Seafood Watch
www.mbayaq.org/cr/seafoodwatch.asp
Whaling
 Hunted since 1600’s: meat, blubber, oil, bones
o Used for: Lamp oil, cosmetics, industrial lubricants, fertilizer, corsets
 1900: 4.4 million whales, Today: ~1 million
o 8 of 11 large species commercially extinct (Fin, blue, humpback, gray)
International Whaling Commission: Moratorium on Whaling (1986)
 Commercial Whaling “ended” in 1987
 Japan & Norway have begun whaling again
 Despite IWC opposition
 Japan takes whales for “scientific purposes”, but whale meat ends up for sale
in markets
 Norway (1993) for food, recently increased quotas
 1,000+ minke killed per year by Japan & Norway
Antarctic Whale Sanctuary
 1994: IWC banned whaling in 8 million mi2 zone
 Often ignored by Norway & Japan
 Chile, Peru, N. Korea interested
 Pirate whalers catch & sell whales to Japan
 Eastern pacific Gray’s removed from endangered list in 1993
 Some species are not recovering (Blue Whale)
Bykill or Bycatch
 Animals unintentionally killed while collecting desirable species
 Young & low-value fish, seabirds, mammals, turtles
 ~30 million tons sea life each year
 2002 fish discards: twice desired commercial & recreational catch
 Shrimp trawlers: 10 lbs. bycatch per lb. of shrimp
 Bottom trawling: most damaging
Bycatch solutions
 Modify gear: change net's mesh size & shape, so young can escape
 Purse seines w/ acoustic alarms
 Longline tuna fishing: Night-setting & Lines w/ metallic streamers (scare birds),
weights (sink)
 Reduce or Limit fishing (economically extinct species)
 Marine reserve network: linked by corridors (protect breeding & nursery grounds)
Marine Mammal Protection Act (1972)
 Bans:
1.
Take of marine mammals in US territorial waters
2.
Take of marine mammals on high seas by persons (vessels) subject to U.S.
jurisdiction
3.
Import of marine mammal products (1988)
 Significantly decreased dolphin "bykill" from tuna industry
 1960’s: 200,000 Dolphin drowned/year in yellowfin tuna nets
 Public outcry & consumer boycott in USA led to government passage of the Marine
Mammal Protection Act (1972)
 No Chasing or netting dolphins, nets set to release dolphins, unbiased observer on
fishing ships
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Dolphin Safe Tuna: In 1990 all 3 major American tuna canners, Star-Kist, Bumble
Bee, and Chicken of the Sea, capitulated to an consumer-led boycott of canned tuna
and agreed to purchase only "dolphin-safe" tuna. Any tuna caught in purse seine nets
in the presence of dolphins could not be labeled "dolphin-safe," according to U.S.
Dept. of Commerce, even if it were certified that no dolphins had been killed.
Is “Dolphin-safe” tuna still safe?
o New proposed regulations: chasing & encircling dolphins o.k. in East
Tropical Pacific
o Dolphin quota would be increased to 5,000/yr.
Other Mammals protected by Marine Mammal Protection Act (sea otters, seals, sea
lions, walrus, manatee, etc.)
 Many fur-bearing species were nearly hunted to extinction
 Hunting quotas/bans allowed most species to recover
 300,000-450,000 still taken/year for fur (Northern Fur Seal, Harp Seal – Canada)
International Law of the Sea (1982)
 148 nations signed (as of Jan. 2005), not U.S.A.
o USA disagrees with high seas sharing (may have to do with migratory species,
U.S. tuna fleets in mexico, etc.)
 Territorial Waters: jurisdiction 12 mi. from shore
 Exclusive Economic Zone (EEZ): Nations sovereign over resources & economic
activities 200 mi. from shore
 High Seas: Outside EEZ’s, world shares common property
 Scientific research freedom
 Protection of sea & wildlife
 Evolving
Is Aquaculture the Answer?
 Farming aquatic species (fresh primarily, but many marine species farmed now too)
 25% of human fish consumption
 Mariculture: farming of marine organisms
o Estuaries, bays, nearshore
 Some can be farmed on land in tanks
 $150 million/yr. Industry (increases 8% annually)
 Common farmed marine species: Salmon, oysters, shrimp, tuna
Shellfish Farming: Oyster, clams, mussels
 Suspended in seawater by rope, trays, or mesh bags
 Filter feeders: require clean H2O
 Supplemental feed not needed
 Produces little waste
Farming Marine Fish:
 Enclosed in open net pens nearshore
 Water & waste pass freely into surrounding habitat

Fish often escape
Mariculture Impacts
 Ocean net pens & ponds:
 Produce tons of waste = pollution (equivalent to a small city)
 Diseases & parasites (sea lice) spread among fish in crowded pens & to wild fish
 Antibiotics to control (prevent?!) disease leak into ocean & create drug-resistant
bacteria (antibiotics lose their potency & may no longer be useful for human
medicine
 Escape pens: take over habitat from wild fish, interbreed (genetically modified)
 Depleting wild stocks of smaller fish
o Carnivore fish (salmon, tuna): Eat 2-5 lbs. of smaller (anchovy, etc.) wild fish
for every1 lb. of farmed salmon
 Tropical habitat destruction:
o Mangrove forests cut down for shrimp farms
o In a few years, salinity & wastes build up in farm ponds
o Farmers move to new location
Improving Mariculture
 Away from sea may be best
 Can’t escape or spread disease to wild fish
 Recirculating systems clean & filter waste water
 Tilapia, trout, catfish (now)
 Salmon & shrimp (experimental)
 Some vaccinate instead of antibiotics
 Eat lower on food chain
 Herbivore fish (tilapia, carp) don’t rely on wild marine fish
 Plant protein for carnivores (up to 60% soy)
Land based Mariculture Examples:
 Inland Ponds
o Fish in enclosed inland body of fresh or salt H2O
o Waste: contained & treated
 Recirculating Systems
o Fish enclosed tanks, water is treated & recirculated through filters
 Raceways (Salmon)
o Fish enclosed in channel system with continuously flowing water
o Waste is captured & treated
Best Farmed Choices:
Invertebrates: Oysters, clams, mussels
Fish: Tilapia, Trout, Catfish