Research Journal of Applied Sciences, Engineering and Technology 2(6): 568-573, 2010
ISSN: 2040-7467
© M axwell Scientific Organization, 2010
Submitted Date: July 01, 2010
Accepted Date: August 02, 2010
Published Date: September 10, 2010
The Recruitment Pattern of Macrobrachium macrobrachion (Herklots, 1851)
from Luubara Creek, Ogoni Land, Niger Delta, Nigeria
1
S.N. Deekae and 2 J.F.N . Abowei
Department of Fisheries and Aquatic Environment, Faculty of Agriculture,
Rivers State University of Science and Techno logy , Port Harcourt, Rivers State, Nigeria
2
Department of Biological Sciences, Faculty of Science, Niger Delta University,
Wilberforce Island, A massom a, Bayelsa State, Nig eria
1
Abstract: The recruitment pattern of Macrobrachium macrobrachion from Luubara creek in Ogoni land area
of Niger Delta region in Nigeria was studied for a period of twelve ca lendar mo nths (January - Dece mber,
2007). The recruitment pattern of M. macrobrachion showed that there were two peaks per year (a major one
in March w hile the second ary one w as in Au gust). How ever, there is a year round recruitment with the highest
recruitment in March (16.16%) while the lowest recruitment was in O ctober (0.42% ). The grow th parame ters
obtained for the recruited shrimps were L 4 = 88.01, K = 0.58, C = 0.05, WP = 0 and t0 = 0. C indicates the
amplitude of seasonal growth oscillations (that is, the magnitude of the growth patterns) and has values ranging
from 0 to 1. WP (winter point) indicates the time of the year during which gro wth is minim al for tem perate
species but may not be applicable for tropical species. Juveniles and females were observed in the creek
throughout the study period. Ovigerous females were also observed in the creek throughout the study period.
There were more females than males in the population and probably this allowed for con tinuou s replac eme nt.
Key words:
Luubara C reek, Macrobrachium macrobrachion, Niger Delta, Nigeria, Ogoni Land, recruitment
pattern
INTRODUCTION
The fresh water shrimp; Ma crob rach ium
macrobrachion belongs to the Phylum, Arthropoda;
Class, Crustacea; Subclass, Malacostraca; Series,
Eumalacostraca; Order, Decapoda; Suborder, Natantia;
Section, Caridea; Family, Palaemonida; Genus,
Macrobrachium; Sp., M. macrobrachion Pow ell (1980).
It can also be found in low salinity brackish water
(Pow ell, 1985).
The body is divid ed into three m ain divisions: the
head, thorax and abdom en. The h ead and thorax are
joined to form a cephalothorax, which carries the
mandibles, flagella, rostrum and the eyes containing a
stalk and has five pairs of walking legs. The abdomen has
six body segmen ts with the last segment bearing a uropod
or telson. The other five segments bear swimming
apparatus known as swimmerets. A definite feature of
Macrobrachium is that the second walking legs are
modified to form the che lae. Mo st species are
distinctively colored having either blue or brownish
colors. The legs also have definitive features such a s hairs
or furs.
Significant differences exist between the male and
female. Mature males are considerably larger than females
and the second walking leg is much thicker. The
cephalothorax is also proportionally larger in the male
than female while abdomen is narrower in the female. The
genital pores of the male are between the bases of the fifth
walking leg (New and S ingho lka, 1982). The female’s
genital pores situates at the base of the third walking legs.
The pleura of the abdomen are lower and broader in the
female than in the male. The pleura of the female form a
brood chamber in which the eggs are carried between
laying and hatching. A ripe ovige rous female can easily
be identified because the ovaries can be seen as large
orange-colored mass occupying a large portion of the
cephalothorax.
Holthius (1951) reported that M. macrobrachion
occurs from Senegal to Angola along the A tlantic C oast.
It is one o f major species of sh rimps occu rring in N igeria
and West Africa. It is found in dams, pools, creeks,
streams and rivers where the salinity allows for its growth.
Studies by Marioghae (1982) on M. macrobrachion in the
Lagos lagoon showed that the u pper limit of salinity was
12%. He observed that the shrimps migrate from the
estuaries to the freshwater in the peak of the dry season
when the salinity is high.
Apa rt from salinity, the physical attributes of the
substratum are considered to be one of the major factors
Corresponding Author: J.F.N. Abowei, Department of Biological Sciences, Faculty of Science, Niger Delta University,
Wilberforce Island, Amassoma, Bayelsa State, Nigeria
568
Res. J. Appl. Sci. Eng. Technol., 2(6): 568-573, 2010
controlling the distribution of shrimps (Khan et al., 1995).
Any change in the composition of the substratum may
affect the distribution. Ma rioghae (19 90) rep orted that it
constituted about 60% of the catch in Lagos lagoon of
Nigeria at a time. It is an important fisheries resource and
stock assessment studies by Enin (1995) showed that M.
macrobrachion was excessive ly harvested from the Cross
River estuary with an exploitation ratio of 0.68.
The gear used for collecting the shrimp is loca lly
known as “Kara”. It is cone shaped and has two nonreturn value mechanisms at the center of the trap. The trap
is constructed from either the blades of bamboo plant or
blades of raffia fronds which are woven around three
round frames made from cane. The total length of each
trap was between 0.95 and 1 m w hile the opening aperture
was between 25 and 30 cm.Fresh palm oil fruits were
used as bait to set the trap along the creek lets against the
water current.
Shrimps and prawns of the genus Macrobrachuim
and Penaeus are highly cherished by the people of the
Niger Delta. They are used as condiments in the
preparation of food because of their high protein value
(Umoh and Bassir, 1977; Deekae and Idoniboye-Obu,
1995). They are highly priced and are in high dem and in
the market (Marioghae, 1990). It has been observed that
there is significant reduction of the natural stock of
shrimps in our coastal waters (Nwosu, 2007). This may be
due to environmental degradation which is detrimental to
the abundance and life cycle of M. macrobrachion. Also,
there are few fishers n ow to exploit the available species
as a result of rural migration.
Recruitment is a complex process inv olving a chain
of events in the life cycle of the shrimp. Recruitment
occurs when an ag e group integrates itself for the first
time into the exploitable stock (Pitcher, 1982). It is more
or less a function of age (or size) when the juveniles grow
large enou gh to stay w ith the main body of adults.
Recruitment depends on where shrimp of catchable sizes
are located and to some extent this depends upon the kind
of gear and fishing boats used. Garcia and Reste (1981)
suggested four situations when shrimps can be said to be
recruited to the fishery:
C W hen the shrimps leave the nursery edges and
become accessible to artisanal fisheries.
C W hen they reach the large bays w here they are
accessible to small trawlers.
C During migration, when they are caught by fixed
nets.
C W hen they reach the sea and are caught by industrial
trawlers.
management of a fishery. It is necessary to know the sizes
(or age) which the shrimp get encountered with the
fishing gears so that the am ount of catch can be
controlled.
Recruitment can be a gradual process where the
young shrimp slowly migrate into deeper water as they
grow larger. There are situations where a whole cohort of
shrimp is recruited and leading to an early end of
recruitm ent. This type of recruitment is termed “Knifeedge recruitment”. It is common in small fishes and
shrimps (K ing, 19 95; A bow ei et al., 2006, 2008).
Recruitment patterns thus v ary co nsiderably in
shrimp species. Rec ruitment can easily be estimated using
such models as FAO ICLARM Stock Assessment Tool
(FISAT) (Gayanilo and Pauly, 199 7), analysis of the
length - frequency data of the shrimp available
(Sparre et al., 1989 ; Abowei et al., 2010) and by using
the electronic
frequency
analysis
(ELEFAN)
(Gayanilo et al., 1988; Ab owe i, 2010).
Various models have been used to describe the type
of curve, stock and recruitment relationships (Ricker
1954; Beverton and Holt, 1957). Pitcher (1982) stated that
Ricker (1954) recruitment model describes a family of
humped curves with low recruitment at high stock levels,
whereas the Beverton and Holt (1957) models covers a
family of asympto tic curves exhibiting constant
recruitm ent beyond a certain stock den sity.
The Ricker (1954) mod el implies strong den sity
dependence, increasing geometrically over a certain range
of stock densities whereas the Beverton and Holt (1957)
model implies an arithmetically progressive reduction in
the recruitment rate as stock density increases. Both
mod els can be used to describe the stock/recruitment
relationships of shrimp. The Ricker model is often applied
when strong density-dependent mechanisms operate (e.g.
cannibalism by adults o n fry) w hile the Beverto n and Holt
model is more applicable when a ceiling of recruit
abundance is imposed by available food or habitat or
when a predator continually adjusts its own attack rate to
changes in prey abundance. A study of The Recruitment
Pattern of Macrobrachium macrobrachion from Luubara
Creek in Ogoni Land w ill provide information for the
management of the sp ecies in the fishe ry and similar
water bodies.
MATERIALS AND METHODS
Study area: The study was carried out in Luubara creek
in Ogoni land area of Niger Delta region in Nigeria was
studied for a period of twelve calendar months (January Decembe r, 2007). The creek is a tributary of the Imo
River and is located between longitudes 7º15! E - 7º32! E
and latitudes 4º32 !- 4º37 ! N in the eastern part of the Niger
Delta. The upper part of the creek extends from Bori and
mean ders through Wiiyaakara, Luegbo, Duburo and joins
the Imo River at K alook o.
If a certain percentage of a shrimp population present
in an area is recruited, a recruitment curve can be obtained
if the percentages are plotted against the size of the
shrimp. Knowledge of recruitm ent is necessary for proper
569
Res. J. Appl. Sci. Eng. Technol., 2(6): 568-573, 2010
Table 1: Recruitment pattern of M . macrob rachion in Lu ubara creek
for 2007
Month
% Recruitment
Janu ary
12.97
Febru ary
11.32
March
16.16
Ap ril
14.87
May
12.14
June
7.80
July
5.74
Aug ust
9.43
September
5.41
October
0.42
Novem ber
3.73
December
0.00
The creek is divided into two distinct sections
brackish water and freshwater. The brackish water stretch
is between Bane and Kalooko while the freshwater stretch
extends from Bane to Bori. The brackish water area has
the normal mangrove vegetation comprising of trees such
as Rhizophora racemosa, Avecenia africana, Laguncularia
racemosa etc. whereas the freshwater has dense
vegetation comprising of large trees, various palms and
aquatic macrophytes at the low intertical zone. In
freshwater area are Cocos species, Eliasis species,
Nymph ea species, L emn a species an d Raffia species.
It is characterized by high ambient temperature
usua lly about 25.5ºC and above; high relative h umid ity
which fluctuates betw een 60 a nd 95% and high rainfall
averaging about 2500 mm (G ibo, 1988). This h igh rainfall
often increases the volume of water in the creek hence
providing good fishing opportunity for the residents.
Fishing is one of the major activities going on along the
creek because it is the main water route of the Khana
people in O goni area of the N iger D elta.
The fishes caught in the area include Chrysichthys
auratus, C. nigrodigitatus, Hydroc ynus forskalii, Clarias
gariepinus, Pellonula leonensis, Malapterurus, electricus,
Gymnarchus niloticus, Synodontis nigri Hepsetus odoe,
Hernichrom is, fasciatus, Tilapia zilli, Tilapia guine ensis;
Sarotherodon melanoth eron a nd Eleotris se negalensis
and shellfish (crabs and shrimps) especially Uca tangeri
Callinectes amnicola , Goniopsis pelli, Cardisoma
armatum M. macrobrachion, M. vollenhoveni, M.
equidens; Palaemonetes africanus; Caridina africana and
Desm ocaris tripisnosa.
the first body segment) was measured with a Vernier
caliper to the nearest 0.1 mm. The shrimps were then
weighed with an Ohaus balance to the nearest 0.1 g.
Measurements were taken for each m onthly collection and
recorded accordingly.
The size at sexu al maturity (Lm) was determined for
the females as sug gested by King (1995) w ith for formula:
P = 1/(1 + exp [-r (L - Lm )]
where;
P
=
L
=
r
=
Lm =
(1)
Proportion o f sexually mature individu als
Length of fish (shrimp)
Slope of curve
Mean length at sexual maturity or the length
which correspond to a proportion of 0.05 (or
50%) in reproductive condition.
The length at first capture (Lc) was obtained
according to the formula of King (1995) as follows:
Specimen sampling: The shrimp samples were collected
fortnigh tly from three stations along the creek: name ly
W iiyaakara, Luegbo and Duburo. Selection of the stations
was purposefully based on fishing activities, ecological
zonation and accessibility of site. For each station five
fishermen were engaged and three traps were used. At
each station the fisher men set the three sets of traps
against the water current among aquatic macrophytes and
left them overnight. The traps were retrieved the
following day after about twe lve ho urs correspo nding to
another low tide. The shrimps collected at each station
were sorted into male and female; females were later
separated into berried (ovigerous) and non-berried (nonovigerous). Sampling lasted for twenty-three months from
January 2006 to November 2007. The shrimp samples
were then preserved in 4% formaldehyde and transported
to the RSU ST F isheries laboratory for analysis after each
day’s sampling. The species was identified by use of the
keys of Powe ll (1980, 1982 ) and H olthius (1980).
For each shrimp th e Total length (the distance from
the tip of the rostrum to the end of telson) and the
carapace length (the distance from the base of rostrum to
P = 1/(1 + exp [-r (L - Lc)
where;
P =
L =
r
=
Lc =
(2)
Probab ility of capture
Length of fish (shrimp)
Slope of curve
Mean length at first capture (or point at which
50% of fish (shrimp) has chance of being retained
by net (trap) or 0.5 probability of being caught).
The recruitment pattern of the shrimps was estimated
by using the FiSAT programme (Gayanilo and Pauly,
1997). In this method recruitment patterns was analyzed
by fitting the frequency data for each month and pooling
them toge ther for each year.
RESULTS
Recruitment pattern estimated during the study
is given in Table 1. Th e recruitment pattern of
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Res. J. Appl. Sci. Eng. Technol., 2(6): 568-573, 2010
shrimps are recirculated throughout the year but seasonal
variations occur.
For instanc e Garcia (1985) and Reste (1978) reported
that penaeid shrimps were more ab undan t in the dry
season than in the wet season. They observed that
annual migration of Penaeus duorarum, (P. notialis) and
P. setiferus was related to the rise in temperature in the
dry season and consequently high recruitment during this
period. Enin (1995) reported a year round recruitment for
M. macrobrachion in Cro ss River estu ary. W ith two
peaks in the months of December and June.
W aribugo (2005) reported that recruitment of
Nematopalacmon hastuius in the R iver Nun estuary had
two peaks which occurred in the months of July and
Nov embe r. She also reported two peaks of recruitment for
Palaemon maculatus which occurred in the months of
September and February equivalent to rainy season and
early dry season, respectively.
Fig. 1: Recruitment pattern of M. macrobrachion in Luubara
creek (2007)
M. macrobrachion (Fig. 1) showed that there were two
peaks per year (a m ajor one in M arch w hile the second ary
one was in August). However, there is a year round
recruitment with the highest recruitment in March
(16.16%) while the low est recruitment was in October
(0.42% ).
The growth parameters obtained for the recruited
shrimps were L 4 = 88.01, K = 0.58, C = 0.05, WP = 0
and t0 = 0. C indicates the amplitude of seasona l grow th
oscillations (that is, the magnitude of the growth patterns)
and has values rangin g from 0 to 1. WP (winter point)
indicates the time of the year du ring w hich g rowth is
minimal for temperate species but may not be applicable
for tropical spec ies.
Juveniles and females were observed in the creek
throughout the study period. Ovigerous females were also
observed in the creek throug hout the study period. There
were more females than males in the population and
probably this allow ed for continu ous replacemen t.
CONCLUSION
C
C
C
C
C
C
The recruitment pattern of M. macrobrachion
showed two peaks in the year similar to other study
reports.
Recruitment w as all year roun d.
The growth parameters indicated the amplitude of
seasonal growth oscillations.
Juveniles and females were present in the creek
througho ut the year.
Ovigerous females were also present in the creek
througho ut the year.
There were more females than males in the
population and probably this allowed for continuous
replaceme nt.
ACKNOWLEDGMENT
DISCUSSION
W e are grateful to God Almighty for the strength,
knowledge and wisd om in researching and w riting this
article. W e also thank our numerous colleques, friends,
wives and students whose names are too nume rous to
mention here due to space but contributed immensely to
the success of this w ork.
The presence of berried females throughout the year
observed in the Luubara creek suggests that recruitment
of M. macrobrachion was continuous and that breeding
activity is all year round. In fact, Sastry (1983) observed
that shrimps exhibit various spawning patterns depending
on the geographical location. Consequently, majority of
tropical shrimps shows several spawning peaks per year.
This trend has also b een reported for M.
macrobrachion (M ariogh ae an d A yinla, 1995),
Macrobrachium olfersi (Mossolin and Bueno, 2002), Atya
Scabra (Galvao and Bueno, 1999), Rimapenaeus
constrictus (Costa and Fransozo, 2004a, b) and in the
spine shrimp Exppolysmata oplophoroides (Fransozo
et al., 2005). There were more females than males in the
population and probably this allowed for continuous
replacement of population hence Luubara creek may be a
breeding / nursery ground for the species. In most cases
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