Research Journal of Applied Sciences, Engineering and Technology 2(6): 568-573, 2010 ISSN: 2040-7467 © Maxwell 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

1S.N. Deekae and 2J.F.N. Abowei 1Department of Fisheries and Aquatic Environment, Faculty of Agriculture, Rivers State University of Science and Technology, Port Harcourt, Rivers State, Nigeria 2Department of Biological Sciences, Faculty of Science, Niger Delta University, Wilberforce Island, Amassoma, Bayelsa State, Nigeria

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 calendar months (January - December, 2007). The recruitment pattern of M. macrobrachion showed that there were two peaks per year (a major one in March while the secondary one was in August). However, there is a year round recruitment with the highest recruitment in March (16.16%) while the lowest recruitment was in October (0.42%). The growth parameters 4 obtained for the recruited shrimps were L = 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 growth is minimal for temperate 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 continuous replacement.

Key words: Luubara Creek, Macrobrachium macrobrachion, Niger Delta, Nigeria, Ogoni Land, recruitment pattern

INTRODUCTION and the second walking leg is much thicker. The cephalothorax is also proportionally larger in the male The fresh water shrimp; Macrobrachium than female while abdomen is narrower in the female. The macrobrachion belongs to the Phylum, Arthropoda; genital pores of the male are between the bases of the fifth Class, Crustacea; Subclass, ; Series, walking leg (New and Singholka, 1982). The female’s Eumalacostraca; Order, ; Suborder, Natantia; genital pores situates at the base of the third walking legs. Section, Caridea; Family, Palaemonida; Genus, The pleura of the abdomen are lower and broader in the Macrobrachium; Sp., M. macrobrachion Powell (1980). female than in the male. The pleura of the female form a It can also be found in low salinity brackish water brood chamber in which the eggs are carried between (Powell, 1985). laying and hatching. A ripe ovigerous female can easily The body is divided into three main divisions: the be identified because the ovaries can be seen as large head, thorax and abdomen. The head and thorax are orange-colored mass occupying a large portion of the joined to form a cephalothorax, which carries the cephalothorax. mandibles, flagella, rostrum and the eyes containing a Holthius (1951) reported that M. macrobrachion stalk and has five pairs of walking legs. The abdomen has occurs from Senegal to Angola along the Atlantic Coast. six body segments with the last segment bearing a uropod It is one of major species of shrimps occurring in Nigeria or telson. The other five segments bear swimming and West Africa. It is found in dams, pools, creeks, apparatus known as swimmerets. A definite feature of streams and rivers where the salinity allows for its growth. Macrobrachium is that the second walking legs are Studies by Marioghae (1982) on M. macrobrachion in the modified to form the chelae. Most species are Lagos lagoon showed that the upper limit of salinity was distinctively colored having either blue or brownish 12%. He observed that the shrimps migrate from the colors. The legs also have definitive features such as hairs estuaries to the freshwater in the peak of the dry season or furs. when the salinity is high. Significant differences exist between the male and Apart from salinity, the physical attributes of the female. Mature males are considerably larger than females 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). management of a fishery. It is necessary to know the sizes Any change in the composition of the substratum may (or age) which the shrimp get encountered with the affect the distribution. Marioghae (1990) reported that it fishing gears so that the amount of catch can be constituted about 60% of the catch in Lagos lagoon of controlled. Nigeria at a time. It is an important fisheries resource and Recruitment can be a gradual process where the stock assessment studies by Enin (1995) showed that M. young shrimp slowly migrate into deeper water as they macrobrachion was excessively harvested from the Cross grow larger. There are situations where a whole cohort of River estuary with an exploitation ratio of 0.68. shrimp is recruited and leading to an early end of The gear used for collecting the shrimp is locally recruitment. This type of recruitment is termed “Knife- known as “Kara”. It is cone shaped and has two non- edge recruitment”. It is common in small fishes and return value mechanisms at the center of the trap. The trap shrimps (King, 1995; Abowei et al., 2006, 2008). is constructed from either the blades of bamboo plant or Recruitment patterns thus vary considerably in blades of raffia fronds which are woven around three shrimp species. Recruitment can easily be estimated using round frames made from cane. The total length of each such models as FAO ICLARM Stock Assessment Tool trap was between 0.95 and 1 m while the opening aperture (FISAT) (Gayanilo and Pauly, 1997), analysis of the was between 25 and 30 cm.Fresh palm oil fruits were length - frequency data of the shrimp available used as bait to set the trap along the creek lets against the (Sparre et al., 1989; Abowei et al., 2010) and by using water current. the electronic frequency analysis (ELEFAN) Shrimps and prawns of the genus Macrobrachuim (Gayanilo et al., 1988; Abowei, 2010). and Penaeus are highly cherished by the people of the Various models have been used to describe the type Niger Delta. They are used as condiments in the of curve, stock and recruitment relationships (Ricker preparation of food because of their high protein value 1954; Beverton and Holt, 1957). Pitcher (1982) stated that (Umoh and Bassir, 1977; Deekae and Idoniboye-Obu, Ricker (1954) recruitment model describes a family of humped curves with low recruitment at high stock levels, 1995). They are highly priced and are in high demand in whereas the Beverton and Holt (1957) models covers a the market (Marioghae, 1990). It has been observed that family of asymptotic curves exhibiting constant there is significant reduction of the natural stock of recruitment beyond a certain stock density. shrimps in our coastal waters (Nwosu, 2007). This may be The Ricker (1954) model implies strong density due to environmental degradation which is detrimental to dependence, increasing geometrically over a certain range the abundance and life cycle of M. macrobrachion. Also, of stock densities whereas the Beverton and Holt (1957) there are few fishers now to exploit the available species model implies an arithmetically progressive reduction in as a result of rural migration. the recruitment rate as stock density increases. Both Recruitment is a complex process involving a chain models can be used to describe the stock/recruitment of events in the life cycle of the shrimp. Recruitment relationships of shrimp. The Ricker model is often applied occurs when an age group integrates itself for the first when strong density-dependent mechanisms operate (e.g. time into the exploitable stock (Pitcher, 1982). It is more cannibalism by adults on fry) while the Beverton and Holt or less a function of age (or size) when the juveniles grow model is more applicable when a ceiling of recruit large enough to stay with the main body of adults. abundance is imposed by available food or habitat or Recruitment depends on where shrimp of catchable sizes when a predator continually adjusts its own attack rate to are located and to some extent this depends upon the kind changes in prey abundance. A study of The Recruitment of gear and fishing boats used. Garcia and Reste (1981) Pattern of Macrobrachium macrobrachion from Luubara suggested four situations when shrimps can be said to be Creek in Ogoni Land will provide information for the recruited to the fishery: management of the species in the fishery and similar C When the shrimps leave the nursery edges and water bodies. become accessible to artisanal fisheries. C When they reach the large bays where they are MATERIALS AND METHODS accessible to small trawlers. C During migration, when they are caught by fixed Study area: The study was carried out in Luubara creek nets. in Ogoni land area of Niger Delta region in Nigeria was C When they reach the sea and are caught by industrial studied for a period of twelve calendar months (January - trawlers. December, 2007). The creek is a tributary of the Imo River and is located between longitudes 7º15! E - 7º32! E If a certain percentage of a shrimp population present and latitudes 4º32!- 4º37! N in the eastern part of the Niger in an area is recruited, a recruitment curve can be obtained Delta. The upper part of the creek extends from Bori and if the percentages are plotted against the size of the meanders through Wiiyaakara, Luegbo, Duburo and joins shrimp. Knowledge of recruitment is necessary for proper the Imo River at Kalooko.

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The creek is divided into two distinct sections Table 1: Recruitment pattern of M. macrobrachion in Luubara creek brackish water and freshwater. The brackish water stretch for 2007 Month % Recruitment is between Bane and Kalooko while the freshwater stretch January 12.97 extends from Bane to Bori. The brackish water area has February 11.32 the normal mangrove vegetation comprising of trees such March 16.16 as Rhizophora racemosa, Avecenia africana, Laguncularia April 14.87 racemosa etc. whereas the freshwater has dense May 12.14 June 7.80 vegetation comprising of large trees, various palms and July 5.74 aquatic macrophytes at the low intertical zone. In August 9.43 freshwater area are Cocos species, Eliasis species, September 5.41 Nymphea species, Lemna species and Raffia species. October 0.42 November 3.73 It is characterized by high ambient temperature December 0.00 usually about 25.5ºC and above; high relative humidity which fluctuates between 60 and 95% and high rainfall the first body segment) was measured with a Vernier averaging about 2500 mm (Gibo, 1988). This high rainfall caliper to the nearest 0.1 mm. The shrimps were then often increases the volume of water in the creek hence weighed with an Ohaus balance to the nearest 0.1 g. providing good fishing opportunity for the residents. Measurements were taken for each monthly collection and Fishing is one of the major activities going on along the recorded accordingly. creek because it is the main water route of the Khana The size at sexual maturity (Lm) was determined for people in Ogoni area of the Niger Delta. the females as suggested by King (1995) with for formula: The fishes caught in the area include Chrysichthys auratus, C. nigrodigitatus, Hydrocynus forskalii, Clarias P = 1/(1 + exp [-r (L - Lm)] (1) gariepinus, Pellonula leonensis, Malapterurus, electricus, Gymnarchus niloticus, Synodontis nigri Hepsetus odoe, where; Hernichromis, fasciatus, Tilapia zilli, Tilapia guineensis; P = Proportion of sexually mature individuals Sarotherodon melanotheron and Eleotris senegalensis L = Length of fish (shrimp) and shellfish (crabs and shrimps) especially Uca tangeri r = Slope of curve Callinectes amnicola, Goniopsis pelli, Cardisoma Lm = Mean length at sexual maturity or the length armatum M. macrobrachion, M. vollenhoveni, M. which correspond to a proportion of 0.05 (or equidens; Palaemonetes africanus; Caridina africana and 50%) in reproductive condition. Desmocaris tripisnosa. The length at first capture (Lc) was obtained Specimen sampling: The shrimp samples were collected according to the formula of King (1995) as follows: fortnightly from three stations along the creek: namely Wiiyaakara, Luegbo and Duburo. Selection of the stations P = 1/(1 + exp [-r (L - Lc) (2) was purposefully based on fishing activities, ecological zonation and accessibility of site. For each station five where; fishermen were engaged and three traps were used. At P = Probability of capture each station the fisher men set the three sets of traps L = Length of fish (shrimp) against the water current among aquatic macrophytes and r = Slope of curve left them overnight. The traps were retrieved the Lc = Mean length at first capture (or point at which following day after about twelve hours corresponding to 50% of fish (shrimp) has chance of being retained another low tide. The shrimps collected at each station by net (trap) or 0.5 probability of being caught). were sorted into male and female; females were later separated into berried (ovigerous) and non-berried (non- The recruitment pattern of the shrimps was estimated ovigerous). Sampling lasted for twenty-three months from by using the FiSAT programme (Gayanilo and Pauly, January 2006 to November 2007. The shrimp samples 1997). In this method recruitment patterns was analyzed were then preserved in 4% formaldehyde and transported by fitting the frequency data for each month and pooling to the RSUST Fisheries laboratory for analysis after each them together for each year. day’s sampling. The species was identified by use of the keys of Powell (1980, 1982) and Holthius (1980). RESULTS For each shrimp the Total length (the distance from the tip of the rostrum to the end of telson) and the Recruitment pattern estimated during the study carapace length (the distance from the base of rostrum to is given in Table 1. The recruitment pattern of

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shrimps are recirculated throughout the year but seasonal variations occur. For instance Garcia (1985) and Reste (1978) reported that penaeid shrimps were more abundant 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 Cross River estuary. With two peaks in the months of December and June. Waribugo (2005) reported that recruitment of Nematopalacmon hastuius in the River Nun estuary had Fig. 1: Recruitment pattern of M. macrobrachion in Luubara two peaks which occurred in the months of July and creek (2007) November. She also reported two peaks of recruitment for Palaemon maculatus which occurred in the months of M. macrobrachion (Fig. 1) showed that there were two September and February equivalent to rainy season and peaks per year (a major one in March while the secondary early dry season, respectively. one was in August). However, there is a year round recruitment with the highest recruitment in March CONCLUSION (16.16%) while the lowest recruitment was in October (0.42%). C The recruitment pattern of M. macrobrachion The growth parameters obtained for the recruited showed two peaks in the year similar to other study shrimps were L4 = 88.01, K = 0.58, C = 0.05, WP = 0 reports. and t0 = 0. C indicates the amplitude of seasonal growth C Recruitment was all year round. oscillations (that is, the magnitude of the growth patterns) C The growth parameters indicated the amplitude of and has values ranging from 0 to 1. WP (winter point) seasonal growth oscillations. indicates the time of the year during which growth is C Juveniles and females were present in the creek minimal for temperate species but may not be applicable throughout the year. for tropical species. C Ovigerous females were also present in the creek Juveniles and females were observed in the creek throughout the year. throughout the study period. Ovigerous females were also C There were more females than males in the observed in the creek throughout the study period. There population and probably this allowed for continuous were more females than males in the population and replacement. probably this allowed for continuous replacement. ACKNOWLEDGMENT DISCUSSION We are grateful to God Almighty for the strength, The presence of berried females throughout the year knowledge and wisdom in researching and writing this observed in the Luubara creek suggests that recruitment article. We also thank our numerous colleques, friends, of M. macrobrachion was continuous and that breeding wives and students whose names are too numerous to activity is all year round. In fact, Sastry (1983) observed mention here due to space but contributed immensely to that shrimps exhibit various spawning patterns depending the success of this work. on the geographical location. Consequently, majority of tropical shrimps shows several spawning peaks per year. REFERENCES This trend has also been reported for M. macrobrachion (Marioghae and Ayinla, 1995), Abowei, J.F.N., S.N. Deekae., M.E. Allison, C.C. Tawari Macrobrachium olfersi (Mossolin and Bueno, 2002), Atya and S.A. Ngodigha, 2006. A review of shrimp Scabra (Galvao and Bueno, 1999), fishery in Nigeria. Pre-Joe Publishers, Port Harcourt, constrictus (Costa and Fransozo, 2004a, b) and in the pp: 53. spine shrimp Exppolysmata oplophoroides (Fransozo Abowei, J.F.N., A.O. Davies and S.A. Ngodigha, 2008. et al., 2005). There were more females than males in the The recruitment patterns of two palaemon shrimps population and probably this allowed for continuous and some physicochemical characteristics in the replacement of population hence Luubara creek may be a River Estuary, Nigeria. Int. J. Nat. Appl. Sci., 4(4): breeding / nursery ground for the species. In most cases 396-401.

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