vol 2 - cont. j. fisheries and aquatic sci

8/9/2019 Vol 2 - Cont. J. Fisheries and Aquatic Sci.

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Continental J. Fisheries and Aquatic Science 2: 1 - 5, 2008

Wilolud Online Journals, 2008.

LENGTH-WEIGHT RELATIONSHIP OF BENTHIC BIVALVES OF THE ANDONI FLATS, NIGER DELTA,

NIGERIA

1Ansa, E. J.,

2Allison, M. E.

1. African Regional Aquaculture Centre/Nigerian Institute for Oceanography and Marine Research, Buguma,

P.M.B. 5122, Port Harcourt, Nigeria.

2. Dept of Fisheries, Niger Delta University, Wilberforce Island, Bayelsa State, Nigeria.

ABSTRACT

The length weight relationship of three benthic bivalves namely, Senilia (= Anadara) senilis

(bloody cockle), Tagelus adansonii (knife clam), Tellina nymphalis (soft shell clam) from the

Andoni Flats were determined. The bivalves which are of ecological importance were

obtained from the intertidal areas of the Andoni Flats. Shell lengths of the bivalves were

measured and corresponding dry weight measurements were also taken. The data obtained

were then subjected to regression analysis using the FAO-ICLARM Fish Stock Assessment

Tools (FiSAT). The length weight relationships obtained from the FiSAT analysis indicated

isometric growth for Senilia (= Anadara) senilis, with slope (b) value of 2.942; positive

allometric growth for Tagelus adansonii, with a b value of 3.395 and negative allometric

growth for Tellina nymphalis with b value of 2.633.

KEYWORDS: bivalves, length-weight, isometric growth, allometric growth, cockle, clam.

INTRODUCTION

Length-weight relationships are useful tools in fisheries research because they can be used in converting length in

weight or in the estimation of biomass from length observations, and in comparing life histories of species in

different regions (Stergiou and Moutopoulos 2001; Park and Oh, 2002). Several studies have been carried out in thisregard for fin-fish species (King, 1991; King, 1996a and b; Cucalon Zenck, 1999; Kleanthidis et al, 1999; Nasser,

1999; Bernardes and Rossi Wongtschowski, 2000; Muto et al., 2003); but there is a dearth of information on

length-weight relationships in shellfish and bivalves in particular from Nigerian waters. Length-weight relationships

of bivalves collected from the southwest coast of Korea were determined by Park and Oh (2002). The data obtained

showed that estimates of b ranged from 2.44 in Atrina (servatina) pinnata japonica to 3.31 in Scaphora

broughtonii; with a mean value of 2.89 0.212. Out of 17 species reported, nine exhibited isometric growth patterns

at 95% confidence limit.

Three species of benthic bivalves of the Andoni Flats, in the Niger Delta were studied in order to provide

information on their length-weight relationship, namely:

a) Senilia (=Anadara) senilis bloody cockle

b) Tagelus adansonii (knife clam)

c) Tellina nymphalis (soft shell clam)

MATERIALS AND METHODS

Study Area

Live specimens of three bivalves (Senilia senilis, Tagelus adansonii and Tellina nymphalis) were obtained from the

intertidal zone of the Andoni Flats. The area is a brackish water habitat characterized by tides, mangroves, several

species of fin and shellfish. Specimens were handpicked from sediments in randomly sampled areas; washed with

water from the creek and preserved in 5% buffered formalin.

Morphometric Measurements and Growth Conversions

Specimens of bivalves, obtained were measured to determine the following morphometric parameters:


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Ansa, E. J and Allison, M. E: Continental J. Fisheries and Aquatic Science 2: 1 - 5, 2008

a) Shell length in mm determined with the aid of a pair of Vernier calipers, model: mechanic type 6911.b) Dry weight in g determined after oven drying specimen for 72 h at a temperature of 60C till constant

weight and measured with Sartorius balance model BP 310S.

Length-weight conversions were then calculated for the different species using the log transformation of the

regression.

W = aLb

(Winberg, 1971)

Where L = length, W = weight, a = constant, b = exponent

Using the FAO-ICLARM Fish Stock Assessment Tools (FiSAT) the relationship between length and dry weight

were calculated and graphs constructed to show the regressions.

Fig. 1: Length dry weight relationship ofSenilia senilis in the Andoni Flats

RESULTS AND DISCUSSION

The growth relationships ofSenilia senilis, Tagelus adansonii and Tellina nymphalis, are shown in Figures 1 to 3;

corresponding values of intercept, slope, standard deviations and coefficient of determination are presented in Table

1. The regression analyses for length-weight relationships were statistically significant at p < 0.01 for Senilia senilisand Tagelus adansonii and p < 0.05 for Tellina nymphalis.

Values of b (Table 1) for Senilia senilis, Tagelus adansonii and Tellina nymphalis were 2.942, 3.395 and 2.633

respectively. Isometric growth pattern was observed in Senilia senilis; similar growth pattern was reported for an

arcid clam Scapharca subcrenata from the coastal waters of Korea (Park and Oh, 2002). From our study positive

allometric growth was observed in Tagelus adansonii while negative allometric growth was observed in Tellina

nymphalis. Similar growth patterns were also reported by Park and Oh (2002) for the arcid clams Scapharca

broughtonii and Tegillarca granosa showing positive allometric growth and negative allometric growth

respectively.

Lo

(d

r

weiht

)

LogW= -3.334+2.942Log L

r = 0.999

Log (shell length mm)


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Fig. 2: Length dry weight relationship ofTagelus adansonii in the Andoni Flats

Fig. 3: Length dry weight relationship ofTellina nymphalis in the Andoni Flats

0

-2

-3Log(dryweightg)


LogW= -5.096+3.395Log L

r = 0.997


Lo

(d

r

weiht

)

LogW= -3.978+2.633Log L

r = 0.994


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Table 1: Regression Analysis of Length Weight Relationships of Three Benthic Bivalves from the Andoni Flats,

Niger Delta.

Species Intercept a S.D.

of a

Confidence

interval of a

Slope

b

S.D.

of b

Confidence

interval of b

r r2

Confidence

interval of

r

Senilia

senilis

-3.334 0.036 -3.408

to

-3.259

2.942 0.032 2.877

to

3.008

0.999 0.997 0.997

to

0.999

Tagelus

adansonii

-5.096 0.075 -5.264

to

-4.928

3.395 0.077 3.224

to

3.565

0.997 0.995 0.991

to

0.999

Tellinanymphalis -3.978 0.075 -4.136to

-3.821

2.633 0.069 2.487to

2.779

0.994 0.988 0.984to

0.998

REFERENCES

Bernardes R. A. and Rossi Wongtschowski C.L.D.B. (2000). Length weight relationship of small pelagic fish

species of the southeast and south Brazilian exclusive economic zone. Naga, The ICLARM Quarterly. 23(4): 27

29.

Cucaln Zenck E. (1999). Growth and length weight parameters of pacific mackerel (Scomber japonicus) in the

Gulf of Guayaquil, Ecuador.Naga, The ICLARM Quarterly. 22 (3): 32 36.

King R.P. (1991). The biology ofTilapia mariae Boulenger, 1899 (Perciformes: Cichlidae) in a Nigerian rainforest

stream. Ph. D Thesis, University of Port Harcourt. 237pp.

King R.P. (1996a). Length weight relationships of Nigerian freshwater fishes.Naga, The ICLARM Quarterly. 19

(3): 49 52.

King R.P. (1996b). Length weight relationships of Nigerian coastal water fishes.Naga, The ICLARM Quarterly.

19 (4): 53 55.

Kleanthidis P.K., Sinis A.I., Stergiou, K.I.(1999). Length weight relationships of freshwater fishes in Greece.

Naga, The ICLARM Quarterly. 22 (4): 37 41.

Muto E.Y., Soares L.S.H., Rossi Wongtschowski C.L.D.B. (2000). Length weight relationship of small pelagic

fish species of the southeast and south Brazilian exclusive economic zone.Naga, The ICLARM Quarterly. 23(4): 27

29.

Nasser A.K.V. (1999). Length weight relationships of tuna baitfish from the Lakshadweep Islands, India.Naga,

The ICLARM Quarterly. 22 (4): 42 48.

Park K.Y. and Oh C.W. (2002). Length weight relationship of bivalves from coastal waters of Korea.Naga, The

ICLARM Quarterly. 25 (1): 21 22.

Stergiou K.I. and Moutopoulos D.K. (2001). A review of length weight relationships of fishes from Greek

Marine waters.Naga, The ICLARM Quarterly. 24 (1&2): 23 39.

Winberg G. (1971). Methods for the estimation of production of aquatic animals. Translated from the Russian by

Annie Duncan. Academic Press. London and New York. 175p.


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Received for Publication: 17/05/2008Accepted for Publication: 15/06/2008

Corresponding Author

Ansa, E. J.

African Regional Aquaculture Centre/Nigerian Institute for Oceanography and Marine Research, Buguma, P.M.B.

5122, Port Harcourt, Nigeria.


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A MESOCOSM ANALYTICAL STUDY ON THE IMPACT OF FRESHWATER MUSSEL

(LAMELLIDENS MARGINALIS LAMARCK) MEDIATED BIOTURBATION AND BIODEPOSITION ON

SOME ECOLOGICAL FACTORS OF A FRESHWATER LAKE

P. Jayakumar, N. Jothivel, A. Thimmappa and V.I. Paul

Department of Zoology, Annamalai University, Annamalainagar 608 002, Tamil Nadu, India.

ABSTRACT

The biotic potential of the benthic filter feeding freshwater bivalve mollusc Lamellidens

marginalis (Lamarck) influencing the nutrient dynamics of the bottom sediments of the lake by

means of biodeposition and bioturbation activities were analysed using a lake mesocosm

experiment. Five control as well as experimental mesocosms was maintained up to 60 days (d).The factors studied included the percentage of water content of the sediment, percentage of total

nitrogen, percentage of organic matter along with the total phosphorus and humic acid content.

While total phosphorus and humic acid content of the experimental mesocosoms showed gradual

and significant increases from 30d of the experiment to reach the maximum levels after 60d, the

percentage of organic matter registered significant increases right from 15d onwards and reached

the maximum values after 60d. On the other hand, while the percentage of water content of the

sediments of the experimental mesocosoms increased only up to 30d experiment, percentage of

nitrogen was increased during the first half and at the fag end of the experiment. All the

investigated ecological factors were found to be significantly influenced by the presence ofL.

marginalis in the experimental mesocosms. The study indicated that the mussel influence the

nutrient dynamics of the inhabitant ecosystem through the processes of excretion, biodeposition of

pseudofaeces and faeces, along with the bioturbation of the sediments brought about by their

ploughing movements.

KEYWORDS: freshwater mussel, Lamellidens marginalis, bioturbation, biodeposition,mesocosms.

INTRODUCTION

The freshwater mussel (Lamellidens marginalis Lamarck) is a benthic filter feeding organism and is continuously

exposed to the water, suspended particles in the water column and bottom sediments. The biotic potential ofL.

marginalis even though largely remains un-attended, plays very important roles in the ecosystem functions.

According to Vaughn and Hakenkemp (2001), freshwater bivalves have the potential to strongly influence the

ecosystem processes in freshwater systems. This also holds true with L. marginalis because of their characteristicfilter feeding and ploughing movements through the bottom sediments. While filter feeding is an important means of

removing particles including plankton suspended in the water column (Widmeyer and Bendell-Young, 2007) and

biodepositing it to the bottom sediments as faeces and mucous bound pseudofaeces, the ploughing movements and

burrowing activity brings in active bioturbation of the medium leading to sediment mixing, improved oxygen

penetration and affects other ecological functions. Due to all these activities mussels can repackage nutrients andact as a nutrient source for other benthic organisms (Christian et al., 2008).

Unionid mussels are historically important bioturbating macrobenthic organisms and as they can move and disturb

large amounts sediments, they may be designated as biological bull dozers. They reportedly burrow themselves

and mix the bottom sediments (Vaughn and Hakenkemp, 2001). The digging and burrowing activities of L.

marginalis leading to the bioturbation of the bottom sediments is a form of ecosystem engineering. However,

according to Vaughn and Hakenkemp (2001), uncertainty over the extent and importance of sediment-related

ecological processes performed by bivalves represent the most significant gap in our understanding of the role of

burrowing bivalves in freshwater ecosystems. The influence of bioturbators in altering the conditions at the sediment

water interface is reported to be due to the biogenic mixing of sediments (Christian et al., 2004; Solan et al., 2004;

De Haas et al., 2005). In this context, attempts have been made in this work to understand the ecological importance

of bioturbation and biodeposition by the freshwater musselL. marginalis through a lake mesocosm experiment.


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P. Jayakumar et al: Continental J. Fisheries and Aquatic Science 2: 6 - 12, 2008

Table 1. Sediment sampling schedule for the control and experimental mesocosms after the expiry of 15, 30, 45 and60 days

To be sampled from the control

mesocosm

Parameter To be sampled from the experimental

mesocosm

C1 C2 C3 % Water content E1 E2 E3

C2 C3 C % Total nitrogen E2 E3 E

C3 C C5 % Organic matter E3 E E5

C C5 C1 Total phosphorus E E5 E1

C5 C1 C2 Humic acid E5 E1 E2

Note: Three samples each were taken from each of the mesocosm on each sampling interval


Setting up of mesocosm

In order to study the influence of bioturbation and biodeposition by the freshwater mussel L. marginalis on selectedecological factors of the freshwater lake ecosystem, a lake mesocosm experiment was done in the Srinivasapuram

lake (10 ha. area) in the Denkanikottai taluk of Krishnagiri district, Tamilnadu, India. Setting up of the mesocosms

was done in the month of February 2008 and was maintained up to May 2008. Altogether ten plastic mesocosms

were setup. Five of them (viz., C1 to C5) were used as controls and the remaining five (viz., E1 to E5) were used as

experimental mesocosms. A distance of about 5 m was maintained between the mesocosms and the duration of the

experiment was 60 days (d).

Each plastic mesocosm was having a diameter of 87.2 and 100 cm height. They were fixed in the shallow region of

the lake in such a way that each of them contained about 30 cm of fine sediments of the lake bottom, carefully

avoiding any unaccounted L. marginalis, other macro invertebrate fauna or fish. However, the benthic infaunal

invertebrates of the lake bottom viz., nematodes, oligochaetes, chironomids and small snails of 2 to 3 mm size along

with the soil bacteria were left undisturbed both in the control as well as experimental mesocosms. In the present

study, even though a sediment depth of 30 cm was maintained, L. marginalis was never found burrowing below 7

cm. Each of the mesocosms was provided with 32 holes (2 cm dia.) above the sediment level and was covered with a

nylon net having about 4 mm2

mesh to allow the free flow of water and movement of other infaunal benthic micro

invertebrates while preventing the entry of fishes and other macro invertebrates. The top of each mesocosm was

about 10 to 13 cm above the water surface and each of them had a sediment surface area of 0.6 m2. In this

condition, all the mesocosms were allowed to equilibrate with the surroundings for 10 days before the introduction

of the mussels.

Test organism and their maintenance

Freshwater mussels (L. marginalis) having a body weight of 31 1.62 g, 7 0.53 cm length and 3 0.5 cm breadth

were collected from the same lake. The shells were cleaned in the lake water and they were introduced into the

experimental mesocosms (E1 to E5) at the rate of eight mussels m-2

i.e., five mussels per mesocosm. The rate of

introduction is based on the fact that on average eight mussels m-2

were obtained on most of the occasions of mussel

collection from the lake. No mussels were introduced into the mesocosms, which severed as controls (C1 to C5). All

the mesocosms were maintained up to 60d and no mortality of mussels were seen during the period.Physico-chemical properties of lake water

The ambient lake water was having an average dissolved oxygen content of 6.3 0.3 ppm, pH 7.5 0.2; water

temperature 26 2 C; total alkalinity 72 8 ppm and total hardness 142 12 ppm. More detailed analysis was not

carried out as the experiment involved only comparative assessment between control and experimental mesocosms

maintained in the same ambient water.

Sediment sampling

In order analyse the selected abiotic ecological factors of the bottom sediment as well as to maintain consistency,

three sediment samples each were taken from each of the mesocosms at each sampling interval as scheduled in the

Table 1. Sampling was done separately from the experimental as well as control mesocosms after the expiry of


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15, 30, 45 and 60d using a core samples of 5 cm diameter and up to a depth of 6 cm. The collected samples wereprocessed separately for each of the parameter as given below.

Table 2. One-way analysis of variance showing significant alterations in the percentage of water content of the

sediment, percentage of organic matter, percentage of total nitrogen, total phosphorus and humic acid content of the

bottom sediment of mesocosms at different intervals of the experiment

Source Sum square

(ss)

df Mean square

(ms)

F P

Percentage of water content in the sedimentTotal 287.81 14

Between groups 279.44 04 69.86 83.46 < 0.001

Within groups 8.37 10 0.83700

Percentage of organic matter in the sediment

Total 16.98 14Between groups 16.90 04 4.23 528.75 < 0.001

Within groups 0.08 10 0.00800

Percentage of total nitrogen in the sediment

Total 0.8286 14

Between groups 0.7828 04 0.1957 42.73 < 0.001

Within groups 0.0458 10 0.00460

Total phosphorus in the sediment

Total 0.0355 14

Between groups 0.0346 04 0.0087 96.67 < 0.001

Within groups 0.0009 10 0.00009

Humic acid content of the sediment

Total 0.2563 14

Between groups 0.2537 04 0.0634 243.85 < 0.001

Within groups 0.0026 10 0.00026

Sediment analyses

In order to quantity to selected ecological factors, three sediment samples each from each of the three respective

mesocosms (Table 1) were used at each sampling interval. Percentage of water content of sediment, percentage of total

nitrogen and total phosphorus content of the sediment were estimated by following the method of Murugesan and

Rajakumari (2005). While percentage of organic matter present in the sediment was calculated by following Trivedy

et al. (1998), humic acid content of the soil was estimated by following Oviasogie and Unuigbe (2006) and

Parthasarathi et al. (2007).

Statistical analysis

In order to ascertain whether the parameters measured were significantly influenced by the activity ofL. marginalis

at various time intervals, the data collected from the control and experimental mesocosms were subjected to one way

analysis of variance (ANOVA) followed by Duncans multiple range test (Tables 2 and 3). Since each category of

parameters collected from the control mesocosms did not very significantly during the entire period of the

experiment, the overall averages of each of them were taken into account.

RESULTS

In order to understand the ecological significance of biodeposition and bioturbation, the various soil parameters

analysed in the lake mesocosm study included percentage of water content of the soil, percentage of organic matter,

percentage of total nitrogen, total phosphorus and humic acid content.


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Percentage of water contentThe water content of the bottom sediment of the experimental mesocosms was found to be greatly influenced by the

presence ofL. marginalis when compared to that of the control ones (Tables 2 and 3). The percentage of water

content was steadily increasing up to 30d of experimentation (Tables 2 and 3; p


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DISCUSSIONThe findings of the present study clearly indicate the significant ecological roles played by the freshwater mussel

L. marginalis in the freshwater ecosystems through bioturbation and biodeposition of faeces and pseudofaeces.

The ploughing movements ofL. marginalis, in addition to making the soil more loose and soft, increase the

penetration of water into the sediments and bring in more dissolved oxygen and nutrients to the deeper layers of

the soil. This finding assumes greater significance due to the fact that the water content of the bottom soil is

reported to influence the micro and macro invertebrates in a variety of ways (Vaughn and Hakenkemp, 2001;

Vaughn and Spooner, 2006). However, after 30d onwards the percentage of water content remains more or less

same in the experimental mesocosms throughout the remaining period of the experiment, but still at a significantly

higher level than the control mesocosms (Tables 2 and 3). This is basically because of the fact that percentage of

water content might have reached the saturation point. In general, the increase in the percentage of water content in

the bottom sediments of the experimental mesocosms as against the control ones is the result of the direct physical

habitat modification by the bioturbation process whereL. marginalis plays an important role.

In filter feeding freshwater bivalves, particle covered by mucus and trapped on the gills are moved forward toward

the labial palps by a set of specialized cilia. The palps then convey these materials to the mouth and during this

process any excess quantity is dropped into the mantle for expulsion (Dillon, 2000). Such mucous laden particulate

materials are known as pseudofaeces. Further, the particles assimilated are only a subset of those ingested and the

particles ingested are only a subset of those gets collected by the cilia. The remaining portion is biodeposited as

pseudofaeces to the bottom sediments (Dillon, 2000; Vaughn and Hakenkemp, 2001; Christian et al., 2008). In

short, removing particles from water column, biodepositing pseudofaeces and faeces along with excretion of

nutrient rich excretory materials are some of the nutrients cycling processes being done by the sediment dwelling

freshwater bivalves such as L. marginalis. Faeces and pseudofaeces are important available organic matters to

the aquatic ecosystems and are having a high degradation rate and rapid turnover (Mirto et al., 2000; La Rosa

et al., 2002). The active biodeposition of faeces and pseudofaeces by the mussels could be the reason for the

increased percentage of organic matter in the experimental mesocosms (Table 3). However, the exact reason for

the significant decrease in the organic matter after 45d of the experiment is not clearly known. It is appropriate to

note that biodeposition of faeces and pseudofaeces by L. marginalis is an important sedimentation process by whichhigh-quality pelagic resources are brought to the bottom soil and thereby contribute to the organic content of the

soil.

Again, the accumulation of the excretory products, faeces and pseudofaeces of the mussels might also be primarily

responsible for the steady increase in the quantity of total nitrogen and phosphorus in the experimental mesocosms.

This observation is in line with the findings that fresh water bivalves produce nitrogen rich hypo-osmotic urine

consisting primarily of ammonia (Vaughn and Hakenkemp, 2001), which by bacterial action gets converted into

nutrients for primary producers. Along with ammonia, unionids reportedly excrete phosphorus also (Davis et al.,

2000; Vaughn et al., 2004; Christian et al., 2008). This observation becomes more credible due to the fact that both

nitrogen and phosphorus contents in the experimental mesocosms increase more or less at the same pace.

While making comparative studies on the seasonal nutrient cycling by unionid species, various authors have

reported that while excretion rates varied seasonally, the direction and magnitude of these changes were

species specific (Davis et al., 2000; McMahon and Bogan, 2001; Spooner and Vaughn, 2006). Recentlyenhancement of denitrification process associated with zebra mussel beds has also been reported (Bruesewitz et al.,

2006). In view of all these ongoing discussions, it is quite vivid that the freshwater bivalve mollusc L. marginalis

plays crucial roles in the ecosystem processes involving nutrient cycling. Epifaunal bivalves such as Driessena

(zebra mussel) are also known to be important in nutrient cycling (Arnott and Vanni, 1996; Vanni, 2002; Gardner et al.,

2001).

Even though the exact source of the increasing quantities of humic acid in the experimental mesocosms at various

stages is not clearly understood, benthic microbial mediated disintegration and degradation of the organic matter

biodeposited by the mussels may at least be partially responsible for it. Therefore, along with other benthic

organisms mussels also would have contributed to the organic disintegration and formation of humic acid. It is also

worth mentioning that the significant increases in the humic acid contents of the experimental mesocosms especially

in the later half of the experiment is accompanied by the appearance of increasing quantities of mucilaginous


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scum/debris containing rich quantities of algal cells. As humic acid is known to play important roles in plant growth(Parthasarathi and Ranganathan, 2002), it might have been contributed to the increased presence of algal cells in

the mucous bound debris from 30d onwards. Further, according to Watson et al. (1997) biodeposition of nutrient

rich organic matter can also increase the algal population. Accumulation of the mucous laden pseudofaeces could

be responsible for the appearance of the scum to a great extent.

CONCLUSION

It may be summarized that the freshwater bivalve L. marginalis through the processes of biodeposition and

bioturbation, could alter the physical and chemical properties of the habitat and thereby play critical roles in

managing the availability of resources to other organisms e.g., primary producers. As organisms that control the

availability of resources to other organisms by physical modifications of habitat, freshwater mussels including

L. marginalis could appropriately be called as ecosystem engineers. However, they being a threatened species,

deleterious anthropogenic environmental alterations could wipe out them leading to unsolicited changes in the

process of bioturbation and biodeposition, which in turn could inhibit or alter a number of critical ecosystem

functions that occur in the bottom sediment or sediment water interface of freshwater ecosystems.

ACKNOWLEDGMENT

Authors are thankful to Annamalai University authorities for providing lab facilities.

REFERENCES

Arnott, D.L. and Vanni, M.J. (1996): Nitrogen and phosphorus recycling by the zebra mussel (Dreissena

polymorpha) in the western basin of Lake Erie. Can. J. Fish. Aquat. Sci., 53: 646-659.

Bruesewitz, D.A., Tank, J.L., Bernot, M.J., Richardson, W.B. and Strauss, E.A. (2006): Seasonal effects of the

zebra mussel (Dreissena polymorpha) on sediment denitrification rates in pool 8 of the upper Mississippi River.

Can. J. Fish. Aquat. Sci., 63: 957-969.

Christian, A.D., Crump, B.G. and Berg, D.J. (2008): Nutrient release and ecological stoichiometry of freshwater

mussels (Mollusca : Unionidae) in 2 small, regionally distinct streams.J. N. Am. Benthol. Soc., 27: 440-450.

Christian, A.D., Smith, B.N., Berg, D.J., Smoot, J.C. and Findlay, R.H. (2004): Trophic position and

potential food sources of 2 species of unionid bivalves (Mollusca : Unionidae) in 2 small Ohio streams.J. N. Am.

Benthol. Soc., 23: 101-113.

Davis, W.R., Christian, A.D. and Berg, D.J. (2000): Seasonal nitrogen and phosphorus cycling by three unionid

bivalves (Unionidae: Bivalvia) in a headwater stream ecosystem. In:Tankersley, R.S., Warmolts, D.O., Watters,

G.T., Armitage, B.J., Johnson, P.D. and Butler, R.S. (Eds.), Proceedings of the Freshwater Mollusk Symposium,

Part II, March 16-20, 1999,Ohio Biological Survey Publication, Columbus, OH, USA, pp. 141-151.

De Hass, E.M., Kraak, M.H.S., Koelmans, A.A. and Admirall, W. (2005): The impact of sediment reworking byopportunistic chironomids on specialized mayflies. Freshwater Biol., 50: 770-780.

Dillon, R.T. (2000): The Ecology of Freshwater Mollusks. Cambridge University Press, UK, pp. 1-509.

Gardner, W.S., Yang, L.Y., Cotrier, J.B., Cotrier, T.H. and Lavrentyev, P.J. (2001): Nitrogen dynamics in sandy

freshwater sediments (Saginaw Bay, Lake Huron). J. Great Lakes Res., 27: 84-97.

La Rosa, T., Mirto, S., Favaloro, E., Savona, B., Sara, G. and Danovaro, R. (2002): Impact on the water column

biogeochemistry of a Mediterranean mussel and fish farm. Water Res., 36: 713-721.

McMahon, R.F. and Bogan, A.E. (2001): Mollusca : Bivalvia. In: Thorp, J.H. and Covich, A.P. (Eds.),

Ecology and Classification of North American Freshwater Invertebrates, Academic Press, New York, pp. 230-250.


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Oviasogie, P.O. and Unuigbe, C.A. (2006): Selective binding affinity of Pb, Cu and Cd to humic acid in the presence

of K and Mg ions.Nigerian J. Soil. Sci., 16: 151-158.

Parthasarathi, K. and Ranganathan, L.S. (2002): Supplementation of pressmud vermicast with NPK enhances

growth and yield of leguminous crops blackgram (Vigna mungo) and groundnut (Arachis hypogaea). Curr. Sci.,

2: 35-41.

Parthasarathi, K., Ranganathan, L.S., Anandi, V. and Zeyer, J. (2007): Diversity of microflora in the gut and casts of

tropical composting earthworms reared on different substrates.J. Environ. Biol., 28: 87-97.

Solan, M., Cardinale, B.J., Downing, A.L., Engelhardt, K.A.M., Ruesink, J.L. and Srivastava, D.S. (2004):

Extinction and ecosystem function in marine benthos. Science, 306: 1177-1180.

Spooner, D.E. and Vaughn, C.C. (2006): Context-dependent effects of freshwater mussels on stream benthic

communities. Freshwater Biol., 51: 1016-1024.

Trivedy, R.K., Goel, P.K., Trisal, C.L. (1998): Practical Methods in Ecology and Environmental Science. Enviro

Media Publications, Karad, India, pp. 1-340.

Vanni, M.J. (2002): Nutrient cycling by animals in freshwater ecosystem.Annu. Rev. Ecol. Syst., 33: 341-370.

Vaughn, C.C. and Hakenkemp, C.C. (2001): The functional role of burrowing bivalves in freshwater ecosystems.Freshwater Biol., 46: 1431-1446.

Vaughn, C.C. and Spooner, D.E. (2006): Unionid mussels influence macroinvertebrate assemblage structure in

streams.J. N. Am. Benthol. Soc., 25: 691-700.

Vaughn, C.C., Gido, K.B. and Spooner, D.E. (2004): Ecosystem processes performed by uninoid mussels in stream

mesocosms: species roles and effects of abundance.Hydrobiologia, 527: 35-47.

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Received for Publication: 17/08/2008

Accepted for Publication: 26/08/2008


V.I. Paul

Department of Zoology, Annamalai University, Annamalainagar 608 002, Tamil Nadu, India.


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PRODUCTION EFFICIENCY IN CATFISH (CLARIAS GARIEPINUS) BURCHELL, 1822 IN CROSS RIVER

STATE , NIGERIA

1ADINYA, I. B, and

2IKPI, G. U.

1Department of Agricultural Economics and Extension,

2Department of Fisheries, Cross River University Of

Technology (CRUTECH) Obubra Campus, Cross River State, Nigeria.

ABSTRACT

In the study, the production efficiency of catfish in Cross River State was determined. Data

was obtained from 120 fish farmers were randomly selected from Cross River Agricultural

Zones, using a multistage random sampling technique. Multiple regression analysis model was

the main tool of data analysis where different functions were tried. The results indicated that

Cobb-Douglass production function had the best fit in explaining the relationship between

output of catfish and inputs used, the coefficient of multiple determinant (R2

= 0.61) indicates

that sixtyone percent of the variability in output of catfish is explained by the independent

variables. The results also indicate that farmers educational level positively influence their

level of efficiency in catfish production in the study area. The F-value of 16.427 indicates the

overall significance of the model at 1 percent level, indicating that there is a significant linear

relationship between the independent variables taken together and the yield of catfish produced

in Cross River State. The marginal value products of fish pond size (farm size), labour and

feed (diet) were N67.50, N 178.13 and N 728.00 respectively, while allocative efficiency for

(farm size), labour and feed (diet) were (0.09 over utilized, 2.85 under utilized and 0.99 over

utilized), respectively, there existed allocative in-efficiency, there is a high potential for catfish

farmers to increase their yields and income. Based on the findings of this study, it is

recommended that fish farmers should expand fish farms, improving on production efficiency

and adopting new technologies. Regular awareness campaign about new technologies in fishfarming should be embarked by extension agents to make fish farmers know the importance of

adopting new technologies.

KEYWORDS: Production efficiency, Catfish, Cobb-Douglass, Production function,

Cross River State

INTRODUCTION

Fish provides an excellent source of protein in the diet of many families in tropical Africa (Sule, 2006). Of all the

animal protein foods produced and consumed in Nigeria, fish is of prime importance as it has remained a major

source of protein which is rich in essential-amino acids for both rural and urban poor households (Murtala, et al

2005).

According to Lale and Sestswa (1996) fish is rich in protein, which is very essential for the health of the body and itaccount for about 40 percent of the total animal protein of an average person in the tropics. Fish is rich in fats,

phosphorus, sulphur, potassium, iron, calcium and copper. Fish fat is characterized by high poly-unsaturated acid,

which provides diet low in cholesterol. Its oil has high quantities of vitamin especially vitamin A, B and D, thiamin,

riboflavin, nicotinic acid and vitamin B12 (Disney, et al 1978). Fish contains less than 1% fat and about 10% protein

with energy value ranging from 220 330 Kilojoules (50 80Kcal/100g) of fish (John 1980). In Nigeria, fish is

consumed fresh or processed (dried). Fish meal and fish flour are two products produced by fishing industries,

which are used as food in dairy animals and poultry (Disney, et al 1978; Sule 2006).

Akpet, et al (2005) revealed that the recent ban on the importation of broilers has further put the cost of animal

protein beyond the reach of many, especially the rural population, they have resorted to consumer fish. The low


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ADINYA, I. B, and IKPI, G. U: Continental J. Fisheries and Aquatic Science 2: 13 - 22, 2008

price per kilogram of fish, is a very strong indicator that they can be used to bridge the wide animal protein gap thathas become the hallmark of most developing countries (FAO, 2005; Essien ,et al 2008).

According to Campbell-Platt (1984) the world population reaching the 6.0 billion mark by year 2000 A.D, a lot of

pressure is being placed on the world fish production in order to meet the high demand from the teaming human

population. This demand is greater in tropical countries including Nigeria with increasingly rising human

population. In Nigeria, fish production over the years has been inadequate to bridge the demand supply gap. Nigeria

with about 13 million hectares of fresh water bodies capable of producing 511,702 metric tones of fish under

adequate management but the actual production is about 334,213 metric tones. Thepotential yield of fish from the

coastal and brackish water of Nigeria has been estimated as follows 22,000 metric tones from demersal resources,

120,000 metric tones from pelagic resource and 48,000 metric a total yield of 190,000 metric tones which is far

below the quantity demanded in the markets (Ayayi, 1996; Ezekiel, 2005).

Cross River State is endowed with natural and human resources being presently exploited. According to Ezekiel

(2005), fish is the most widely exploited natural resources by man. The state has the potential to be self-sufficient in

fish production because of the presence of rivers and suitable ecological zone for its production either in ponds,

dams or rivers. In the local markets in Cross River State, there is a great gap between production and consumption

offish. Unfortunately, fish production in Cross River State has been inadequate to bridge the demand-supply gap.

There exists a high incidence of protein malnutrition as a result of non-optimal use of resource and enormous losses

in post-harvest of fish. To reserve this trend, the rural farmers must learn to use improved technologies and

improvement in efficiency of resource use (Idiong , et al 2006). However, given the low rate of adoption of fish

technologies by farmers, improvement in efficiency remains the most cost effective way in enhancing productivity

in the shortrun.

Efficiency could be measured from a production function or profit function approach. Efficiency of production is a

very important factor for productivity especially in areas where resources are meager as in Nigeria (Adinya, et al

2008). Efficiency of production is achieved through optimal resource allocation such that more output is achieved

with the same resource level or the same level of output is achieved using fewer resources. Production functiongives the possible output that can be produced from given quantities ofa set of inputs (resources) and their quantities

can be varied to obtain optimal output. In carry out econometric analysis, production function provides the basis of

decision making for fish farmers.

Economic theory identifies three important production efficiencies (Farrel, 1984). These include allocative, technical

and economic efficiencies. Allocative efficiency is the ability of the farmer to use the inputs in optimal proportions

given their respective prices and the production technology. Technical efficiency is the measure of the farms success

in producing maximum output from a given set of resources (inputs) i.e. ability to operate on the production frontier

(Farrel, 1984).

Economic efficiency is the product of the technical efficiency and allocative efficiency. There is evidence that fish

farmers in developing countries fail to exploit fully the potential of resources and make allocative errors; which

results to low yields.

Several studies have shown that resources are not efficiently utilized by fish farmers in Nigeria (Adeleye,1996; Lale

and Sestswa 1996; Murtala , et al 2005; Ezekiel,2005; Sule, 2006; Ibrahim and Olayemi,2006). Therefore, having

established the obvious fact that resources are not efficiently utilized in fish production in Cross River State, itis the

aim of this study to examine critically the problems of resource use in fish production. Ultimately, it is hoped that

the study will help to bridge the gap between resources availability and efficient utilization in fish production in

Cross River State. This study seeks to examine the production efficiency in catfish (Clarias gariepinus ; Pisces;

CLARIIDAE) in Cross River State, Nigeria; therefore this paper tried to provide some useful information in

policies towards increasing fish production in Nigeria. Hence, this study had the following objectives:

(i) To analyze the production function of fish in the study area.

(ii) To analyze the costs and returns of fish production in the study area.

(iii) To determine resource use efficiency (allocative efficiency) in fish production.


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ADINYA, I . B, and IKPI, G. U: Continental J. Fisheries and Aquatic Science 2: 13 - 22, 2008

METHODOLOGYSTUDY AREA: The research study will be conducted for a period of one year and three months from 15th

October,

2005 to15th December,2007 in Cross River State,Nigeria. The state occupies an area of about 22, 342.176 Square

Kilometers (Quarterly News Letter of the Ministry of Local Government Affairs, C.R.S 2006 Pp 4-8). It is located at

Latitude 5o

25N and longitude 25o

00E (Figure 1). The soils of Cross River State are utisols and alifisol but

predominantly utisol (USDA) or (FAO/UNESCO, 1974).

The states geographical almalgam strecting from the mangrove swamps, criss-crossed by rivers on the Atlantic-

coast in the central to the rugged and mountain savannah in the north. Cross River State has the largest rainforest

covering about 7,290 square kilometers described as one of Africas largest remaining virgin forest harbouring as

many as five million species of animals insects and plants (MOFINEWS, 2004). Cross River State is located within

the evergreen rainforest zone. There are two distinct climate seasons in the area, rainy season from March to

October and dry season from November to February. The annual rainfall varies from 2,942mm to 3,424mm. The

averagetemperature is around 28oc (CRADP, 1992). Cross River State is characterized by presence of numerous

ecological and zoo-geographically important high gradient streams, rapids and waterfalls. About 2,888,966 people

inhabit the area, of which the Efiks, Ejaghams and Bekwarras are the major ethnic groups (Population Census 2006

In MOFINEWS, 2007. Fishing and subsistence agriculture are the main occupations of the people. Crops grown in

the locality include rice, maize, yam, cassava, plantain and banana. Population depends largely on natural water

sources for all their water-related activities, as piped water supply is limited and grossly inadequate. Health services

in the area require a lot of improvement. Level of hygiene in the communities is generally poor (Arene,et al 1991).

A multi-stage stratified random sampling technique was used to select the respondents. This procedure recognized

the delineation of the study area into zones. The Cross River Agricultural Development Project (CRADP) divided

this agricultural zone into Northern Zone (Ogoja Zone), Central Zone (Ikom Zone) and Southern Zone (Calabar

Zone) of the state. There are 18 Local Government Areas in Cross River State. The agricultural zones consists of 17

blocks, 8 circles and 136 cells with 5200 contact farmers. At the first stage seventeen (17) local government areas

were selected from eighteen (18) local government areas, four (4) farming communities were randomly chosen from

each of the three agriculturalzones of the state. For better coverage in the study area, one village was randomlychosen from each of the communities (therefore twelve villages were taken from the three agricultural zones). Ten

respondents were randomly chosen from each of the selected villages. In all, 120 respondents were randomly

selected from a list compiled by the extension agents of Cross River Agricultural Development Programme.

DATA COLLECTION AND ANALYTICAL TECHNIQUE

The researchers visited the villages to administer copies of the questionnaire to selected respondents as a pilot

survey to pretest the instrument. Thereafter, the instrument was corrected based on the experience gained in the pilot

survey. Thus, the problem of ambiguity and misperception was sufficiently dealt with and enough time was spent on

the administration of interview schedule to ensure that the records are accurate. The completed questionnaires were

checked for quality. In the course of doing this, 120 questionnaires were distributed to respondents in the three

agricultural zones at the rate of 40, 40 and 40 to Northern Zone (Ogoja Zone), Central Zone (Ikom Zone) and

Southern Zone (Calabar Zone), respectively.

Data for this study was subjected to different types of analytical tools. This study employed the following analytical

tools in order to achieve the already stated objectives of the study:

(1) The descriptive statistics such as frequencies distribution, and percentages were used.

(2) The inferential statistics is the regression analysis. Regression analysis is important and useful for

describing the relationship between the exogenous and endogenous variables. It estimates the statistical

significance of the exogenous variables as well as the overall effect of all these variables on the

endogenous variables. The data obtained were analyzed using the Ordinary Least Square (OLS)

multiple regression technique to determine the relationship between fish output and the selected

variables. The linear, double-log and semi-log function forms were used to determinewhich of the

forms would best fit the relationship between fish output and the explanatory variables.


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The implicit form of regression model for this analysis was given as:Y = f (X1,X2, X3, X4, X5 e1) and explicitly form of the regression model for this analysis is given by:

Y= bo + b1X1 +b2X2+b3X3 +b4X4+b5X5+e

Where Y = Output of fish (kg)

X1 = Fish pond size (Farm size) (ha)

X2= Labour (man-days)

X3,= Feed(Diet containing 40% crude protein was used in feeding fish( fish ingredient was measured

on a 9 point scale of yellow maize =1, groundnut cake=2, fish meal=3, brewers grain=4, oil =5,bone meal= 6

oyster shell=7, AD-Vitamin=8, salt=9)

X4=Adoption of improved technologies (measured on a 3 point scale of improved management of fish

farm=1, improved catfish fry/fingerlings production=2, construction of fish pond=3)

X5= Educational level of the respondents (measured on a 4 point scale of First School LeavingCertificate=1, JSSC/SSC=2, Tertiary Institutions=3, no formal education=4 )

e1= Error term (error or disturbance term is included to capture the effects of exogenous and

endogenous variables not included in the model).

Three linear function forms were tried; these are Linear, Cobb-Douglas production function (double logarithm), and

semi-log production function forms. Whichever model that has the highest R2

and shows many statistical significant

variables will be adopted following (Kmenta, 1971; Koutsoyiannis, 1977 and Awoke, 2001). The functional forms

fitted are specified below:

(a)Linear production function: Y= a + b1X1+ b2X2 + b3X3 + b4X4+ b5X5+ eequation (1)

X1-X5= are defined in the implicit form

b1-b5=Regression coefficients of variables X1-X5 a = Constant term

e = Error term

(b) Cobb-Douglas Production Function (double log)Log Y=Log a +b1LogX1+b2LogX2 + b3LogX3 +b4LogX4+b5LogX5 +eequation (2)

(c) Semi-Log Production Function:

Y =Log a+b1LogX1+b2LogX2 + b3LogX3 +b4LogX4+b5LogX5 +e equation (3)

Each resource was measured using the formula:

The average physical product (APP) was derived by dividing total output by total input i.e. APP= Y

X

The marginal physical product (MPP) was derived by dividing total output by total inputs MPP= DY

DX

MPP x Price of product= marginal value product (MVP)

The allocative efficiency (AEL) of resource was determined by ascertaining whether or not the ratio of the marginal

value product to the inputs price was equal to one

AEL= MVP=1

P

where MVP= Marginal Value Product

P= Unit Price of Input

The marginal Products (MP) were derived by multiplying the average product (AP) by the elasticity of

production(EP), given that: MP= AP x EP


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EP= MPAP

RESULTS AND DISCUSSION

Table1: Distribution of respondents according to socio-economic characteristics of fish farmers in Cross River State

EducationalAttainment

Northern Zone(Ogoja Zone

Central Zone (IkomZone

SouthernZone(Calabar

Zone),

Frequency Percentage (%)

FSLC 4 10 14 28 23.33

JSSC/ SSSC 21 13 13 47 39.17

Tertiary

Institution

15 14 12 41 34.17

No formal education - 3 1 4 3.33Total 40 40 40 120 100

Farm size

(Ha)

0.1-2 34 37 27 98 81.67

3-4 6 3 1 3 22 18.37

5-6 - - - - -

7-8 - - - - -

9ha andAbove

- - - - -

Total 40 40 40 120 100

Labor

(man-days)

1 9 5 4 18 15.00

2 12 10 10 32 26.673 8 12 9 29 24.17

4 4 9 7 20 16.67

5 5 1 6 12 10.00

6 man-days and above 2 3 4 9 7.50

Total 40 40 40 120 100

Adoption of improvedtechnology

Improved management offish farm

10 19 10 39 32.50

improved catfish fry/

fingerlings production

1 5 13 19 15.83

Construction of pond 29 16 17 62 51.67

Total 40 40 40 120 100

Diet

31% of protein diet 11 10 7 28 23.33

34% of protein diet 8 10 8 26 21.67

37% of protein diet 1 6 4 20 16.67

40% of protein in diet 10 8 15 24 20.00

48.8 -50% of protein diet 10 6 6 22 18.33

Total 40 40 40 120 100

Source: Field survey, 2008

Analysis of table 1 revealed that 39.17% of the respondents had Junior Secondary School Certificate (JSSC)/ Senior

Secondary School Certificates (SSSC). However, 34.17% of the respondents revealed that they attended high

education. While 23.33% of the respondents disclosed that they had First School Leaving Certificates (FSLC). Only

3.33% of the respondents never had any formal education. The result implies that education acquired by fish farmer is


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very important for taking positive decisions aimed at improving their income. Of course, this goes to confirm the earlierdeduction by (Adinya,2001; Idiong , et al 2006 ) that technical and commercial education broaden farmers

intelligence and it also enable fish farmer to perform the farming activities intelligently and improve their income.

Table 2: Average Production Costs, Inputs Usage and Returns Per Hectare of Catfish Production in Cross River

State


Table 1, also revealed that 81.67% of the respondents farm sizes were between 0.1-2 hectares While 18.37% of them

had farm sizes ranging from 3-4 hectares. The result suggests that most people practicing fish farming are mostly inthe low- income class. The result confirms similar findings by Etim, et al (2006) that farmers who had plot size 1.5

hectares are mostly in the low- income class who farm mainly to augment family income and nutrition supply.

Further analysis of Table 1 revealed that 24.17% of the respondents spent 3 man-days. Whereas, 10% of them spent

5man-days. Only 7.50% of the respondents spent 6 man-days and above. Table 1 revealed that 32.50% of the

respondents adopted improved management of fish farms, while 15.83 percent of them adopted improved catfish

fry/ fingerlings production. The result suggests that most fish farmers refused to adopt improved catfish fingerlings

production. The result of findings agrees with the findings of Ajayi and Madukwe (2001)that some illiterate farmers

refused to adopt improved technologies in agricultural production. Food crisis in Nigeria can be arrested through

agricultural research, adoption improved technologies, improvement in efficiency of resource use and effective

/efficient agricultural extension services. However, some farmers in the rural areas are illiterates, therefore cannot


Variables Unit

price(N)/kg

Northern

Zone

(Ogoja

Zone

Central

Zone

(Ikom

Zone

Southern

Zone

(Calabar

Zone),

States

average

States

average

value

1. Fish output(FO)kg

100 3.56 4.30 4.58 12.44 1,244,0002. Capital operating inputs

*Catfish fingerlings/ fry

** Feed input

30

735.17

1.78

25,065

2.15

28,075

2.30

35080

6..23

-

186,900

88,220

3.Labour input(man-days)

*Family Labour

**Hired labor

62.5

62.5

60

36

72

42

84

48

216

126

13,500

7,875

4 Fixed cost rent on land

Fish pond size (farm size)

Maximum

Minimum

meanDepreciation 1000500

750

2.01.0

3.00

2.51.2

303.3

2.81.6

306.7

7.33.6 7,3001,800

910

5 Total variable cost

(TVC=TCO=TLI) 2,900

6.Total fixed cost (TFC)

966.66 966.66 966.66

7. Total cost TC=TVC=TFC 9405

8. Net Return 934595


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19

read or write, they need agricultural extension agents through which such information from research station(s) will

be interpreted to them. Agricultural extension service is a necessary prerequisite to widespread and sustained

agricultural development. Further analysis of table 1 revealed that 20.00 per cent of the respondents used 40% ofprotein in diet to feed fish, this promote the growth of fish. The result of findings agrees with the findings of

Ugwu , et al 2001 that the linear increase in specific growth rate (specific growth rate of the Africa catfish fry )

of experimental fish fry with increasing dietary protein level to 40 percent. WhileClarias gariepinus fry fed

48.8percent of protein in diet showed relatively poor growth response( Ugwu , et al 2001).

Table 2 revealed that the per hectare states average value of catfish production was N1244000.00. A total of 342

man-days was used in catfish production. The average yield was 12.44(tons) per hectare. The profit margin obtained

was N 934595.00 per hectare.

Table 3: Multiple Regression Equations for Catfish Production in Cross River State, Nigeria

Source: Field survey, 2008 Note: = Values significant at 1%

Figure in parentheses are standard errors.

Table 4: Estimated Elasticities of Production Function (EP), Average Product(AP) Marginal Product(AP), Marginal

Value Product(MVP) and Allocative efficiency(AEL)

Variables EP AP MPP MVP P AEL Inference

X1

Fish pond

size (Farm

size)

0.00082 10.9 0.09 67.50 750.00 0.09 Over

utilized

X2Labour

0.0083 342 2.85 178.13 62.50 2.85 underutilized

X3

Feed

(Diet)

0.00825 119.9 0.99 728.00 735.17 0.99 Over

utilized


Table 3: Judging from the value of the R2

in the analysis above for the three production function forms, one can

conclude that double log equation is a good one compared to all other functional forms (linear and semi-log

production functions). Double log (Cobb-Douglass production function) is the lead equation because it has the


Production

function

forms

CONSTANT X1

Fish

pond

size

(Farm

size)

X2

labour

X3

Feed

(Diet)

X4

Adoption

of

improved

tech.

X5

edu.

Level

R2 AdJ

R2

F-

l

Linear -2.659

(1.498

0.130

(0.117)

1..237

(0.163)

1.295

(0.0492)

0..281

(0.374)

0.134

(0.212) 0.601 0.565 16.427

Semi-log -5.754(5.058

1.053(0.912)

7.249(1.182)

4.018(1.681)

0.991(1.306)

0.579(1.008) 0.551 0.510 13.393

Double-

log

-1.313

(0.710

0.252

(0.128)

-0.941

(0.166)

0.553

(0.236)

0.164

(0.183)

9.687E-

02

(-0.142)

0.612 0.576

17.163


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20

highest R2

value (0.612) and meeting other econometric criteria. The F-value for the functions are also significant at

1 percent indicating that there is a significant linear relationship between the independent variables taken together

and the yield of catfish produced in Cross River State, Nigeria.

The regression analysis, however, revealed that education has positive influence on output of fish production and are

significant at 1 percent level of significance.

Further analysis of Table 3, revealed that labour, farm size, diet has positive influence on output of catfish

production and it is significant at 1 per cent level of significance. The F-value of 17.163 indicates the overall

significance of the model at the one percent level. Karlirajan(1981) and Fujimoto (1988) reported similar results for

labour in the aggregate; while (Ugwu, 1984;Ugwu , et al ,2001) reported similar results for diet and Clarias

gariepinus fry.

Table 4 revealed the marginal value products of fish pond size (farm size), labour and feed (diet) were N67.50, N

178.13 and N 728.00 respectively, while allocative efficiency for (farm size), labour and feed (diet) were (0.09 over

utilized, 2.85 under utilized and 0.99 over utilized), respectively, there existed allocative in-efficiency, there is a

high potential for catfish farmers to increase their yields and income. This findings agrees with the findings of

Adeleye, 1996; Ohen and Dixie, 2007 that fish farmers are

in-efficient in catfish production because not all of them possess the skills necessary to know how to improve

productivity and this implies that actually farmers are operating below their full potential due to lack of skills, the

cost per unit output was proportionately higher.

CONCLUSION AND RECOMMENDATIONS

This study has revealed that catfish production was profitable but catfish farmers are not allocative efficient. There

is a very high potential for fish farmers to increase yield. Based on the findings of the study, it is recommended that

catfish farmers should increase their yield and income by expansion of their fish farms, improving efficiency and

adopting new technologies. Beside that, extension agents should train fish farmers on the adoption of new

technologies in fish production.

Food crisis in Nigeria can be arrested through agricultural research and effective /efficient agricultural extensionservices. However, some farmers in the rural areas are illiterates, therefore cannot read or write, they need

agricultural extension agents through which such information from research station(s) will be interpreted to them.

Agricultural extension service is a necessary prerequisite to widespread and sustained agricultural development.

REFERENCES

Adeleye O.A (1996); Conservation needs of fisheries resources and re-orientation for sustainable captive and culture

practices FISON Proc. Abeokuta.12th-15thOctober,1996 .

Adinya I. B. (2001) Factors influencing Labour Utilization in Small Scale Cassava Production: A Case Study of

Uyo Agricultural Zone of Akwa Ibom State. M.sc. Thesis Unpublished, University of Uyo, Akwa Ibom State.

Pp1 109.

Adinya I.B., O.O Kuye, M.U. Awoke, S. Ajayi, I.E. Ele; K.I. Ogbonna, S.O. Akpet and O.A. Agba (2008),Production Function Analysis of Cassava Role Cropping System in Akwa-Ibom State, Nigeria. Global Journal of

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Ajayi S.S. (1996), Fish and Wildlife Biodiversities and Development. FEPA Report, Abuja, Nigeria Pp1-12.

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Innovation Generation and Adoption in Developing Countries: A case Study of Nigeria. Jounal of the Science of

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Campbell-Platt G. (1984). Traditional West African Food Processing of Institute of Food Science and Technology,

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July 2008.

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Received for Publication: 17/08/2008

Accepted for Publication: 26/09/2008


ADINYA, I. B

Department of Agricultural Economics and Extension, Cross River University Of Technology (CRUTECH) Obubra

Campus, Cross River State, Nigeria.




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EVALUATION OF PROCESSED GROUNDNUT (ARACHIS HYPOGAEA)CAKE MEALS IN THE FEEDING

OF CLARIID CATFISH, CLARIAS GARIEPINUS, FINGERLINGS.

FAPOHUNDA Olawumi OluwafunmilolaP. O. Box 4440, Akure, Ondo-State, Nigeria. E-mail: [email protected]

ABSTRACT

Groundnut cake (GNC) meal is an important source of dietary protein for domestic animals

with a cost advantage over the conventional animal protein sources used in aquaculture feed

production. It would be useful to evaluate the effects of GNC processing methods on the

density and nutritional values of processed GNC meals. The use of processed GNC meals in

the diets of Clarias gariepinus fingerlings was evaluated. Seven iso-proteic and iso-caloric

diets were formulated, replacing fish meal with roasted and boiled GNC meals, each at three

inclusion levels of 30%, 35%, and 40%. Diet I is 100% fishmeal, Diet II is 30% roasted GNC

meal, Diet III is 35% roasted GNC meal, Diet IV is 40% roasted GNC meal, Diet V is 30%

boiled GNC meal, Diet VI is 35% boiled GNC meal and Diet VII is 40% boiled GNC meal.

Results showed that the crude protein content of GNC meals was 40.5% and 40.8% in boiled

and roasted GNC meals respectively; the lower protein content for processed GNC meals

might be due to heat denaturation of the seed protein, with boiled GNC meal being more

adversely affected. The mean weight gain of fingerlings fed roasted GNC meals ranged

between 5.29 5.64 while for boiled GNC meals, it was between 4.60 5.22. Generally, fish

performed better when fed diets containing roasted GNC meals, than boiled GNC meals, and

compared favorably with fish fed fish meal based diet. Body mass increase, total feed increase,

protein efficiency ratio and specific growth rate by C. gariepinus fingerlings in all diets,

showed no significant differences, suggesting that processed GNC meals could partially

replace diets for C. gariepinus fingerlings without adverse consequences. This study showed

that processed GNC meals could partially replace fish meal up to 30% without significantly

influencing fingerling growth and health. It is recommended that the use of fish meal as the

main basal ingredient for fingerlings could be discontinued, since GNC meal was a cheaper

alternative, and could replace fish meal up to 35%, without any significant adverse effects onthe fingerling performance.

KEYWORDS: Clarias gariepinus, Fingerlings, Groundnut cake meal, Nutrient utilization,

Performance.

INTRODUCTION

Groundnut (Arachis hypogaea L.) cake meal is an important source of dietary protein for domestic animals, and has

a cost advantage over the conventional animal protein sources used in aquaculture feed production. It has been

considered among others as a good substitute for fish meal Ezenwa (1982), Ekanem (2003).

Groundnut cake is an abundant, cheap and easily available plant protein source that is high in crude protein content

(40-45%). Feed ingredients used for fish rearing are usually chosen on the basis of their nutrient content (proximate

composition), cost, availability and acceptability by fish, as food Eyo and Ezechie (2003). The protein content ofGNC meal has sub-optimal amount of cystine and methionine, although the first limiting amino acid in GNC is

lysine Jackson et al. (1982).

When GNC meal is used in a diet with a high cereal composition, adequate supplementation with animal protein is

necessary, to ensure that the deficiencies of vitamin B12 and calcium would be corrected (Fagbenro et al., 2000).

There are many constraints on the use of legume seeds in fish feeding; these include the presence of anti-nutrients

such as trypsin-inhibiting tannin, Lemaglutannins, phytase, anthocyanniona, unacceptable taste or flavour, and the

long and tedious cooking/processing time. Many methods have been employed to reduce or remove these problems

FAPOHUNDA Olawumi Oluwafunmilola: Continental J. Fisheries and Aquatic Science 2: 23 - 30, 2008


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associated with legumes in fish feed. The effects of sprouting, cooking, roasting, autoclaving, soaking and

germination on legumes had earlier been reported Egwaikhide et al. (2005).

In Africa, Clarias gariepinus is of some great economic importance, as an esteemed fish food with a higher dressingpercentage and consumer preference than most cultured fish species in freshwater Balogun and Fasakin (1996). It is

hardy and can be bred in captivity.

However, the provision of adequate, cheap and nutritive feed has hindered the development and profitability of

catfish farming, especially in developing countries. The possibility of supplementing or replacing one meal with

another in the aquaculture industry exists. Several authors (Ekanem 1992, Balogun and Fasakin 1996, Fagbenro et

al., 2000, Arimoro 2005, Eyo and Ezechie 2003, Oresegun et al., 2004, Oharei 2005) have successfully carried out

these replacements. But there is a lack of information on the use of processed GNC meals in fish feed. Therefore,

this study was conducted to evaluate the effects of two processing methods (roasting and boiling) on the density,

nutritional values of processed GNC meals, and growth performance ofC. gariepinus fingerlings.


Location of investigation

The experiment was conducted in Akure, Ondo-State, Nigeria. Akure is located in the humid forest region of

southwestern Nigeria. The town has tropical climate with two distinct seasons, namely: rainy season (April -

October) and dry season (November March). Temperature ranges vary from 21oC during the rainy season to 28oC

during the dry season, while humidity is relatively high. It is located between longitudes 5o.

22

and 5o.23

East of

Greenwich Meridian and latitudes 7o.15

and 7

o.17

North of the equator. The town is mainly on upland zone, rising

above 250meters above the sea level.

Preparation of GNC meals

Raw groundnut seeds (2 kg) were purchased from Divine Mills, Akure, Nigeria. The seeds were manually selected

to remove dirt, after which they were washed, and dried at 600C for 24 hours AOAC (1990) methods in a

domestic/kitchen oven. When dry, they were divided into two equal batches.

Boiled sample

One batch of raw groundnut seeds was boiled at 900C for 30 minutes, sieved to remove water, and then sun-dried atambient temperature (25

0C) for two weeks. Thereafter, the seeds were ground in a hammer mill, sieved (25 mm wire

mesh), and stored in an airtight container prior to chemical analysis.

Roasted sample

The second batch of raw groundnut seeds was roasted in a sauce pan containing sand that was heated over a Bunsen

burner. The sample and sand were roasted for 30 minutes, stirring occasionally using a wooden spoon. The roasted

sample was allowed to cool for 20 minutes, after which the seeds were ground with a hammer mill, sieved (25 mm

wire mesh) and stored in an airtight container, awaiting chemical analysis.

Chemical analysis

The proximate composition (moisture, crude protein, crude lipid, crude fibre and total ash) was performed using

standard AOAC (1990) methods.

Diet formulation

Based on the nutrient composition of the feedstuff (Table 1), seven isoproteic and isocaloric diets were formulated

as presented in Table 2. Diet I, serving as the control diet contained 100% fishmeal with 0% GNC meal, whereas the

other six test diets (II to VII) contained GNC meal (roasted or boiled) as partial replacement for fishmeal (Table 2)

providing 30%, 35% and 40% of total protein. The description of diets was as follows: I, 0% GNC meal; II, 30%

roasted GNC meal; III, 35% roasted GNC meal; IV, 40%, roasted GNC meal; V, 30% boiled GNC meal; VI, 35%

boiled GNC meal; and VII, 40%, boiled GNC meal. The lipid content of all diets was adjusted with 2.5% groundnut

oil while gelatinized cornstarch 3.0% was supplemented to adjust gross energy content (Fagbenro et al., 2000). After

mixing all ingredients together, the prepared starch was added. This helped to hold the ingredients as well as being a



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source of gross energy. Carboxymethyl cellulose (CMC) was added at 10 g per kg, as a non-nutritive binder,

(Fagbenro et al., 2000).

Table 1. Proximate composition (%) of feedstuff.Nutrient Fishmeal Maize Roasted groundnut

cake

Boiled groundnut

cake

Crude

protein

65.670.01 9.130.01 40.750.01 40.520.04

Crude lipid 13.100.01 2.700.02 9.810.01 9.670.01

Crude

fibre

- 2.420.01 4.250.03 4.330.02

Ash 4.360.04 3.610.01 5.310.02 5.290.01

Moisture 7.600.02 7.240.01 7.010.02 7.310.02

*NFE 9.270.01 74.900.02 32.870.02 32.880.02

*NFE (Nitrogen free extract), calculated as 100-(Moisture + crude protein + crude lipid + ash).

Table 2. Composition of the experimental diets (dry matter basis, %).

Ingredients Fishmeal

100%

Roasted GNC

30%

Roasted

GNC

35%

Roasted

GNC

40%

Boiled

GNC

30%

Boiled

GNC

35%

Boiled

GNC

40%

Fishmeal 57.0 26.0 36.9 42.0 26.0 36.9 42.0

GNC meal 0.0 20.5 18.1 18.0 20.5 18.1 18.0

Maize 33.0 43.5 35.0 30.0 43.5 35.0 30.0

Vit-min

premix

2.5 2.5 2.5 2.5 2.5 2.5 2.5

Bone meal 1.0 1.0 1.0 1.0 1.0 1.0 1.0

Groundnut

oil

2.5 2.5 2.5 2.5 2.5 2.5 2.5

CMC 1.0 1.0 1.0 1.0 1.0 1.0 1.0

Starch 3.0 3.0 3.0 3.0 3.0 3.0 3.0

Calculated Nutrient Composition%

Crude

protein

40.30 39.86 39.85 39.74 39.87 39.71 39.78

Crude

fibre

2.08 5.56 4.12 4.02 5.66 4.32 4.47

Crude

lipid

8.12 8.99 7.78 7.62 9.74 8.38 8.27

Ash 4.75 5.45 5.34 5.22 5.40 5.31 5.10

*NFE 44.75 40.18 43.05 43.05 39.40 42.28 42.55

*NFE: Nitrogen free extract.

The feedstuff was blended in a Hobart A120 food processor (Hobart, Troy, OH, USA), and the resultant mash was

moistened and pressed through a 3-mm die. The resulting strands were oven-dried at 450C for 24 hours,

(Fagbenro1999), broken into pellet lengths of 1.0 cm, and stored in airtight plastic containers at ambient

temperature. Water stability of pellets was determined in triplicate samples (Wood 1987).

Experimental fish and systems

Hatchery-bred fingerlings of C. gariepinus (mean mass: 3.690.01g) were procured from the Agricultural

Development Project (ADP), Akure, Nigeria, and randomly allotted to 15 plastic circular tanks (50-litre capacity) at

20 fingerlings per tank. The fish were acclimated to experimental conditions for seven days, and starved for 24



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hours prior to the feeding trial Ekanem (2003). Water from a borehole was passed through a circulatory filtration

system before entering the experimental tanks to filter away impurities and to aerate the water.

Each diet was fed to C. gariepinus fingerlings in triplicate tanks per treatment to apparent satiation twice daily (9amto 4 pm) for 56 days. Fish mortality was monitored daily. Individual fish in each tank was weighed at the start of the

experiment and weekly for the appropriate indices (Steffens 1989).

Table 3. Performance ofC. gariepinus fingerlings fed processed groundnut cake meals dietary inclusion for 56 days.

Diets

Fishmeal

100%

Roasted

GNC

30%

Roasted

GNC

35%

Roasted

GNC

40%

Boiled

GNC

30%

Boiled

GNC

35%

Boiled

GNC

40%

Initial mass g 3.81ab

3.86 3.96 3.40a

3.76ab

3.64ab

3.40a

Final mass g 10.49c

9.50 9.25 8.80ab

8.98ab

8.54ab

8.00a

Mean Weight

Gain g

6.68c

5.64ab

5.29ab

5.40ab

5.22ab

4.90a

4.60a

Average DailyGrowth

0.12 0.10a 0.09a 0.10a 0.09a 0.09a 0.08a

Body Weight

Increase %

175.33 146.11ab

133.59a

158.82 138.83a

134.62a

135.29a

Specific

Growth Rate

0.44 0.39ab

0.37a

0.41ab

0.38a

0.37a

0.37a

Protein

Efficiency

Ratio

2.78c 2.62c 2.17ab 2.56 2.01a 2.00a 1.89a

Total Feed

Intake g

3.45c

3.33 3.12ab

3.28 2.89ab

2.81a

2.69a

Daily Feed

Intake g

0.029 0.025 0.021a

0.022a

0.020a

0.021a

0.021a

Survival % 96 97 87a 91 89a 90a 95

Growth performance parameters

Mean weight gain (MWG): mean weight gain was estimated according to the method of Pitcher and Hart (1982).

MWG = mean final weight mean initial weight.

Average daily growth (ADG) = mean weight (MWG)/ rearing period (days)

% Body weight increase (%BWI): this was obtained according to Stuart and Hung (1989).

% BWI = mean weight gain (MWG)/ mean initial weight X 100

Specific growth rate (SGR): this was estimated from the logarithmic difference between final and initial meanweight of fish per time (Hogendoorn 1980).

SGR = Log Wf Log Wi / t X 100

Where Wf = mean final weightWi = mean initial weight

t = rearing period (days).

Feed gain ratio (FGR): Tf/ Wf Wi



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Where Tf = total amount of diet fed to a tank for the rearing period divided by the number of fish in the same tank.

Survival: this was monitored daily by examining experimental tanks each morning and dead fish were removed and

counted. At the end of every week, fish in each tank were counted.

% Survival = Nf/ Ni X 100

Where Nf = final number of fingerlings per tank

Ni = initial number of fingerlings per tank

Daily weight gain (DWG) = body weight gain/ rearing period (days) i.e. Wf Wi/ t

Total feed intake (TFI) = feed weight/ no of fish per tank

Daily feed intake (DFI) = TFI/ t

Protein intake (PI) = protein content X DFI

Protein efficiency ratio (PER) = ADG X PI

Statistical analysis

All data obtained were subjected to one-way ANOVA test (P 0.05) dietary protein, lipid and ash than those of the roasted GNC meals.

According to Fagbenro et al., (2000), boiling, fermentation and roasting of seeds have affected their nutritional

contents. Crude lipid, crude fibre and ash of the processed samples were similar, but were higher than the values

reported for maize ( Zea mays). The data from the present study indicated that processed GNC meals could

conveniently be incorporated into the diet ofC. gariepinus fingerlings. The substitution of fishmeal with processed

GNC meals enhanced the energy, ash and fibre profiles of the diets (Table 1). Similar enhancement has been

reported by Arimoro (2005) who replaced artificial Stanlor with Brachionus calyciflorus larvae in catfish.

Growth performance of fingerlings

Mean weight gain was highest in diet with 30% inclusion of roasted GNC meals and least in diet with 40% inclusion

of boiled GNC meal. Total feed intake was least in diet with 40% boiled GNC meal, while it was highest in diet with

30% roasted GNC meal. Protein efficiency ratio was also found to be lowest in fingerlings fed diet with 40% boiledGNC meal while the highest value was obtained in fingerlings fed diet with 30% roasted GNC meal.

Growth performance and nutrient utilization of fish fed on all the treatment diets are summarized in Table 3. The

responses of fish to the different diets showed that growth and nutrient utilization were significantly (P< 0.05)

influenced by the processing methods. Fish fed diets containing boiled GNC meals had significantly (P< 0.05) lower

body mass, total feed intake, protein efficiency ratio and specific growth rate compared to the control diet. This is

evidenced in the proximate composition of the major protein sources in the experimental diets (Table 1). Table 3

shows that the best growth response was obtained in C. gariepinus fingerlings fed the control diet (Diet 1). C.

gariepinus fingerlings fed diets II, III and IV had comparatively similar growth response as those fed the control



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diet, although lower. The different processing methods applied

vol 2 - cont. j. fisheries and aquatic sci

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