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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 this regard 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 60°C 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 of Senilia senilis in the Andoni Flats RESULTS AND DISCUSSION The growth relationships of Senilia 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 senilis and 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.

Log

(dr

y w

eigh

t g)

Log W = -3.334+2.942 Log L r = 0.999

Log (shell length mm)

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Ansa, E. J and Allison, M. E: Continental J. Fisheries and Aquatic Science 2: 1 - 5, 2008 Fig. 2: Length dry weight relationship of Tagelus adansonii in the Andoni Flats Fig. 3: Length dry weight relationship of Tellina nymphalis in the Andoni Flats

0 -2 -3 L

og (d

ry w

eigh

t g)

Log (shell length mm)

Log W = -5.096+3.395 Log L r = 0.997

Log (shell length mm)

Log

(dr

y w

eigh

t g)

Log W = -3.978+2.633 Log L r = 0.994

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

Tellina nymphalis

-3.978 0.075 -4.136 to -3.821

2.633 0.069 2.487 to 2.779

0.994 0.988 0.984 to 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. Cucalón – 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 of Tilapia 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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Ansa, E. J and Allison, M. E: Continental J. Fisheries and Aquatic Science 2: 1 - 5, 2008 Received for Publication: 17/05/2008 Accepted 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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Continental J. Fisheries and Aquatic Science 2: 6 - 12, 2008 © Wilolud Online Journals, 2008.

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 of L. 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 of L. 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 characteristic filter 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 and act 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 mussel L. 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 and 60 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 C4 % Total nitrogen E2 E3 E4 C3 C4 C5 % Organic matter E3 E4 E5 C4 C5 C1 Total phosphorus E4 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 MATERIALS AND METHODS Setting up of mesocosm In order to study the influence of bioturbation and biodeposition by the freshwater mussel L. marginalis on selected ecological 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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P. Jayakumar et al: Continental J. Fisheries and Aquatic Science 2: 6 - 12, 2008 15, 30, 45 and 60d using a core samples of 5 cm diameter and up to a depth of 6 cm. The collected samples were processed 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 sediment Total 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 14 Between 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 of L. 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 Duncan’s 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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P. Jayakumar et al: Continental J. Fisheries and Aquatic Science 2: 6 - 12, 2008 Percentage of water content The water content of the bottom sediment of the experimental mesocosms was found to be greatly influenced by the presence of L. 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<0.01). However after 30d, it remained more or less at the same level through out the experiment. No significant change in the percentage of water content was noticed in the control mesocosms.

Table 3. Alterations in the percentage of sediment water content, percentage of organic matter, percentage of total nitrogen, total phosphorus and humic acid content of the bottom sediment of the mesocosms at various intervals of the experiment

Control 15d 30d 45d 60d Percentage of water content in the sediment

40.65 ± 0.16 45.78 ± 0.52 52.24 ± 0.28 50.75 ± 0.93 50.96 ± 0.40 a** a** b** a** b NS a** bNS

Percentage of organic matter in the sediment 1.11 ± 0.033 1.8 ± 0.038 3.33 ± 0.012 2.84 ± 0.046 4.08 ± 0.047

a** a** b** a** b** a** b** Percentage of total nitrogen in the sediment

1.66 ± 0.0360 1.92 ± 0.0404 2.06 ± 0.0289 2.11 ± 0.0549 2.35 ± 0.0284 a** a** b* a** bNS a** b**

Total phosphorus in the sediment 0.19 ± 0.0033 0.20 ± 0.0033 0.22 ± 0.0058 0.27 ± 0.0067 0.32 ± 0.0058

aNS a** b* a** b** a** b** Humic acid content of the sediment

0.3033 ± 0.0033 0.330 ± 0.0058 0.4066 ± 0.0088 0.4933 ± 0.0088 0.6633 ± 0.0145 aNS a** b** a** b** a** b**

Note: X ± SEM (Duncan’s multiple range test); a = between the respective experimental group and control group; b = between the respective experimental group and the preceding experimental group; d = days; NS = not significant; * = p < 0.05; ** = p < 0.01. Percentage of organic matter The organic matter content was also increasing up to 30d in the experimental mesocosms. But after 45d it decreased significantly (Tables 2 and 3; p<0.01). However, in contrast to the percentage of water content, the organic matter again registered a significant increase after 60d. There were no significant changes in the organic matter contents of the control mesocosms. Percentage of total nitrogen In contrast to the percentages of water content and organic matter, the percentage of total nitrogen in the experimental mesocosms showed a steady increase throughout the experiment (Tables 2 and 3) reaching the maximum after 60d. No significant changes in the nitrogen content were noticed in the control mesocosms. Total phosphorus The phosphorus content of the experimental mesocosms also increased gradually (Tables 2 and 3) reaching the maximum after 60d (p<0.01). The increase was however not significant during the initial stage (e.g., 15d). The phosphorus content of the control mesocosms was more or less same throughout the tenure of the experiment. Humic acid content The humic acid content (Tables 2 and 3) in the experimental mesocosms remained more or less at the control level up to 15d and after that it started an increasing trend to reach the maximum value of 0.6633 ± 0.0145 after 60d (p<0.01). As in the case of the other ecological parameters, humic acid content in the control mesocosms remained statistically unchanged. From 30d onwards, highly increased quantities of muscilaginous scum/organic debris rich in algal cells were also seen on the walls and bottom sediments of the mesocosms.

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P. Jayakumar et al: Continental J. Fisheries and Aquatic Science 2: 6 - 12, 2008 DISCUSSION The 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 of L. 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 where L. 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 which high-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). Recently enhancement 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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P. Jayakumar et al: Continental J. Fisheries and Aquatic Science 2: 6 - 12, 2008 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 by opportunistic 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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P. Jayakumar et al: Continental J. Fisheries and Aquatic Science 2: 6 - 12, 2008 Mirto, S., La Rosa, T., Danovaro, R. and Mazzola, A. (2000): Microbial and meiofaunal response to intensive mussel-farm biodeposition in coastal sediments of the Western Mediterranean. Mar. Pollut. Bull., 40: 244-252. Murugesan, A.G. and Rajakumari, C. (2005): Environmental Science and Biotechnology, 1st edn., M.J.P. Publication, Chennai, India, pp. 1-460 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. Watson, S.B., McCauley, E. and Downing, J.A. (1997): Patterns in phytoplankton taxonomic composition across temperate lakes of differing nutrient status. Limnol. Oceanogr., 42: 487-495. Widmeyer, J.R. and Bendell-Young, L.I. (2007): Influence of food quality and salinity on dietary cadmium availability in Mytilus trossulus. Aquat. Toxicol., 81: 144-151. Received for Publication: 17/08/2008 Accepted for Publication: 26/08/2008 Corresponding Author V.I. Paul Department of Zoology, Annamalai University, Annamalainagar 608 002, Tamil Nadu, India.

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Continental J. Fisheries and Aquatic Science 2: 13 - 22, 2008 © Wilolud Online Journals, 2008.

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

1ADINYA, I. B, and 2 IKPI, 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 fish farming 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 it account 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 that has 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 function gives 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 METHODOLOGY STUDY 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 25’N and longitude 25o 00’E (Figure 1). The soils of Cross River State are utisols and alifisol but predominantly utisol (USDA) or (FAO/UNESCO, 1974). The state’s 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 Africa’s 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 randomly chosen 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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ADINYA, I . B, and IKPI, G. U: Continental J. Fisheries and Aquatic Science 2: 13 - 22, 2008 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, brewer’s 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 Leaving Certificate=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+ e…equation (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 +e…equation (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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ADINYA, I . B, and IKPI, G. U: Continental J. Fisheries and Aquatic Science 2: 13 - 22, 2008 EP= MP AP RESULTS AND DISCUSSION Table1: Distribution of respondents according to socio-economic characteristics of fish farmers in Cross River State

Educational Attainment

Northern Zone (Ogoja Zone

Central Zone (Ikom Zone

Southern Zone (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 3.33 Total 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 and Above

- - - - -

Total 40 40 40 120 100 Labor (man-days)

1 9 5 4 18 15.00 2 12 10 10 32 26.67 3 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 improved technology

Improved management of fish 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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ADINYA, I. B, and IKPI, G. U: Continental J. Fisheries and Aquatic Science 2: 13 - 22, 2008 very important for taking positive decisions aimed at improving their income. Of course, this goes to confirm the earlier

deduction by (Adinya,2001; Idiong , et al 2006 ) that technical and commercial education broaden farmer’s 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

Source: Field survey, 2008

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 in the 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),

State’s average

State’s average value

1. Fish output(FO)kg 100

3.56

4.30

4.58

12.44

1,244,000

2. 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 � mean � Depreciation

1000 500 750

2.0 1.0 3.00

2.5 1.2 303.3

2.8 1.6 306.7

7.3 3.6

7,300 1,800 910

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 309405 8. Net Return 934595

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ADINYA, I. B, and IKPI, G. U: Continental J. Fisheries and Aquatic Science 2: 13 - 22, 2008 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% of protein 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 state’s 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

X2 Labour

0.0083 342 2.85 178.13 62.50 2.85 under utilized

X3 Feed (Diet)

0.00825 119.9 0.99 728.00 735.17 0.99 Over utilized

Source: Field survey, 2008 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- Value

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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ADINYA, I. B, and IKPI, G. U: Continental J. Fisheries and Aquatic Science 2: 13 - 22, 2008 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 extension services. 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 Pure and Applied .14 (1): 13 - 17 . Ajayi S.S. (1996), Fish and Wildlife Biodiversities and Development. FEPA Report, Abuja, Nigeria Pp1-12. Ajayi, A.R.and Madukwe (2001). The Potential Role of Agricultural Extension in Agro- Biotechnological Innovation Generation and Adoption in Developing Countries: A case Study of Nigeria. Jounal of the Science of Agriculture,Food Technology and The Environment, 1(1):39-46.

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ADINYA, I. B, and IKPI, G. U: Continental J. Fisheries and Aquatic Science 2: 13 - 22, 2008 Akpet S.O., G.E. Arikpo, E.A. Agbogo, and L.O Ogbonnaya (2005); Indigenous knowledge in supplementary dietary protein needs Among the Rural Population of Cross River State. A paper presented at the 2nd annual conference of the Nigerian Society of Indigenous Knowledge and development held at Cross River University of Technology Obubra, Cross River State, Nigeria. Pp.1-5 Arene, F.I.O.,Ibanga, E.S. and Asur, J.E(1999). Freshwater Snail Crab Intermediate Host of Paragonimus Species in Two Rural Communities in Cross River Basin,Nigeria. Global Journal of Pure Sciences 5(2):184-187. Awoke, M.U.(2001).Econometrics: Theory and Application, WillyRose and Appleaseed Publishing Company Abakaliki, Nigeria p10.

. Campbell-Platt G. (1984). Traditional West African Food Processing of Institute of Food Science and Technology, United Kingdom 17(4). Cross River Agricultural Development Project (1992) Crop Production guide pp 1 – 10.

Disney, J.G. A. Hoffman, J. Olley, I.J Clucas, A.Barranco, and B.J. Francis (1978.) Development of Fish Silage/Carbohydrate Animal Feed for Use in the Tropics. Tropical Sciences. 20(2): 127-145 . Effiong E.O. and C.E. Onyenweaku(2006). Profit Efficiency in Broiler Production in Akwa Ibom State. Global Journal of Agricultural Sciences 5(1):43-47 Essien A, G.O Alonge, S.C. Etop , E.E. Umoh and I.B. Adinya(2008) Consumer Preference for Different Poultry Species in Calabar . A Paper Presented at Annual Conference of World’s Poultry Congress in Brisbane Australia 30th June – 4th July 2008. Etim, N.A., Azeez, A.A. Asa U.A.(2006).Determinants of Urban and Peri – Urban Farming in Akwa Ibom State, Nigeria, Global Journal of Agricultural Sciences .5(1):13-16. Ezekiel A.O. (2005), Indigenous knowledge and aquatic Resources Conservation and Management in Nigeria. A paper presented at the 2nd annual conference of the Nigerian Society of Indigenous Knowledge and development held at Cross River University of Technology Obubra, Cross River State, Nigeria. 9 – 12th November, 2005. pp. 78 –84. FAO/UNESCO(1974). Soil Map of the World Report.pp1-10 Farrel M.J. 1984. The Measurement of Production Efficiency. Journal of Royal Statistic Society Series120(3):253 281. Food and Agricultural Organization (FAO), (2005). World Tables on Meat Production , Imports, Exports and Consumption. Ibrahim F.D. and Olayemi (2006), Marketing of Smoked Fish in Some Selected Areas of Niger State. A paper presented at the 20th Annual National Conference of Farm Management Association of Nigeria held at Forestry Research Institute of Nigeria, Federal College of Forestry Bauchi, Plateau State. Date: 18th – 21st September 2006. Pp.371 – 377. Idiong C.I, D.I. Agom and S.B. Ohem (2006) Comparative Analysis of Technical Efficiency in Swamps and Upland Rice Production System in Cross River State, Nigeria. A paper presented at the 20th Annual National Conference of Farm Management Association of Nigeria held at Forestry Research Institute of Nigeria, Federal College of Forestry Bauchi, Plateau State. Date: 18th – 21st September2006. Pp. 30 – 38. John T.R. (1980), Elementary Food Science. Second Edition, AVI Publishing Company 205pp. Jories.

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ADINYA, I. B, and IKPI, G. U: Continental J. Fisheries and Aquatic Science 2: 13 - 22, 2008 Kmenta, J(1971).Elements of Econometrics, Macmillan Co.Inc.New York.pp1- 18. Koutsoyiannis,A.(1977).Theory of Econometrics.Published by Macmillan London,.pp1- 667. Lale, N.E.S. and B.M Sestawa (1996). The Effect of Sun-Drying on the infestation of the African Catfish Claries gariepine Against Post Harvest Insect in the International Journal of Pest Management 42:28, - 283.

MOFINEWS (2004). Why Agriculture? Cross River State: Producing Milk and Honey for the Nation. A Bi-monthly Journal of Finance Incorporated, Calabar, Cross River State, Nigeria. July- August 2004 3 ( 6): 4– 5. MOFINEWS (2007) Population Census 2006 Murtala O ,S.,H. O. John and D.S. Peter(2005) Fish Feeds in available in Nigeria and evalution of two commercial pangas feeds through growth trial in ponds , Ministry of Fisheries and Livestock and Department of Fisheries. Ohen S.B. and G.Dixie (2007). Evaluating the supply Chain for Interregional Quacultured Catfish Trade in Nigeria .Global Journal of Agricultural Sciences 6 (1): 5- 10.

Onu, D.O., Adesope, O.M and Udokang D.O.(2003). Evaluation of work- Related Stress Characteristics Among Agricultural Extension Agents, Journal of Agricultural,Forestry and Social Science 1 (1):13.

Quarterly New Letter of The Ministry of Local Government Affairs Cross River State(2006).pp4-8. Sule H. (2006), Fish Processing and Preservation for sustainable Food Security in Nigeria. A paper presented at the 20th Annual National Conference of Farm Management Association of Nigeria held at Forestry Research Institute of Nigeria, Federal College of Forestry Bauchi, Plateau State Date: 18th – 21st September 2006.

Ugwu L.L C.,B.O.Mgbenka, H.O.Nwamba and B.I. Odo (2001). Nitrogen Metabolism and Specific Growth Rate of Africa Catfish Fry (Clarias geriepinus ) Fed different protein Levels. Journal of the Science of Agriculture Food Technology and The Environment 1 (1): 5-8. Ugwu L.L C( 1984). Protein Requirement of Africa Catfish (Clarias lazera) fry . M.Sc Thesis University of Ibadan, Nigeria Pp180-184. Received for Publication: 17/08/2008 Accepted for Publication: 26/09/2008 Corresponding Author 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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Continental J. Fisheries and Aquatic Science 2: 23 - 30, 2008 © Wilolud Online Journals, 2008.

EVALUATION OF PROCESSED GROUNDNUT (ARACHIS HYPOGAEA) CAKE MEALS IN THE FEEDING OF CLARIID CATFISH, CLARIAS GARIEPINUS, FINGERLINGS.

FAPOHUNDA Olawumi Oluwafunmilola

P. O. Box 4440, Akure, Ondo-State, Nigeria. E-mail: olawumif@yahoo.com

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 on the 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 of GNC 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

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FAPOHUNDA Olawumi Oluwafunmilola: Continental J. Fisheries and Aquatic Science 2: 23 - 30, 2008 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 dressing percentage 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 of C. gariepinus fingerlings. MATERIALS AND METHODS 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 7o.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 at ambient temperature (250C) 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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FAPOHUNDA Olawumi Oluwafunmilola: Continental J. Fisheries and Aquatic Science 2: 23 - 30, 2008 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

65.67±0.01 9.13±0.01 40.75±0.01 40.52±0.04

Crude lipid 13.10±0.01 2.70±0.02 9.81±0.01 9.67±0.01 Crude fibre

- 2.42±0.01 4.25±0.03 4.33±0.02

Ash 4.36±0.04 3.61±0.01 5.31±0.02 5.29±0.01 Moisture 7.60±0.02 7.24±0.01 7.01±0.02 7.31±0.02 *NFE 9.27±0.01 74.90±0.02 32.87±0.02 32.88±0.02

*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: 3.69±0.01g) 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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FAPOHUNDA Olawumi Oluwafunmilola: Continental J. Fisheries and Aquatic Science 2: 23 - 30, 2008 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 (9am to 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 of C. 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 3.86b 3.96b 3.40a 3.76ab 3.64ab 3.40a Final mass g 10.49c 9.50b 9.25b 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 Daily Growth

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

Body Weight Increase %

175.33b 146.11ab 133.59a 158.82b 138.83a 134.62a 135.29a

Specific Growth Rate

0.44b 0.39ab 0.37a 0.41ab 0.38a 0.37a 0.37a

Protein Efficiency Ratio

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

Total Feed Intake g

3.45c 3.33b 3.12ab 3.28b 2.89ab 2.81a 2.69a

Daily Feed Intake g

0.029b 0.025b 0.021a 0.022a 0.020a 0.021a 0.021a

Survival % 96b 97b 87a 91b 89a 90a 95b 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 mean weight of fish per time (Hogendoorn 1980). SGR = Log Wf – Log Wi / t X 100 Where Wf = mean final weight Wi = mean initial weight t = rearing period (days). Feed gain ratio (FGR): Tf/ Wf – Wi

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FAPOHUNDA Olawumi Oluwafunmilola: Continental J. Fisheries and Aquatic Science 2: 23 - 30, 2008 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). Where ANOVA revealed significant differences, Duncan’s multiple-range test (Zar 1996) was applied to characterize and quantify the differences between treatments using Statgraphics 5 Plus Package for Windows (Mannugistics Inc. and Statistical Graphics Corp, Maryland, US. 1998). RESULTS AND DISCUSSION Proximate composition of GNC meals Table 1 shows the results of proximate composition of differently processed GNC meals. Crude protein content of GNC meals was 40.52% and 40.75% in boiled and roasted GNC meals, respectively. These values fell within the range of 40-55% as reported by Pillay (1993) and 40.7% to 41.2% reported by Fagbenro (1999). The lower protein content recorded for processed GNC meals may be due to heat denaturation of the seed protein with boiled GNC being more affected. Heat-treated protein cause irreversible denaturation leading to association and precipitation of the polypeptide chains as high molecular weight compounds, (Wolf 1970). The results showed that boiled GNC meals had measurable lower (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 of C. 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% boiled GNC 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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FAPOHUNDA Olawumi Oluwafunmilola: Continental J. Fisheries and Aquatic Science 2: 23 - 30, 2008 diet, although lower. The different processing methods applied on the GNC meals might have led to decreased dietary protein utilization, since the protein had been denatured, leached and vaporized, hence reduced performances, although roasted GNC meal produced better results. According to Emiola and Ologhobo (2006), heat treatments are less effective in the detoxification of tannin, phytate and oxalate in seeds. Roasting appears to be partially effective in inactivating the lectins and trypsin inhibitiors. The results obtained in this study affirms that the good performance of fish fed diets containing roasted GNC meal may be due to the processing technique (roasting) compared to boiling to remove anti-nutrients which probably influenced nutrient availability, palatability and utilization of the meals. Acceptance of the diets was good and fingerlings became accustomed to the diets within the first week because there were no morphological defects observed during this period. Body weight mass increase, total feed increase, protein efficiency ratio and specific growth rate by C. gariepinus fingerlings in all diets (Table 3), showed no statistical differences, which suggests that processed GNC meals could partially replace diets for C. gariepinus fingerlings without compromising growth and fish health. This deduction is in agreement with observations made by Fagbenro (1999) on the performance of winged bean meals on African Clariid catfish; Eyo and Ezechie (2003), on the performance of rubber meals on Heterobranchus bidorsalis and C. gariepinus; Arimoro (2005) on the performance of Brachionus calyciflorus on H. longifilis larvae; and Okoye et al. (2006) on the performance of graded levels of sorghum meal on broiler chicks. Each of them discovered no significant differences in the TFI, SGR, PER and BWI of fingerlings fed the test diets and the control diets. Means with the same superscripts along the same row are not significantly different, according to Duncan ’s Multiple Range test. Fish mortality It was observed that survival rate was high with the lowest at 87% and the highest was 97%. The fingerlings easily got acclimatized to the test diets and accepted the diets readily without compromising their health thereby reducing the rate of mortality. CONCLUSION AND RECOMMENDATION This study revealed that processing GNC meals can successfully partially replace fishmeal up to 30% without significantly affecting growth and fish health. Replacing fishmeal with GNC meal up to 30% will lower the cost of feeding fish since GNC meal is relatively cheaper than fishmeal which hitherto was used as the main basal ingredient in formulating diets for fish. Under critical fishmeal shortfall GNC meal can be used as main basal ingredient in formulating fish diet, since replacing fishmeal up to 35% GNC shows that fish were still gaining weight. It is recommended that the use of fishmeal as the main basal ingredient could be discontinued, since GNC meal was a cheaper alternative, and could replace fishmeal up to 35%, without any significant adverse effects on fingerling performance. REFERENCES Association of Official Analytical Chemists, AOAC (1990). Official method of analysis, 15th Edition Association of Official Analytical Chemists, Arlington , Virginia , USA . Arimoro, F. O. (2005). Preliminary Investigation into the Isolation, Culture and Suitability of the Freshwater rotifer, Brachionus calyciflorus as starter feed for the African catfish, Heterobranchus longifilis larvae. Journal of Scientific Agriculture 61: 273-275. Balogun, A. M. and Fasakin, E. A. (1996). Flesh yield and aspects of chemical composition of flesh of some commercially important freshwater fish species in Nigeria . Journal of Agricultural Technology 4: 33-40. Egwaikhide, P. A., Eguavren, I. O. and Akporhonor, E. E. (2005). Effect of sprouting on in vitro digestibility of some locally consumed leguminous seeds. Journal of Food Technology 3(3): 346-349. Ekanem, S. B. (1992). Studies on the Freshwater pond Culture of Chrysicththys nigrodigitatus (Lacepe). Unpublished Ph.D. Thesis, University of Calabar , Calabar , Nigeria .

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FAPOHUNDA Olawumi Oluwafunmilola: Continental J. Fisheries and Aquatic Science 2: 23 - 30, 2008 Ekanem, S. B. (2003). The Biology and Culture of the silver catfish (C. nigrodigitatus). Journal of Sustainable Tropical Agricultural Research 10: 1-7. Emiola, I. A. and Ologhobo, A. D. (2006). Nutritional Assessment of raw and differently processed underutilized legume seeds in broiler diets. Journal of Animal Veterinary Advances 5(2): 96-101. Eyo, J. E. and Ezechie, C. U. (2003). The effects of rubber (Havea brasiliensis) seed meal based diets on acceptability and growth performance of Heterobranchus bidorsalis (male) X Clarias gariepinus (female) hybrid. Journal of Sustainable Tropical Agriculture Research 10: 20-25. Ezenwa, B. (1982). Production of catfish, C. nigrodigitatus in brackish water ponds in Nigeria using groundnut cake as supplemental feed. Aquaculture 27: 197-203. Fagbenro, O. A. (1999). Equi-protein replacement of soybean meal with winged bean meals in diets for African Clariid catfish, C. gariepinus (Burchell). Journal of Aquculture in the Tropics. 14(2): 93-99. Fagbenro, O. A., Smith, M. A. K. and Amoo, A. I. (2000). Acha (Digitaria exilis Stapf) meal compared with maize and sorghum meals as a dietary carbohydrate source for Nile tilapia (Oreochromis niloticus L.). The Israeli Journal of Aquaculture – Bamigedgeh 52(1): 3-10. Hogendoorn, H. (1980). Controlled Propagation of the African catfish, Clarias lazera (C&V) III. Feeding and growth of fry. Aquaculture 21: 233-248. Jackson , A. J., Capper, B. S. and Matty, A. J. (1982). Evaluation of some plant proteins in complete diets for the tilapia, Sarotherodon mossambicus. Aquaculture 27: 97-109. Mannusgistics, (1998). Mannugistics Incorporation and Statistical Graphics Corporation, Maryland , US. Oharei, O. C. (2005). Comparing blood clotting times on Oreochromis niloticus (L.) and Clarias gariepinus (Burchell) concurrently fed with Elaeis guineensis Jacq. Scientific Industrial Studies 3(1): 4-6. Okoye, F. C., Uguuene, M. C. and Ubaeduonu, L. C. (2006). Effects of the replacement of maize with graded levels of sorghum malt (Sorghum bicolor) on the performance of broiler chicks. Agriculture Journal 1(2): 77-80. Oresegun, A., Alegbeleye, W. O. and Oguntade, O. K. (2004). Growth response of tilapia (Oreochromis niloticus) fed varying levels of cassava peel-based ration supplemented with DL-methionine. Journal of Sustainable Tropical Agricultural Research 10: 26-30. Pillay, T. V. R. (1993). Aquaculture, Principles and Practices. Fishing News Books. Blackwell Scientific Publication Ltd., London , 575pp. Pitcher, T. J. and Hart, P. J. B. (1982). Fisheries Ecology. The AVI Publication Company, Inc. West Port-Connecticut. 107-147pp. Stiffens, W. (1989). Protein utilization by rainbow trout (Salmo gairdneri) and carp (Cyprinus carpio): A brief review. Aquaculture 23: 337-345. Stuart, G. S. and Hung, S. S. O. (1989). Growth of Juvenile White Sturgeon (Acipenser transmontanus) fed different proteins. Aquaculture 76: 303-316. Wolf, W. J. (1970). Soybean proteins: Their functional, chemical and physical properties. Journal of Agriculture and Food Chemistry 18: 969.

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FAPOHUNDA Olawumi Oluwafunmilola: Continental J. Fisheries and Aquatic Science 2: 23 - 30, 2008 Wood, J. F. (1987). The functional properties of feed raw materials and their effects on the production and quality of feed pellets. Animal Feed Science and Technology 18: 1-17. Zar, J. H. (1996). Biostatistical Analysis 3rd edn. Prentice-Hall, Upper Saddle River , New Jersey , USA . Received for Publication: 29/11/2008 Accepted for Publication: 10/12/2008

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Continental J. Fisheries and Aquatic Science 2: 31 - 34, 2008 © Wilolud Online Journals, 2008.

A FIELD AGRONOMIC EVALUATION OF TYPHA GRASS IN TOMAS DAM KANO STATE NIGERIA

Y. A. Birnin Yauri M. L. Balarabe* Mohammed. H. A. and S.O. Owotunse Aquatic Vegetation Programme, National Institute for Freshwater Fisheries Research.PMB 6006 New Bussa,

Nigeria * AHMADU BELLO UNIVERSITY ZARIA, Biological sciences Department.

ABSTRACT The study was carried out by measuring plant height, length of leaves, width of the leaves, length of inflorescent, length of inflorescent tip were also measured with a measuring tape. Number of tillers per plants was counted. Soil auger was used to take soil samples randomly from ten different locations in Tomas Dam Kano states Nigeria. At the depths of 0-5cm, 5cm – 10cm, 10cm – 15cm. The soil samples were put into polyethylene bags and labelled according to their depth for mineral analyses. In the two season calcium, nitrogen and phosphorus constitute the highest concentration of the minerals at 0―5 cm depth. There is no significant differences in terms of mineral composition between wet season and dry season. (P<0.005).There is significance differences between plant Length of inflorescent and length of inflorescent tip when the two season are compared. KEYWORDS: Typha grass, field, agronomic evaluation,

INTRODUCTION Typha grass can be found in wetland, sedges and meadows along moving streams, rivers banks and lake edges. The plant is found in areas of fluctuating water level such as road side ditches and reservoirs (Morton 1975). It is an erect perennial freshwater aquatic herb which can grow up to 3 or more meters in height. The leaves are thick ribbon like structure which have a spongy cross-section exhibiting air channels. The subterranean stem arises from thick creeping rhizomes. Flower structure is a dense, fuzzy, cylindrical spike on the end of stem, with a gap 1-3 cm of naked stem between the upper, male portion (stamina) an lower, female (Pistillate) portion. is a clonal monocotyledon with sword-like leaves that grow vertically from the shoot base. The leaves are made of aerenchyma tissue and a large portion of biomass allocation is directed toward sexual reproduction(Mal, Mal, T. K., J. Loveet-Doust and L. Lovett-D0ust (1997). At maturity the spike bursts under dry condition releasing the fruits. The fruits have bristly hairs that aid in wind dispersal. When the fruits come in contact with water, the pericarp opens rapidly, releasing the seed. The fruits often fall to the ground in dense mats. Vegetative reproduction occurs through an extensive rhizomes system which is responsible for the maintenance and expansion of existing stands (Shekhov, 1974).Studies conducted on Typha germination suggests that seeds germination can be 100 percent in slightly flooded condition (Smith, 1967). Typha studies revealed that its basic requirements are wet pure sand, peat, clay and loamy soil. It also requires higher percentage of nitrogen. Best germination of Typha grass is obtained under non saline condition and germination decrease with increase in salinity. Absence of light completely inhibited seed germination of Typha grass (Gulzar, 2002). Typha grass causes a variety of problems in Nigeria that are broadly similar to those caused by Typha grass elsewhere in the world (Morton, 1975). Earlier studies (NIFFR, 2000) revealed that, this plant caused problems in Hadejia|Jama`are, Jigawa state, and Bagga Kano state, in Nigeria. Such problems includes interfering with water from flood lands; impeding the movement of boats for transport, fishing and recreation among others It also interfers with various methods of catching fish; competing with rice in paddy systems, leading to degrading of

32

Y. A. Birnin Yauri et al: Continental J. Fisheries and Aquatic Science 2: 31 - 34, 2008 water quality by adding taints and odours to the water, thus, decreasing dissolved oxygen content. It also alters the flora and fauna of aquatic ecosystems as well as a reduction in light penetration within the aquatic system. The aim of this study is to evaluate Environmental factors which favours growth of Typha grass in Kebbi and Katsina state with the aim of determining its current status. Results of the study are expected to provide appropriate recommendations to solve problems posed by Typha grass on the water bodies so that, optimal uses of the lakes and rivers in this two states may be enhanced, and also to provide information on seasonal variation in the plant morphology and minerals composition.

Table 1: Morphological features of Typha grass during dry season in Tomas Dam Kano States. Plant height 2m 2.5m 2.8m 2.5m 2m Length of leaf 2.1m 2m 1.8m 19m 2m Width of leaf 0.5cm 0.4 cm 0.5 cm 0.8 cm 0.8cm Length of inflorescent tip

22cm 31.0 cm 19.6 cm 25 cm 30cm

Length of inflorescent

42cm 90 cm 36 cm 39 cm 42cm

No. Of tiller 8 9 10 5

Table 2: Morphological features of Typha grass during wet season in Tomas Dam Kano States. Plant height. 2.0m 2.5m 3m 1.5m 2m length leaf 2m 1.75m 1.75m 2m 1.8m width of leaf 0.5cm 0.8cm 0.5cm 0.5cm 0.5cm Length of inflorescent tip

Absent in wet season

Length of inflorescent

Absent in wet season

No. of plant 8 6 5 2 5

MATERIALS AND METHODS This study was carried out at Tomas Dam, Kano state Nigeria in 2007.The plant height, length of leaves, width of the leaves, length of inflorescent, length of inflorescent tip was measured with a measuring tape. Number of tillers per plants was counted. Soil auger was used to take soil samples randomly from ten different locations, at the depths of 0-5cm, 5cm – 10cm, 10cm – 15cm. The soil samples were put into polyethylene bags and labelled according to their depth for mineral analyses. Depth of the water was also measured, with measuring tape and samples were collected into plastic bottles. The soil samples were air dried to stop microbial activities before taken to laboratory. The soil was analyzed at Ahmadu Bello University, Zaria using Flame Photometer (Model Jeaway pf p7) . All data collected on morphology of the plant were subjected to statistical analysis using one- way ANOVA . RESULTS AND DISCUSSION The result in tables 1and 2 show the morphological characteristics of Typha grass during wet season and dry season in Tomas dams Kano state. Soil nutrient figures) 1, and 2 showed the mineral composition of Tomas Dam Kano state at different season and soil depth studied. Figure 1 showed that soil depth between 5-10cm has the highest percentage of nitrogen, phosphorus, calcium, magnesium and potassium during dry season compared to other depth. It also follows the same pattern during wet season. DISCUSSION. The mineral composition of the two season indicated higher concentration of minerals at soil depth 5-10 cm. How ever potassium was found in higher percent at 10-15cm depth. This may be due to leaching. In the two seasons calcium, nitrogen and phosphorus constitute the highest concentration of the minerals at 0―5 cm depth. This might

33

Y. A. Birnin Yauri et al: Continental J. Fisheries and Aquatic Science 2: 31 - 34, 2008 be as a result of extensive use of fertilizers by farmers which might have been leached by rain to Typha infested areas. The same observation was reported by Singh et. al. (1976) that, sometimes the chemical fertilizer applied by the farmer may not be useful to the plant rather it gets leached or washed away by rain water to lowland areas.

0.58

0.32

1.1

0.4

0.58

0.74

0.41

1.18

0.42

0.560.61

0.31

1.05

0.39

0.48

0

0.2

0.4

0.6

0.8

1

1.2

1.4

Nitrogen% Phosphorus% Calcium% Magnessium% Potassium%

per

cen

tag

e co

mp

osi

tio

n (%

)

Mineral compositionFigure1. Mineral composition of soil from Tomas Dam Kano state at differnt depths during the wet season

0-5cm5-10cm10-15cm

0.55

0.38

0.91

0.44

0.34

0.63

0.47

1.01

0.48

0.41

0.59

0.39

0.83

0.37 0.38

0

0.2

0.4

0.6

0.8

1

1.2

Nitrogen% Phosphorus% Calcium% Magnessium% Potassium%

Per

cent

age

com

posi

tion

(%

)

Mineral compositionFigure 2. Mineral composition of soil from Tomas Dam Kano state at different depths during the dry

season

0-5cm 5-10cm

10-15cm

From the study it is recommended that the best time for controlling Typha grass is during wet season. That is the time when the grass does not bear flowers. The soil nutrient studied at different depths in the two states showed that calcium and nitrogen have the highest percentage for the two seasons studied. This may be associated with the fact that during the wet season farmers use chemical fertilizer in their farms which gradually wash away into to Typha infested area. Therefore this study recommend that, excess use of chemical fertilizer by the farmer should be minimized if possible organic manure should only be used only. REFERENCES. Gulzar, S. (2002). Effects of salinity on germination, dormancy, growth, and osmoregulation of perennial halophytes. PhD dissertation University of Karachi, Pakistan.

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Y. A. Birnin Yauri et al: Continental J. Fisheries and Aquatic Science 2: 31 - 34, 2008

Mal, T. K., J. Loveet-Doust and L. Lovett-D0ust (1997).Time-dependent competitive displacement of Typha angustifolia by lythrum salicaria, Oikos 79:26-33. Morton, J. F. (1975). Cattails (Typha sp.) Weed: Problem or potential crop? Economic Botany 29: 7 – 29 NIFFR (2000). National survey of infestation of water hyacinth, Typha grass and other noxious weeds in water bodies of Nigeria. A report prepared by NIFFR, April, 2002.52p Singh, S. P. Dahuja; S. S. and Moolani, M. K.(1976).Cultural Control of Typha angustata at different stages of growth. In: C. K varshney and J. R Zoska(Eds). Aquatic weeds in south East Asia Jonk. The Hague; Pp 245-247 Shehov, A. G. (1974). Effect of moving times on regeneration .of reed and reed mace Growths. Hydrobiology 211. 10(3): 61-65. Smith, S. G.(1967). Experimental and natural hybrids in North America Typha Received for Publication: 24/06/2008 Accepted for Publication: 11/12/2008 Corresponding Author Y. A. Birnin Yauri Aquatic Vegetation Programme, National Institute for Freshwater Fisheries Research.PMB 6006 New Bussa, Nigeria

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Continental J. Fisheries and Aquatic Science 2: 35 - 40, 2008 © Wilolud Online Journals, 2008.

MICROBIAL QUALITIES OF POTASSIUM SORBATE ON TREATED SMOKED TILAPIA (Oreochromis

niloticus)

Omojowo, F.S1, Omojasola, P.F2, Olokor, J.O1, Ihuahi J.A1 Ogunfowora, O.O1 1NIFFR, P.M.B. 6006, New-Bussa, Niger State, 2Department of Microbiology, University of Ilorin, Ilorin

ABSTRACT This study was carried out to assess microbial quality of potassium sorbate on Tilapia (Oreochromis niloticus) treated with varying concentration (1-5%) before smoking looking at its effects on the microbial load during 8-week storage at room temperature. The non-treated tilapia served as control and showed diverse and high microbial load while the treated smoked samples were negative for E. coli and Streptococcus sp. and recorded low TVC, coliform, staphylococcus and fungi count maintaining that low count till the end of the 8th week storage. Among the treatments, 3-5% proved very good. However, 3% treatment proved to be a better concentration since it was organoleptically acceptable and also reduced the Staphylococcus count to 0 even till the end of the 8th week storage. KEY WORDS: Potassium sorbate, smoked tilapia, microbial load and storage

INTRODUCTION Fish is becoming increasingly important in the diet of the Nigerian as there is an increase awareness that regular red meat intake in adult above 40 years of age is not healthy. Fish constitutes 40% of animal protein intake in Nigeria at present (Olatunde, 1989). This is because fish are a cheap source of animal protein with little or no religious rejection of it, which gives it an advantage over pork or beef. Fish are a very perishable commodity, more than cattle, sheep, and poultry, and get spoiled very easily even in temperate climates. So unless it is disposed of quickly after capture, it must be preserved in some way. World fish production was estimated at 100 million tons in 1989, 15% of which was cured in one or another way. One third of the cured fish was smoked and about 20% of the smoked fish goes into international trade. Smoking of fish and/or meat products is one of the most ancient processing technologies. It has been for centuries used for preservation, and is still widely used for this purpose among several communities in the third world where up to 70% of the catch is smoked for preservation (Ward, 1995). Hard curing by salting and smoking permits lengthy preservation by removing moisture, which is essential for bacteriological and enzymatic spoilage. Increasing consumer awareness of the nutritional value of seafood has stimulated a strong demand for seafood and seafood products (Pigott and Tucker, 1990) hence an increase in demand. To satisfy the consumer demand, it is necessary to produce good quality and safe smoked seafood products. Fish and fisheries products are among the most perishable commodities worldwide mainly due to microbial spoilage. About one-third of the world’s food production is lost annually as a result of microbial spoilage. In fact, microbial activity is responsible for spoilage of most fresh and of several lightly preserved seafoods (Lund et al., 2000). Smoked fish and shellfish products can be a source of microbial hazards including Listeria monocytogenes, Salmonella spp., and Clostridium botulinum (Heintz and Johnson, 1998). Omojowo and Ihuahi (2006) recorded that smoked fish samples from 4 local Markets in Kainji Lake area of Nigeria were dominated by gram-positive bacteria, potential pathogens, coagulase-positive Staphylococcus, and Escherichia coli. In addition, human infections may be caused by bacteria endogenous to fish. Bacterial pathogens, which may be transferred from fish to human beings include: A. hydrophila (septicemia, diarrhea), Clostridium botulinum type E (botulism), Edwardsiella tarda (diarrhea), Plesiomonas shigelloides (gastroenteritis), Pseudomonas aeruginosa (wound infections), Salmonella sp. (food poisoning), and vibrio parahaemolyticus (food poisoning) (Austin and Austin, 1989). Delay or prevention of microbial spoilage of fish may be achieved by different preservative methods that include the use of smoking and chemical preservatives like Sorbates. Sorbates are the most effective preservatives against a wide spectrum of food spoilage microorganisms; they include sorbic acid and potassium sorbate. They are among the safest, most efficient and versatile preservatives used in the food industry today. Sorbates are tasteless and odourless. Because they are non-toxic, they are used in a wide variety of foods, including cheese, yogurt, sour cream, bread, cakes, baking mixes, icing, beverages, margarine, fermented vegetables, fruit products, salad dressing, smoked and salted fish and mayonnaise. The antimicrobial activity of Sorbates against moulds, bacteria etc have been reported (Sofos and

36

Omojowo, F.S et al: Continental J. Fisheries and Aquatic Science 2: 35 - 40, 2008 Busta, 1993 and Sofos, 2000). Considering the antimicrobial activity of Sorbates, this study was carried out to determine the microbial impact of 1-5% concentration of potassium sorbate in smoked tilapia during 8-week storage at room temperature.

TABLE 1: MICROBIAL LOAD OF TILAPIA TREATED WITH POTASSIUM SORBATE (Log10)

Microbial group

Control 1% 2% 3% 4% 5%

B/4 Smoking TVC 5.97 a 5.46 b 5.39 b 5.26 c 4.88d 4.80 d After ,, TVC 4.51 a 3.97 b 3.83 c 3.78 c 3.24d 2.16e 2nd week TVC 6.16 a 4.25 b 4.27 b 4.25 b 3.90 c 3.00 d 4th ,, TVC 6.75 a 4.95 b 4.77 c 4.80 c 4.77 c 3.86 c 6th ,, TVC 7.37 a 5.55 b 5.48 b 5.49 b 5.32 c 4.10 d 8th ,, TVC 8.91 a 6.87 b 7.01 b 6.24 c 6.03 d 4.32 e B/4 smoking Coliform 4.56 a 4.06 b 4.00 b 3.95bc 3.71 bc 3.20 c After ,, Coliform 3.32 a 1.08 b 1.04 b 1.00 b 0.84 c 0.67 c 2nd week Coliform 3.41 a 1.52 b 1.45 b 1.40 b 1.20 c 0.95 d 4th ,, Coliform 4.06 a 1.97 b 1.83 b 1.71 b 1.64 c 1.30 d 6th ,, Coliform 5.00 a 2.48 b 2.43 b 2.35 bc 2.29 c 1.68 d 8th ,, Coliform 5.86 a 2.74 b 2.66 bc 2.60 bc 2.56 c 2.21 d B/4 smoking Staph. 4.51 a 3.81 b 3.80 b 3.77 b 3.21 c 2.90 d After ,, Staph. 3.20 a 0.86 b 0.70 b 0.0 c 0.0 c 0.0 c 2nd week Staph. 4.15 a 0.90 b 0.83 b 0.0 c 0.0 c 0.0 c 4th ,, Staph. 4.74 a 1.13 b 1.08 b 0.0 c 0.0 c 0.0 c 6th ,, Staph. 5.10 a 1.60 b 1.41 c 0.0 d 0.0 d 0.0 d 8th ,, Staph. 6.32 a 2.21 b 1.93 c 0.0 d 0.0d 0.0 d B/4 smoking Fungi 4.68 a 4.36 b 4.31 b 3.78 c 3.24 d 3.02 e After ,, Fungi 3.34 a 1.18 b 1.10 b 1.00 b 0.41 c 0.0 d 2nd week Fungi 4.64 a 1.68 b 1.54 b 1.21 c 0.62 d 0.0 e 4th ,, Fungi 5.20 a 2.32 b 2.26 b 1.64 c 0.78 d 0.0 e 6th ,, Fungi 5.58 a 3.01 b 2.88 b 2.82 b 1.0 c 0.0 d 8th ,, Fungi 7.52 a 3.70 b 3.53 c 2.45 c 1.52 d 0.30e

Using superscript a, b, c, d, e., means in the same rows with different superscript are significantly different (p < 0.05). MATERIALS AND METHODS Sample - Treatment Fresh Tilapia (Oreochromis niloticus) was obtained from a private fish pond in National Institute for Freshwater Fisheries Research (NIFFR) Housing Estate, New Bussa, Niger State in November, 2007. The fish samples measuring 12-18cm and weighing 75-90g were transferred within 30 minutes to the laboratory in a sterile polythene bags and then killed by severing the spinal cord with a sterile scalpel and aseptically eviscerated, washed and rinsed in sterile water. The fish samples were randomly chosen and divided into 6 groups of 5 fish each and 5 of the groups were subjected to treatments of 1,2,3,4 and 5% concentration for 5 minutes respectively while the 6th group served as control (untreated samples. A sample from each group was separated from each treatment for microbial analysis. Smoking was done according to the methods described by Omojowo and Ibitoye (2005). After smoking and the fish were allowed to cool down and stored in different boxes. This was done to mimic commercial practices. The samples were drawn after two, four, six and eight weeks of storage; then subjected to analysis.

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Omojowo, F.S et al: Continental J. Fisheries and Aquatic Science 2: 35 - 40, 2008 Microbiological and other Analysis Total viable count (TVC), Coliform, Staphylococci and Fungi count were evaluated according to the methods described by Harrigan and McCance 1976; Speck 1984 and Sneath et. al. 1986). Moisture contents were estimated as per AOAC (1980). All samples were done in duplicates. Sensory evaluation was carried out according to the method of Afolabi et. al. (1984). Statistical analysis was according to SAS, Institute, Inc, (1992) at P < 0.05. TABLE 2. ORGANOLEPTIC ATTRIBUTES OF FRESHLY SMOKED AND 8TH WEEK STORED TILAPIA TREATED WITH POTASSIUM SORBATE

Taste Flavour Texture Appearance

Overall-acceptability

CONTROL 4.2 4.1 4.2 4.1 4.1 FRESHLY SMOKED - 1 % 4.7 4.6 4.6 4.8 4.8 2 % 4.5 4.3 4.3 4.9 4.7 3 % 3.8 3.6 3.3 3.3 4.1 4 % 3.3 3.5 3.0 2.9 3.0 5 % 2.8 2.1 2.9 3.4 2.5 CONTROL (8TH WK) 3.3 3.5 3.6 3.6 3.0 8TH WEEK OLD - 1% 4.0 4.2 4.1 4.3 4.3 2% 4.2 4.2 4.3 4.1 4.3 3% 4.0 3.8 3.8 4.1 4.0 4% 3.1 2.9 3.0 3.7 3.2 5% 2.8 2.9 2.9 4.1 3.2

RESULTS AND DISCUSSION Microbial Analysis A study for the absence and presence of the target food borne pathogens such as Salmonella, Staphylococcus, and E. coli is required to evaluate microbial safety of smoked clarias and tilapia. Pathogens can enter the process through raw materials. They can also be introduced into foods during processing from the air, unclean hands, unsanitary utensils and equipment, unsafe water, and sewage, and through cross contamination between raw and cooked product (FDA, 2001). The range of specified microbiological limits recommended by ICMSF (1986) for fish and fishery products is as follows: for the TPC, the maximum recommended bacterial counts for good quality products (m) is 5x105 (5.7 log10 CFU/g) and the maximum recommended bacterial counts for marginally acceptable quality products (M) is 107 (7 log10 CFU/g). For E. coli, the m value is 11 (1.0 log10 CFU/g) and the M value is 500 (2.7 log10 CFU/g), and for Staphylococcus, m value is 103 (3 log10 CFU/g) (ICMSF, 1986). Total Viable count (TVC), Coliform, Staphylococci and Fungi count in log CFU/g of fresh and smoked tilapia samples plated on selective and non-selective media are shown in Tables 1. TVC of the fresh non-treated (control) tilapia was 5.97 log CFU/g but after the sample were subjected to treatments with potassium sorbate the reduction was highest in 5% (4.80 log CFU/g and least in 1% (5.46 log CFU/g as shown in Table 1). Similarly, coliform was reduced from 4.56 log CFU/g in the control to 3.20 log CFU/g in 5% and least in the treatments was 4.06 log CFU/g of 1% concentration. In the same vein, staphylococci count was reduced from 4.51 log CFU/g in the control to 2.90 log CFU/g, in 5% and least in the treatments was 1% (3.81 log CFU/g) in treated sample. Fungi count reduced from 4.68 log CFU/g (control) to 3.02 log CFU/g in 5% conc. and least in 1% (4.36 log CFU/g. Smoking sharply reduced the total viable count in all samples but the sample treated with 5% potassium sorbate showed the greatest reduction and maintained a low level throughout 8 weeks of storage, especially on day 0 with 2.16 log CFU/g. The TVC of smoked control (untreated) samples was the highest throughout the period of storage reaching 8.91log CFU/g on the 8th week. The results obtained were similar to those reported by Efiuvwevwere and Ajiboye (1996), where the samples treated with 0.4% potassium sorbate showed the lowest microbial load and maximum shelf stability. Similar to TVC, the coliform count of the smoked samples treated with 5% potassium

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Omojowo, F.S et al: Continental J. Fisheries and Aquatic Science 2: 35 - 40, 2008 sorbate had the highest reduction to 0.67 log CFU/g on day 0 and remain the lowest of the treatments throughout the period of storage. Significant increases in coliform population of all samples occurred after 4 weeks of storage. However, Coliform count of all treated samples was less than 3.0 log CFU/g throughout the 8-week storage. In the control samples, the Coliform population showed 5.86 log CFU/g on the 8th week The high coliform count recorded in this report may be due to contamination from the animal manure used in fertilizing the ponds at one time or the other. In the staphylococcus population, the smoked sample treated with 3-5% potassium sorbate reduced the staphylococcus count to 0 and remained 0 until the end of 8th week storage (Table 1.) The isolation of Staphylococcus in smoked samples on day 0 may be attributed to post processing contamination. However, Staphylococcus was killed by the treatments 3-5% potassium sorbate. The population of the fungi reduced in all the treatments and at the end of the 8-week storage time; however, the sample treated with 5% potassium sorbate showed 0 counts till the 4th week with very few count at the end of the storage. These results were also similar to that reported by Virginia, (2002) where the coliform, staphylococcus and fungi count in the control sample of blue catfish was the highest compared to other treated sample. Actually, the control sample was completely covered by mold on the 6th week.

Fig. 1. Moisture contents of Smoked Tilapia Preserved with Potassium sorbate

0

5

10

15

20

25

1 2 3 4 5Storage period

% c

ompo

sitio

n control

1%

2%

3%

4%

5%

Note, in x-axis 1= Day 1, 2= 2n d Wk, 3 = 4th Wk, 4= 6th Wk and 5= 8th Wk It is of interest to observe that in spite of the slightly reduced moisture contents (from 2nd to 6th week) in almost all the samples, microbial load still increases dramatically. This suggests that one single factor may not account for these microbial changes. Cross contamination, pH, purity of preservatives is among other factors that can influence microbial changes. The bacterial contamination of hot smoked fish just out of the smokehouse is usually below 103 per gram (Doe, 1998). The TVC of the treated samples were all about 5x105 CFU/g to the 6th week which belong to m in a three-class attribute plan and signifies good quality. Low levels of coliform bacteria were detected and the pathogens Staphylococcus aureus counts were below 103 in all the treated samples till the 8th week. The control however, has TVC higher than 5x105 CFU/g in the second week and higher than the recommended limit 7.0 log CFU/g (ICMSF, 1986) after the 4th week. In addition the coliform count already exceeded 103 even immediately after smoking. This finding is of concern as a result of the associated public health implications. For example, generally, hot smoked fish are consumed in the tropics with little or no further processing/cooking; thus, they fall into the high-risk category of foods (ICMSF, 1986). Hence there is a need for the use of appropriate percentage of choice antimicrobial agent. BACTERIAL ISOLATES All treated smoked sample were negative for E. coli and Streptococcus sp The control and the fresh fish treated samples showed the following bacteria flora Bacillus coagulans, B. cereus, Klebsiella ozanae, Proteus vulgaris, Escherichia coli, and Staphylococcus aureus, while the fungi isolated include, Aspergillus niger, A. candidus, A. flavus and A. nidulan while the smoked untreated dominated by the following

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Omojowo, F.S et al: Continental J. Fisheries and Aquatic Science 2: 35 - 40, 2008 organisms B. coagulans, (about 70% of the isolates) while the remaining being S. aureus, and Streptococcus sp. The treated sample showed the microbial load in the following pattern; 1% and 2% potassium sorbate of the fish samples contains the following spp B. coagulans, S. aureus, K. ozanae, A. candidus and A. nidulan while in 3% and 4% potassium sorbate treated samples have the following isolates B. coagulans, K. ozanae and A. nidulan while 5% treatment have only B. coagulans. Proximate Analysis Moisture contents were within 74% - 77.0% before and after treatment prior to smoking. 79.4% for fresh tilapia and catfish respectively. Moisture content decreased sharply after the smoking to 20.55 - 21.35. The moisture content continues to decrease till the 4th week before increasing again. (Fig.1.). This decrease was due to loss of water during smoking (Asiedu et al., 1991). The moisture content of all treatments remained similar throughout 8 weeks of storage. Organoleptic Assessment The quality of the smoked fish (both treated and untreated) was evaluated immediately after smoking and after storage for 8th week on taste, flavour, texture, appearance and overall acceptability using 5- hedonic scale of { 5= like much, 4 = like, 3 = neither like nor dislike, 2 = dislike, 1= dislike much.. The fish flesh overall score was given to both untreated (control) and the one of various treatment using a hedonic scale of 1- 5 fish scoring less than 2 being regarded as unacceptable. This assessment was done for both tilapia and the catfish. Table 2 summarizes the taste panel results. From the result, the trend of scores for the overall acceptability of freshly smoked tilapia is as follows 1% > 2% > 3% = C > 4% > 5% while on the 8th week the trend is 2% = 1% > 3% > 4 % > 5 % From this study therefore, tilapia treated with 1%, 2% and 3% potassium sorbate, smoked and stored for 8 weeks are well accepted by the consumers since they fall into the LIKE group and above. CONCLUSION AND RECOMMENDATION This study has reveals that the samples treated with 5% potassium sorbate before smoking showed the greatest reduction and maintained a low level throughout the 8th weeks of storage. However, organoleptic study has reveals that the samples treated with 1-3% potassium sorbate are well preferred by the consumers since it fall in the group of LIKE and above. Hence, 1-3% potassium sorbate can be used as a choice preservative in smoked catfish without adversely affecting quality in terms of lipid oxidation, color, microbial and nutritional quality. However, for better output 3% potassium sorbate as a choice antimicrobial agent is hereby recommended since it has been found to keep smoked fish in wholesome state for 8th week, reducing the TVC to 6.24 log CFU/g, the coliform to 2.60log CFU/g, staphylococcus count to 0.0s and fungi to 2.45 log CFU/g at the end of 8th week storage. This will ensure prolonged shelf life and safe consumption of smoked fish of ICMSF standard of smoked fish quality. REFERENCES Afolabi, O.A., Arawomo, O.A. and Oke, L.O. (1984). Quality changes of Nigerian traditionally processed

freshwater fish species. I. Nutritive and organoleptic changes. Journal of Food Technology 19, 333-340. AOAC (1980). Official methods of analysis of the AOAC (W. Hortwitz E.d.), 13th ed. AOAC, Washington D.C.,

U.S.A. 858pp. Asiedu, M.S., Julsham, k., and Lie, O. (1991). Effect of local processing methods on three fish species from Ghana:

Part I, Proximate composition, fatty acids, minerals, trace elements, and vitamins. Food Chem. 40: 309-321.

Austin, B. and Austin, D.A. (1989). General introduction. In Methods for the Microbiological Examination of fish and Shellfish, B. Austin and D.A. Austin (Ed.) Ellis Horwood Limited, England, p19-24.

Doe P.E., (1998). Fish drying and smoking Production and Quality. Technomic Publishing Co., Inc. Lancaster, Pennsylvania.

Efivuvwevwere, B.J.O. and Ajiboye, M.O. (1996). Control of Microbiological quality and shelf-life of catfish (Clarias gariepinus) by chemical preservative and smoking. Journal of Applied Bacteriology 80, 465-470.

FDA, Department of Health and Human Services, (2001). FDA & EPA Safety levels in regulations and Guidance. In Fish and fisheries Products, Hazards & controls guidance: Third Ed. Appendix 5, p. 285.

Harrigan, W.F. and McCance, M.F. (1976). Laboratory Methods in Food and Dairy Microbiology, 2nd Edn. London: Academic Press.

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Omojowo, F.S et al: Continental J. Fisheries and Aquatic Science 2: 35 - 40, 2008 Heintz, M.L., and Johnson, J.M. (1998). The Incidence of Listeria spp., Salmonella spp., and Clostridium botulinum

in smoked fish and shellfish. Journal of Food Protection, 61 (3): 318-323. ICMSF (International Commission on Microbiological Specifications for Foods (1986) Micro organisms in Foods 2,

Sampling for Microbiological Analysis. Principles and Specific Applications, 2nd edn. Oxford: Blackwell Science.

Lund, B.M., Baird-Parker, A.C. and Gould G.W. (2000). The Microbiological Safety and Quality of Foods. Aspen Publishers, Inc. Gaithersburg, Maryland, USA, 1885.

Olatunde, A.A. (1989). Focusing on research approaches to the study of fishery biology in Nigeria inland waters. In proceedings of the conference on two Decade of Research on Kainji. NIFFR, New Bussa, 29th Nov- 1st Dec. 1989, 538-541

Omojowo F.S. and Ibitoye A. (2005). Comparisons of the Microbial qualities of smoked Clarias gariepinus using four different kilns. In Fison proceeding, Port Harcourt 14th-18th Nov. 2005.

Omojowo F.S. and Ihuahi J.A. (2006). Microbiological Quality and Safety of smoked fish from Kainji Lake area. In African Scientist, Vol. 7, No. 4, 177-181.

Pigott G.M. and Tuckker. B.W. (1990). Seafood Effects of Technology on Nutrition, Marcel Deckker Inc. N.Y. p 155-170. Pike, O. A. 1998. Fat characterization. In Food Analysis Nielsen S.S. (2nd ed) p. 229.

Ward, A.R. 1995. Fish smoking in the tropics. A review. Trop. Sci. 35, 103 – 112. SAS Institute, Inc. (1992). SAS User’s Guide: Statistics. SAS Institute Inc., Cary, NC. Sofos, J.N. and Busta, F.F. (1993). Sorbic acid and sorbates. In Antimicrobial in Food, ed. P.M. Davidson and A.L.,

pp. 49-94. New York: Marcel Dekker, Inc. Sofos, J.N. (2000). Sorbic acid. In Natural Food Antimicrobial Systems, ed. A.S. Naidu, pp.637-659. Boca Raton,

FL: CRC Press. Sneath, P.H.A., Mair, N.S., Sharpe, M.E. and Holt, J.G. (1986). Bergey’s Manual of Systemic Bacteriology, Vol. 2.

Baltimore: Williams and Wilkins. Speck, M.L. (1984): Compendium of Methods for the Microbiological Examination s of Foods, 2nd edn.

Washington, D.C: American Public Health Association. Ufodike, E.B.C. Obureke, J.U. (1989). Effects of preservation techniques on quality of Oreochromis niloticus muscle. J. Aqua. Sci. 4: 1-5. Virginia L.T.A, (2002). Hazard Analysis and Critical Control Point (HACCP), Microbial safety and Shelf life of

Smoked Blue catfish (Ictalurus furcatus). M.sc Thesis submitted to the Graduate Faculty of the Louisiana State University.

Received for Publication: 24/06/2008 Accepted for Publication: 11/12/2008 Corresponding Author Omojowo, F.S NIFFR, P.M.B. 6006, New-Bussa, Niger State.

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Continental J. Fisheries and Aquatic Science 2: 31 - 34, 2008 © Wilolud Online Journals, 2008. Received for Publication: 24/06/2008 Accepted for Publication: 11/12/2008 Corresponding Author