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International Journal of Fisheries Science and Research

Comparative Effect of Monoculture and Polyculture in Two Species of Clariidae: Heterobranchus longifilis and Clarias gariepinus in Post Fingerlings Growth

Abstract Citation Introduction Material and Methods Results Discussion Conclusion References
Details

Received: 28-Jan-2018

Accepted: 18-Feb-2019

Published: 22-Feb-2019

Nana Towa Algrient¹, Nanmegni Rostand Romeo¹, Tonfackachille Peguy², Efole Ewoukem Thomas¹ and Jouokou Salifou²

¹Laboratory of Ichthyology and Applied Hydrobiology, University of Dschang, Cameroon ²Institute for Agricultural Research for the Development of Foumban, Cameroon

Corresponding Author:

Nana Towa Algrient, Laboratory of Ichthyology and Applied Hydrobiology, University of Dschang, Cameroon, Tel: (237) 673180089

Keywords

Monoculture; Polyculture; Clarias gariepinus; Heterobranchus longifilis; Cannibalism; Survival; Mortality; Growth

Abstract

In order to improve the production of Clariidae, a study on the type of cultivation of Heterobranchus longifilis and Clarias gariepinus in post fingerlings growth phase was carried out in tanks. It took place from March to May 2018 at the IRAD fish station in Koupa-Matapi (LN: 5º 21 ‘to 5º 58’ and LE: 10º 17 ‘to 11º 02’) west region Cameroon. For this fact 180 fry therefore 90 Heterobranchus longifilis and 90 Clarias gariepinus with an average weight 3.55 ± 0.68 g; 8.46 ± 0.41cm of total length and 7.37 ± 0.30 cm of standard length were used. The 180 fry were divided into three treatments of 60 individuals (T1 treatment: Clarias gariepinus, T2 treatment Heterobranchus longifilis and T3 treatment: Clarias gariepinus + Heterobranchus longifilis). Each treatment was repeated twice. The fish were fed twice per day at a rate of 10% of the ichthyobiomass readjusted each month after control fishing with a feed at 42% crude protein. From the results of this trial, it appears that unlike the higher mortality rates (11.66 ± 2.36%) recorded in monoculture Clarias gariepinus, the highest cannibalism rates were obtained in monoculture of Heterobranchus longifilis (13.33 ± 4.71%). The survival rate was not influenced by the type of culture. Nevertheless, the highest rate (94.44 ± 0.00%) was observed in Heterobranchus longifilis in polyculture. The highest growth values were recorded for C. gariepinus in polyculture and the weakest for H. longifilis in polyculture. For linear growth, the highest values were recorded in C. gariepinus in monoculture. In order to reduce the rate of cannibalism and mortalities in Clarias gariepinus and Heterobranchus longifilis in post f ingerlings growth phase, it is preferable to combine these two species.

Citation

Algrient NT, Romeo NR, Peguy T, Thomas EE and Salifou J. Comparative Effect of Monoculture and Polyculture in Two Species of Clariidae: Heterobranchus longifilis and Clarias gariepinus in Post Fingerlings Growth. Int J Fisheries Sci Res. 2019; 3(1): 1010.

Introduction

Low cost and easy accessibility make fish the most consumed animal protein source in the world in general and in developing countries in particular. Its demand increased from 10 to 20 kg/inhabitant/year between 1960 and 2016 [1]. In sub-Saharan Africa and particularly in Cameroon, fish contributes about 50% of animal protein to human nutrition [2]. However, the ever-increasing strong demand is not accompanied by a significant national production (fishing and fish farming). In 2013, it was estimated at 180000 tones, i.e. only 1000 t (1%) from fish farming for a demand estimated at 300000 tones [3]. However, Cameroon has many aquaculture assets, including 400 km of inland water [4] for an estimated potential of 20,000 t per year [5]. Exploiting this potential would not only help to reduce imports, which cost each year nearly 100 billion CFA francs in Cameroon [6], but also to create new jobs. Unfortunately, many constraints still hinder the growth of this sector, including the high cost of food, lack and access to capital, and the unavailability of quality fry [7]. In spite of these constraints, Cameroonian fish farming is full of a variety of species among which African catfish Clarias gariepinus are and Heterobranchus longifilis.

According to Legendre [8] these two species are of remarkable piscicultural importance because of their hardiness, their rapid growth; of a diversified diet [9]). Consumed fresh or smoked, African catfish pulpit is much more appreciated in Cameroon compared to other fish species [10]. However, their expansions are still limited by the unavailability and inaccessibility of quality fry. In current practices in local hatcheries, fry are delivered to very young fish farmers (less than 5g) without respecting the pre-enlargement phase, which induces yields of less than 50% at emptying [11]. This is due to cannibalization and increased mortality in these species before the size of 12g [12]. Knowledge of the best types of precooking crops could reduce these problems and contribute to the improvement of C.gariepinus and Heterobranchus longifilis production. The present work aims to contribute to the improvement of the production of juveniles of Clarias gariepinus and Heterobranchus longifilis. More specifically, the aim is to evaluate the effect of crop type on the survival rate, cannibalism, mortality and growth performance of Clarias gariepinus and Heterobranchus longifilis.

Material and Methods

Period and area of study

The study took place from March to May 2018 at the IRAD fishing station in Foumban, more precisely at the Koupa-matapit fish farm (5º 21 ‘to 5º 58’ North LE: 10º 17 ‘to 11º 02 ‘10 ° 48,826’ Longitude East and an altitude of 1147m in the Western Region of Cameroon. The climate is of the Sudano-Guinean type and includes a rainy season (March-October) and a season Dry (November-February) The average values of the temperature and the rainfall recorded annually are respectively 22°C and 1800 mm [13].

Animal material

A total of 180 fry including 90 Clarias gariepinus and 90 Heterobranchus longifilis were used. The fry came from a nursery pond at the IRAD fish station with a mean weight of 3.55 ± 0, 68 g; 8.46 ± 0.41cm and 7.37 ± 0.30cm respectively as total length and standard length.

Breeding structure

Six concreted tanks (length 2m, width 0.7m, height 1m) were used. A water supply system consisting of a PCV pipe and valves arranged in parallel allowed the entry and control of the flow of water in each of these tanks. A mosquito net was installed at the entrance for water filtration and to prevent predators from entering the bins. The average flow rate per tank was 0.015 ± 0.002 l/s for a water renewal of 200% per day. A basin was placed under a floating plastic frame allowed to collect food refusals from each tray. Each tray was covered with a net screen over which straws were placed to prevent the entry of predators into the bins and also create a shading to facilitate food consumption [14].

Conduct of the test

The 180 fry were divided into three treatments of 60 individuals each (T1 treatment: Clarias gariepinus, T2 treatment: Heterobranchus longifilis and T3 treatment: Clarias gariepinus + Heterobranchus longifilis). Each treatment was distributed in duplicate.

All treatments received 42% protein feed twice per day, consisting of fishmeal, soybean meal, yellow cornmeal, blood meal, palm oil and vitamin premix. The physicochemical characteristics of the water (pH, temperature, dissolved oxygen and conductivity) were measured weekly. The live weight, the total and standard length as well as the refusals collected made it possible to evaluate the following growth characteristics:

Food consumption (CA) = Food served - refusal

Weight gain (GP) = final weight - initial weight

Average daily gain (ADG) = (final weight-initial weight)/(time (day))

Specific growth rate (TCS) = lnfinal weight-lninitial weight/((time day))

Consumption index (CI) = (Quantity of food consumed)/(Weight gain)

Mortality, cannibalism and survival rates were assessed as follows:

Mortality = (Number of initial fish-mortality)* 100/(Number of initial fish)

Cannibalism rate = (Number of initial fish - number of missing fish)* 100/(Number of initial fish) with 

Number of fish missing = number of initial fish - number of deaths

Survival rate = (Number of initial fish - number of finfish)* 100/(Number of initial fish)

Statistical analyses

The one-way analysis of variance (ANOVA) was used to test the effect of crop type on cannibalism, mortality, survival and growth performance of Clarias gariepinus and Heterobranchus longifilis. Where there were significant differences between the means, the Duncan test was used for the 5% cut-offs. Regressions were used. The statistical software SPSS 14.0 made it possible to carry out all analyses.

Results

Effect of crop type on the evolution of total length and live weight of Clarias gariepinus and Heterobranchus longifilis

The evolution of live weight and total length according to the type of culture thus illustrated in Figure 1, shows that the trend, profile and overall appearance are comparable between crop types regardless of the period.

Figure 1: Evolution of weight (a) and linear (b) growth as a function of time.

T1 = Clarias gariepinus in mono culture, T2 = Heterobranchuslongifilis in monoculture, T3c = Clarias gariepinus in polyculture T3H = Heterobranchuslongifilis in polyculture.

At the end of the trial, the highest weight growth values were recorded in C.gariepinus fry in polyculture and lowest in juvenile fry of H. longifilis in polyculture. In terms of linear growth, the highest values were obtained in juvenile Clarias gariepinus fry, while the lowest values were in monoculture batches of Heterobranchus longifilis.

Influence of crop type on growth characteristics of Clarias gariepinus and Heterobranchus longifilis

The effect of crop type on growth characteristics as shown in Table 1 shows that the highest food consumption was obtained in monoculture of C.

Table 1: Variation in growth characteristics by crop type.

  Treatments
growth characteristics T1 T2 T3C T3H
Live weight (g) 13,10 ± 2,55a 12,40 ± 4,60a 14,30 ± 4,49a 11,40 ± 2,11a
Weight gain (g) 9,40 ± 2,83a 8,750 ± 4,76a 10,70 ± 4,08a 7,80 ± 1,93a
Length (cm) 12,28 ± 0,77a 11,41 ± 1,36a 11,95 ±1,51a 11,65 ± 1,17a
Length gain (cm) 3,56 ± 1,01a 2 ,68 ± 1,54a 3,27 ± 1,18a 2,93 ± 1,15a
Average daily gain (g) 0,15 ± 0,04a 0,14 ± 0,07a 0 ,17 ± 0,06a 0,13 ± 0,03a
Specific growth rate (%) 2,12 ± 0,51a 1,96 ± 0,73a 2,25 ± 0,42a 1,92 ± 0,37a
K 0,70 ± 0,09c 0,80 ± 0,11ab 0,82 ± 0,11a 0,73 ± 0,14bc
CA (g) 959,50 ± 3,53a 896,00 ± 9,14b 907,00 ± 10,87ab 907,00 ± 10,87ab
IC 3,38 ± 0,19 a 3,37 ± 0,08a 3,47 ± 0,31a 3,47 ± 0,31a

a,b: averages with the same letters on the same line are not significantly different (p> 0.05), TCS = specific growth rate, IC = consumption index, CA = food consumption, K = condition factor. T1: C.gariepinus in monoculture, T2: H.longifilis in monoculture, T3C: C.gariepinus in polyculture, T3H: H.longifilis in polyculture.

gariepinus, which was comparable to the polyculture of C. gariepinus and H. longifilis. The highest values of condition factor K were recorded with C. gariepinus in polyculture (T3C) and lowest in monoculture C. gariepinus (T1). Although not significant difference, the highest live weight and specific growth rate were obtained in polyculture with C. gariepinus and lowest with H. longifilis in polyculture (T3H).

Weight-length relationship of species according to crop type

The weight-length relationship as a function of crop type is illustrated in Figure 2 (T1, T2, T3C and T3H).

Figure 2: Weight-length relationship of juveniles of Clarias gariepinus and Heterobranchus longifilis depending on the type of crop.

It appears that in both monoculture and polyculture of the two species of Clariidae the coefficient of determination R² is very close to 1 showing that the weight is 98% related to the size of the fish.

Effect of crop type on Cannibalism, mortality and survival rates in Clarias gariepinus and Heterobranchus longifilis

Analysis of the variance showed that the culture type had a significant effect (p<0.05) on the mortality and cannibalism rate in juvenile Clarias gariepinus and Heterobranchuslongifilis as presented in Table 2. At the high mortality rates (11.66 ± 2.36%) observed in monoculture Clarias gariepinus, the highest cannibalism levels were obtained in monoculture of Heterobranchus longifilis (13.33 ± 4.71%). The survival rate was not influenced by the type of culture. Nevertheless, the highest rate (94.44 ± 0.00%) was obtained in polyculture in Heterobranchus longifilis in Table 2.

Table 2: Survival rates, cannibalism rates and mortality rates by Crop Type.

  Monoculture polyculture
Parameters T1 T2 T3C T3H
Mortality rates (%) 10,00 ± 2,36a 3,33 ± 2,70b 6,66 ± 0,00b 3,33 ± 2,714b
Cannibalism rates (%) 3,33 ± 0,00b 13,33 ± 4,71a 3,33 ± 2,71b 3,33 ± 2,71b
Survival rates (%) 86,67 ± 0,00a 83,56 ± 9,42a 90,56 ± 4,49a 94,44 ± 0,00a

a, and b: averages with the same letters for the same line are not significantly different (p>0.05), T1 = Clarias gariepinus in monoculture, T2 = Heterobranchus longifilis in monoculture, T3C = Clarias gariepinus in Polyculture, T3H = Heterobranchus longifilis in fry polyculture.

Discussion

The growth characteristics results show that apart from food consumption and the k factor, the other growth characteristics of Clarias gariepinus and Heterobranchuslongifilis were comparable regardless of crop type. These results are similar to those obtained by Teugels et al. [15] in Heterobranchuslongifilis and Clarias gariepinus larvae for 17 days after hatching. Whatever the type of crop, the growth characteristics obtained during the experiment was low. They are due to the nitrite content, ammonia and high conductivities (45-60 μS) indicated as harmful by the recommended values (15-45μS) for farmed animals in ponds. In addition, regardless of crop type, the temperatures obtained were low (22.5-26.5) and below the recommended limits (27.5-32.5°C) by Anderson and Fasta [16] for optimal growth. Dissolved oxygen values (1.70-1.95) were well below that recommended (5 mg/l) by Saloom and Duncan [17]; the pH obtained in the tanks was lower (4.5-5.5) than the recommended values 6.5 and 9 for the breeding of catfish. These could explain the low food consumption and therefore the low growth rates recorded in this study.

The maximum values of average daily gain recorded in Heterobranchus longifilis (0.15 g/d) are greater than 0.12 g/day obtained by Coulibaly [14] in Heterobranchus longifilis with a loading weight of 0, 8g high in bins covered for 90 days but very low compared to 3 g/d obtained by Legendre [18] in breeding of Heterobranchus longifilis in pond in phase of enlargement and still much lower than 5g/day obtained in Heterobranchus longifilis raised at low density in pens and in association with Tilapia; the highest average daily gain obtained in Clarias gariepinus in combination (0.18g) shows that the latter has more valorized the food than in other System; it is slightly higher than 0.14g obtained in Clarias gariepinus with a feed based on Néré seeds and containing 42% of proteins and very much less than 3 g/day obtained by Micha [19] in the same species. These poor performances could be justified by the physicochemical conditions of the water. Whatever the type of crop, the specific growth rates (2.10 ± 0.51% - 1.92 ± 0.37%) are lower than 3.77%; 3.61%; 3.59%; 3.57% obtained by Coulibaly [20] from Heterobranchus longifilis reared respectively without a refuge system, with white, blue and black refuge systems; also less than 4, 26% and 3.85% obtained by Toko [21] at Clarias gariepinus respectively with a food at 45% 42% protein. Factor K values that provide information on fish overweight were significantly influenced (p<0.05) between treatments and ranged from 0.71 to 0.83. Although higher than 0.71 to 0.76 found by Ekoue [22] in Clarias gariepinus, the maximum value (0.83) was lower than 1.86 reported by Melwa et al. [23]. These values remain below to 1, which indicates that the fish is not well condition. This difference in values would probably be related to the age of the fish and the physicochemical conditions of the water. Significantly high cannibalization rates (p<0.05) in bins containing only Heterobranchus longifilis (13.33±4.7%) would be caused or increased by a range of biotic factors (such as aggressiveness) and abiotic (water transparency, brightness). This reflects the great voracity of the fry of Heterobranchus longifilis by contribution to the fry of Clarias gariepinus. These results are lower than 21.8% obtained in fry Heterobranchus longifilis in breeding without a refuge system [14]. The low rate of cannibalism obtained in polyculture with Heterobranchus longifilis could be the results of a concealment of fry this species among those of Clarias gariepinus which decreased aggression towards each other.

Mortality rates were significantly different between treatments. The highest rate obtained in Clarias gariepinus (10.00 ± 2.35%) shows that the latter is less hardy than Heterobranchus longifilis. These mortalities were due to the stresses caused by the handling of the species during control fisheries combined with the physicochemical parameters of the water. Nevertheless, regardless of the species, the results are lower than the 15.0±1.7% and 14.0 ± 2.0% obtained by Coulibaly [14] in Heterobranchus longifilis grown in uncovered vats and feeding respectively the day and the year. Night Survival rates are virtually high regardless of crop type and range from 83.56±9.42% to 94.44±0.00% and are well above 64.0%; 71.1%; 74.0%; 70.9% obtained by Coulibaly [22] in Heterobranchus longifilis reared with respectively without refuge system, with a white, blue and black refuge system, but very weak compared to the 100%. This difference squeezed out of cannibalism due to stress caused by handling (catching and weighing) fish during control fisheries.

Conclusion

At the end of this study, it appears that, except for the condition factor K and the consumption index; all the growth characteristics were not influenced by the type of crop whatever the species. Rates of cannibalism and mortality were influenced by the type of crop.

Thus, the highest cannibalism rate was recorded in H. longifilis and the mortality rate in C. gariepinus in monoculture.

To reduce the rate of cannibalism and the mortality rate in Clarias gariepinus and Heterobranchus longifilis in post fingerlings growth phase, it is recommended to combine these two species.

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Empirical Assessment of Fish Diversity of Uttar Pradesh, India: Current Status, Implications and Strategies for Management

About 60-70% of world’s biological resourcesis contributed by India, of which fish represents 80% of the global fishes. Uttar Pradesh blessed with vivid aquatic bioresources in innumerable forms contributes about 14.68% of Indian fish biodiversity with substantial scope of inland fisheries development and aquaculture. Ganga, the mighty river of this state reportsabout 265 freshwater species from its river system [1]. Besides, other rivers viz. Ramganga, Gomti, Ghaghara, Yamuna, Gandak, Kosi and Damodaract as reservoir of different f ish stocks. In past, no study highlights the assessment of the fish biodiversity of this state in holistic way except by Khan (2000) who justreported a compilation of 129 fishes under 27 families [2]. To substantiate and revise the assessment, the fish diversity of this state was assessed by investigating these rivers, analyzing and documenting the information on different fisheries measurements including biology, distribution and conservation status. About 10,000 individuals were collected and the analysis of individuals revealed 126 fish species under 28 families and 74 genera nearly mitigating the earlier reports. The highest species diversity was recorded in the river Ganga (90) followed by Gerua (87) and then Gomati (68). 37 species were found common in Gomati, Ghaghara, Ganges, Son, Tons and Yamuna. Out of 90 species, 6 species were recorded from the river Ganga. In addition, the new distribution of a threatened torrent catfish Amblyceps mango is was recorded from the rivers Gomati, Ganga and Ramganga. The economical assessment unravels nearly 33% as ornamental, 87% as food and 10% as sport fishes.

Pathak AK*


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Stranding of Small Cetaceans with Missing Fins Raises Concerns on Cetacean Conservation in Ecuador: Bycatch or Targeted Fisheries?

Among anthropogenic threats to marine mammals, bycatch is one of the major and increasing concerns. This report describes three species of small cetaceans, including a short-beaked common dolphin (Delphinus delphis), a bottlenose dolphin (Tursiops truncatus), and two dwarf sperm whales (Kogia sima), which were found stranded with pectoral fins, dorsal fins and caudal fin removed. The dolphins were found at the beaches of San José de Las Nuñez and San Pablo, respectively (Santa Elena Peninsula Province on 14 August 2017), while the dwarf sperm whales were found in Puerto Lopéz and Crucita (Manabí Province) in July 2014 and August 2015, respectively. Possible explanation for the dolphins and dwarf sperm whales missing fins support the event as a possible case of fishery interaction or bycatch with systematic removal of their fins. Although remnants of artisanal gillnets were not found near the two dolphin species, one of the dwarf sperm whales showed marks of artisanal gillnets on the body as evidence of bycatch. Trade of dolphin carcasses and their parts for bait by fishers cannot be ruled out as there is some evidence of this practice in the past. Both dolphins species are vulnerable species at the national level and commonly involved in incidental captures with gillnets of artisanal fisheries in Coastal Ecuador. Cetacean bycatch is a grave conservation problem affecting several cetacean species in Ecuador’s waters. Fisheries and environmental authorities must be vigilant and enforce actions to proactively mitigate possible anthropogenic impacts and promote environmental education activities in fishing communities to conserve vulnerable dolphin species in Ecuador’s waters. Further, to comply with new rules and regulations of the US Marine Mammal Protection Act (MMPA) intended to reduce the bycatch of marine mammals in foreign commercial fishing operations that export fish and fish products to the United States, a regulatory program is urgently needed to mitigate and reduce fisheries interactions with marine mammals in Ecuador.

Pedro J Jiménez1, Juan José Alava1,2*, Cristina Castro3, Jorge Samaniego4 and Patricia Fair5


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Sodium Arsenite-induced Morphological, Behavioral, Hematological and Histopathological abnormalities in Labeo Rohita

Toxic metals have contaminated the aquatic ecosystems to a large scale, and they eventually enter human systems by contaminated air, food, water and soil. Recently, arsenic toxicity has become an alarming concern around the globe. Major areas of North-Eastern states of India have been demarcated with an arsenic content of 50-1000 µg/l in drinking water sources and aquatic ecosystems. Arsenic range in Barak Valley is many folds higher than the permissible limit of WHO and BIS as 10µg/l and 50µg/l respectively, which is present in the form of Sodium Arsenite in water. Fishes are the major dwellers of aquatic ecosystem and serves as good bio-indicators for determination of health status of an aquatic ecosystem. They also form the staple diet of North Eastern people. Labeo rohita is one of the most commonly available and consumed in large scale. The present study was carried out in Labeo rohita in vivo. Labeo rohita (n=10) of similar size and weight were exposed to sodium aresnite at concentrations 100 µg/l and 250 µg/l along with controlled set up for 10 days. The morphological, behavioral, hematological and histopathological changes were evaluated. Fishes exposed to Sodium arsenite showed irregular ocular movement, fin movement, swimming pattern and loss in scales with higher prominence in 250 µg/l of arsenic group than those at 100 µg/l. The hematological indices revealed decrease in RBC count and increase in WBC count in both sodium arsenite exposed groups. The histopathological study of liver revealed parenchymal disorganization and atypical residual body in both sodium arsenite treated groups. Results obtained showed major damages to fishes due to contamination with sodium arsenite. These fishes, when consumed by humans, leads to increase in several thousand folds of sodium arsenite by means of biomagnification. High exposure of arsenic in human through fishes leads to several disorders. The possible way of eradicating sodium arsenite entry into humans is banning fishing activities in highly contaminated aquatic ecosystems. Community education and local participation are also essential to get a fruitful outcome.

Rajib Biswas1* and Soumitra Nath2


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Reconstruction of Historical Fisheries Profile of Cameroon

This work attempts to reconstruct historical fisheries profile by filling in the missed underestimated catch information for some reasons of industrial fishing, artisanal fishing, inland fishing, illegal fishing, discards and aquaculture production of Cameroon from 1950 to 2016.This reconstruction was carried out based on data published by various authors, the Ministry of Fisheries and Livestock (MINEPIA), the Limbe Research Center on Fisheries and Oceans and FAO reports. The dataset allowed us to reconstruct the fishing profile of Cameroon by completing the missing data by interpolation. Then we compare the data obtained with those of FAO. Reconstructed catches were estimated at 13,834 tons and aquaculture production was estimated at 19 tons in 1950 compared to 12,000 tons and 14 tons published by FAO, With the agricultural reforms and development of projects focused on the primary industry, catches increased around 94,122 tons in 1977(compared to 70,167 tons reported by the FAO) to 102,975 tons in 1981(compared to 79,761 tons reported by the FAO), declined to 78,790 tons in 1986 because of the reduction of the Exclusive Economic Zone of Cameroon (EEZ) by the geographical presence of the insular part of Equatorial Guinea (Malabo Island), then increased to 186,204 tons in 2005(compared to 142,345 tons reported by the FAO), declined to 154,800 tons in 2008(compared to 129,000 tons reported by the FAO). Since 2011 it became stable and reached around 240,000 tons against 220,000 tons published by FAO. Overall, there are discrepancies between the reconstructed data and the data provided to FAO: the reconstructed data is 30% higher than the FAO data. This information about fisheries production in Cameroonian waters shows that many locals, fisheries managers and stakeholders depends on fish products for either incomes or food safety; therefore, the recent decline of fish production in Cameroon is of no good sign to the abovementioned persons. These observed fish production decline indirectly threatens the food security of the people of Cameroon and low financial income to the state coffers.

Nyatchouba Nsangue Bruno Thierry, Richard Kindong and Liuxiong Xu*


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Effect of Fishmeal Substitution by Lima Bean Meal on the Zoo Technical Performances of African Catfish (Clarias gariepinus) in the Bati

A study on the effect of the substitution of fishmeal by Lima bean flour was conducted between March and May 2018 within the AIO ICG of the Batié District, with the global objective of contributing to the development of alternative sources of animal protein. Specifically, the aim of the study was to evaluate the effect of the substitution of fishmeal by Lima bean flour on the growth performance, survival and feed cost of Clarias gariepinus. For this purpose, 300 fry of Clarias gariepinus with an average weight of 3 ± 1.41g were divided into five batches and fed three times a day with rations corresponding to 5% of their ichthyo biomass. The rations R0, R25 R50, R75 and R100 respectively corresponded to the substitution rates of 0, 25, 50, 75 and 100% of fish meal by that of Lima bean. The physic-chemical characteristics of the water (pH, temperature, dissolved oxygen, nitrites and nitrates) were measured daily. The following results were obtained: The highest weight gains were obtained with the rations R25 (20.56 ± 0.40 g), R50 (20.64 ± 0.32 g), R75 (20.98 ± 0.46 g) and the lowest with the ration R100 (16.21 ± 0.28 g). For this average daily gain, the highest values were 0.36 ± 0.02 g; 0.37 ± 0.01 g, 0.38 ± 0.01 g respectively for the R0, R50 and R75 rations and the lowest with R100 (0.29 ± 0.01 g). The highest value of the specific growth rate (2.47 ± 0.07%) was obtained with the ration R0 and the lowest (1.61%) with the ration R100. The consumption index reached its highest and lowest values with the rations R100 (4.74 ± 0.42) and R50 (3.57 ± 0.43) respectively, compared to the value of the ration R0 (3.31 ± 0.37) for this parameter. Concerning the condition factor K, the highest value was recorded with the R50 diet (1.11 ± 0.49) while the lowest value was obtained with the R75 diet (0.95 ± 0.45). The cost of producing one kilogram of food was higher with the R25 ration (504.59 FCFA) and lower with the R100 ration (443.20 FCFA). This study found that incorporating 75% Lima bean flour into the feed increases the growth performance of Clarias gariepinus fry and reduces the cost of food production.

Emile Miégoué1*, Pégis Davy Tagning Zebaze2, Fernand Tendonkeng1, Lemoufouet Jules1, Nadège Elvire Njoh2, Ronald Komguep Nganyo2 and Etienne Tedonkeng Pamo1


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Delayed Fertilization of Landlocked Fall Chinook Salmon Eggs Stored with Oxygen at Two Temperatures

This study examined the use of supplemental oxygen and two temperatures (1° and 11°C) during the four hour storage of unfertilized landlocked fall Chinook salmon (Oncorhynchus tshawytscha) eggs from Lake Oahe, South Dakota, USA. There was a significant and positive effect of oxygen use on egg survival to the eyed-stage and hatch. In addition, survival to egg eye-up and hatch was significantly affected by storage temperature, with decreased survival at 1°C. However, there was no significant interaction observed between the use of oxygen and storage temperature. Mean survival to hatch ranged from 50% for those eggs stored with oxygen at 11°C compared 17.8% for those eggs stored on ice at 1°C in air. To maintain landlocked Chinook salmon egg fertility, storage with supplemental oxygen at 11°C is recommended.

Hunter Eide and Michael E Barnes*