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During its storage in the maritime coastal zone in Littoral-Cameroon region, the treated fish is destroyed by various factors. These factors can be the source of poisoning for the populations. The objective of the study was to evaluate the post-smoking losses of fish in 3subdivisions in maritime coastal area: Youpwe (Douala II), Manoka (Douala VI) in Wouri Division and Mouanko in Sanaga Maritime Division. The identification of the fish species smoked was made in these 3subdivisions by permanent monitoring at the level of landing points and smocking units. 429 stakeholders were surveyed and 305 storage facilities were inspected and then characterized. Three in vivo collections of 7 species of smoked fish from each of the localities were collected and put in observation at the laboratory for 6 weeks. From these collections, molds and insect pests emerged. For each collection, the factor of loss is observed, the insects emerged were counted, identified and the damage assessed. For this study, it appears that 31 marine fish species belonging to 17 families have been identified. The Clupeidae (27%), the Sciaenidae (18%), the Polynemidae (12%) and the Ariidae (10.1%) are the most represented families. Ethmalosa fimbriata (Clupgeidae), Cynoglossus senegalensis (Cynoglossidae), Trichiurus lepturus (Trichiuridae), Arius heudeloti (Ariidae) and Raja africana (Rajidae) are the most smoked species. The racks and baskets are the most widespread and used storage tools. Molds and Insects (Coleoptera: Dermestes maculatus, Necrobia rufipes and Diptera (Calliphora sp) are the main biotic factors of loss of stored smoked fish in the three localities. N. rufipes is the major pest with 772 individuals on the 911 counted. The study presents the main loss factor which depreciates the quantity and quality of smoked fish during storage.

WOS:000459212600005; International audience; The gross energy content of spawning batches and the microchemistry of sagittal otoliths in individual female bonga shad Ethmalosa fimbriata were compared between contrasting sampling sites at the Senegalese southern coast and inside the hypersaline Sine Saloum Estuary. Results show that females spawning in the estuary's middle reaches invested almost three times more energy into reproduction (115 ± 65 J g?1 body mass) than their neritic counterparts (39 ± 34 J g?1 body mass). Also, female otolith levels of Ba:Ca, Sr:Ca and Zn:Ca either differed significantly between study sites or could be linked to heterogeneous environmental variables. A quadratic discriminant function analysis provided evidence of segregated spawning populations of E. fimbriata in southern Senegalese waters.

Assessments of many West African fish stocks rely on fishery dependent catch and effort data. Typically, these treat the catch data as error free and some assume that fishing power does not change over time. To address these issues we develop a fleet based surplus production model that accounts for increases in fishing power. It allows errors both in effort and catch data so avoiding the assumption that catch data are exact. Mean annual fleet fishing power increase can be estimated when data from multiple fleets are available provided it can be specified for at least one fleet. The model is tested using simulated data and then applied to western stocks of anchovy (Engraulis encrasicolus) and bonga shad (Ethmalosa fimbriata) in the Fishery Committee for the Eastern Central Atlantic (CECAF) area. Both stocks appear to be over-exploited and near to collapse. Corrections for fishing power are important in the anchovy assessment and help to explain conflicting trends in the data. Uncertainty in the assessments is explored with a range of sensitivity tests.

Growth and exploitation parameters Ilisha africana were determined from the size frequency for the first time in Senegal. The size distribution showed average sizes equal to 19.26 ± 1.70 and 19.75 ± 2.03 cm, respectively in the estuary and at the sea. The values of allometric rates of the length-weight relationship were, respectively equal to 2.88 and 2.93 in the estuary and at the sea indicating a negative allometric growth for this species. Von Bertalanffy growth parameters are estimated to L∞ = 24.7 cm, K = 0.33 year-1, t0 = -0.53 in the estuary and L∞ = 25.5 cm, K = 0.34 year-1, t0 = -0.51 at the sea with growth performance index, respectively equal to Φ' = 2.30 and Φ' = 2.34. The values calculated for the total mortality (Z), natural mortality (M) and the fishing mortality (F) were: Z = 1.08, M = 0.93, and F = 0.14 year-1 in the estuary while at the sea these mortality rates were estimated respectively at Z = 1.25, M = 0.91, and F = 0.33 year-1. The current exploitation rates in the estuary (0.10) and at the sea (0.25) indicated that I. africana was under-exploited in Senegal. Key words: Allometric, mortality, Von Bertalanffy, condition factor.

Pollutants in aquatic food are a major global concern for food safety and are a challenge to both national and international regulatory bodies. In the present work, we have reviewed available data on the concentrations of polycyclic aromatic hydrocarbons (PAH), persistent organic pollutants, metals, and microplastics in freshwater and marine fish in Nigeria with reference to international maximum levels for contaminants in food and the potential risk to human health. While most of the contaminant levels reported for fish do not imply any health issues, iron and lead may represent potentially toxic levels in fish from specific areas. Studies on PAHs in marine fish are scarce in Nigeria, and the main focus is on the environmental pollution caused by PAHs rather than on their presence in food. The findings suggest that the consumption of smoked Ethmalosa fimbriata poses a higher potential carcinogenic risk than the other fish species that were investigated. Most of the other studies on PAHs in smoked fish are focused on the smoking method, and little information is available on the initial level of PAHs prior to the smoking process. Metal contamination in fish appeared to be affected by mineral deposits in the environment and industrial effluents. In general, heavy metal levels in fish are below the maximum levels, while there is limited data available on POPs of relevance to food safety in fish from Nigeria, particularly in terms of dioxins, brominated flame retardants, and fluorinated compounds. Furthermore, there is currently limited information on the levels of microplastics in fish from Nigerian waters. This work revealed the need for a more systematic sampling strategy for fish in order to identify the most vulnerable species, the hot spots of contaminants, and applicable food safety control measures for fish produced and consumed in Nigeria.

Mauritania has recently developed a fishmeal industry based on small pelagics. The fish are caught by Senegalese canoes that work under charter for the fishmeal factories, most of which are situated in the northern port of Nouadhibou. After a slow start in 2005–2010, the industry showed a strong development after 2010 as the result of high prices for fishmeal and oil. Catches of small pelagics landed for fishmeal increased from 50,000 t in 2011 to 240,000 t in 2014. Because new factories were still being built by the end of 2014, a further expansion of the catches used for fishmeal is expected. Data are presented on the species composition of the catches for fishmeal, and the length distribution of the individual species. It is shown that the catches consist of round sardinella (Sardinella aurita), flat sardinella (S. maderensis), and bonga (Ethmalosa fimbriata). Changes in species composition and length composition from 2012 to 2014 may indicate different responses of the coastal stocks of small pelagics to the increased fishing pressure. Some of the species exploited for fishmeal belong to regional stocks that are shared with neighbouring countries. The paper discusses the potential effects of the expanding fishmeal industry in Mauritania on these regional stocks.

WOS:000488278100001; International audience; Successful recruitment in small pelagic fish populations inhabiting upwelling zones is subject to variation in fecundity and is driven by spatial and temporal fluctuations in environmental conditions, that is, mainly sea surface temperature, salinity and food availability. These fluctuations in abiotic factors have stimulated small pelagic fish populations to exhibit specifically adapted spawning tactics. To better understand to what extent a short-lived exploited fish species such as bonga shad Ethmalosa fimbriata has adapted to an upwelling environment, we have investigated the interrelationship between upwelling intensity as a proxy for productivity and population fecundity by means of a virtual population analysis. We found that females of intermediate size contributed significantly more eggs to the population's fecundity than smaller or larger ones. Our model results further indicate that E. fimbriata exhibits a spawning preference at water temperatures of around 25 degrees C and upwelling intensities of around 2.5 m(3) s(-1) m(-1). Hence, we hypothesize that climate change-driven increases in sea temperatures and modifications of upwelling-favourable winds could significantly impact the species' reproductive biology. To understand how climate change might impact fisheries, spawning tactics of small pelagic fishes are important to assess as well as their recruitment success. Such information is particularly relevant in countries where the fishery is critical at socio-economic level, to better implement fisheries management addressing multiple stressors.

Fisheries management is difficult especially in developing countries where there are little or no data available for stock assessment. Here, a simple model based on the length-based Bayesian biomass (LBB) is applied to length frequencies collected on the two sardinella species (Sardinella maderensis and S. aurita) collected in Senegalese waters (2004 to 2014) to diagnose these stocks and to support the development of fishery management options that may improve the livelihoods of artisanal fishermen. Annual mean length of both species of sardinella showed a large variation during the decadal study period. It is assumed that such variations are due to environmental changes. According to our results, based on the current exploitation rate, both sardinella species are overexploited. To reverse these bad stock status, three management indicators were estimated for both sardinella: (i) length at first capture (Total Length (TL); L c 24 and 27 cm for S. maderensis and S. aurita, respectively); (ii) the length at maximum possible yield per recruit (TL; L o p t 26 and 29 cm for S. maderensis and S. aurita, respectively); and (iii) the optimal length for the first capture (TL; L c _ o p t ; 25 and 28 cm for S. maderensis and S. aurita, respectively). According to Senegalese maritime fishing code, which sets the small pelagic fish size of the first capture ≥ 18 cm, we urge the Senegalese governments to press ahead with much needed reforms of the fishing code. We recommend capturing sardinella at the size L c _ o p t to provide a natural safeguard against any recruitment failure related to environmental variability and allow individuals to grow and ensure the long-term survival of populations and thus sustainable fisheries. The results suggest that LBB model could be a tool to assess data-poor fisheries allowing the possibility to include in the analysis several years of length–frequency data with a minimum of prerequisites.

WOS:000449553500016; International audience; Small pelagic fish occupy a significant component of the food supply in West Africa and are vitally important for the nutritional needs of local people. The bonga shad (Ethmalosa fimbriata Bowdich, 1825) is the third most-exploited of the small pelagic species fished from coastal waters of Senegal (after Sardinella aurita and S. maderensis) and is routinely consumed by Senegalese people. Bonga shad fishing is practised mainly by artisanal fishermen and of great importance to the Senegalese economy and food security in the region. Our study was designed to examine population dynamics of bonga shad to support the development of fishery management options that may improve the livelihoods of artisanal fishermen. The current rate of exploitation (E = 0.8) suggests that the bonga shad in Senegal is over-fished. In addition, we describe seasonal variability in recruitment and biomass of bonga shad along the Senegal coast, its downward trend in landings over a 17-y study period, and its decline (18%) in maximum size over a 63-y period. We attribute the declines to an increase in fishing pressure and/or changes in local climate. To reverse the effects of overexploitation of the bonga shad stock, it will be necessary to drastically reduce fishing effort, apply and enforce regulatory restrictions on the capture, sale and processing of juveniles, and prohibit seiners and monofilament nets in the fishery.

Lake Nokoué and Cotonou Lagoon are the most important and most productive continental freshwaters in Bénin, with an estimated fish production of over 2 tonnes per hectare in Lake Nokoué. Organochlorine pesticides are used in agriculture and to repel tsetse flies, malaria mosquitoes and other diseases raised. Sediment, fish, shrimp and oyster species were collected in Lake Nokoué and Cotonou Lagoon for pesticide residues analysis. The main pesticides identified in sediment were pp′-DDT and its metabolites pp-DDE and pp′-DDD, with residue levels between the detection limit and 24.4 μg/kg dry weight. Fish species commonly consumed such as Elops lacerta, Podamasys jubelini, Gobbienellus occidentalis, Ethmalosa fimbriata, Mugil cephalus and Hemichromis fasciatus were contaminated with residues of seven to nine pesticides, including pp-DDE, op′-DDD, pp′-DDD, op′-DDT, pp′-DDT, α-endosulfan, aldrin, dieldrin and γ-hexachlorocyclohexane. The levels ranged from detection limit to 289 ng/g lipid. The same pesticides were also detected in other aquatic species, such as shrimp and oysters. A summed risk assessment, comparing pesticide intake levels through fish consumption with tolerable daily intake levels proposed by the World Health Organization, showed in all cases a low risk for human health. © 2013 Springer Science+Business Media Dordrecht.

The effect of water pollution in Koluama Area in the Niger Delta region of Nigeria to determine its effects on fish species composition, histology, shrimp fishery and fishing gear type. A total of twenty (20) species belonging to eleven (11) families were recorded. Strongylura senegalensis, Lagocephalus laevigatus, Tarpon atlantica, Pristis pristis, Galeoides decadatylus and Butis koilomatodon were rare. Ephippion guttifer, Chaetodipterus goreensis, Sardinella maderensis, Sardinella aurita, Liza falcipinnis, Mugil bananensis, Pentanemus quinquarius, Polydactylus quadrafilis and Trichuris lepturis were common. Ethmalosa fimbriata, Liza grandisquamis, Sphyraena guachancho, Mugil curema, Sphyraena guachancho and Dormitator pleurops were abundant. None was dominant. The highest number of fish species (16) were recorded in fish town and none was recorded in Kuloma 1 and one (1) was recorded for Kulauma 11. Foroupa, Ekeni, Ejetu and Ikebiri fishing port 1 and 2 recorded 8, 7, 3 and 5 fish species respectively. Artisanal fishing is based on traditional methods of fishing using essentially canoe and different fishing nets which depend on the season and target fish species. Canoes may be motorized or hand-paddled. Common gear types include shrimp traps, drift gill nets, set gill nets, cast nets, seine nets, hook and lines. Lift nets may be use by women folk who target small shrimp species in the creeks and creek lets. Other fishing methods include hand-picking for periwinkles, oysters and other shellfish by women folk and children. Prominent among the fishing devices are edek, a type of fish fence used in the creeks; alot, a large trap used on sand and mud-banks in the estuaries; and otunwa, a barbed spear. Fishers using these devices either operated from their home villages, exploiting the nearby waters, or staged long distance fishing expeditions, during which they lived in distant camps or house-boats. The heavy metals concentration level values are: Cd

Mangrove forests are unique habitats in their function as potential food source and nurseries, and support an important fisheries resource. In the Benin coastal zone, the mangrove fishes have been surveyed to investigate fish species diversity, community structures and ecosystem degradation impacts in order to protect and to improve the mangrove fish resources. Results from wet, high-water and dry season samplings revealed that the two dominant mangrove species, Rizophora racemosa and Avicennia africana, are being intensively degraded for domestic use such as firewood and house building. Fifty one (51) fish species belonging to 25 families were recorded with Eleotridae (7 species), Cichlidae (5 species), and Mugilidae (5 species), the most speciose families. Dominant trophic guilds were detritivores (54.57%) and planktinovores/microcarnivores (30.41%). Six (6) species, Sarotherodon melanotheron, Dormitator lebretonis, Gerres melanopterus, Hemichromis fasciatus, Ethmalosa fimbriata, and Aplocheilichthys spilauchen, dominated the samples and accounted for about 80.27%. Sarotherodon melanotheron constituted the major dominant species and accounted numerically for about 29% of the total catches and 46.7% of the total biomass. The Margalef index of species richness ranged between 2.42 and 4.43, the Shannon-Weaver index of species diversity between 1.39 and 2.27, and the evenness between 0.50 and 0.62. Lower indices were observed for the highly degraded and the moderately degraded sites whereas higher indices were recorded for the less degraded and the restored sites. Species richness, species diversity and dominant species abundance were positively correlated with depth and transparency and negatively correlated with temperature. Multi-species fisheries dominate the coastal zone with Sarotherodon melanotheron, Dormitator lebretonis, Gerres melanopterus, Ethmalosa fimbriata, Liza falcipinus, Mugil sp. and Chrysichthys nigrodigitatus, the major species in the commercial catches. In addition to the mangrove destruction, the hydro electrical dam have greatly modified the Mono River flooding regime, water quality and the fish composition of the Benin coastal lagoon system. An integrated approach of the mangrove resource management/conservation, including intensive mangrove restoration, management of key fish species, freshwater prawns (Macrobrachiun sp.), peneids shrimps, mangrove oysters (Crassostrea sp.), and crabs (Callinectes sp., Cardiosoma sp.), and habitat protection is required for ecosystem recovery and sustainable exploitation.

his study assessed the concentrations of cadmiu m, lead, manganese, copper and iron in the tissues of commercially important Croacker fish (Pseudolithus senegalensis) and Bonga fish (Ethmalosa fimbriata) obtained from Carter Bridge river and Makoko river,in Lagos State, Nigeria. These metals were determined using Perkin-Elmer Analyst 300-Ato mic Absorption spectroscopy (AAS). Heavy metal content varied significantly (p

International audience; Small pelagics are the main fish resource in North West Africa. In Senegal, these are mainly sardinellas (Sardinella aurita and S. maderensis) and bonga shad (Ethmalosa fimbriata). The fisheries, mainly encircling gillnets and purse seines, are predominantly performed by artisanal fishers and are of great importance for the Senegalese economy and for food security in the region. However, in recent years, the main conditions for these fisheries have changed and recent observations have shown strong declines in profit. An analysis over the last twenty years (1993–2013) show that the fisheries lost profit between 65% and 100% while operating costs increased by 25% and 90%, for encircling gillnet and purse seine, respectively. While the fuel price dominates as determining factor during the survey period, important other drivers during the last five years were a decrease in fish biomass and an increase in fishing effort.

For many decades, fisheries research has focused on stock assessment and the impact of the fishery effort on resources. Although this knowledge remains necessary, a more integrated analysis of the joint dynamics of resource and operational activities is needed to provide more useful advice for the management of fishery systems. Since 1994 a new approach to fishery science has been carried out for Cameroonian small-scale fisheries, the aim being the incorporation into fishery science of research on fishery management, fishing processes and fishermen's behaviour. This paper presents a more systemic data approach which combines biological parameters and operational factor analyses with the goal of sustainable development. From two years of data collected on the purse seine fishing units operating in the Bay of Biafra (2002 and 2003), a set of three correspondence analyses is applied: (1) to the length frequency distribution of Ethmalosa fimbriata, (2) to the number of visits per fishing ground, and (3) to th...

Studies were conducted on the dynamics of the exploited population of Ethmalosa fimbriata (bonga) from purse seine fishery in the Cross River Estuary and adjacent Gulf of Guinea. Growth parameters were determined using the length–frequency distribution over an 18-month period. The asymptotic length, L ∞ =35.95 cm total length, von Bertalanffy growth function, K =0.90, winter point, WP=0.1, signifies that growth slows down in February which was attributed to high temperature and reproductive activities. The longevity was 40 months. The instantaneous rate of total mortality, Z =6.91 per year, natural mortality, M =1.61 per year and fishing mortality, F =5.30 per year, were estimated. The current rate of exploitation ( E ) was given as 0.77, indicating that the bonga stock is over-fished. From the yield-per-recruit analysis, E max , the exploitation rate giving maximum relative yield-per-recruit was estimated as 0.65, confirming that the stock is being over-fished. To reverse the overexploitation of the bonga stock in the Cross River Estuary, and the attendant adverse socio-economic consequences, it was suggested that effort should be reduced in the fishery and the economy of the fishing communities diversified.

The biology of the clupeid Ethmalosa fimbriata (Bowdich) was studied as a potential bio-indicator of pollution in three bays of the Ebrie Lagoon, an inter-tropical lagoon in the Ivory Coast (western Africa). Bietri Bay was the most impacted by Abidjan's industrial and urban waste, Cocody Bay was characterized by the presence of eutrophic water, and Sud Boulay Bay, located in a rural zone, was least impacted. Sizes at first maturity (fork length) of E. fimbriata were lowest in the most polluted bay (Bietri: 80.8 and 83.5 mm for males and females, respectively), higher in the intermediately polluted bay (Cocody: 125 and 137.5 mm, respectively), and highest in the unpolluted bay (Sud Boulay: 135 and 145 mm, respectively). Owing to its hardiness, E. fimbriata is the dominant species in polluted water, constituting more than 75% of the total number of fish caught. As a consequence, fish diversity decreased and the community was less structured in the polluted environment than in the unpolluted one.

This work compiles hydroacoustic recordings and catch data over Senegambia (Senegal and The Gambia) from assessment surveys on the major clupeid species to identify sources of bias in abundance estimates caused by their horizontal distribution. The latitudinal distribution of small pelagic fish is often well known, while their “across shelf” distribution on the continental shelf is less understood. The southern part of the Senegambian shelf has a wide shallow water (2) of the total shelf surface, while the northern part accounts for 3% (200 NM2). These areas are not assessed by conventional fisheries acoustics surveys and therefore increase the uncertainty of the assessment of these species. Our findings show that this likely introduces a bias in the assessment of Sardinella maderensis, while for S. aurita no major estimation-error is caused by their horizontal distribution. The data confirm that Ethmalosa fimbriata and Ilisha africana are challenging to assess by conventional surveys, due to their mostly inshore distribution. We emphasise the usefulness of assessing S. aurita through fisheries independent hydroacoustic surveys, and propose alternative methods to survey shallow water areas to reduce biases in biomass estimates and distribution mapping.

A statistical survey of the artisanal fisheries of south-eastern Nigeria conducted from September 1992 to August 1993 showed that the mean catch per canoe fishing unit per year was 6204 kg and well within the 95% confidence interval of existing earlier estimates. Bonga, Ethmalosa fimbriata , dominated the catch of the coastal/estuarine fisheries; in the freshwater sector, the catfish Chrysichthys nigrodigitatus was the dominant (albeit relatively seasonal) species in the landings. Regression/correlation analysis indicated positive linear relationships between the mean monthly catch ( Y (MA)) as well as the catch-per-unit effort (CPUE) ( Yf −1 (MA)) of the marine inshore fisheries and air and water temperatures ( θ A and θ W , respectively) and estuarine salinity (SAL). No such linear relationships were observed in the case of freshwater fish catch ( Y (FW)); however, the regression of CPUE (i.e., Yf −1 (FW)) on the river/floodplain water level gave a highly significant negative correlation reflecting the difficulty of catching fish in the very much expanded volume of water during floods.

Little is known about the concerted influence of temperature and salinity on the fecundity of clupeid fishes. Due to a globally changing climate, both physical parameters might act as stressors, severely affecting the reproductive potential of clupeid fish populations inhabiting tropical estuaries. Differences in relative batch fecundities, the gonado-somatic index, and the condition index of bonga shad (Ethmalosa fimbriata) were analysed in individual females sampled at the Senegalese coast and inside the inverse Sine Saloum estuary, where salinity increases upstream in all seasons. Multiple linear regression models on fecundity and gonadal energy storage show that clupeids can adapt towards increasing their reproductive investment at temperatures (26–30 °C) and salinities (42–51), which by far exceed marine conditions, in an effort to maximize recruitment success. This reproductive strategy, however, is accompanied by a trade-off between reproductive effort and somatic growth, which ultimately limits the species’ reproductive potential inside the estuary. The observed high variability in batch fecundities might be a viable mechanism to adjust to fluctuating and rather extreme environmental conditions. Understanding the spawning biology of exploited clupeid fishes in drastically changing environments is crucial for evaluating the reproductive potential of stocks at the outer reach of their physiological performance curve.

Ethmalosa fimbriata is a very abundant species in marine and estuarine waters of Senegal. It is caught only by artisanal fisheries. Some aspects of its reproduction are studied in order to provide some contribution to a rational and sustainable management of the fishery. To evaluate the reproduction of Ethmalosa fimbriata , the sex ratio, the size at first maturity, the evolution of sexual maturity stages and the gonadosomatic index (GSI) were used. The results show that the sex ratio is 46% of males and 54% of females in the estuary while at sea it is 42% of males against 58% of females. Size at first maturity is 16.2 cm for males and 17.5 cm for females in the estuary , while at sea these sizes are respectively equal to 17.2 and 18.7 cm for females and males. The main breeding periods are during the cold season in the estuary and the hot season at sea. Ethmalosa fimbriata is a species with small eggs and high fecundity. The absolute and relative fecundity are higher in the estuary than at sea.

Length-weight relationship (LWR) of 320 fish populations covering 3 families, 4 genera and 5 species inhabiting Epe Lagoon, were studied. The fishes ( Clarias gariepinus (Burch), Illisha africana Bloch ), Chrysichthys nigrodigitatus (Lacepede), Chrysichthys walkeri (Gunther) and Ethmalosa fimbriata (Bowdich)) were obtained from fish landing site at Epe market from November 2001 to October 2002, and January to December 2003. The parameters a and b of the length-weight relationship of the form W=aL b and condition factor (c.f.)=W100/L 3 are presented for the five fish species. The c.f. values significantly (P African Journal of Biotechnology Vol. 4 (7), pp. 749-751, 2005

The food and feeding habits of four fish species: C itharinus latus, Ethmalosa fimbriata, Hepsetus odoe and Trichiurus lepturu s, from the Cross River Estuary, Nigeria were investigated. In studying the diets and feeding habits of the fishes, both the frequency of occurrence and numerical methods were used. Results show that C. latus at both the juvenile and sub adult was phytoplanktonic and planktonic at adult stage. E. fimbriata was omnivorous at the juvenile stage, monophagus (solely phytoplanktonic) at the sub-adult stage and planktonic (99.94% phyto and 0.04% zooplankton) at adult stage. H. odoe was found to be carnivorous at both the juvenile and adult stages but tilted towards omnivory (68.18% phytoplankton, 13.63% zooplankton, 4.54% nemata, 13.63% pisces) at sub adult stage. T. lepturus was carnivorous at all three stages. It fed on 99.99% Nemata at juvenile; 44.44% Nemata, 44.44 Ostracoda and 11.11% pisces at sub adult, and at adult stage 30% Nemata, 65% zooplankton and 5% pisces. The study showed that the food and feeding habits of most fish species vary with the age and stage of development. Keywords : Citharinus latus, Ethmalosa fimbriata, Hepsetus odoe and Trichiurus lepturus, food

The productivity, nutrient status and ichthyofauna of the Imo River Estuary at Ikot Abasi, Akwa Ibom State, Southeastern Nigeria, were studied to establish the primary production, nutrient load and the predominating pathway of organic carbon production. Monthly sampling was done at fishing grounds designated as upper, middle and lower course of the estuary in the wet months of April to September 2011. The mean primary productivity of organic carbon was 1.2 x 109 gC/m 2 /day. Sediment nitrate and phosphate levels were 7.04 mg/kg and 1.28 mg/kg respectively. TOC was 7.194%C, representing 12.438% organic matter. Sixteen fish and shellfish species from twelve families including Chrysicthys nigrodigitatus, Tilapia niloticus, Lutjanus agennes, Ethmalosa fimbriata and Cynoglossus senegalensis were observed. The middle course had significantly higher primary productivity of 2.034±0.277gC/m 2 /day, nitrates in water (7.25±0.218 mg.l -1 ), nitrate in sediments (12.198±0.365 mg.kg -1 ), phosphate in water (1.457±0.180 mg.l -1 ) and TOC in sediments (3.715±0.060 %C) than other locations (p

A comparative study of different gill net sizes in the exploitation of bonga (Ethmalosa fimbriata) and sardines (Sardinella eba) were conducted for 3 months between January and March 1998 in Brass River. The area is located between Latitude 4o 2" and 4 o 6 " and longitude 6 o 2 " and 6o 5" stretching from Akassa at the River mouth to Doukungbene near the upper edge of Clarendou. Three Mesh size of gill nets (35mm, 60mm and 70mm) were used for Bonga and Sardine fishing. The result obtained indicated that larger size classes of fish were obtained with the increase in mesh sizes of nets. In addition, marked variation in mean values (t test > t 0.05) and distribution ( w > P0.05) of the size classes were observed (for Ethmalosa fimbriata and Sardinella eba ) irrespective of the mesh sizes. Also the Principal component analysis (PCA) showed high selection for larger fish sizes (in the component weighting) in the catch, which were favoured by the bigger mesh sizes (70mm).

Lake Nokoue, in southern Benin, is a heavily exploited fishery, but it is also inhabited by numerous piscivorous birds, especially kingfishers. This chapter considers the similarity between the diet of kingfishers and fish available on the local market between midFebruary to mid-May 1999, during a low water level period. Excretory pellets were collected on the top of breeding banks and inside brood chambers. The diet was determined by comparing the bones recovered from the pellets with a reference collection. Eighteen prey categories were recognised in the 1099 diagnostic items. Kingfishers preyed mostly on cichlids (Sarotherodon melanotheron Ruppell and Hemichromis fasciatus Peters), clupeids (Ethmalosa fimbriata (Bowdich)), eleotrids (Kribia sp.) and Hyporhamphus picarti (Val.). Prey size of H. fasciatus ranged from 22 to 73 mm (46.4 11.6 mm) and for S. melanotheron from 24 to 65 mm (44 9.2 mm). The composition of the diet varied depending on time and location. Overlap with marketed fish is limited to S. melanotheron.

Allometry and feeding habits of Ethmalosa fimbriata from Cross River estuary were studied. Total length of the fish ranged from 57 to 62 mm for males and 58 to 65 mm for females. The weight varied between 8.0 and 17.0g for males and 4.0 and 20.0g for females. Females had greater weights than males at 58, 59 and 60 mm total lengths. Growth gradients of weight, stomach length and standard length indicate allometric growth with growth centers at 60 mm total length. The main food items observed were detritus, phytoplankton and sand grains. Detritus and phytoplankton were considered the primary items. Sand grains were considered incidental items. Males had more empty stomachs than females and were considered having less feeding intensity than females. Small sized individuals had higher index of food preponderance in detritus while large sized individuals had higher index of food preponderance in phytoplankton. Ontogenetic diet shifts sustained co-existence of various age groups. Females had higher condition factor than males. Condition factors also increased with increasing total lengths. Ethmalosa fimbriata in Cross River estuary was concluded to exhibit isometric and allometric growths, and were considered to be feeding primarily on detritus and phytoplankton. Key words : Allometric growth, trophic indices, Ethmalosa fimbriata, Cross River Estuary, Nigeria Journal of Aquatic Sciences Vol.18(1) 2003: 9-14

The effect of Indomie industrial effluent discharge on the fish fauna of New Calabar River was investigated in order to ascertain the influence of BOD, COD, DO, TDS, TSS, pH, salinity, phosphate and temperature on the composition and distribution of fish fauna. The diversity of the fish fauna was found to be poor, only 12 fish species in 6 families were identified. The highest number (10) of fishes was recorded in station 4 while the least number (1) of fishes was observed in station 1. The fish families were: Cichlidae (38.89%), Clupidae (33.33%), Pomadasyidae (16.67%), Bagridae (11.11%) while Genidae and Muglidae had zero percentage of fishes in its abundant. The resident fish species (Ethmalosa fimbriata and Tilapia guinensis) were highly adapted to the changes in the study environment and this was dependent on their trophic relationship within the environment. These species had great affinity for indomie industrial waste, because they feed on waste remains, mud/sediment silts and annelids, juveniles of shrimps and crabs. The deterioration of water quality was evident by the high BOD (12.80mg/L), COD (130mg/L), TDS (37mg/L), TSS (62mg/L), pH (5.2), salinity (50.54mg/L), phosphate (0.14mg/L) and temperature (270C) as well as the low dissolved oxygen (2.8mg/L) values observed. It was recommended that a routine treatment of the effluent before discharge into the water should be carried out so to maintain safe levels of industrial effluent in the immediate and extended environment. Keywords: Effluent, pollution, environment, fish and fauna.

Studies on the length distribution of bonga, Ethmalosa fimbriata, in the Cross River estuary and adjacent coastal waters were conducted from October 1999 to December 2000. A total of 15,182 specimens of bonga from gill nets, purse seine and boat seine fisheries were measured. Post-larvae measuring between 2 cm and 9 cm were found in the lower estuary with a modal length of 4 cm. Juveniles from gill net fishery ranged in length from 8 cm to 20 cm with a modal length of 13cm. Adults and sub-adults ranging in size from 16 cm to 33 cm were caught from the coastal waters alongside the juveniles, by the purse seine fishery. Two modal lengths of 17 cm and 25 cm were observed in the coastal waters. Three modal length classes were observed in the catches from the Cross River estuary and adjacent coastal waters: these are 4 cm, 13 cm and 25 cm. It is concluded that the Cross River estuary is a nursery ground for bonga, Ethmalosa fimbriata. Key Words: Ethmalosa fimbriata, length distribution, Cross River estuary, coastal waters, nursery. (Global Journal of Pure and Applied Sciences: 2002 8(3): 299-304)

The Bonga ( Ethmalosa fimbriata ) is the third most abundant clupeid in Senegal after the round and flat sardines. This study allowed updating some growth parameters of Ethmalosa fimbriata witch can contribute to the management of the fishery. The size frequency distribution showed that bonga whose size range from 19 cm to 21 cm are more common in the landings of the estuary. At sea fisheries generally target individuals of average size from 18 cm to 22 cm with the dominance of class size from 19 cm to 20 cm. The study of the condition factor shows that the diet of Ethmalosa fimbriata is the best during the hot season also in estuary and at sea. This study also allowed estimating the growth parameters of marine and estuarine Ethmalosa fimbriata from size frequency by ELEFAN (Electric Length Frequency Analysis) software. Seasonal growth is faster in hot season in estuary and at sea.

The monthly feeding activity and food habits of populations of Ethmalosa fimbriata occurring in the sea and an estuary in Cape Coast, Ghana district were investigated during a 14-month period. The juvenile fish, whose total length (T.L.) ranged from 5.3 to 14.7 cm, occur in the estuary and appeared to be more active feeders than the marine samples which measured 15.0–30.4 cm. The peak feeding activity in the marine population coincided with the onset of‘upwelling’ in the sea, which period is characterized by high salinities, decreasing temperatures and high zooplankton production. The species is primarily a plankton feeder. The stomachs of the marine samples contained mainly protozoa, crustacea, molluscan larvae and a considerable amount of detritus while the stomachs of the estuarine fish contained mainly phytoplankton, protozoa, sand grains and organic detritus. These observations have been discussed in relation to other reports on populations occurring along the West African coast.

The distribution of and fisheries for bonga, Ethmalosa fimbriata (Clupeidae), in Nigerian inshore waters east of the Niger delta are discussed. Data on length frequency collected between 1973 and 1982 are analysed to obtain the von Bertalanffy's growth parameters (L∞=30 cm, K=0.43 and T0=−0.20) which are then used to estimate the instantaneous total (Z), natural (M) and fishing (F) mortality coefficients. Catch-per-effort statistics (1973–1982) allow for a simple graphical treatment of Schaefer's logistic model from which the maximum sustainable yield (Ymax=30 075 t year−1) is derived for the stock of bonga in this part of the Nigerian coast. Considering the level of mean catch (25 030 t year−1), which is very close to the optimum level of yield (Yec) and the mean value of the exploitation ratio ( F Z =0.57 ), it is concluded that the stock of E. fimbriata of the inshore waters east of the Niger delta is being fished at about its Yec. Although this is the desirable level of exploitation if profit is to be maximized, this fishery might be allowed to expand beyond Yec to contribute to the solution of an important socio-economic problem, namely, reduction of unemployment, but fishing at Ymax should be avoided to prevent the collapse of the stock.

The gonads of Ethmalosa fimbriata have been classified according to five and four maturity stages in the male and female, respectively. The species appears to mature at 22.0 cm in Ghana waters. The fecundity and frequency distribution of oocytes have been determined. Monthly changes in the proportions of gonadal stages and gonadosomatic index indicate that the species spawns in the sea from October to March. The results have been compared with data on populations occurring in other West African countries.

The biology of the population of Ethmalosa fimbriata occurring in the Lagos lagoon was investigated. Three size groups, 35–69 mm (Yoyo), 70–169 mm (Efolo) and 170 mm and above (Agbodo) occur in the lagoon and the spatial distribution of these size groups and the length frequency distribution of the species is given. The relationship between length, weight, age and growth is discussed and the food and feeding intra-relationship of the size groups is shown. Information on the fecundity and possible spawning periods is discussed.

Assessing the ecological status of rivers, creeks, and streams is a fundamental and increasingly important water management issue worldwide. This study examines the variations in fish community structure along an increasing pollution gradient in a small Niger Delta creek in Nigeria in both time and space. Salinity of the area fluctuated between fresh and mesohaline brackish waters with values ranging from 0.4 to 5.2 PPT and electrical conductivity values ranging between 16.9 and 136.0 µS/cm. The site in the upper creek (Site 1) was relatively free from gross pollution, with significantly high dissolved oxygen levels and low nutrient and salinity levels. Site 3 recorded relatively higher values of 5-day biochemical oxygen demand (BOD5) and high nutrient levels, indicating substantial input of organic matter to the creek upstream. Six (6) species, Tilapia guineensis (Cichlidae), Bostrychus africanus (Eleotridae), Hemichromis fasciatus (Cichlidae), Ethmalosa fimbriata (Clupeidae), Gerres melanopterus (Gerreidae), and Clarias macromystax dominated the sample and accounted for about 70 % of the total catch. Tilapia guineensis constituted the major dominant species and accounted numerically for about 20 % of the total catches and 45 % of the total biomass. Multi-species fisheries dominate the coastal zone with Tilapia guineensis, Gerres melanopterus and Ethmalosa fimbriata, Liza falcipinus, Mugil spp., and Chrysichthys nigrodigitatus, the major species in the commercial catches. Canonical correspondence analysis indicated that dissolved oxygen, electrical conductivity, total nitrogen, BOD5, and temperature were important variables structuring the overall fish assemblages. Overall, salinity was the major environmental variable determining the diversity of fish communities at the various sites. The effect of anthropogenic activities and land use practices around the creek only marginally affected the abundance of the fish species but not the diversity. These findings indicate that the water body is still useful as a good fishing ground for the rural communities and every effort should be put in place to ensure its protection and conservation for the production of healthy fish.