The decline in the commercially important species of fish and predominance of Clarias lazera in Lake Chad

About 86 species of fish have been recorded in the Lake Chad. Most of the species occurring in the lake are widespread including most of the commercially important species. Fish distribution in the lake was adversely affected by the 1972/73 and 1983/84 droughts. The commercially important species before the 1972/73 drought were; Lates, Labeo distichodus, Heterotis, Gymnarchus, Hydrocynus, Citharinus and Bagrus. Other species which had less commercial value at that time include, Clarias, Gnathanemus, Polypterus, Protopterus, Tilapia and Synodontis. Lates niloticus was the most predominant species of commercial importance comprising 50-60% of the total catches of fishermen between 1962 and 1973. Before the 1972/73 drought, occurrence of Clarias lazera was negligible and restricted to long line catches and had little commercial value. As a result of the drought of 1972/73 which resulted in near drying up to the northern sector of the lake, fish populations were confined to isolated pools and were completely scooped out. The remaining fish populations retreated to the southern basin where enough water always remained to hold the surviving representatives of the population. The effects of the drought resulted in occurrence of the little known C. lazera along with other hardy species like Tilapia and Protopterus to dominate the existing fish species composition. In 1976, C. lazera dominated the total catches of fishermen with 85.6%. An overview of the fish population in the lake, their relative abundance, changes in species composition, the effects of drought on the fauna of the lake based on the available data are discussed in this paper

Modern aquaculture practices for increased fish production in Nigeria

Various modern aquaculture practices applied in fish production especially in Asia are reviewed. The vast Nigerian aquatic medium of numerous water bodies like rivers, streams, lakes reservoirs, flood plains, irrigation canals, coastal swamps offer great potentials for aquaculture production, if optimally utilized. Constraints to modernization of aquaculture in Nigeria among other factors are: 1) a serious shortage of trained manpower; 2) lack of knowledge on profitability of aquaculture as an industry; 3) limited availability of fund (or capital); 4) non-recognition of indigenous trained aquaculture personnel; 5) inadequate data base on the biology and ecological requirements of endemic fish species with aquaculture potentials; 6) insufficient data on production and management techniques; and 7) lack of rational aquaculture development planning. Recommendations are made towards combating these constraints

The potentials for commercial production of fish feeds in Nigeria

Studies in fish feed technology revealed that there is a potential for big time investment into fish feed production and marketing in view of the growing awareness of fish farming in Nigeria. Intensification of aquaculture is one of the primary methods of food (finfish) production which requires technical knowledge and expertise in the formulation and manufacture of adequate feeds for the cultured species. Studies also revealed that all sort of food items were used by fish farmers ranging from animal dung, groundnut cake etc, to culture fish to table size because of non-availability of rightly prepared feeds. Inadequate knowledge of detailed requirements of tropical cultured species was found to pose a hindrance to formulation despite the fact that a lot has been accumulated in terms of biochemical and nutritive values of food sources in Nigeria. The investigation further revealed the challenges posed to researchers in aquaculture, fish nutritionists and fisheries biologists among others to elucidate the complete requirements of local fish species in terms of their protein, lipid and carbohydrate requirements such that their patents could be made available to companies like PFIZER, IBRU etc, and individuals alike to make commercialization of fish feeds a reality

Aquaculture Asia, Vol.14, No.4, pp.1-52, October - December 2009

Sustainable aquaculture Peter Edwards writes on rural aquaculture Edwards, P. Mussel farming initiatives in North Kerala, India: A case of successful adoption of technology leading to rural livelihood transformation Laxmilatha, P., Thomas, S., Asokan, P.K., Surendranathan, V.G., Sivadasan, M.P., and Ramachandran, N.P. Selective study on the availability in indigenous fish species having ornamental value in some districts of West Bengal Panigrahi, A.K., Dutta, S. and Ghosh, I. Aquaculture livelihoods service centres in Aceh, Indonesia: A novel approach to improving the livelihoods of small scale fish farmers Ravikumar, B. and Yamamoto, K. Research and farming techniques e-Sagu Aqua - an innovative information and communication technology model for transfer of technology for aquaculture Vimala, D. D., Ravisankar, T., Mahalakshmi, P., and Kumaran, M. Freshwater pearl crop: an emerging enterprise in the Indian subcontinent Misra, G., Jena, J. and Kumar, K. Genetics and biodiversity Preliminary risk assessment of Pacific white leg shrimp (P. vannamei) introduced to Thailand for aquaculture Senanan, W., Panutrakul, S., Barnette, P., Chavanich, S., Mantachitr, V., Tangkrock-Olan, N., and Viyakarn, V. Farmer profile Aquatic animal health Asian fish health experts visit Australia Olsen, L. and Ingram, B. (Fisheries Victoria) Black gill disease of cage-cultured ornate rock lobster Panulirus ornatus in central Vietnam caused by Fusarium species Nha, V.V., Hoa, D.T. and Khoa, L.V. Marine Finfish Aquaculture Network Effects of the partial substitution fish oil by soybean oil in the diets on muscle fatty acid composition of juvenile cobia (Rachycentron canadum) Hung, P.D. and Mao, N.D. Growth response of cobia Rachycentron canadum (Pisces: Rachycentridae) under the hypersaline conditions of the Emirate of Abu Dhabi Yousif, O.M.*, Kumar, K.K. and Abdul-Rahman, A.F.A. NACA Newsletter

Species Profiles: Life Histories and Environmental Requirements of Coastal Fishes and Invertebrates (Mid-Atlantic): Alewife/Blueback Herring

This profile covers life history and environmental requirements of both alewife (Alosa pseudoharengus) and blueback herring (Alosa aestivalis), since their distribution is overlapping and their morphology, ecological role, and environmental requirements are similar. The alewife is an anadromous species found in riverine, estuarine, and Atlantic coastal habitats, depending on life cycle stage, from Newfoundland (Winters et al. 1973) to Soutn Carolina (Berry 1964). Landlocked populations are i n the Great Lakes, Finger Lakes, and many other freshwater lakes (Bigelow and Sch roeder 1953; Scott and Crossman 1973). The blueback herring is an anadromous species found in riverine, estuarine, and Atlantic coastal habitats, depending on life stage cycle, from Nova Scotia to the St. Johns River, Florida (Hildebrand 1963)

The survey of Lake Victoria's fishers

The findings are presented of a survey conducted regarding the fishers of Lake Victoria, which examined the relationships affecting supply flows of raw material on to the market, and also the characteristics of fishing activities and their effects on fish quality and distribution. Fish marketing plays a vital role in the lives of much of the lake basin's population, both in terms of employment and nutrition. The results of the survey comprise, in part, a base-line data set which will facilitate further research, analysis and management decision-making in relation to stakeholders of the lake's resources. Data collection, methods and research difficulties encountered are described and details given of a profile of a boat owner/renter and aslo of a profile of a crew member. The survey shows that Lake Victoria's fishery is one of very limited diversity. The fishers recount that they consistently target one or more of the 3 most common species within the lake (Nile perch, tilapia and dagaa) and very rarely consider any other species type. The largest proportion of fishers on the lake are Nile perch fishers; there is considerable demand for this species, and hence fishers have little incentive to either target alternative fish species, not to try and establish firm marketing outlets through the creation of arrangements with their principal buyers. In Kenyan waters, however, the number of Nile perch fishers is equaled by the number of dagaa fishers; this fish now commands a considerable portion of the market for fish from Lake Victoria through its availability as well as its relatively low prices. The tilapia fishery is in decline, and all 3 riparian states would not appear to be attracting investment almost certainly as a result of declining catches. For many of those working in Lake Victoria's fishery, the problems faced appear most often to be associated with the vagaries of an unstable market which may rise or fall depending on the state of the international market or the state of access roads to fish landings. (PDF contains 42 pages)