Approaches to national fish breeding programs: pointers from a tilapia pilot study

Details are given of a framework for developing breeding programmes using experience from the Genetic Improvement of Farmed Tilapias project which focussed on Nile tilapias (Oreochromis niloticus ). The following aspects are outlined: Analysis of targeted production and marketing systems; Breeding goals; Systematic documentation and evaluation of available genetic resources and choice and genetic base; Number of strains; Breeding strategy; Selection criteria and evaluation; Production and dissemination of improved strains; and, social, economic and environmental impacts.

Biochemical and morphometric approaches to characterize farmed tilapias

Biochemical (electrophoresis and mitochondrial DNA) and morphological analysis are important tools for the characterization of strains. Reference is made to studies conducted in the framework of the Genetic Improvement of Farmed Tilapias project to establish a new base tilapia population for culture purposes, describing the basic concepts of electrophoresis and morphometric analysis.

Comparison of two approaches for estimating natural mortality based on longevity

Vetter (1988) noted that her review of the estimation of the instantaneous natural mortality rate (M) was initiated by a discussion among colleagues that identified M as the single most impor ta nt but least well-estimated parameter in fishery models. A lthough much has been accomplished in the inter vening years, M remains one of the most difficult parameters to estimate in fishery stock assessments. A number of novel approaches using tagging and telemetry data provide promise for making reliable direct estimates of M for a given stock (Hearn et al., 1998 ; Frusher and Hoenig, 2001; Hightower et al., 2001; Latour et al., 2003; Pollock et al., 2004). However, such methods are often impracticable and fishery scientists must approximate M by using estimates made for other stocks of the same or similar species or by predicting M from features of the species’ life history (Beverton and Holt, 1959; Beverton, 1963; Alverson and Carney, 1975; Pauly, 1980; Hoenig, 1983; Peterson and Wroblewski, 1984; Roff, 1984; Gunderson and Dygert, 1988; Chen and Watanabe, 1989; Charnov, 1993; Jensen, 1996; Lorenzen, 1996).

Synthesis of aquaculture policy and development approaches in Africa

The WorldFish Center was tasked to undertake a study to access, collate and develop background materials to produce an internationally linked and Africa-wide perspective on sectorally relevant policy issues. The specific objective of the study was to assess and define conditions and impact pathways, in Africa or elsewhere, where markets, policies, resources and technologies have combined to promote steady and sustainable growth of aquaculture, and where have been clear direct impacts on food supply, income, employment and consumption opportunities, as well as increase in supply that has led to stabilised prices. The study was also aimed at providing guidelines for scaling up the implementation of the synthesis study via Afri-FishNet (CAADP Fish Expert Pools) at the national and regional levels.

Application of remote sensing to marine fisheries: alternative approaches

A discussion is presented on the applications of remote sensing to fisheries. The measurement of temperature, wind stress, and ocean colour using remote sensing techniques is considered.

Feasibility study: the methods and approaches to implementing a SEREAD teacher training programme in BOBLME countries

Objectives included a desk-top feasibility study to explore opportunities to adapt the Scientific Educational Resources and Experience Associated with the Deployment of Argo profiling floats in the South Pacific Ocean (SEREAD) to BOBLME country schools.The programme included teacher resources on climate change and facilitating interactions between scientists, students and teachers.

Approaches to the evaluation and management of the fish stock in Kainji Lake, Nigeria

Estimates of potential yield for Kainji Lake, and the methods of analysis by earlier workers are discussed. Also summarized is the state of the fishery after impoundment, between 1969 and 1971, based on experimental gillnet catches. Recent sampling of the young of the year along the littoral margin indicates that most of the commercially important species have spawned successful1y in the lake. An intense fishing mortality of juvenile fish, owing to the use of small mesh nets by local fishermen, presents a possible threat to the future establishment of the fish in the lake. The results of gill-net selection studies based on HOLT'S (1957) method are given. The data have been extracted from experimental gill-net catches with graded fleets of nets between 1969 and 1971. Recommendations based on the above studies have been made to ensure a successful establishment of the fish species in the lake and an increase in catch-per~unit effort in subsequent years.