A procedure is proposed by which recruit numbers and parental biomass of shrimps stocks can be derived, given a series of catch-per-effort data and estimates of a few ancillary variables. In the Gulf of Thailand, shrimp recruitment decreased with decreasing egg production, but increased with decreasing total (mainly fish) standing stock. The net result of these counteracting effects was an overall increase in shrimp recruitment, attributable to a greatly reduced prerecruit mortality.
While Africa’s inland fisheries are widely recognized to be of great importance to local people, accurate and up-to-date information on their value is sparse and its absence is a serious constraint to the formulation of effective fisheries policies and management practices. As a contribution to current efforts to address this constraint, this paper reviews the different methods that are potentially applicable to the valuation of inland fisheries and discusses their respective rationales and limitations within a multi-sectoral, multi-user context.
This selection of methods is based on lecture notes used at a FAO/DANIDA training course held in Mombasa, Kenya, in May-June 1980. The methods presented are: regression and correlation, estimation of growth parameters from length-frequency data, estimation of mortalities (total, natural, fishing mortality) and analysis of catch and effort data.
Details are given of a mathematical model for the derivation of monthly time series of recruitment for the Kuwait Penaeus semisulcatus stock.
The importance of quantifying the economic returns to investments in aquatic resources research together with the social, environmental and institutional impacts of such investments is widely recognized among ICLARM's donors, trustees and beneficiaries. As with other Consultative Group on International Agricultural Research (CGIAR) centers, ICLARM is being asked to provide specific accounts of the outputs of its research and their impact on farms and on fisheries, including their socioeconomic impact.
A discussion is presented on the topic of fish stock assessment methodologies and fisheries management, considering various research programmes conducted which concern fishery-derived data such as Virtual Population Analysis or catch-and-effort, or recruitment. Meaning, sense and value in fisheries science is examined.
This proceedings include the twenty-two papers which were originally presented in in a conference on The Theory and Application of Length-Based Stock Assessment Methods which took place on 11-16 February 1985 at the Istituto di Tecnologia della Pesca e del Pescato (ITPP) in Mazara del Vallo, Sicily, Italy. This conference was the first ever to be devoted solely to length-based methods for stock assessment.
The use of length-structured methods for the assessment of fish stocks is reviewed in relation to the present status of tropical fisheries science. It is concluded that these methods, which emerged largely as a result of the development of sophisticated, yet relatively cheap, programmable calculators and microcomputers, will enable significant advances to be made in assessment of tropical stocks.