Fao Fisheries Technical Paper

Elasmobranch - describes a group of fish without a hard bony skeleton, including sharks, skates, and rays.

Transshipment is a widespread practice in marine capture fisheries, that has recently been associated with a possible risk of introducing catches derived from illegal, unreported and unregulated (IUU) fishing into the supply chain. This in-depth study was carried out in order to shed more light on the practice and make recommendations to inform future discussions on the development of international guidelines for the regulation, monitoring and control of transshipment. The report presents a background to the study, its approach and methodology, the key findings including possible elements of the guidelines, and discusses the main issues from the perspective of the risk of transshipment in supporting IUU fishing.

In Part 1, Manual, a selection of methods on fish stock assessment is described in detail, with examples of calculations. Special emphasis is placed on methods based on the analysis of length-frequencies. After a short introduction to statistics, it covers the estimation of growth parameters and mortality rates, virtual population methods, including age-based and length-based cohort analysis, gear selectivity, sampling, prediction models, including Beverton and Holt's yield per recruit model and Thompson and Bell's model, surplus production models, multispecies and multifleet problems, the assessment of migratory stocks, a discussion on stock/recruitment relationships and demersal trawl surveys, including the swept-area method. The manual is completed with a review of stock assessment, where an indication is given of methods to be applied at different levels of availability of input data, a review of relevant computer programs produced by or in cooperation with FAO, and a list of references, including material for further reading. In Part 2, Exercises, a number of exercises is given with solutions. The exercises are directly related to the various chapters and sections of the manual.