Simulation modelling in marine fisheries for fish stock assessment a bio-statistical analysis

Exploited fish stocks are assessed with the help of micro analytic and macro models (Alagaraja, 1990). Catch in numbers (age specific or length specific) or catch in weight and the corresponding fishing effort expended are the main inputs to the fish population models. The quality of this input data governs the performance (predictive or interpolative) of the models and determines the relevance of management decisions inferred from the stock assessment studies. Catches usually are estimated from sampling of commercial landings. These sampling schemes are often complex and multistage in nature. In India marine fish catch statistics are collected by the Central Marine Fisheries Research Institute, Cochin through a sampling system based on the theory of sampling(Bane~i, 1971). Most of the catches are from the inshore regions and landed at about 2400 landing centres spread all along the coast line in the various 9 maritime states of India. Keeping pace with the changing pattern of the fishery the mode of collection has also undergone change periodically without any significant alterations in the basic structure of the sampling design