Sampling and a mortality model of a Norwegian fjord cod (Gadus morhua L.) population

摘要

An assessment model was developed of a coastal cod population integrating data on catch-at-age from commercial catches and survey data and tag returns from commercial and survey trawl fisheries. Cod were tagged during the period 1990-1995 and recaptured in the commercial and research survey. Quarterly trawl surveys were conducted during 1990-1996, and cod were also sampled from the commercial catches during 1994-1996. The model was fitted to the different sets of data using a weighted least square minimisation. The model appeared to fit the data sets reasonably well, and the sensitivity analysis indicated that the major tensions tended to be between the survey and the commercial catch-at-age data.