Natural fish behaviour and catchability of groundfish

摘要

Imprecision in estimates of abundance and population parameters obtained from trawl surveyscould be reduced if the sources of variability were understood and properly described. Fishbehaviour in relation to sampling gears has been widely studied, with the main goal of providinginformation which might lead to improved reliability of abundance estimates. However, thegeneral applicability of the results may in many cases be questionable due to unidentified effectsof natural behaviour of the fish on catchability. Variability of natural behaviour may affectcatchability directly and, therefore, if aspects of natural behaviour are taken into account indesign and analysis of bottom trawl surveys, the reliability of the information obtained fromthese surveys could be improved.