Fishing efficiency estimated based on the abundance from virtual population analysis and bottom-trawl surveys of Pacific cod Gadus macrocephalus in the waters off the Pacific coast of northern Honshu, Japan

Abstract

Fishing efficiency is one of the most important parameters to estimate population size using the swept area method based on bottom-trawl surveys. In the present study, the fishing efficiency of the stock of Pacific cod Gadus macrocephalus in the waters off the Pacific coast of northern Honshu, Japan was estimated based on the abundance obtained from virtual population analysis. Fishing efficiencies were estimated to fit the population size obtained from the swept area method to that obtained from virtual population analysis. Fishing efficiency was estimated as 0.54 for 1-year-old and 0.12 for 2-year-old fish, which had a significant difference. This is because, the fishing efficiency of 2-year-old fish was mainly affected by encounter rate to fishing gear caused by the difference of distribution area among the fish of different ages; many of the 2-year-old and over fish distributed on un-trawlable parts, e.g. rough-bottomed reefs.