Diel Variability in Trawl Catches of Greenland Halibut from the Channels off Coastal Labrador and Implications for Resource Assessment

Abstract

Catch data for Greenland halibut (Reinhardtius hippoglossoides) from trawl surveys conducted off the coast of Labrador were analysed for diel trends. Numbers of fish caught during 4-h intervals from both repetitive fishing and resource surveys were higher and more variable during hours of daylight. There were concomitant changes in availability of fish of various sizes (ages) to the sampling gear. The demonstrated diel trends represent a potential for bias in the estimation of stock abundance, stock composition, and recruitment indices of Greenland halibut as derived from resource survey data.