Research Document - 2000/091

Distribution and biomass of capelin, Arctic cod and sand lance on the Northeast Newfoundland Shelf and Grand Bank as deduced from bottom-trawl surveys.

By Lilly, G., Simpson, M.

Abstract

Changes in the distribution and trawlable biomass of capelin (Mallotus villosus), Arctic cod (Boreogadus saida) and sand lance (Ammodytes sp.) are deduced from their by-catches during standard resource assessment bottom-trawl surveys in Divisions 2J3KL during the autumn and in Divisions 3LNO during the spring. Three different bottom trawls were used during the study period (1978-1999), and the estimates of biomass changed substantially with each change in gear. In particular, biomass estimates increased dramatically starting in the autumn of 1995 when the Engel 145 Hi-rise trawl was replaced by the Campelen 1800 shrimp trawl. There has been no attempt to conduct comparative fishing experiments for these three species with these two trawls, so the change in gear represents a break in the timeseries for each species. In general , Arctic cod were found mainly toward the coast in Divisions 2J3K, capelin were found throughout the area and exhibited seasonal changes in distribution, and sand lance were found only on the plateau of Grand Bank. The most notable changes in distribution involved a move toward the southeast in Division 2J3K by both capelin and Arctic cod in the early to mid-1990s. In 1998-1999 both species appeared to be returning to distributions seen in the 1980s. Other notable features include an increase in the trawlable biomass of Arctic cod in the early to mid-1990s and a decline in the trawlable biomass of capelin during the same period.

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