Changes over time of the size structure in an exploited shelf fish community

Abstract

After a long decline that began in the 1960s, the great fisheries of Newfoundland collapsed, and since 1992 a moratorium has applied to most stocks from Labrador to the U.S. border. Cold water temperatures and other environmental factors have been suggested as the underlying cause of the observed declines, but the data now emerging show that overfishing has been the prime agent. Study of scientific survey data for the years 1978-1993 shows that all species, commercial and non-commercial, in the fish community have undergone changes. Numbers and biomass decreased and for both target and non-target species mean size in the 90's has dropped dramatically from what it was in the early 80's. The decline in size results from the removal of the larger (and presumably older) individuals with the result that the population structure has been fundamentally changed. The trend of decreasing mean size over time is not an isolated occurrence on the Northeast Newfoundland and Labrador shelf, but is also observed in the groundfish community off west Greenland during a similar time period.