Research Document - 2003/039

Abundance of resident Atlantic cod in Gilbert Bay, Labrador, based on mark recapture, sampling catch per unit effort and commercial tag return data collected from 1998 to 2002

By Morris, C.J., Green, J.M., and Simms, J.M.

Abstract

Gilbert Bay is located along the southern coast of Labrador (52° 35'N, 56° 00'W) near the communities of Williams Harbour and Port Hope Simpson. It was designated as an Area of Interest (AOI) in the Marine Protected Areas (MPA) Program by the Department of Fisheries and Oceans (DFO), on October 12, 2000. Mark-recapture data from an arm of Gilbert Bay, catch per unit effort data from research sampling, and commercial tag return data were used to estimate the size of the resident cod population. Atlantic cod tagged and later recaptured during scientific sampling form the basis of the population estimate. Catch per unit effort from several locations in the bay indicates that cod are not uniformly distributed during the spring spawning period. Tags returned by commercial fishers indicate that the largest fish in the population are disproportionately caught by commercial fishers. The mark recapture data indicates that the Gilbert Bay cod population has a biomass of less than 70 tons. Commercial fishing mortality during 1998 and 1999 was estimated at
18 t and 16 t respectively, while recreational fishing mortality during 1998 was estimated at 1000 kg. If the biomass is about 70 t, the population can not sustain commercial fishing at 1998 and 1999 levels. More research is necessary to assess the assumptions on which our estimate is based. Management decisions concerning this stock should be made separately from northern cod and reflect the small and uncertain size of the population.

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