Stock assessment of NAFO subdivision 3Ps cod .: Fs70-6/2017-002E-PDF

"The overall biomass of the fish community in 3Ps has remained relatively stable since the mid-1990s, whereas the overall abundance has increased due mainly to an increase in small planktivorous (plankton-eating) fishes (e.g. sandlance). Atlantic Cod has historically been the dominant piscivorous (fish-eating) species in 3Ps but since 2010 there has been a sharp rise in the biomass of Silver Hake (Merluccius bilinearis), typically considered a warmer-water species. The increase in Silver Hake biomass may be linked to the warming trend in this ecosystem. Cod in 3Ps have a highly variable diet, with the dominant prey species changing over time (e.g. redfish in 1993-95, small pelagic fishes like capelin and sandlance in 1996-97). In 2013-16 the diet of smaller cod tended to be dominated by sandlance and crabs, with Snow Crab increasing in importance in the diet with cod size. The current invertebrate-dominated diet is likely of poorer quality than one based on fish. Preliminary diet data for Silver Hake in 3Ps suggest that this species is not in direct competition with cod for food. These changes in species composition and cod diet are evidence that the structure of the ecosystem in 3Ps may be changing. Although the full impacts of these changes on cod are still unknown, they seem to imply that at least some aspects of cod productivity may be impaired"--Intro., p. 2-3.

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