Is Atlantic Cod and Haddock Recruitment Influenced by the Planktonic Environment and Feeding Success During the Larval Stage?

Joel K. Llopiz, Woods Hole Oceanographic Institution

ABSTRACT

Atlantic cod (Gadus morhua) and haddock (Melanogrammus aeglefinus) are iconic species in the New England groundfish fishery. Both species are divided into Georges Bank and Gulf of Maine stocks. These four stocks share a history of overexploitation that peaked in the early 1990s and resulted in low population levels. However, since that time the trajectories of the four stocks have diverged. Various explanations have been proposed to explain the recruitment patterns of these stocks individually, but most of these analyses are based on correlations of recruitment from the stock assessments to regional-scale indices, with the additional predictions of the proposed mechanisms rarely tested. This project will specifically examine inter-annual, regional, and species-specific variability in both feeding success and diet composition of larval cod and haddock from Georges Bank and the Gulf of Maine. These results will then be related to inter-annual differences among stocks in the zooplankton communities and temperature environment experienced by the larvae using concurrently collected oceanographic, zooplankton and ichthyoplankton data, allowing for the ability to test the hypothesis that the contrasting patterns in recruitment success among the four stocks can be linked to larval feeding success and environmental drivers. If supported, the work will make strides towards integrating a zooplankton index into the assessment models’ stock recruitment function.