Title: Consequences of Increased Pelagic Fish Biomass for a Continental Shelf Ecosystem

Background: Atlantic herring and mackerel biomass has increased on the northeastern U.S. continental shelf while Atlantic cod stocks have fallen, resulting in an order of magnitude rise in the ratio of planktivorous pelagics to cod. Pelagic biomass increased by a factor of four in 25 years in response to environmental conditions and reduced fishing. This increase is inversely related to young cod survival, possibly reflecting predation on cod eggs and larvae, and competition with young cod for zooplankton. Survival of adult stages of Calanus finmarchicus, an important food resource for herring, mackerel, young cod, and the endangered Northwest Atlantic right whale, decreased in concert with the pelagic increase. Fishing gear entanglements and ship strikes are primary issues of concern in the recovery of right whales, but pelagics also compete for Calanus, the principal prey of right whales, likely reducing reproductive health

Thesis: Fisheries management practices are causing non-recovery of cod and right whales

Importance: It is just now being recognized that a decline in copepod availability is contributing to the decline in North Atlantic Right Whale populations (2021 State of the Ecosystem Report, New England, NOAA 2021). We plan to explore how the management of pelagic fisheries in the North Atlantic is exacerbating this decline to the further detriment of species of concern including cod and North Atlantic Right Whales. From here we can better inform policy decisions regarding pelagic species. 

Approach: We plan a full ecosystem analysis to examine the role of all trophic levels, potential increased populations of managed species, and the response of other species of concern. In addition, we see a need for more comprehensive analysis and sampling of Copepod data so the relationship among species to this essential food source can be better understood.

Contacts Info: MaryOdum@evcarf.org

Please feel free to contact us with any comments or questions or informationon you could partner with us in our activities.

Everett-Vehrs Conservation and Research Foundation
4007 N. Abingdon Street
Arlington, Virginia USA 22207