FishSec regularly highlights research which can contribute to the ongoing dialogue on Baltic fisheries. These two papers examining cod stocks in the Northwest Atlantic may be informative for Baltic cod stock recovery and ecosystem considerations in population modelling.

– Warmer oceans mean some cod stocks will never fully recover

Cod stocks in the Gulf of Maine in the US, between New England and Nova Scotia, have plummeted to four percent of their former levels, despite massive cuts in fishing since 2010. Warm waters might be one of the reasons for this decrease, according to a new study. Researchers found that “the warmer the water, the more larval and 4-year-old cod died, possibly because warmth boosts zooplankton that eat larvae, and speeds up the metabolism of older fish reaching sexual maturity, so they need more food – which they may not find”.

According to the authors, one thing is clear: fisheries modelling must change. Fisheries models need to take account of temperature, as the study shows that failure to include sea temperatures into the models have lead fisheries managers to overestimate stocks by two to five times. Without these changes the long-term sustainability of cod fisheries may be jeopardized. Learn more.

– Protecting strong incoming year classes of northen cod

New research on Canada’s northern cod, led by George Rose at the Centre for Fisheries Ecosystems Research at the Marine Institute in Newfoundland, highlights the importance of protecting strong incoming year classes.

Rose and his team conclude “that the northern cod is making a remarkable comeback. Since 2007, cod biomass in overwintering and spawning aggregations in the Bonavista Corridor has increased from a few thousand to >200 thousand tonnes. Abundance, size structure, and condition have all improved. The main factors that kickstarted the increase appear to be capelin abundance and perhaps immigration of at least one strong year-class, which occurred during a period of favorable climate and low removals through the fishery.”

This research is evidence that the protection of strong incoming year classes is critical to stock recovery, something which we at FishSec have argued is crucial for rebuilding the Western Baltic cod stock. Learn more.