Fisheries in Canada and U.S. becoming tropicalized, research shows

An increase in MTC means fishers are catching more warm-water species. This means that the warmer it will get in the coming years, the more changes fishers will see in their nets and consumers on their dinner table.

The data shows that Canadian and U.S. fisheries have become tropicalized over the past few decades, with more and more warm-water species being caught over time. The range of these species is expanding further north, while cold-water species have in many cases been declining.

These changes point towards a clear impact from climate change, that is visible despite the confounding effects of historical overfishing or local management regulations, which could be masking some of these signals.

Climate-adapted fisheries management

The tropicalization of fisheries has consequences for ecosystems, seafood supply, and fisheries revenue. In general, it alters species composition, which can disrupt existing food webs, and force fishers to travel further away into new fishing grounds and target new species.

For example, the warm-water longfin squid used to occur more in the mid-Atlantic ocean. During periods of time when the temperature was very warm, fishers have encountered them north of their historical range, in an area where northern shrimp are typically found.

“Higher longfin squid predation has been suggested as a significant factor in the collapse of the northern shrimp population in the Gulf of Maine that used to support a locally important fishery,” says Dr. Dimarchopoulou.