August 31, 2023 — Prolonged periods of unusually warm ocean temperatures, known as marine heatwaves, can have devastating effects on marine ecosystems and have been linked to widespread coral bleaching, harmful algal blooms, and abrupt declines in commercially important fish species. A new study, however, has found that marine heatwaves in general have not had lasting effects on the fish communities that support many of the world’s largest and most productive fisheries.
The study, published August 30 in Nature, relied on data from long-term scientific trawl surveys of continental shelf ecosystems in North America and Europe from 1993 to 2019. The analysis included 248 marine heatwaves with extreme sea bottom temperatures during this period. Trawl surveys, done by towing a net above the seafloor, assess the abundance of bottom-dwelling species that include commercially important fish such as flounder, pollock, and rockfish.
The researchers looked for effects on fish biomass and community composition in the year following a marine heatwave. To their surprise, they did not find evidence that marine heatwaves in general have big effects on regional fish communities.