Changes in ocean temperature are changing fish distribution and productivity. From 1930 to 2010, ocean warming led to an estimated 4.1 percent drop in sustainable catches, on average, for many species of fish and shellfish according to a study by NMFS-Sea Grant Population and Ecosystem Dynamics Fellow Chris Free and colleagues.

The study was published in the March 2019 edition of Science Magazine and “used historical ocean temperature and fisheries data to determine how ocean warming affects the amount of fish that can be harvested sustainably from wild-populations.”

Seafood has become an increasingly important source of nourishment as the world population has grown, especially in coastal, developing countries where it provides up to half the animal protein eaten. More than 56 million people worldwide work in the fisheries industry or subsist on fisheries. “We were stunned to find that fisheries around the world have already responded to ocean warming,” said Malin Pinsky, study coauthor and associate professor in Rutgers’ Department of Ecology, Evolution, and Natural Resources. “These aren’t hypothetical changes sometime in the future.”

The study reports that the effects of ocean warming have been negative for many species, but also finds that other species have benefited from warming waters.

“Fish populations can only tolerate so much warming, though,” said senior author Olaf Jensen, an associate professor in Rutgers’ Department of Marine and Coastal Sciences. “Many of the species that have benefited from warming so far are likely to start declining as temperatures continue to rise.”

Free’s dissertation adviser, Olaf Jensen, says that the NMFS-Sea Grant Fellowship was instrumental in allowing Free to pursue this groundbreaking work. “This fellowship gave him the freedom to really devote himself to this research rather than [teaching] or applying for small grants,” said Jensen.

Sea Grant and the National Marine Fisheries Service (NMFS) partner to train students through this joint fellowship program in two specialized areas: population and ecosystem dynamics as well as marine resource economics. Population and ecosystem dynamics involve the study of fish populations and marine ecosystems to better assess fishery stock conditions and dynamics. Since 1999, 126 students have received fellowships. Over 90% of fellows remain in the industry following their fellowships and 40% work in NMFS as fisheries scientists.  

Material for this story was taken from a story previously posted by Rutgers University. Additional funding and support for Free’s research was provided by New Jersey Sea Grant Consortium and other sources; full acknowledgements and funding sources provided in publication. More information about the NMFS-Sea Grant Joint Fellowship Program, visit the National Sea Grant website.

More information: Free, C., Thorson, J., Pinsky, M., Oken, K., Wiedenmann, J. and Jensen, O. (2019). Impacts of historical warming on marine fisheries production. Science, 363(6430), pp.979-983.