Study: Climate Change Results in Fewer Productive Fish Species

school of fish
A school of fish. File photo courtesy of Oceana/Eduardo Sorensen.

A new Rutgers University study finds that as temperatures warm during climate change, predator-prey interactions could prevent some species from keeping up with conditions where they could thrive, resulting in fewer productive fish species to catch in the future.

The study, published April 13 in the biological research journal Proceedings of the Royal Society B, presents a mixed picture of ocean health. Not only could large species and commercially important fisheries shift out of their historical ranges as climate warms, but they would likely not be as abundant even in their new geographic ranges. For instance, a cod fisherman in the Atlantic might still find fish 200 years from now but in significantly fewer numbers.

According to study coauthor Malin Pinsky, the findings suggest from a fisheries perspective that while the species fished today will be there tomorrow, they won’t be there in the same abundance. In such a context, overfishing becomes easier because the population growth rates are low.

“Warming coupled with food-web dynamics will be like putting marine biodiversity in a blender,” Pinsky said.

Previous studies of shifting habitat ranges focused on the direct impacts of climate change on individual species. While these “one-at-a-time” species projections offer insights into the composition of ocean communities in a warming world, they have largely failed to consider how food-web interactions will affect the pace of change.

The study looked at trophic interactions—the process of one species being nourished at the expense of another—and other food-web dynamics to determine how climate change affects species’ ranges.

Lead author E. W. Tekwa, a former Rutgers postdoctoral student now at the University of British Columbia, said that computer models employed in the study suggest that over the next 200 years of warming, species will continually reshuffle and be in the process of shifting their ranges.

“Even after 200 years, marine species will still be lagging behind temperature shifts, and this is particularly true for those at the top of the food web,”
Tekwa said.

Researchers said that as climate warms millions of species are shifting poleward in a dramatic reorganization of life on earth. However, they said, understanding of these dynamics has largely ignored a key feature of life, that animals and other organisms must eat.

The researchers said they filled this knowledge gap by examining how the basic need for nourishment affect species’ movements by developing a spatially explicit food-web model that includes parameters such as metabolism, body size and optimal temperature ranges.

By accounting for climate change, researchers said, their model revealed that dynamic trophic interactions hamper species’ ability to react quickly to warming temperatures, and that larger-bodied top predators stay longer than smaller prey in historical habitats, in part because of the arrival of new food sources to their pre-warming ranges.