World fisheries may be ‘resilient’ to impacts of heat waves

Climate change drove ocean temperatures to record heights this summer.

But in a rare piece of good climate news, a study released Thursday suggests that the global fisheries that feed much of the world seem to have weathered heat waves well. 

“While [fish populations] are changing in response to climate change, we don’t see evidence that marine heat waves are wiping out fisheries,” Alexa Fredston of Rutgers University, lead author of the study published in Nature, said in a statement.

There’s a big caveat: Fredston’s team looked at heat waves that happened between 1993 and 2019, so the study has little to say about the impact of rising temperatures since then.

And because the studies began back in the 1980s, the bulk of their samples come from a climate that is fundamentally cooler — and more stable — than the one projected for the rest of this century.

Other studies in Nature have found that the risk and disruptive impacts of heat waves are rising across much of the globe, and increasing the impacts of climate change in the northeast Pacific specifically.

But Thursday’s report show that decades of trawl surveys — more than 80,000 samples taken by dragging a net along the ocean bottom and seeing what comes up — found that, at least as of 2019, “there have been hundreds of marine heat waves with no lasting impacts,” Fredston said.

That doesn’t mean that there were no impacts from heat waves, however. The 2014-16 heat wave in the northeast Pacific known as “the Blob” led to a loss of nearly a quarter of biomass in the Gulf of Alaska.

On the other hand, a 2012 heat wave in the Northwest Atlantic led to a 70 percent gain in biomass.

Both of these, authors noted, were within normal limits for natural ecosystems.

“We found that these negative impacts are unpredictable and that other heat waves had no strong impacts,” said co-author Malin Pinsky.

But Pinsky noted that “each heat wave that hits is like rolling the dice: Will it be a bad one or not? We don’t know until it happens.”