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Some Fish Win, Others Lose As Gulf Warms

Morley et al., 2018
Pew Charitable Trusts
As climate change continues to warm the oceans for the next several decades, many aquatic species will move toward the poles in search of cooler water. That means big changes for some species and the people who depend on them.

A report out this month says that the world’s oceans are warming much faster than expected. That’s already causing some fish species to move north, and could bring more changes to the ocean in the future.

To better understand how this will impact Gulf of Mexico fisheries like shrimp, snapper, and oysters, WWNO’s Travis Lux spoke with Dr. Rebecca Selden, a Marine Ecologist at Rutgers University.

The transcript below has been lightly edited for clarity:

Q: This new report says our oceans are warming much faster than expected. The main culprit is increasing greenhouse gas emissions, so if we stop carbon emissions tomorrow, can we also stop the ocean from warming?

Most of the emissions that we have emitted so far have been absorbed by the oceans. In some ways, that has slowed the total amount of warming that we’ve seen in the atmosphere. But that actually means that if we stop emitting today, we’re still expecting to continue warming. So we really need to think about making these changes [to emissions] soon to avoid even further warming above what we’ve already seen.

Q: So if this change is bound to continue for another several decades - even if we get a better handle on emissions - what is that going to mean for fisheries? Particularly in a place like the Gulf of Mexico? I’m thinking about species like shrimp, snapper, or oysters.

For me, fisheries really represent the frontline of the industries in the U.S. that are going to be hit by climate change. We’re already seeing that species are shifting poleward [moving north or south] and deeper in response to the warming that we’ve already seen.

That’s worrying for coastal communities that rely on those species and may not be able to follow the fish where they’re going. Because the Gulf of Mexico is physically constrained by the state of Florida, species aren’t necessarily going to be able to move north in the same way that they might, and may lose a lot of habitat in the Gulf of Mexico.

One example from our studies is that pink shrimp habitat is set to decline by about 70% in the Gulf of Mexico by the end of the century. That is worrisome for the many shrimpers that are in the Gulf of Mexico that rely on that species.

Q: You’re saying that some species will be able to essentially swim around Florida, but that doesn’t apply to all species, like shrimp?

Right, yeah. Some species are really mobile as adults and may be able to get around that barrier. Other species rely on passive currents to transport their babies to new areas. So there’s likely going to be winners and losers in this scenario with climate change. Unfortunately, many of the commercial species like shrimp don’t have a very rosy picture.

Credit W.W.L Cheung; Morley et al. 2018 / Pew Charitable Trust
Pew Charitable Trust
Warming oceans are already causing some species to move in search of cooler waters.

  Q: If, in general, those species that can move north do move north, does that also mean that in a place like the Gulf of Mexico we’ll see a migration of more tropical, southerly species coming from places like the Caribbean?

Yes, definitely. Some of the big unknowns are which species might emerge from the Caribbean, and whether we can take advantage of those species for fisheries. Will the markets be able to adapt? We don’t even necessarily know which species are on their way, so I think one big goal for the future of scientific research is to try to understand what species might be moving into regions like the Gulf of Mexico -- so that we can have more advanced notice to be able to get ready for those.

Q: The Gulf of Mexico has plenty of recurring issues, like the yearly dead zone. The dead zone is an area in the Gulf where the oxygen is so low that it can kill certain species. It forms every summer. How will warming oceans overlap with that? Is it going to make it worse or better?

Climate change is likely to make some existing stressors - like low-oxygen dead zones - even worse because they’re likely to get more frequent. Warmer water actually holds less oxygen, so we’re projecting that warmer waters are going to make those low-oxygen dead zones more frequent and potentially bigger.

Q: Is there any potential good news here? There’s a lot of negative news when it comes to climate change and warming oceans. Could there be some surprise benefits?

We do have evidence from our research that there are some species that will be gaining quite a lot by these warmer temperatures -- those species that are limited by colder water. For example, gray snapper is a species that is currently thriving in the warmer waters, and it is likely to have habitat gains by the mid-century.


For interactive graphics about how climate change will impact different fisheries in the Gulf of Mexico, and across the country, visit Rutgers University's OceanAdapt database

Support for the Coastal Desk comes from the Walton Family Foundation, the Greater New Orleans Foundation, the Foundation for Louisiana, and local listeners.

As Coastal Reporter, Travis Lux covers flood protection, coastal restoration, infrastructure, the energy and seafood industries, and the environment. In this role he's reported on everything from pipeline protests in the Atchafalaya swamp, to how shrimpers cope with low prices. He had a big hand in producing the series, New Orleans: Ready Or Not?, which examined how prepared New Orleans is for a future with more extreme weather. In 2017, Travis co-produced two episodes of TriPod: New Orleans at 300 examining New Orleans' historic efforts at flood protection. One episode, NOLA vs Nature: The Other Biggest Flood in New Orleans History, was recognized with awards from the Public Radio News Directors and the New Orleans Press Club. His stories often find a wider audience on national programs, too, like NPR's Morning Edition, WBUR's Here and Now, and WHYY's The Pulse.

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