Half a century of warming in Narragansett Bay is transforming the bay’s waters from a hybrid of the southern and northern Atlantic Ocean into a year-round southern estuary similar to the ones found in Maryland and the Carolinas, researchers say.
The rise in the bay’s temperature, in turn, is affecting the composition of its fish, which is leading commercial fishermen to change what they catch. Cold-water northern species of marine life are now less able to thrive, while warm-water southern fish are becoming more prevalent.
“Up in Narragansett Bay, I don’t doubt that we have felt the effects of warming,” said Chris Brown, president of the R.I. Commercial Fishermen’s Association, which includes most of the state’s major finfish trawlers. “We have more mid-Atlantic species than we used to,” particularly scup and summer flounder, he said.
The surface temperature of the bay during the spring and summer months increased by 2.8 degrees between 1959 and 2005, according to a new study by scientists at the University of Rhode Island that analyzed decades of weekly survey data collected by the Graduate School of Oceanography. Their findings were published in the July issue of the Canadian Journal of Fisheries and Aquatic Sciences.
Narragansett Bay, which is the largest estuary in New England, “has had a very interesting ecology in the past, because we have characteristics of both regions,” said Peter August, director of the URI Coastal Institute. Now, however, “it’s becoming more of a mid-Atlantic southern ocean.”
As a result, the composition of marine life in Narragansett Bay “has changed dramatically since 1959,” the URI study found. There has been a significant decline in bottom-dwelling, cold-water fish, such as winter flounder and silver hake, and a corresponding increase in warm-water fish, such as scup and butterfish, as well as invertebrates like lobster, crab and squid.
“It’s a dramatic change,” said Najih Lazar, supervising marine biologist at the R.I. Department of Environmental Management. “The winter flounder [was] the trademark, if you will, of Narragansett Bay in the ’50s and the ’60s,” but herring, squid and summer flounder are now more common, he said.
The tautog, one of the few fish species native to Narragansett Bay, has also declined significantly. “If you talk to the old-timers about what they used to catch for tautog in the bay, they could fill a boat in a matter of half a day just by rod-and-reel fishing,” Lazar said. “Today, you can search for half a day and if you catch one you’d be lucky.”
Even gradual changes in the type of fish in bay can have an economic effect on fishermen due to the difference in price. Winter flounder, for example, sells for up to $2 per pound, while menhaden and scup sell for only $0.10 to $0.75 per pound.
Despite that, the warming of the bay isn’t causing major problems for commercial fishermen, because the total amount of fish in the bay hasn’t decreased even though the types available has changed, Brown said.
“It’s probably interchangeable,” said Brown, who has been a fisherman for about 30 years. “We lose out on one, we gain on another.”
Moreover, if one sort of fish disappears, commercial fishermen will switch to catching the types of fish that are still around, Brown said.
“Anybody that’s a successful fisherman in 2008 fishes for dollars,” he said. “They don’t fish for specific species. We’re opportunistic, we’re adaptable, and if it’s there, we’re going to go forward.”
Jody King, vice president of the R.I. Shellfishermen’s Association, said his members have noticed only a tiny decrease in the amount of shellfish in Narragansett Bay.
Beyond commercial considerations, the changing bay has led to other concerns. Warming is one factor that increases the likelihood of another fish kill like the August 2003 disaster that killed more than a million fish in Greenwich Bay.
Nevertheless, August, the Coastal Institute’s director, said he doesn’t see the warming of Narragansett Bay as strictly negative. He pointed out that many changes, such as reduced pollution and improved monitoring, are improvements.
“In my personal opinion, it’s change,” August said. “Things are changing. And I’m not going to put a value judgment on it – I’m not going to say that the changes are for the better or the worse. … Ecosystems are very resilient and people in society are very resilient.” •
