Rhode Island's Tropical Visitors

From July through September, scuba divers and snorkelers converge in the parking lot at the Fort Wetherill State Park to explore the underwater world. But some are here for a rather unexpected reason: the tropical fish.

(ABC News)
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For years, scientists and avid divers have come to this rocky cove in Jamestown, R.I., to try to catch a glimpse of spotfin butterflyfish, snowy groupers, and other tropical varieties carried north from Florida and the Caribbean by the Gulf Stream.

"It's not a new phenomenon," says David Beutel, a Sea Grant fisheries extension specialist at the University of Rhode Island, Kingston (URI), but people who are used to seeing only native fish like cunner and striped bass may be surprised. "I don't think the average person would know," Mr. Beutel says.

During the summer, storms create warm-water eddies that split off from the Gulf Stream, carrying millions of eggs or thumbnail-size young tropical fish on a 1,500 to 2,000-mile journey up the Atlantic coast as far as Buzzards Bay, Mass.

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Jeremy Collie, a professor of oceanography at the University of Rhode Island's Graduate School of Oceanography, has been studying these pilgrim fish since 1993, when he arrived at URI.

Professor Collie says there's been an increase over time, in tropical fish in Rhode Island waters since the university began trawling for fish in two locations in Narragansett Bay in 1959. One reason is warmer water, he says: The average temperature of Narragansett Bay has risen four degrees F. in the past 50 years. That encourages warmer-water species like butterfish and scup while also discouraging cold-water varieties such as winter flounder and silver hake. Changing fishing practices and a shift in the ecosystem are other possible factors for the decline of cold-water fish in the Bay and the rise of warmer-water ones, Collie adds.

The array of tropical fish arriving along the North Atlantic coast has grown in the past few years. Some tropical fish have been found as far north as Nova Scotia and Maine, says Todd Gardner, a biologist at the Atlantis Marine World Aquarium on Long Island, N.Y.