Tropical fish spotted in Narragansett Bay, oceanography students study species

10/16/08 - Through weekly studies with a trawl boat, a URI graduate school professor has proven an increase in the tropical fish population in the Narragansett Bay, possibly caused by a four-degree increase in water temperature.Jeremy Collie, a professor of oceanography at URI's graduate school, studies bottom-dwelling fish populations. He takes students out trowling on a research boat by the mouth of Narragansett Bay on a weekly basis to collect data about the local fish.

Collie said he has found 130 different species, but the number of tropical fish species, 31, is on the rise. A URI graduate student, Abby McLeod, studied 12 different surveys from the past 20 years taken from the bay to determine the number of species in the bay.

Collie studied the size of fish species compared to water temperature in various years, and found a link between higher water temperature and smaller body size, which could have a negative effect on the fishing industry.

Also, because of the increase in temperature, the region's native species could be hurt. A slight change of water temperature may be responsible for the decreasing populations of species such as cod and winter flounder, and increasing sightings of tropical and temperate-water fishes.

The trawler Collie uses has an odd history of its own. The University of Rhode Island department of fisheries, animal, and veterinary sciences owns the R/V CAP'N BERT, which was captured in the early 1980s.

It was renamed in honor of former URI professor Albert Hillier, who taught fishing and marine technology classes during the 1970s and 1980s. Once known as the ANGELITA, the R/V CAP'N BERT was involved in the drug dealing industry and captured in the early 1980s by the U.S. Coast Guard. The URI Graduate School of Oceanography has been using the 53-foot vessel to conduct trawl surveys since 1987.

Collie trawls weekly in and at the mouth of Narragansett Bay and has recorded more than 130 marine fish and invertebrate species. However, he said "the tropical fish are rare occurrences."

Most of the data collected is further analyzed at the URI Graduate School of Oceanography. McLeod is finalizing a paper to be printed in the Fishery Bulletin. Her work is based upon research collected from 12 surveys that have been taken in Narragansett Bay during the last 20 years.

Regarding his research, Collie said he and his team of researchers carefully catch and release the fish they study, only keeping a subject if another researcher requests it.

"If someone wants it [a specific marine species] for research, we'll put it in a cooler and take it back," Collie said.

Collie believes that current fishing industry methods may also be to blame for this unusual ecological distribution of marine organisms. The eggs of these tropical fish are carried up to 2,000 miles north, along the eastern coastline. Tropical storms churn the seas and create warm eddies that carry the eggs away from the Gulf Stream. Occasionally, small warm-pockets of water confuse the navigational systems in marine organisms and result in misguided migrations.

Earlier this year in Jamestown, scientists, divers and fish-lovers gathered from July to September along the rocky coast of Fort Wetherill State Park to view the non-native marine species. Tropical fish such as the snowy grouper, spotfin butterfly, and the red lionfish have been sighted frequently over the last 16 years.

In Rhode Island, it is legal to collect marine specimens. Organizations such as the Rhode Island Tropical Fish Society obtain these tropical fish and rehabilitate them if necessary.

After successfully breeding the various tropical species, the group donates them to New England aquariums. Organizations and collectors generally regard it as ethical to remove the fish from Rhode Island waters because they are already out of their normal ecological environment.