Story from the 10/12/04 Boston Globe
Aquarium's tropical fish come from unlikely waters
By Beth Daley, Globe Staff | October 12, 2004

JAMESTOWN, R.I. -- As tropical fish-finding missions go, it may seem like someone got hold of a really bad map. Every fall, New England Aquarium volunteers dive for tropical fish -- not off a Caribbean reef -- but in the dark waters off Rhode Island and Martha's Vineyard, normally home to the dark-colored cod.

There, the scuba divers and snorkelers scoop up brightly colored tropical fish swept -- inexplicably -- thousands of miles from home.

The search for the baby, often dime-size fish is a mercy mission of sorts between late August and early November because they will otherwise be wiped out by the first real cold snap.

''The fish are going to die anyway and it really helps us," said Holly Martel Bourbon of the New England Aquarium.

Over the years, volunteers have donated scores of these tiny reef visitors, from baby barracudas to the cornet fish. ''You never know what you are going to see [off Rhode Island's coast]," she said.

On a recent Sunday, Tom Kemper of Wayland spent 40 minutes searching a bay in Fort Wetherill State Park for tiny fish in a rocky area. He dumped three yellow spotfin butterfly fish into a container. Any fish the aquarium doesn't need, he'll keep for his family's own tank.

Collecting the hard-to-find fish is an art that can take years to develop, and new hunters can search for hours without finding any tropical fish. ''Some of them are as small as a pea," Kemper said.

While tropical fish collecting has long been an open secret off Rhode Island, scientists are at a loss to fully explain the phenomenon. What is known is that unlucky fish eggs or larvae get swept into the powerful Gulf Stream that flows north from the Gulf of Mexico, bringing warm, salty water up to New England.

But the Gulf Stream bends east around Cape Hatteras and then wobbles up the coast, never getting closer than a few hundred miles or so to New England. The tiny tropical fish are far too weak to escape it and swim to Rhode Island.

''No one really knows how they get here," said Abby McLean, a master's degree candidate at the University of Rhode Island who is writing her thesis on the yearly tropical fish event. Her research, which looks at data back to 1959, shows that the abundance of the fish hasn't changed, but ''more recently we see more diversity" -- although she isn't sure why.

As the Gulf Stream becomes more unstable in northern waters, warm eddies spin off from it and travel north to northwest. But the eddies stop about 80 to 100 miles offshore from New England -- once again too far for the tiny fish to swim to coastal waters.

It's here where the mystery deepens. Some scientists believe warm water ''streamers" of the eddies find their way to shore, bringing the tropical fish with them. Others believe that fingers of salty warm water -- unrelated to the Gulf Stream -- stretch into the cooler, less-salty waters closer to shore.

''We don't actually understand how they are formed -- but as far as we can understand these intrusions are swept around by the currents," said Steve Lentz, senior scientist at the Woods Hole Oceanographic Institution in Falmouth.

The New England Aquarium has relied on its local dive club for more than a decade to find tropical fish -- allowing the museum to focus on other species when its researchers travel to the Caribbean to collect fish. The dive club usually gives anywhere from a dozen to two dozen fish a year to the aquarium, and many keep extras, like Kemper does, for their own tanks.

The aquarium puts the tiny fish into a ''Southern visitors" tank until they grow to the size of a quarter or a half-dollar. Then they go into the main tank at the center of the museum.

This year, dive club environmental affairs liaison Alicia Lenci -- who spends her free time driving a blue ''scuba bus" to introduce ocean life to the public -- found a young scrawled file fish. The fish, about 5inches long, can grow to more than 2 feet.

For Lenci and her partner, Michael Schruben, hunting tropicals is only a part of the fun: Showing them off is even better.

''In New England waters, people . . . are still unfamiliar with the ocean," Lenci said. ''It's cold, it's dark, they think there is nothing here. People are amazed when they find out what we have here."

Beth Daley can be reached by email at bdaley@globe.com.