August 7, 2008

Little Fish Add Flash to Waters of North

By Bina Venkataraman

Fishing season has begun in northern waters, not for prize tuna or marlin, but for tropical fish small enough to fit on an angler's fingertip. Luckily, the fishermen here are seeking neither trophies nor dinner.

From July to late October, the Gulf Stream carries these young, dime-size reef dwellers from tropical waters near the Florida Keys and the western Bahamas, and abandons them along the coastline of Long Island. In ichthyologists' lingo, they are known as orphans, strays, expatriates. For an increasing number of aquariums, they are also the catch of the day.

Taking a cue from deep-sea fishermen who track Atlantic Ocean currents, aquariums in the Northeast have recently started to collect more - and more kinds - of the tropical fish in nearby waters.

Catching the fish up north is cheaper and less disruptive to ocean ecosystems than trapping them in the tropics. And the collections are rescue missions of a sort, because these Gulf Stream travelers are unlikely to survive the winter.

It is possible the practice is increasing because there are more fish.

"It's gathered a lot more steam," said Joseph Yaiullo, curator of Atlantis Marine World in Riverhead, New York, which, along with the New England Aquarium in Boston and the Mystic Aquarium in Connecticut, has been catching fish abandoned by the Gulf Stream to some extent for decades. Recently the aquariums have started to collect them in greater numbers, representing a bigger portion of the fish they put on display.

The fish are more abundant, said Don Harrington, curator for fish and invertebrates at Mystic Aquarium. "Before the last 10 years we would have never seen so many animals coming up in the Gulf Stream."

Scientists do not know why the fish numbers seem to have increased.

But some species that are vulnerable to cold shock, like the Atlantic croaker, appear to be expanding their range and ability to survive in the Northeast because of climate change, said Kenneth Able, director of the Institute of Marine and Coastal Sciences at Rutgers University in New Jersey.

"We think it's correlated with the generally warmer temperatures we are experiencing," Able said. "Some species may be moving further north because we are having milder winters. Secondly, more fish may be surviving further north because winter temperatures are warmer."

What scientists do know is that each summer the Gulf Stream carries millions of larval and newborn tropical fish bred in warm Caribbean waters and deposits them sporadically in rocky coves and eelgrass beds off the Northeast coast.

The Gulf Stream travels like a meandering river, pulling ocean water from the Gulf of Mexico along the Eastern Seaboard and toward Britain. As it snakes through the Atlantic, whirlpools of warm water the size of multiple city blocks spin off from the current's northern front and sweep toward the shore, taking tropical fish with them.

"It's essentially like carrying a bucket of water from Florida to New York, with everything that's in it," Yaiullo said. The Gulf Stream can travel up to 3.5 miles per hour, or 5.6 kilometers per hour, transporting water at a rate that is about 2,000 times the flow of the Mississippi River. Young, pelagic fish and fish eggs caught up in it cannot escape.

Long Island, with its arm that juts into the Atlantic, catches the fish on its south shore. Aquariums as far south as Baltimore travel here to replenish their exhibits.

Biologists collect Gulf Stream orphans in two ways: sweeping up fish by dragging nets along the shore or scuba diving with small hand-held nets to catch darting angel fish in the crevices of rocks and jetties.

Todd Gardner, a biologist at Atlantis Marine World, has been snatching up stranded fish here since he was 6, when his father told him they could not afford the tropical fish at the local pet store. He did not envision that he would one day catch them in the thousands for aquarium exhibits.

On a recent weekday, Gardner waded waist-deep into Shinnecock Bay with his team, dragging a 50-foot-long, or 15-meter, seine along the shore at low tide to gather the young spotfin butterflyfish and amber jacks that signal the start of the Gulf Stream season.

"In September, it's not uncommon for us to get a hundred or more butterflyfish in one haul of the seine net," Gardner said. "Some days, I go out and it's like I'm in the Caribbean."

During the season last year, Atlantis Marine World gathered around 2,500 fish - about 25 species - some for the aquarium's exhibits and others to give to zoos and aquariums around the country.

Catching tropical fish in the North has certain benefits.

"These are zero-impact collections," said Brian Nelson, senior aquarist at the New England Aquarium. "These animals aren't going to make it through their first year. If we go to the Bahamas, we've got to spread our collecting efforts out to not impact the breeding sites."

Gulf Stream fish are not likely to survive long in northern waters, said Ken Lindeman, a marine biologist at the Florida Institute of Technology, not only because of the colder water but also because they have not adapted to the region's habitats. The dark brown and green algae characteristic of these coastlines do not camouflage tropical fish like vibrantly colored coral reefs do.

"They're gaudy and they're obvious," said Nelson, so if they do not die from the cold, they will be easy prey.

The practice also makes it easier for aquariums to find species that are elusive or hard to trap when they are adults. For example, aquariums without Gulf Stream fish rarely exhibit the snowy grouper - a puffy, brown fish with white speckles - or the blue spotted coronet fish, a long-nosed creature resembling an eel that grows up to eight feet long and as thick as a wrist.

As "juveniles," tropical fish adjust better to life in an aquarium, Yaiullo said. "Kids adapt to new environments a lot better than adults. Fish are the same way, when they're young they feed better and get along with the other fish in the tank better."

Still, many young tropical fish captured up north do not survive. The New England Aquarium estimates that almost 40 percent of the butterflyfish they collected last year died because of parasite or bacterial infections, or because they were inadvertently damaged by divers during their capture. Nelson, a self-described "coral reef geek," is experimenting with medicines to treat fish infections to improve their odds for survival.

Originally published by The New York Times Media Group.

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