Do fish farms attrack sharks?

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Posted by on April 11, 2005 at 10:42:13:

Increased shark activity prompts a study to assess risk

There are at least 40 different species of sharks swimming in Hawaii's waters.

Most people never see them, but Leeward Oahu residents say they have seen more of the large, toothy predators hanging around since a fish farm growing moi took up residence about two miles offshore at Ewa Beach almost six years ago.

William Aila, a resident and fisherman, said residents are concerned that more aquaculture businesses could attract more sharks to their coast.

Since companies have approached the Waianae community during the last year with plans for new aquaculture farms off their coast, residents want to find out if they should be concerned, he said.

"We know that any structure attracts predators. ... I want to know where do the predators go once they are attracted to this area," Aila said.

On Friday, state lawmakers approved a state-funded study of sharks off Oahu's Leeward Coast to learn if the fish farm is bringing the much-maligned creatures closer to shore.

Conducting such a study might not be such a bad idea, since similar farms are being considered for other parts of the islands, bringing the potential of more jobs and investment in Hawaii, Aila said.

Another deep-sea fish farm just opened last month a half-mile off Keahole Point on the Big Island's Kona Coast.

Offshore fish farming, where submerged pens containing thousands of fish are tended by scuba divers, is limited commercially to waters within state jurisdiction, where permits have been easier to get. But in December, President Bush proposed making it easier to put fish farms off the nation's coasts.

Sharks have been spotted around the Ewa Beach farm's four pens, which are each about the size of a small house and anchored in 150 feet of water.

But the sharks have never caused trouble for workers at the facility, are seen only occasionally and are exclusively of a species not known to be aggressive to humans -- the sandbar shark, said Randy Cates, owner of the company that runs the cages, Cates International Inc.

Any Hawaii lifeguard will tell you that there are about 40 varieties of sharks swimming about the islands, ranging from the inches-long pygmy shark to the resident bad guy -- the tiger shark -- held responsible for most violent, sometimes fatal local shark encounters with humans.

Cates said the presence of sharks around his fish cages should not be surprising. The cages function as an artificial reef and create a reef ecosystem, which naturally includes the predators.

"Will they attract sharks? Yes, they will, but so will everything else that you put in the ocean that's an artificial reef," said Cates, who noted that he would assist the state on any study.

The managers of the nation's two other longtime deep-sea fish farms, one in New Hampshire and another in Puerto Rico, have also reported sharks among the marine species attracted to their cages, said Kate Naughten, outreach coordinator for the U.S. National Oceanic and Atmospheric Administration's aquaculture program.

Neither has reported any negative encounters with the fish, she said.

The jury is still out as to whether artificial reefs just bring together species that are in the area anyway, said Randy Honebrink, spokesman for the state Shark Task Force.

"Obviously if the cage wasn't there, the sharks wouldn't be milling about in that area," Honebrink said.

But if the sharks are sandbar sharks, there is no evidence to indicate there is any public safety issue at stake, he said.

"In order to do an experiment, you have to have the right question, and we're not there yet," he said.

The $25,000 cost of the study mentioned in previous versions of the bill would not go very far, said Kim Holland, a researcher at the Hawaii Institute of Marine Biology, which would conduct the proposed shark study along with the state Department of Land and Natural Resources.

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