LI researchers aim to boost sea horse population

Looking for a sea horse off Long Island is like trying to find a needle in an aquatic haystack.

It wasn't always that hard. Sea horses were commonly found in fishing nets and spotted in shallow waters. But their preferred habitat, a form of sea vegetation called eelgrass, was decimated by a pathogen called "wasting disease" in the 1930s, then poisoned by runoff from shoreline development before brown tides smothered much of the surviving beds in the 1980s.

Now researchers at a Cornell Cooperative Extension lab in Southold are trying to turn things around by unlocking some of the mystery surrounding the species known as Hippocampus erectus - or the "lined sea horse" because of their distinctive markings - and breeding them in captivity with an eye to placing them in local waterways to jump-start the natural population.

No systematic count of sea horses, which are a food source for crabs and larger fin fish, has ever been attempted.

Rare and elusive

"They're very rare and they're very elusive," said Kim Petersen Manzo, a Cornell eelgrass and sea horse expert. "We only see a few every year. They're very habitat-dependent and the estimate is that less than 10 percent of the eelgrass is left from what was here in the 1930s."

Despite their rarity, Manzo said "three years ago we started seeing sea horses in the eelgrass we were monitoring. Out of curiosity, we brought a few back to keep at the lab for the public to see and they just started breeding - like crazy."

She began taking the babies out of the large tank away from the adults and placing them in smaller tanks to see if they could survive. "Sea horses are notoriously difficult to raise in captivity," she said, adding survival rates can fluctuate widely.

At the moment, she has three tanks going in the laboratory at Cedar Beach. One is for breeding adults, including Manzo's biggest success story so far, a female bred 14 months ago in the lab that has grown to about 5 inches long. The others contain babies.

Manzo, who hopes to obtain a grant to pay for a sea horse population survey of East End waters, eventually would like to breed enough sea horses to release some into local waters. "The ultimate goal is to raise them to a size where they would be less vulnerable to predation and bring them back out into the wild . . .," she said.

Manzo regularly seeks advice from Todd Gardner, a biologist at Atlantis Marine World aquarium in Riverhead, which captures sea horses in Shinnecock Bay for display and breeding for their exhibits. Gardner said the aquarium has had up to an 85 percent survival rate in its breeding, with some sea horses surviving more than two years.

Possible ethical qualms

Manzo and Gardner have discussed introducing lab-bred sea horses into East End waters, but acknowledge much research and discussion would be required. Some marine biologists have scientific and ethical qualms with the concept, questioning the propriety of increasing the survival rate, affecting the natural selection of the fittest offspring. And there are concerns about introducing harmful bacteria or diseases.

To avoid contamination, Manzo said, "we'll want to keep everything as natural as possible," particularly the food.

Manzo said she improved the survival rate by switching from processed feed to natural food. That requires gathering plankton and other nutrients daily from a nearby creek and changing tank water frequently.

"It's really like a full-time job," Manzo said. But she doesn't mind coming in on weekends to feed the sea horses because "they're almost a mystical creature."