Lobster traps
Researchers say recipe for disaster led to die-off
By Gwendolen Groocock

A lethal cocktail of warm water, low oxygen levels, disease and chemicals, including pesticides, killed the Long Island Sound lobsters in 1999.

After four years of research costing millions of dollars, that's the big picture from New York and Connecticut scientists who presented their findings to about 200 people at a final symposium on the subject at SUNY/ Stony Brook on Monday.

"It was a combo of all the bad things that could happen in one year," said Mattituck lobsterman Jim King, who attended the daylong meeting. "It turns out there were smaller die-offs in the western Sound in the years before, so the warning signs were there. But it took a disaster to get our attention."

Scientists also said that the numbers of larval and adult female lobsters in the Sound remain at the lowest levels in 20 years, not a good sign for the future. And, they said, the combination of events that triggered the mass death is likely to occur again.

After the sudden die-off, many lobstermen pointed to the widespread spraying of mosquito-control chemicals triggered by the outbreak of the West Nile virus in 1999. A $3.75 million preliminary settlement has been reached and is awaiting a judge's approval in a class-action lawsuit brought by 110 lobster harvesters on both sides of the Sound against pesticide manufacturers; initially $125 million was sought.

As arthropods, lobsters are closely related to insects and have been described as "big bugs." Scientists ruled out the idea that pesticide poisoning was primarily to blame for the deaths, but in light of new findings about the crustaceans' high sensitivity to the chemicals, they agreed it was a likely factor.

"They concede the possibility that pesticides might be involved, but I think they're downplaying it," said Mr. King.

One pesticide, resmethrin, initially thought to be less harmful, was found to have a lethal effect on lobsters in very low concentrations. It's likely that enough resmethrin to kill lobster larvae and harm the immune systems of adult lobsters was in the waters of the Sound, researchers concluded.

"The short story is that it was in concentrations close to the range that could be toxic," said Sylvain DeGuise, associate professor of pathobiology and veterinary science at the University of Connecticut. "As they were stressed by high temperatures and low oxygen, could they have been more susceptible? We don't know that without further studies."

Researchers found that another pesticide, malathion, was also within the range of concentration that could affect lobsters. A third, methoprene, was found to be a thousandfold below the range.

The Sound is at the southernmost edge of the lobsters' territory, and researchers said a major factor in the die-off was higher-than-normal summer water temperatures prior to, and including, 1999. That summer, a large area of the western Sound also became oxygen-deficient, and, stressed, some lobsters succumbed to two types of disease, the researchers said.

Not studied was the effect of intensive fishing on the lobster population.

"Nobody wants to come out and say it, but that fishery was terribly overexploited," said Mr. King. "If you're removing adults and leaving just a population of juveniles, it's not natural."

The hypothesis that a combination of factors is to blame -- what one scientist called a "perfect storm" -- isn't the final word in unraveling the mystery of the lobster deaths.

"It's definitely a good start, but certainly there are further tests that need to be done," said Dr. DeGuise. "It raised probably as many questions as it answers, but that's the way in science."

Meanwhile, Mr. King has taken in his lobster pots for the season. It was a disappointing summer, he said.

"We saw a little sign of life in the spring -- strong lobsters, nice and healthy -- but that was it," he said. "The rest of the summer, it was real slow."