Scientists hope to get to the bottom of a seafood mystery: Why does the number of lobsters in Long Island Sound keep dropping?

The answers may come from a study being undertaken this month by the state Department of Energy and Environmental Protection, said DEEP Commissioner Daniel C. Esty.

The new study builds off earlier research and will focus on the impact of pesticides on the lobster population, he said.

The total lobster catch in the Sound has dropped from 3.7 million pounds in 1998 to 142,000 pounds last year, state data shows. The average annual catch was 2.3 million pounds between 1984 and 1998.

"We are now developing the procedures and protocols for a study that will rely on a Soundwide sampling of lobsters and sophisticated laboratory tests to obtain a better understanding of why this species -- and an industry it has historically supported -- is now in danger of collapse in Long Island Sound," Esty said.

Many lobstermen have complained to DEEP and state Department of Aquaculture officials at several public forums that the increased use of pesticides, including spraying to control mosquito larvae, has affected lobster shells.

The central and western Sound has seen the greatest decline in lobster abundance, according to DEEP data, a 99 percent drop since 1998.

Preliminary tests done last fall looked at the effect of warmer water temperatures on the lobster population, as well as bacterial or parasitic infection, but found no evidence of a consistent pattern of tissue injury that would explain the mortalities, said DEEP spokesman Dennis Schain.

"The study planned by DEEP will fill in major gaps in our understanding of the decline of the lobster population in Long Island Sound," Esty said. "There has not been a thorough study conducted with the type of sophisticated laboratory tools now available to us.

"Lobsters and lobster fishing in Long Island Sound are an important part of the history and cultural identity of shoreline communities in this state.

"We look forward to launching this study and sharing the results with everyone who has an interest in this critical issue, so we can consider any steps that might reasonably help rejuvenate our lobster population."