The Connecticut Department of Energy and Environmental Protection (DEEP) is undertaking a study seeking reasons for the widespread deaths of lobsters in Long Island Sound. The state will look into whether pesticides are to blame.
"We are now developing the procedures and protocols for a study that will rely on a Sound-wide 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," said DEEP Commissioner Daniel C. Esty.
Esty said the study will include the possible role played by pesticides in the mortality of lobsters, given attention this issue has received from lobstermen and others, the availability of more sophisticated and sensitive test technology, and the results of preliminary tests conducted by DEEP and UConn on lobsters taken from Long Island Sound this fall.
Declining Population
Lobster landings in Long Island Sound have declined from 3.7 million pounds in 1998 to just 142,000 pounds in 2011.
Between 1984 and 1998 state lobster landings averaged 2.3 million pounds. Lobster abundance and landings in the Sound have declined steadily, to present record low levels, since that time.
The central and western Sound, where landings have fallen by 99 percent since 1998, has seen the greatest decline.
Failed 2012 Legislation
During the 2012 session of the General Assembly legislation was introduced, and approved by the House of Representatives substitute House Bill 5260), to restrict the use of the pesticide methoprene, a larvicide used to combat mosquitoes, in coastal areas. This legislation did not come to a vote in the state Senate.
Preliminary Study
Working with the University of Connecticut’s Veterinary Medical Diagnostics Laboratory, DEEP staff conducted tests on lobsters taken from the catch of a lobsterman in an area in the middle of the Sound, south of Norwalk, in September, 2011. Nine weak lobsters and one that appeared healthy were taken to the lab for necropsies, which involved macrosopic and microscopic examination of tissues. The collections and laboratory examinations were undertaken in response to fishermen reports of dead and weak lobsters in the western basin on the Sound last fall.
Although thermal stress associated with warm fall water temperatures in Long Island Sound is often viewed as the fundamental cause of lobster mortality, DEEP staff took samples and arranged for tests in order to determine whether the mortalities could be attributed directly to excessive temperatures or potentially due to bacterial or parasitic infection capitalizing on the stressed condition of the lobsters.
The final necropsy results provided no evidence of a consistent pattern of tissue injury that would explain the mortalities.
DEEP Marine Fisheries staff also asked the UConn lab to test lobster tissues for the presence of pesticides, in order to take advantage of technological advances that now allow for detection of compounds in concentrations as low as 1.5 parts per billion, or one tenth the former detectable concentrations.
The lobster tissues (tomalley or liver and reproductive organs) were tested for the presence of three mosquito control agents: malathion, methoprene, and resmethrin. The tests showed some lobsters collected in the mid-Sound waters were exposed to resmethrin and at least one was exposed to methoprene.
Given the preliminary nature of these tests and the small sample size, it is not yet clear what the presence of the pesticides in the lobster tissue means to the relative health of the lobster population.
Background on the Pesticides
Resmethrin and malathion are used to control mosquitoes through fogging. Very small amounts of these products were used in Connecticut for mosquito control in 2011. In addition, malathion can be applied to landscapes as a pesticide. Resmethrin is also applied on interior sites as a general pesticide.
Methoprene is an insect growth regulator that prevents insect pupa from maturing into the adult stage. It is used to control mosquito larvae in stagnant water and is also used in homes and on pets to control fleas. The three pesticides decay rapidly in nature and are not expected to accumulate in the environment, which made their presence in lobster tissue an issue meriting further study
When it comes to human health and safety, the detection of pesticides in the organs from a small number of lobster samples does not warrant a change in consumption advisories now in place – which remind consumers that tomalley can be high in contaminants and should not be eaten.
Next Steps
Ongoing lobster resource abundance and fishery monitoring will continue to be important components of the agency’s lobster population monitoring efforts along with the year-round Long Island Sound water temperature monitoring the agency has conducted for more than 20 years.
Moving forward, a comprehensive Sound-wide lobster health assessment program will be designed and implemented. While plans for the study are still being finalized, DEEP expects to:
- Begin taking individual lobsters from the Sound for health assessment this summer
- Start lab tests in July
- Have results available for analysis beginning in the fall
“The study planned by DEEP will fill in major gaps in our understanding of the decline of the lobster population in Long Island Sound,” said Esty. “There has not been a thorough study conducted with the type of sophisticated laboratory tools now available to us.”
