Lobster Study Comes East

High-tech Monitoring tracks Movement

By Aaron Porter

STONINGTON — Lobster biologist Diane Cowan will meet with local lobstermen next week to rouse support for community-based research she has led in Muscongus Bay and is proposing for East Penobscot Bay.

Lobsters have been the one bright spot for Maine fisheries in recent years. Their contribution to the state’s coastal economy is undisputed, bringing as much as $211 million in 2002. The financial boom is the result of record-breaking catches in Maine, coupled with faltering catches elsewhere in New England, and indications that the state’s lobster population remains strong.

It’s obvious that more lobsters and steady prices are keeping the industry hardy. What’s keeping the state’s healthy supply of crustaceans on the sea floor is less than obvious, however.

That’s where Cowan and her research come in.

Cowan, founder and president of the Friendship-based Lobster Conservancy, has been working to protect the American lobster and the fishery it supports.
To do that she’s trying to understand details of their behavior, environmental needs and reproductive habits. Working with lobstermen and other researchers in Muscongus Bay, Cowan recently completed a study that tagged 191 egg-bearing female lobsters with acoustic transmitters and temperature loggers. In autumn, the lobsters were fitted with the research gear when eggs appeared on the underside of their tails.

A team of 15 lobstermen was paid to keep track of individual lobsters, using hydrophones and their working knowledge of places lobsters frequent.

Divers were used to check on specific lobsters and to retrieve any transmitters and temperature recorders that were shed and left on the bottom.
In brief, Cowan said, observations show the larger female lobsters traveled out into deeper water as winter weather dropped the temperature in the shallows. She said the larger females traveled as far as 140 miles and generally stayed in water at 40 degrees Fahrenheit or more.

The smaller females tended to stay in shallower water, not moving far from where they originally were returned to the bay when fitted with their transmitters. Cowan said one lobster stayed in 20 feet of water through the winter in sustained temperatures of 29 degrees Fahrenheit.

The differences in temperature and mobility during the lobsters’ nine- to 13-month egg-carrying period don’t seem to have had an effect on whether eggs hatch.

Cowan said the results indicate it might be important for the health of the Maine lobster stock to have female lobsters of all sizes — the smaller ones staying local and the larger ones spreading genetic diversity in lobster populations up and down the coast.

However, Cowan is quick to point out the study’s limitations. “It’s almost like a pilot project,” she said.

Similar studies have to be repeated along the coast to see whether the Muscongus Bay results repeat elsewhere. But repeating the effort along the coast isn’t a matter of simple replication. Cowan’s research relied heavily on local lobstermen to work with her to monitor transmitters and return to her any data loggers they caught. She said local lobstermen also have a very specialized and precise knowledge of the bottom conditions where they fish, allowing them to predict roughly in what direction lobsters will head.

“There’s something valuable about knowing something so intimately,” she said.

Cowan said she’s looking to Stonington as a base for a similar study, which is why she is holding the meeting.

The Penobscot East Resource Center would coordinate the study of East Penobscot Bay, she said.

“One problem is making sure there’s someone there who’s really dedicated to it, and taking the data,” she said.

Cowan’s trip to Stonington is intended as a chance to explain the study to area lobstermen.

In Mucongus Bay, the effort involved about 80 fishermen contributing in some capacity, with about 15 paid individuals serving as the core of the effort.

She said the funding to pay for the research would likely be secured for fall 2006. That allows some time for planning.

She said her presentation in Stonington will be held Jan. 5 at the Penobscot East Resource Center Office starting at 10:30 a.m. In the event of poor weather, the presentation will be postponed until the same time Jan. 6.

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