According to a preliminary report released by Bob Steneck, marine ecologist at the University of Maine and project director of the recently completed R/V Argo Maine research cruise, lobsters are generally abundant throughout the Gulf of Maine. However, he points out that the number of lobsters in each habitat is affected by how many shelter spaces are available.

The study covered five sites from Head Harbor, Maine in the northern part of the Gulf to Nahant, Massachusetts in the south. Researchers studied lobsters living in shallow coastal sites in 10 to 40 feet of water, within about five miles of shore. They found that, to a large extent, the geological characteristics of the area determine how many lobsters can live there.

Bob Steneck and graduate student Rick Wahle found that the number and sizes of shelter spaces controlled the number and sizes of lobsters. However, even when very large shelters were available, large (reproductive size) lobsters were relatively rare in shallow coastal areas. Small rocks or cobbles contained "baby" lobsters (1 to 4 years old, called Early Benthic Phase or EBP) while larger rocks or boulders contained significantly larger lobsters (about 5 to 10 years old). If kelp was very abundant in an area, lobsters used it for shelter. Most lobsters were found in cobble, then boulders, and there were very few lobsters in sediment and ledge habitats.

One of the most interesting results of the study was that outer cold water habitats north of Penobscot Bay (in the Head Harbor and Swan's Island/ Mt. Desert region) generally had no EBP lobsters (less than 1-1/2" carapace length). The sites closer to shore where the water is warmer did have some of these "baby" lobsters. South of Penobscot Bay, EBP lobsters were found but only in cobbles. In addition, the highest overall density of lobsters was found in cobble habitats where EBP lobsters were present, with an equivalent density of 14,000 lobsters per acre.

Researchers found that as they went from the northern Gulf to the southern Gulf, lobsters living in boulder habitats were smaller and there were more of them. Although there were more lobsters in cobbles and boulders in the southern Gulf of Maine (Nahant), these habitats appeared to be limited. Dan Belknap, a geologist at the University of Maine, will help answer this question through a detailed analysis of side scan sonar records. In addition, reproductive-size lobsters were found to be very large in the north and relatively small in the southern region - a concept known to scientists for a long time.

Lew Incze of the Bigelow Lab found lobster larvae at all locations, even those where EBP lobsters were not found on the bottom. Further studies need to be conducted to determine why this is true.

Another interesting observation was that lobsters appear to lose their ability to live in high densities when they get larger. Researchers discovered that in sites and locations where lobsters were most abundant, they tended to be small. Where there were fewer lobsters, they were generally larger. Long-term experimental data, as well as underwater video footage, suggest that the aggressive nature of larger lobsters may be responsible for this pattern.