The New England Lobster Settlement Index

Life History of Homarus americanus

The American lobster has a complex life history which includes a planktonic larval phase and a large-bodied benthic phase. Larval and post-larval lobsters can drift in the water column for a couple of months before settling on the bottom. Once they do settle, they find shelter in beds of cobbles and boulders until they are large enough to defend themselves.

Click to see a summary of the lifecycle of a lobster. To learn more about the life history of the lobster, play Bigelow's interactive game, Hatch to Catch.

Figure 1: A young-of-year lobster - now no bigger than a fingertip - it will feed on detritus and small invertebrates, and may eventually attain a carapace length of 150mm or more. Photo credit: J.S. Cobb

Figure 2: Divers using the suction sampler to survey recent settlers.

Research

Divers from Bigelow Laboratory employ a suction sampler to collect newly-settled lobsters (Fig. 2). Cryptic in behavior at this stage, juvenile lobsters prefer to settle in shelter-providing cobble-boulder habitats.

The suction samples are sorted in the laboratory for young -of-year lobsters, about an inch (2.5cm) in total length. In their first year, lobsters grow slightly larger in the southern part of their range than in the colder waters to the north. Thus, it takes lobsters in Rhode Island 4-5 years to reach harvestable size, whereas it can take up to 9 years for lobsters in the colder Gulf of Maine.

Figure 3: Sketch of a lobster. Size bar measures 1cm.

Figure 4: Sampling sites for New England Lobster Settlement Index

New England Lobster Settlement Index

The New England lobster settlement index is a sampling program supported by Maine, Rhode Island, and Massachusetts. The goal of the program is to evaluate the strength of lobster year classes as they first arrive by larval settlement in shallow, nearshore nurseries.  The information obtained from the research can then be used in stock assessment, and in forecasting trends in the fishery.

The map to the left (Fig. 4) illustrates the sampling sites for the settlement index. The boxes surround sites that were used to calculate regional averages.

To view the latest developments in PDF format, choose an update below.

Update 2001

Update 2002

Update 2003

Update 2004

Update 2005

Update 2006

Update 2007

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