Sustaining a thriving lobster fishery through science and community.
The Casco Bay Bulletin
"Improving and protecting the health of Casco Bay"
Searching for Lobster Nursery Grounds
Who doesn't love a mystery? Our volunteers may soon be doing some sleuthing to help solve a long-standing enigma: Where do baby lobsters live?
Only within the last decade have scientists reported finding the smallest bottom-dwelling lobsters in sheltered habitats such as cobble bottom, eelgrass beds, and mud burrows. No one ever expected to find these inch-long crustaceans in the rough and tumble environment of rocky tidepools where pounding waves and drying sun deter all but the hardiest marine organisms.
Dr. Diane Cowan, the founder of The Lobster Conservancy, was the first scientist to document that newly-settled baby lobsters also live under loose rocks just above the low tide mark along the rocky shore. A long-term study of one cove on Orr's Island that she began eight years ago has now grown into a comprehensive program of 43 volunteers monitoring lobster nursery grounds at 25 intertidal sites in Maine and New Hampshire.
Lobster Conservancy volunteers record the size, sex, molt stage, and incidence of injury to any resident lobsters they find and describe the bottom type and any other animals and plants in the study area. Diane believes FOCB's skilled Citizen Stewards could be a great help in discovering and monitoring critical lobster nursery habitats in other parts of Casco Bay.
Diane Cowan has had a lifelong passion for the little critters ever since she researched lobsters for a science report in the seventh grade. She discovered that lobsters monitor their environment primarily through their senses of smell and taste, making them extremely sensitiveand vulnerableto pollutants like oil spills. In her junior high paper she predicted the demise of many lobsters as a result of a catastrophic spill. Her interest in lobsters and their chemical sensibility eventually earned her a doctorate in the Boston University Marine Program at Woods Hole.
After completing her graduate studies, she returned to Maine searching for a suitable place to continue her crustacean research. She visited Lowell's Cove at the end of Orr's Island in Harpswell, and with the help of some neighborhood kids, discovered dozens of tiny lobsters hiding under the rocks.
The Perfect Home
Diane is now in her eighth year of data collecting at Lowell's Cove. Although now a Marine Policy Fellow at Woods Hole Oceanographic Institution in Massachusetts, Diane returns to her study site several days each month to continue her sampling. She hunts for lobsters under rocks along a 20-meter line spread over the rocks. Like her volunteers, she counts and measures baby lobsters. In eight years of monitoring, Diane has only missed one month's data, December, 1994, when storm after storm kept the cove submerged all month.
Diane tags any baby lobsters longer than about 1.5 inches. Using a modified hypodermic needle, she inserts a coded wire tag the size of a pepper flake between the pinchers of one of the baby lobster's walking legs. Scientists in England demonstrated that this type of tag persists in lobsters into adulthood, whereas most other kinds of tags are lost after one or two molts.
Each month she checks for lobsters she had tagged previously. A lobster outfitted with one of her magnetic tags elicits a loud beep from a portable metal detector that Diane brings into the field with her. She then removes the leg, extracts the tag, and scrutinizes it under a microscope in order to decipher the bar code imprinted on it. After tagg1ng more than 9,000 lobsters since 1994 (an impressive sample size for any species!), Diane has decided to stop tagging and concentrate on documenting returns to Lowell's Cove.
Implications for the Future
Besides, who can resist the appeal of a tiny lobster the length of your thumb? By helping to identify and protect their first hiding places, we can help ensure that Maine's most popular crustaceans grow to take their place in the ecosystem, in their breeding population, and in Maine's coastal economy.