Populations of sea urchins have fluctuated off the coast of Maine over the last thirty to forty years. A rapid rise in sea urchin numbers was observed during the 1970 s and 80 s. Researchers believe this increase was due to overharvesting of fish and other marine animals who preyed on sea urchins. Our research has shown that wolffish, cod, and other large fish species, along with many seabirds, are important predators of urchins. Crabs and lobster are known to feed on smaller urchins closer to shore.
Researchers believe the current coastwide decline in urchin numbers is caused by overharvesting.
At least in some areas, disease may have added to this decline during the past year. Over twenty study sites off the Maine coast have reported diseased urchins. The cause of the disease is still under investigation. The next article in Cobscook Bay Soundings will explore how the rise and fall of sea urchin populations has changed the structure of subtidal communities. This column was prepared by Cheryl Daigle and Jim Dow.