Lobster Larvae Resilience Informs Fishery's Future

Like all crustaceans, lobsters begin as plankton – tiny organisms that drift in the water column. The select few that reach adulthood achieve status as cultural icons and economic giants, particularly in the state of Maine. Lobsters are the single most valuable fishery species in the United States, and earned fisherman more than $430 million in Maine alone during 2017. They are also facing serious threats from global climate change.

To learn more about the future of Maine’s signature seafood, Senior Research Scientist David Fields is studying several crustaceans in their planktonic stages to learn how climate change effects like ocean acidification and rising temperatures will shape their future.

“We're finding interactive effects between acidification and warming that other people have missed by looking at them separately,” Fields said.

As Gulf of Maine waters continue to warm, Fields predicts that the American lobster will keep expanding its range northward, making the region’s dominant crustacean species transition from the American lobster to the invasive European green crab, which is far more tolerant of warm water.

“Lobster larvae are smaller, have higher breathing rates and die more readily at conditions predicted to occur in the future,” Fields said. “We think that green crabs will fare better than lobsters as the Gulf of Maine warms, and might even out-compete lobsters for resources like food and habitat.”

Another way to understand how lobster populations may change in the future is by looking at how they have adapted to the different locations in which they live. Fields’ team is conducting a comparative study of the current lobster populations from Rhode Island, midcoast Maine, and Down East Maine. As climate change has shifted important environmental variables like ocean acidity and temperature in these regions, lobster populations have adapted to survive changing conditions. Fields believes the southern lobster populations may be better suited to survive higher temperatures and acidity levels than those that live at more northern latitudes.

“As the ocean warms, the water conditions favorable to lobsters are steadily retreating up the coast,” Fields said. “We think that the current Rhode Island population gives us a way to look at the future of Maine’s Down East population, and the current Down East population is likely representative of a future Canadian population.”

Despite the challenges facing the fishery, new use of genetic tools may help scientists and managers better understand and prepare for these shifts. Fields hopes that monitoring for changes in the genes of Maine’s lobster populations may provide an early-warning system.

“When you're getting a cold, before you even have a runny nose, your genes indicate something is happening before it actually manifests,” Fields said. “These tools might be used as a canary in the coal mine, so that lobsterman and fishery managers can anticipate changes to lobster populations.”