Rising temperatures along the bottom of the Atlantic Ocean will force American lobsters farther offshore and into more northern waters, according to a new study led by researchers at the Woods Hole Oceanographic Institution (WHOI).
Climate models project that bottom temperatures in the Atlantic along the U.S. East Coast may rise by up to 4.3 °C by the end of the century.
“That’s a significant change, and lobsters are particularly sensitive to warming water temperatures,” says WHOI researcher Jennie Rheuban, lead author of the study. Higher temperatures can affect lobster egg hatching and larval survival, Rheuban says. Females carry their eggs with them, and when the eggs hatch is largely determined by the temperature history the eggs have experienced.
The northeast U.S. continental shelf, which is home to a highly productive and commercially important marine ecosystem, has experienced some of the highest sea surface temperature warming rates in the world in recent decades.
“We wanted to find out specifically what was happening at the bottom, so that we could identify potential impacts to ecologically and commercially important species living there,” says Rheuban. “We focused our analysis on the American lobster, but really the data could be used to look at impacts on other bottom-dwelling species, such as sea scallops.”
They analyzed 33 years of historical ocean temperature data from the Northwest Atlantic Ocean. They found bottom temperatures have increased throughout the region. The iconic crustaceans are currently found in waters from southern New England up to Canada, but regional warming is already causing a decline in lobster catch in southern New England.
The research team then coupled these historical data with future projections of ocean temperatures from climate models from Intergovernmental Panel on Climate Change (IPCC). Results showed that conditions in the southernmost range of the species will likely become less hospitable in the future for juveniles. The study also found that warming bottom temperatures may push lobsters farther offshore while the population will likely increase and expand northward in the Gulf of Maine.
Coastal environments act as a nursery habitat for both larvae and juveniles, providing them with a protective area that is food-rich and relatively safe from predators. “If adult females are forced into deeper water because the temperatures are more ideal, larvae may hatch outside of the nursery habitat and be less likely to survive,” says Rheuban. “Juveniles also may be forced into offshore waters that are less safe from predators.”
The American lobster fishery is a highly profitable fishery and grossed more than $600 million in revenue in 2016. It employs thousands of people in the region and leads to substantial regional economic benefits.