Changes in Species Distribution

Sea Surface Temperature and Species Migration

Gulf of Maine sea surface temperature, which includes Salem Sound, has increased faster than 99% of the world’s oceans. Human impacts to the marine environment, such as warming oceans and sea level rise, have created new challenges for both marine and terrestrial organisms to overcome. Species are forced to either quickly adapt to changing environmental conditions or relocate to more optimal areas. In fact, 80% of marine organisms are migrating to new locations or changing their typical behavior due to warming ocean water. Many native fish are heading north to find cooler water, while other marine species are becoming more frequent visitors in North Atlantic waters due to rising ocean temperatures.

The colors on this map depict how the world’s sea surface temperatures have changed from the long-term 1985-1993 average. Dark red indicates significant warming, while dark blue indicates significant cooling.

The increase in the dark red bars indicates larger and more frequent warm anomalies in recent years. The frequency and duration of Marine Heatwave events (black lines) have become more pronounced in the past decade. Since 2012, the Gulf of Maine has experienced far more persistent marine heatwave conditions than at any other time between 1982-2022.

“Ocean species are migrating in response to a changing climate 10 times faster than land species.”

NEEF

Local Species' Response to Climate Change

Atlantic Cod

Atlantic cod fishery has been closely managed to rebuild its stock after it was decimated by decades of overfishing. Now, a warming ocean is threatening cod, a cold-water fish. A rapidly warming Gulf means their range is shifting towards cooler water, either heading north or to deeper waters offshore.

Rainbow Smelt

Rainbow smelt spawn upstream in some of the Salem Sound tidal rivers, North River and Sawmill Brook. SSCW with the MA Division of Marine Fisheries have made a substantial effort to improve their spawning habitat and increase the smelt population.

After decades of “restocking” fish, cleaning polluted rivers, and removing tide gates, rainbow smelt are facing a new challenge exacerbated by climate change. As a cold-water species, rainbow smelt are moving northward towards cooler waters.

Explore the actions Salem Sound Coastwatch has taken to improve the habitat for rainbow smelt!

American Lobster

American lobsters have been following a similar path, as warming water impacts their reproduction and increases their vulnerability to disease. In 2020, New York and Southern New England reported record low lobster stock abundance, while the Gulf of Maine and Georges Bank reported record high catches!

This animation tracks the change in American lobster catches from 1967-2014, with dark purple representing the highest catches. Lobsters have been moving steadily northward, following colder waters

New species are becoming established in the Gulf of Maine as the water warms.

Fiddler Crabs

Fiddler crabs have also historically lived south of Cape Cod, but now their range has extended to Massachusetts and New Hampshire. Fiddler crabs build extensive burrows in the marsh. How this burrowing will affect the marshes and their ability to store carbon is unknown.

Blue Crabs

Blue crabs have made their way into the Gulf of Maine following warming waters. A commercially important species in Louisiana, Maryland, Virginia, and North Carolina, ongoing research is exploring how the arrival of blue crabs, an aggressive predator, will impact the Gulf’s ecology and its commercial fisheries.

Black Sea Bass

Black sea bass are becoming increasingly common, as their range has extended north to include the Gulf of Maine. Since black sea bass eat small crustaceans, such as juvenile lobsters, it is unclear how their increasing abundance will impact Massachusetts’ dwindling lobster fishery.