Blue Crabs Now Migrating to Maine From Chesapeake Bay

The Gulf of Maine continues to warm at the fastest rate of any body of water in the world in the last five years

Blue crabs are now in Maine. 

This means they are no longer exclusive to Chesapeake Bay.  The Gulf of Maine continues to warm at the fastest rate of any body of water in the world in the last five years.  And this could be a reason why the crabs are expanding their migration pattern northward. 

In one year scientists found one dead crab in the marsh, “to seven live blue crabs in a marsh pool.  So that was definitely really surprising.  And we decided we really need to start investigating this,” said Laura Crane, a researcher at the Wells National Estuarine Research Reserve in Wells Maine.

Crane is helping to track these crustaceans, alongside Jason Goldstein and other researchers, scientists, and volunteers from the community.  They periodically check crab traps and are starting to document the crab movements. 

"Blue crabs are typically seen south of us, but as far north as Massachusetts. And now we're seeing them sort of infiltrate coastal waters of Maine, possibly due to temperature changes. So they're shifting where they typically are, and we call that a range expansion. And so with that expansion comes the presence of these blue crab. In our marsh, in our estuaries, in our bays, and in our Gulf of Maine,” Goldstein said.

Blue crabs are a warm water species so it is surprising that they are in such a historically cold body of water.  And especially where lobster is king.  We may see more blue crabs and other species move in the water warms. 

”The Gulf of Maine could potentially stay a hospitable environment for them to live, and they could potentially set up long-term populations by doing these the long-term monitoring,” Goldstein explained.

This isn’t the first time the crabs have been observed here.

“But what we're seeing now is a little different because we're catching blue crabs in the same areas year after year. So what we want to know is, is this a permanent population now that, you know, are they able to survive Maine winters and set up permanent populations in the Gulf of Maine?” Crane said.

The researchers track the air temperature, water temperature, changes in weather, salinity, and more.

So we compare all this data together and see what was the water temperature when the blue crab moved from this place to that place or when all of a sudden we weren't catching as many blue crabs? Did the water temperatures get colder?" Crane said. “So this is all data that we're looking forward to analyzing this winter and being able to pull all these pieces together to understand where blue crabs go, when and why and where.”

The research is early, but there could be both a positive and negative impact from the Blue crabs showing up in Maine. 

They could be a resource, a fishery resource that has instant marketability. As we know, blue crabs are very popular in other areas of the country, like the mid-Atlantic states, coastal areas. On the negative side of things and again, we're not sure how this is going to all flesh out, but blue crabs may actually be formidable predators on some of our most prized, you know, marine organisms such as lobster,” said Goldstein.

Everyone is encouraged to get involved, from local beachgoers to local fisherman.

“We've been trying to get local fishermen involved, actually, and in trying to understand where these blue crabs are located. So fishermen, for example, and other harvesters are pulling traps up, you know, off the coastal ocean. We don't have the capacity to go out and monitor out of the ocean,” said Crane.

And as you’re on a beautiful morning beach stroll, keep an eye out for any creatures out of the ordinary. 

Take a picture of it. Document it. Call. Call us. There's other places you can report that's now online. And so that's really important to have this database and this knowledge base so we can understand better how that distribution is changing,” said Goldstein.

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