Blue Crabs in the Gulf of Maine

Hey, all! So, a quick question for anyone going out to the shorelines (and particularly marshes and muddy places) of the Gulf of Maine (north of Cape Cod all the way up to the Bay of Fundy) - can you be on the lookout for Blue Crabs? I ask as, I’m a marine biologist working out of UMB (and use iNat in my classes) and was doing some casual marsh work the other day and lo and behold, one of these beautiful savory swimmers showed up in one of my traps along the Rowley River in Mass. - this is notable as they are starting to expand their range due to warming climate (see The Savory Swimmer Swims North - ) - and previously Cape Cod served as a barrier. They’ve been seen here since at least 2012 regularly, but only for folk who were REALLY looking for them, or in the occasional lobster trap. A reproductive female was found off of Nahant last year (can’t find the news article) which was HUGE as it means they’re not just moving up here in the summer warm months and then dying off, but rather that they are STAYING and thriving.

So, after seeing our guy yesterday (checked - it was a guy - I’m from Baltimore, so I know a wee bit about blue crabs as anyone from there should!), I looked on iNat, and aside from one shell in Wells from a molt, I didn’t see anything north of the Cape (well, except Nova Scotia - but that’s a whole different story about the Gulf Stream, and hence why I’m being specific to the Gulf of Maine only).

If any of you are going to the shore, throwing out crab traps for fun, fishing, or just poking around in muddy waters, please please please, try and look for these guys! It would be great to have iNat show us how far up they’ve come - and in future years see where they go!

Happy to talk more about this. See also and this great set of slides [pdf]


Thanks for sharing! I’m in the water a bunch in the north shore of MA and have yet to see one up here, though I don’t frequent many muddy spots. I’ve seen plenty in Rhode Island so I’m familiar with them in any case. I’ll keep an eye out and if I find any I’ll be sure to upload an observation.

Wow, interesting! As transplanted Marylander I’m really fascinated by this development and will keep an eye out for shed shells next time I’m at the Cape :-)
This shell was observed in October 2019 and is farther north! Perhaps a stray?

I will be on the bay side of the Cape in the fall, and will definitely keep my eyes out. This also reminds me that I have to send off a possible invasive snail shell to a researcher from my last trip. Oops. Is it wrong that I’m hungry now thinking about old bay seasoning and MD? (rhetorical :) )

Yup! That’s one of them! Not sure if they have been sighted there before! Super cool! Hopefully we will see more observations on iNaturalist soon!

To all mentioning old bay… YES. I’m a Bawlmer boy myself, so, it’s the one upside of climate change I see. Really looking forward to some steamed or soft shell blue crabs… but let’s see how far they’ve moved up! So curious!!!

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