NORWALK, Conn. (AP) — Experts at a Connecticut aquarium are trying to figure out how crabs native to the Pacific Northwest ended up in the waters of Long Island Sound.

The Hour (http://bit.ly/2tkD98Z ) newspaper reports that oyster fishermen hauled up four unusual crabs off the coast of Norwalk last week, threw three back, but brought one to the Maritime Aquarium in the city.

Aquarium experts identified the 2 1/2 -pound crustacean as a male Dungeness crab.

Senior aquarist Sandi Schaefer-Padgett said the discovery is "not normal" and scientists are now trying to figure out how they ended up off Connecticut's coast. She says it's most likely someone purchased them and then released them.

State marine officials are monitoring the situation, and telling fishermen to contact authorities if they catch one.

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Information from: The Hour, http://www.thehour.com