BALTIMORE (AP) — It's a place nearly synonymous with its beloved regional delicacy: soft-shell blue crabs. For residents of Maryland, tucking into a crab cake or cracking into a bushel of steamed crustaceans along with a cold beer is practically a cultural institution.

That's why an animal rights group's new campaign of encouraging people in Maryland's biggest city to stop eating their iconic blue crab and other marine creatures is raising eyebrows. A number of residents reacted Friday with bewilderment or outright laughter.

In recent days, the People for the Ethical Treatment of Animals erect...