Peeler crabs are held in tanks inside a crab shanty owned by waterman Butch Walters in Deal Island, Md., on May 26, 2020. The crabs are held until they shed, and then packaged and sold as soft-shell crabs. (Photo by Will Parson/Chesapeake Bay Program)

The Chesapeake Bay blue crab is a fascinating species that goes through many differ stages in its life cycle. As invertebrates, the species has a hard exoskeleton that they have to molt (or shed) as they grow.

Peeler crabs are actually just hardshell blue crabs that are showing signs of molting. Molting occurs when a crab's hard shell is shed and a new soft shell is grown. “Peeler crab” is a term assigned to crabs that are in pre-molt stages.

Crabs in the peeler stage are considered good bait and are sometimes harvested since they will have a soft shell after the molt. Soft shell crabs do not stay in this form for long since their shell will harden, so they are considered a delicacy. Hard shell, soft shell and peeler crabs are all harvested and knowing the difference between them can be helpful when you’re out on the water.

You can tell a crab is about to molt by changes to its shell and shell color:

  • The new soft shell should be visible beneath the hard outer shell, which is easily seen on the outer edges of the swimming fins.
  • The new shell will first appear as a white line around the edge, gradually turning pink and then red.
  • A red line is a pretty reliable sign of a peeler about to shed its shell.
  • Fine white wrinkles may also appear on the blue skin between the wrist and upper arm.

The blue area inside the edge of a crabs swimming fin turns thinly white, deepens to pink and then red in the days before it molts.

The blue area inside a crab's swimming fin becomes translucent and develops a thin white line, which deepens to a pink and then red line before it molts. (Photo by Will Parson/Chesapeake Bay Program)

Abdomen color may also be a sign, but that is a much less reliable sign than the emergence of the new shell. A freshly shed male crab’s abdomen is often whiter, but a crab with a yellow abdomen can still be weeks from shedding.

Blue crab population numbers have fluctuated since they were first recorded in 1990 and

one part of the Sustainable Fisheries Goal of the Chesapeake Bay Watershed Agreement is to maintain a sustainable blue crab population. The target is 196 million adult females and in 2021, there were 158 million adult female blue crabs in the Bay. The threshold for the minimum acceptable population number of adult females is 72.5 million and the Blue Crab Abundance Outcome is “on course” and expected to be met by 2025.

Do you have a question about blue crabs? Leave a comment we’ll try to get you an answer!




What is difference between peeler and soft shell crabs?

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