Thousands upon thousands of Dungeness crab shells have washed up on the beach in the Cherry Point area in recent weeks.
There have been so many that beachgoers contacted the Washington Department of Fish & Wildlife earlier in April and emailed photos of what they saw, worried that they were witnessing a massive die-off.
They weren’t, officials said, because the shells and legs found in north Whatcom County were from crabs that were molting.
That’s a process in which crabs shed their hard shells, or exoskeletons, so they can grow into new, larger shells. By the time they’re 2 years old, Dungeness crabs have molted about 12 times.
“These are common phenomenon,” explained Don Rothaus, a crustacean biologist who oversees the commercial program for Fish & Wildlife.
What stands out, though, is the sheer number of shells in the Cherry Point area, where one access point is off Gulf Road.
“This is unusually large. The pictures are very dramatic,” Rothaus said of details gleaned anecdotally from photos and reports from the public.
Could the large number of shells of various sizes — there were more last week, according to one beach visitor — mean there will be an abundance of Dungeness crabs in the area when crabbing season opens? Maybe.
Their presence could “simply be the result of tides, currents, wind and weather all working together to windrow a large number of molts onto this one area,” Rothaus said of the beachfront deposit of rows of shells.
Or, commercial, tribal and recreational crabbers in region 1 and region 7 could be celebrating this crabbing season or the next. A few years back, a big molting event in Saratoga Passage, between Whidbey and Camano islands, later turned out to mean a higher-than-expected abundance of crabs for the next two years.
“We really won’t know for sure (about the Cherry Point molting) until we conduct surveys or fisheries in late June and July,” he said.
As for how they know the shells were a mass molting instead of a large die-off, Fish & Wildlife officials said they figured it out by looking at the photos sent in by beachgoers and by asking whether there were a lot of birds, such as seagulls and crows, pecking away at the crab.
A lot of birds means there are dead crabs in their shells. A few birds means the shells are empty, and thus from molting.
“In an event this size you would see birds everywhere,” Rothaus said of telling the difference between die-off and molting. “It’s the scavenging behavior we’re looking for. Certainly, a dead crab is a free meal.”