Community Environment

Dearth of Dungeness again cancels South Sound crabbing season

Posted on July 14th, 2022 By:

The Puget Sound crabbing season opened last week. For the fifth straight year, most of the waters surrounding the Gig Harbor and Key peninsulas weren’t included.

Since 2018, the area south of the Tacoma Narrows bridges (Marine Area 13) has remained closed to allow the weak Dungeness crab population to increase. The closure extended north through Marine Area 11 (Tacoma-Vashon, including Gig Harbor proper) in 2018 and 2019.  Numbers have recovered enough there to offer a limited season — July 3 through Aug. 30 on Sundays and Mondays.

Dungeness have always been fewer in the South Sound. They typically range from less than 1 percent to 4.3 percent of the total Puget Sound harvest, said Washington State Department of Fish and Wildlife crustacean biologist Don Velasquez. Marine Area 7 (Whidbey Island), by comparison, comprises 42 percent to 61 percent of the catch.

But beginning in 2013, South Sound harvests began a staggering decline from even that low share. In 2012, recreational and tribal fishers pulled up 214,404 pounds of Dungeness crab. By 2017, the catch had plummeted to just 8,679 pounds. Despite the four-year closure, they haven’t recovered.

“Dungeness crab commands a lot of money to fisherman so everybody is concerned — recreational, treaty, commercial,” Velasquez said. “It was a big hit.”

State biologists have been conducting test-fishing since 2015 and found Dungeness crab numbers to be down and not increasing.

State biologists have been conducting test-fishing since 2015 and found Dungeness crab numbers to be meager and not increasing.

Test-fishing showing little improvement

The department has conducted preseason test-fishing since 2015, Velasquez said. Fifteen commercial pots are set for 24 hours at eight sites for a total of 120 sets. The catch has been scant, topping out at 2.43 total crabs per set the first year.

In 2018 there were just 0.3 legal-size male Dungeness per trap (0.7 total crabs). A healthy Whidbey Island fishery produced 17 to 34 per pot.

This year there were 1.16 Dungeness per pot, almost all legal-sized males. Only a few small males (0.2) and almost no females (0.03) were caught. A healthy population should have plenty of males and females of all ages. During an open season, only males measuring 6 ¼ inches across the back can be retained; no females.

“When you plot the sizes of Dungeness crab in MA 13, it is very apparent that there are fewer Dungeness crabs in all sizes and the smaller crabs are underrepresented when compared to healthier populations in North Sound,” Velasquez said.

If the low numbers were simply the result of overharvesting — removing too many adult males before they could mate — then closing the fishery should allow the population to recover on its own over a few years as Dungeness grow to legal size in about four years. It hasn’t. That points to other environmental factors.

Washington State marine area map

The South Sound is Marine Area 13, everything south of the Tacoma Narrows bridges.

It must be something more than overharvesting

A couple notable ones being researched are whether adequate crab larvae are present, and surface water temperatures.

Female crabs hold onto their fertilized eggs until they hatch. Then the larvae are suspended in the water for about three months before they settle back to the bottom.

During that time they’re at the whim of the tide and currents. They might remain close to where they were born or get transported all the way from the Pacific to Puget Sound. The best chance for local larval production is probably nearby females, Velasquez said.

Biologists deploy light traps to determine how many Dungeness larvae arrive at various Puget Sound locations and when they are present. Data collected since 2019 suggests that larval supply in the South Sound is much less than in North Sound or the Strait of Juan de Fuca.

“We might expect the females to disappear as time goes on if new-year classes of younger crab have not successfully settled the area,” Velasquez said. “This is probably due to existing females reaching the end of their lives without replacement.”

Research has also shown that higher surface water temperatures during some South Sound summers are likely to be lethal to young Dungeness crabs. Acidification and pollution could also be factors.

A Dungeness crab being measured

During an open season, crabbers can only keep male Dungeness that are at least 6 1/4 inches across the back.

Fisheries managers have not tried to relocate crabs from other areas or use hatchery techniques to  seed the area. No hatchery program exists here, though they have been used on the East Coast in an effort to boost blue crab numbers, Velasquez said.

Red rock crabs don’t seem to be affected

Despite Dungeness travails, test-fishing has revealed plenty of red rock crabs in South Sound. They aren’t as susceptible to warmer water temperatures. Dungeness prefer sandy bottoms and eat more types of prey than just clams and oysters. Red rock crabs prefer harder substrates and are particularly adapted to breaking open shells.

However, there has not been a red rock-only season because it could lead to repeated handling and likely death of some of the few Dungeness that remain. That perspective could be changing.

“Without a substantial recovery evident in the Dungeness crab population, there is no current prediction of opening a season on that species,” Velasquez said. “The bigger question is whether state and tribal managers can negotiate a way to allow some targeted harvest of red rock crab if the Dungeness population remains very low.”

Fish and Wildlife work together with the tribes on crab policy as the 1995 Rafeedie Decision entitles the tribes to half of the state’s shellfish.