#3. Puget Sound Crab Populations are Flourishing

Back in August, boaters in my neighborhood near Port Townsend decided to throw a community crab feed.  Over a few days, they caught and cleaned and cooked more than 150 Dungeness crab, iced them down in a dinghy and treated some 250 friends and family.

It’s been that kind of year for local crabbers. While Northwest biologists and policy makers try to deal with diminished stocks of salmon and other finfish, crab seem to be doing just fine – at least in northern areas from Port Townsend to the San Juans, where more than 90 percent of Salish Sea crab are generally harvested.

Rich Childers, who managed crab fisheries at the state Department of Fish and Wildlife (WDFW) before retiring to Port Townsend, recalls when Puget Sound crab harvests ranged from two to four million pounds annually in the 1990s.  Over the past 15 years, catches have averaged nearly 10 million pounds.

This despite heavy fishing all summer by treaty tribes, commercial crabbers and up to 240,000 recreational fishers, who pay $8 to add crab to their state fishing licenses.  Navigating a small boat out on Townsend Bay during July and August becomes an obstacle course, zigging and zagging to avoid snagging somebody’s crab line.  By mid-summer, local crabbers are filling their freezers and begging neighbors to take their excess catch.

Why are crab prospering while salmon aren’t? No one knows for sure.  Banning bottom trawls, which drag huge nets across the sea bottom, probably helped. But for all their efforts, biologists acknowledge that Puget Sound remains a black box, where crab eat and get eaten in an impossibly complex ecosystem. 

That said, scientists have a number of theories, or educated guesses, among them:

Adult males only:  For many years, the basic management strategy has been to limit the season while requiring crabbers to keep only large males.  All females and smaller males (shells measuring less than 6 1/4 inches across) must be thrown back.

That strategy dates back decades to when crabbing was driven by San Francisco buyers, Childers says.  “Fishermen were told: Don’t bring in any females, and no males smaller than a dollar bill, because they don’t sell.  And that became the management strategy that continues today.”

So more than half of the crab captured are thrown back to reproduce and perhaps be caught another day.  That works well with the crab life cycle.  Mature crab grow mostly in spurts timed to their annual molting, when they wriggle out of their old shells and quickly grow new ones.  “It’s amazing,” Childers says. “They’ll grow an inch and a half in a very short period of time.”  A five-inch crab immediately absorbs water and becomes a six-inch crab, while the six-incher becomes 7 ½.  It’s a form of delayed gratification; Throw back today’s smaller crab and you’ll get a bigger one next year.  And the females go back and reproduce.

Predation: Who eats whom?  Like most fish, crab are stunningly productive.  A mature female will produce from 1 million to 2.5 million eggs per year. The hatched larvae drift with ocean currents, where the vast majority – more than 99 percent — are eaten by something larger. 

And the predators include salmon.  As salmon runs dwindle, there are fewer fish eating larval crab, so more larvae survive to reach maturity, Childers says. 

Do crab traps feed crab? Crabs are harvested with a simple device called a crab trap – a disc or box roughly two by two feet by one foot deep, made of two-inch steel mesh that resembles a chain-link fence. The trap is baited with fish heads or chicken legs or (in my case) freezer-burned meats from neighbors’ basements.  There is a one-way door on each side, hinged at the top, allowing hungry crab to crawl in for the bait.  The larger crab can’t get out, but smaller critters wander in, feast on the bait, then leave through the two-inch mesh or a couple of larger four-inch “escape ports.”

Biologists believe that baited crab traps have become significant “feeding stations” for females and smaller crab.  “Think about it,” Childers explains. “There are thousands of traps out there, each one baited, pulled and rebaited every day for the season.  When people pull the traps, they throw the old bait back in the water….  That’s a lot of food.”

Whatever the reasons, the summer crab fishery appears to have been successful in northern waters, says Don Velasquez of State Fisheries.  The recreational season closed on schedule after Labor Day, giving the state time to assess stocks.  But regulators expect that it will be reopened October 1.