CRACKING A CRAB MYSTERY.

Byline: Winston Ross The Register-Guard

CHARLESTON - Bent over in the cab of his pickup truck, crab fisherman Jeff Reeves took refuge from the rain and wind for a few moments to scribble out a deposit slip for his latest paycheck.

It's not much money and most of the check is already spent on bait, ice, debt and other associated costs for the next trip, but Reeves is grateful to have it.

He persuaded a Charleston processor to settle his tab right after offloading 900 pounds of fresh Dungeness crab.

That meant Reeves could fix a blown generator that had forced him to fish only during daylight hours on his two-day trip.

And he earned the highest price per pound - $2.40 - he's ever seen, thanks to a dwindling supply of crustaceans.

For all intents and purposes, the 2006-07 season of Oregon Coast's most valuable fishery is over now.

Although the season doesn't officially end until August, most of the crab is caught during the mad dash that characterizes the first eight weeks, so crabbers such as Reeves are cashing their last significant paychecks about now - and wishing it had been a better haul.

After three straight years of record catches for the fleet - 25 million to 30 million pounds each season - the Dungeness fishery is back to average.

With 80 percent of the crabs already caught, boats have landed only 11 million pounds.

Why?

"That would be the magic answer everybody would love to know," said Patty Burke, marine resources program manager with the Oregon Department of Fish & Wildlife. "There are a lot of theories: food, temperature, variations in the ocean, changes in fishing practices."

University of Oregon researcher Alan Shanks has another idea - one that could have revolutionary implications for the fishermen's planning, negotiations with processors and spending for an upcoming season.

Shanks may have hit upon a way to predict the abundance of crab in Oregon and Northern California four years ahead of time.

For decades, Shanks has studied the life cycle of Dungeness crab, from eggs to larvae to molt to adulthood.

Five years ago, he and a postdoctoral student at the UO's Oregon Institute of Marine Biology in Charleston put light traps in Coos Bay to measure the "megalopae" of Cancer magister, Dungeness' Latin name.

Megalopae are pelagic larvae, like the kind produced by most fish. They travel out to sea and return to shore with the aid of ocean currents, where they grow into adult crabs four years later.

Shanks' aim was to figure out how the larvae return to shore and, ultimately, what predicts their abundance - a finding that could be used to guess at adult populations.

That's possible because unlike other fisheries, where catch is restricted to a finite number, the commercial crab fleet is allowed to catch every single adult male crab of a certain size available.

Each year, the fleet does indeed catch the vast majority of the ocean's crabs, Shanks explained, so he had a set of data rarely available for marine life: a reliable count of crab in their earliest stages of life and a reliable count at 4 years old.

"In marine biology, getting those two numbers is really hard," Shanks said.

The question: whether the returning - or "recruitment" - of larvae to the continental shelf could be used to predict how many crabs live to 4 years old.

That might seem like a common-sense correlation. But the ocean is a dynamic place, so there was no guarantee that weather conditions, predators and food sources wouldn't throw the equation out of whack, rendering the larvae count useless.

Shanks was shocked, then, to discover that magister larvae are not just a reasonable predictor of adult populations, but a near-perfect one. He found correlation rates as high as 98 percent.

"It was amazing," Shanks said. "That's a huge correlation."

What's more, Shanks discovered that the larvae's recruitment, or return, rate depends on the timing of the "spring transition," the point at which winter's southerly winds give way to summer's northerly gusts.

The transition causes ocean "upwelling," with deep offshore water replacing surface water closer to land, bringing nutrients - and larvae - with it.

If the spring transition happened early, larvae arrived at the coast in greater numbers and, four years later, crabbers had a banner year. If the transition happened late, much of the larvae died in deep water and the fleet raked in meager profits.

Shanks' research is of keen interest to the Oregon Dungeness Crab Commission, which has agreed to pay to keep his light traps in the water for the next couple of years.

If the correlation stands, it could mean dramatic changes in the fishery: Before a bad season, crabbers could negotiate with processors for a higher price upfront, knowing the resource would be scarce. On the flip side, however, processors could lowball the fleet in advance of a big year.

Either way, fishermen could plan accordingly.

Reeves figures he'll do about a third of the business he did last year as a crabber, a prospect he blames as much on new state limits on the pots he can set as he does on the amount of crab in the ocean.

"I've given up on trying to make a profit," Reeves said. "Now I'm just trying to exist."

If Shanks' research holds up, next season will be another boom haul for the fleet, thanks to an early spring transition three years ago - good news for Reeves.

Winston Ross can be reached at [phone] or rgcoast@ oregonfast.net.