State budget trap kills bay's green crab studies

Andrea Randall unearths a trap for the invasive European green crab. Randall's research position tracking the crab was cut this month in Washington state's effort to cope with a massive budget shortfall. KELLY STEWART photo

NAHCOTTA - Wearing black hip waders, Andrea Randall slushes through the Willapa Bay mudflats to remove her last trap for the invasive European green crab.

Her part-time research position tracking the crab was cut in the wake of the state's largest budget shortfall in decades. Her last day was Tuesday.

Randall is the final green crab researcher to leave the Willapa Bay Field Station. The Washington Department of Fish and Wildlife trimmed a full-time green crab-focused biologist from the staff last year.

Randall's departure from the field station leaves Washington with no researchers assigned to control the green crab population at a time when green crab survey data provide no conclusive trends toward a decline or increase.

After shoveling out a five-gallon pit trap near the field station, Randall dumps the murky water that has collected inside of it. No crabs spill out of the trap.

But this isn't Randall's most productive trap. She's caught many green crabs in the mudflats near Stackpole Road at the tip of the Peninsula.

Green crab data inconclusive about invasion

In both 1998 and 1999 - the first two years of the crab's presence in Washington - Randall and local volunteers found more than 300 green crabs in Willapa Bay.

Numbers decreased to 144 in 2000, and 94 in 2001. But last year, the number increased to 156. This year, through June, Randall has trapped 11 crabs.

These numbers are hardly the mark of an invasion, like the one in Maine that decimated the soft-shell clam industry a century ago.

Has the threat from the notorious green crab subsided? Or will the crabs, left uncontrolled, multiply and begin infesting the area?

"It's hard to tell if they're on a decline or a rebound," said Oregon State University researcher Sylvia Yamada, the sole green crab scientist in Oregon. "It's a shame when Washington's program is shutting down when [green crab research] is getting interesting."

Young green crabs found in Oregon

Green crabs aren't always green, but the crustaceans are easily identified by five large spines behind each eye.

Their small size belies their huge appetite for shellfish; green crabs were thought to be a threat to Washington's oyster, clam and crab industries.

Yamada's students recently spotted several young and adult green crabs in Oregon's Yaquina Bay. Most crabs that Yamada finds are large adults - four years is the average life span on the West Coast.

But smaller crabs have been appearing recently, signaling that the species is not going to die off after just one generation in Oregon.

Washington faces the same problem with green crab reproduction, Randall said.

"The little ones are showing up in Oregon, so they'll probably show up here," Randall said. "We won't know because there's no one monitoring them here."

Scott Smith, WDFW's aquatic invasive-species coordinator, said that Randall's green crab control work was one of only two efforts to track the crab in the state. Volunteers in Puget Sound are monitoring, but not trapping, green crab. So far, Puget Sound hasn't been colonized.

Ironically, the state of Washington is funding a volunteer green crab monitoring program in Puget Sound, where no green crabs have been found, at a time when it is cutting a less expensive program in Willapa Bay, where a population of green crabs has been living since 1998.

Washington state's budget for the biennium appears to dedicate $161,000 for volunteer-run green crab monitoring efforts in Puget Sound, according to Kevin Anderson, aquatic nuisance species lead for the Puget Sound Action Team.

Anderson said he understands the difficulty of cutting budgets during the state's fiscal crisis, and he's worried that the green crabs that have colonized Willapa Bay and Grays Harbor will move into the productive shellfish areas.

"We're really concerned about what precedent this sets for future invasions," he said.

Monitoring and control programs for green crab are limited along the West Coast, Smith said.

"By far, the Washington program was the best one on the coast," Smith said. "The time to deal with an invasion is at the beginning of the invasion. If we miss that window, it could end up like Maine, where there's no hope of control."

The Oregon and Washington Departments of Fish and Wildlife require incoming inspections of shellfish shipments, and encourage citizens to report green crab sightings, but have no other formal control programs.

Egg-laying females difficult to track

There's no way to know how many young green crabs will come back in a given year because traps don't yield many females, according to Yamada, the Oregon green crab researcher.

Yamada's findings ring true in Washington, as well. In Willapa Bay, since trapping began in 1998, 60-70 percent of green crabs found were males.

Whereas males prefer intertidal areas where the food supply is plentiful, Yamada thinks that females dwell in deep water to harbor their eggs.

P. Sean McDonald, a University of Washington Ph.D. candidate studying the green crab, isn't sure where the females hide, but he believes that they remain stationary to protect themselves from predators.

"A female green crab is somewhat like a Twinkie," McDonald said. "It's soft, it doesn't put up much of a fight, and it has a lot of goodies inside. It's one of those rare food items that if you come across it, you want to devour it."

A female in its first year of life can lay up to 185,000 eggs, Yamada said. Larger females can lay even more.

Although the mortality rate is high, just a 1 percent return would yield 1,850 young crabs per female.

Even if traps could remove 99 percent of the males from a given area, the population would still grow, said McDonald. Females can store sperm and fertilize multiple broods.

The perfect invasive species

According to Yamada, green crabs have several characteristics that allow them to rapidly disperse and invade new areas: high reproductive rates; rapid growth rates; tolerance to salinity and temperature changes; ability to eat most anything; and even withstand starvation.

"Just like any weed, they are tolerant," Yamada said.

"It's like a race," she added. "Their greatest danger is hitting young bivalves. Most of the damage [from an invasion] has already occurred at that point."

They will eat worms and decaying marsh vegetation if no other food sources are available.

"They're not fussy," Yamada said.

In addition, green crab larvae can travel with the ocean currents, which makes the creatures particularly sticky once they land in a particular area. Even if all of the crabs were eradicated in one area, larvae could always float back.

The history of the green crab illustrates the tenacity of the species.

Already present in Europe, Australia, South Africa, Japan, and the U.S. East Coast, green crabs were discovered in San Francisco Bay in 1989, perhaps brought into the area via international shipping.

Warm El Nino years in the late 1990s were marked by fast-moving northward ocean currents, according to Yamada.

Green crab could have traveled on the 50-kilometer-per-day currents to reach Oregon in 1997 and Willapa Bay just a year later, she said.

Red rock crabs defend against invasion

While studying green crab in Yaquina and Tillamook bays, Yamada's graduate student Chris Hunt found that the invasive species stays away from the cool, low-salt habitat where native red rock crabs thrive. Those green crabs he did find bore scars or missing claws.

In laboratory tests, Hunt discovered that green crab mortality was high when it was paired with red rock crab, while same-species interactions led to minimal mortality. He guesses that green crabs haven't been found in Puget Sound because red rock crabs are prevalent there.

Hunt and Yamada recently published a study about their green crab-red rock crab findings.

"In the crab hierarchy, the red rock crab is on top on our coast," Yamada said.

However, Randall warns against the belief that red rock crab will hold down the green crab population in the future.

"Some year, the Dungeness and red rock populations might be a little low, and [green crabs] will come in here when the conditions are right for them," she said.

McDonald's research in central California showed that green crab tend to congregate in isolated pockets in a narrower range of habitat than they do in other parts of the world. They usually live in places that native crab species find too extreme: high intertidal areas, and areas highly disturbed by humans.

Yet the areas where green crabs can thrive are growing, which might lead to a shift in crab species along the West Coast, according to McDonald.

"I'd hate to think that people would misconstrue our results and think that green crab were not having an impact," McDonald said.

Spread of spartina provides more green crab habitat

The spread of the invasive cordgrass Spartina alterniflora coincides with the dispersion of green crab, said McDonald.

"They form these large populations in small areas and wipe out native populations," McDonald said, noting that the West Coast boasts the highest diversity of crabs in the world.

"As spartina expands, it reduces the amount of habitat that Dungeness crab can use, and increases the amount of habitat that green crab can use," he said.

There's a time lag between a species' first appearance and when it becomes a problem, McDonald said.

"Green crab could easily be the same way," he said.

But it's not an immediate threat.

Willapa Bay oysterman Fritz Wiegardt said he hasn't seen a green crab for a couple of years.

"Of all of our problems, that's not one of them," he said. "Currently, it's not a problem, but you never know what the future is going to bring."

Consistent green crab monitoring is crucial to keeping populations from growing, McDonald said.

"I don't see green crabs as a threat to human enterprise right now," McDonald said. "With the economy now, it's hard to get a lot of support for baseline monitoring."

Randall has worked on the green crab project at the field station since 1999. WDFW recently offered her a full-time appointment in Olympia removing coded wire tags from salmon snouts, but she will continue to live on the peninsula, where her husband farms oysters.

"We learned a lot from the program, and it's sad to see it go," she said.

Recommended for you

(0) comments

Welcome to the discussion.

Keep it Clean. Please avoid obscene, vulgar, lewd, racist or sexually-oriented language.
PLEASE TURN OFF YOUR CAPS LOCK.
Don't Threaten. Threats of harming another person will not be tolerated.
Be Truthful. Don't knowingly lie about anyone or anything.
Be Nice. No racism, sexism or any sort of -ism that is degrading to another person.
Be Proactive. Use the 'Report' link on each comment to let us know of abusive posts.
Share with Us. We'd love to hear eyewitness accounts, the history behind an article.