Oystermen, scientists digging up ways to fight burrowing shrimp

<I>ELIZABETH LONG photo</I><BR>Brett Dumbauld, with the USDA-ARS Hatfield Marine Science Center, sucks up some burrowing shrimp from a Nahcotta oyster bed for local and visiting experts to view during last week's conference.

LONG BEACH - Willapa Bay may be saved from the invasive weed spartina only to be lost to another threat - burrowing shrimp.

Two species found in the bay, ghost shrimp and mud shrimp, get their name from their behavior, they burrow in the bay's 47,000 acres of intertidal mudflats. Although considered native species, their numbers have exploded, taking over huge areas so nothing else can grow or live.

Imagine a backyard with a lawn, flowerbeds, perhaps some vegetables. Then imagine that yard is over-run with 500 gophers all continuously digging and burrowing. The gophers push up mounds of dirt, soon covering and killing the lawn and flowers and stripping the vegetable beds clean. Because of the huge number of them, their holes are everywhere, making it impossible to walk without sinking into the loosened soil. Soon the yard has been churned into nothing but muck. Now imagine the same thing occurring on every acre of land on the Peninsula.

Just off shore, in the tidal flats and bay, burrowing shrimp are causing that type of damage. In effect, large areas have become underwater desert wasteland where nothing exists except for the shrimp - no fish, no plants, no shellfish.

70 from around U.S. attend shrimp conference

More than 70 experts, including local oystermen and 37 scientists, gathered Feb. 1 and Feb. 2 at the Washington State University Extension in Long Beach to analyze the problem. They came from as far away as Louisiana and brought together a range of knowledge from agriculture and ecology to civil engineering and GIS.

"I'm glad we have a diverse group here," oysterman Dick Sheldon told the gathered conference attendees. "We need some answers."

The oyster industry is particularly affected and could potentially be decimated by the shrimp. Oysters must remain above ground, but the shrimp turn the bottom into the consistency of quicksand, sinking and smothering the oysters. They simply disappear.

The oyster industry is vital to the region and the state's economy, and in many ways, its traditions. Taylor Shellfish began in 1895. The Wiegardt family have been oystermen for five generations. It was the first industry here in the 1800s, when a huge quantity of the native "silver dollar" oysters where shipped out. When they began to become scarce, Eastern oysters were imported, then Japanese, or Pacific oysters were cultivated starting around 1921.

At the turn of the century in a unique move, in recognition of the industry's importance to the state, tidelands were sold into private ownership with the condition they be used to cultivate oysters. Now Willapa Bay supplies more than 25 percent of the nation's oysters and employs more than 600 people. The industry has also often campaigned to ensure the bay's water quality is maintained, at a time when other oyster growing areas are being shut down because of pollution, particularly in Puget Sound. In many ways, the oyster represents the area as much as the salmon.

Not just oysters are threatened. Other shellfish, such as clams and mussels are killed off by the shrimp infestation. Eelgrass is also wiped out, destroying critical fish nursery habitat. Crabs have lost foraging ground.

The oysterbeds are not just critical to the economy, they have become one of the few remaining nursery habitats, harboring young crab and fish.

"I don't consider this an oyster versus shrimp problem, I consider this a habitat problem," said Sheldon.

Oysterman Brady Engvall spoke about how radically the shrimp have changed the mudflats. "I use to run around on the mudflats as a child. The mudflats in Grays Harbor were hard." Now, anyone who tries that potentially risks his lives getting stuck in the mud, particularly dangerous on an incoming tide. The shrimp dig to 18 inches or more, completely altering the water-soil interface and consistency. "I would have remembered sinking up to my knees," said Engvall.

Oyster growers started to notice an increase in the shrimp population in the 1930s and '40, and began to hunt for a solution. After some experimentation, a chemical called carbaryl, sold under the brand name Sevin, was established as the most effective means of control. It was first used in 1963. In 1965 its use became regulated. In the 1980s the shrimp population jumped, probably driven by the warm ocean current event of El Nino.

"Carbaryl is the best product you've got," John Stark with WSU Puyallup told the group. "It works really well, has short acting effects."

Not everyone was happy with carbaryl. A group called the Toxics Coalition filed suit to stop its use in the bay. Amid increasing regulation and the lawsuit it became increasing difficult to use. In 2001 there was no spraying at all. In 2005 just over 560 acres in the bay was treated.

In 2003 the suit was settled out of court, with the oyster growers agreeing to stop the use of carbaryl by 2012. Recognizing the threat to the industry and the ecosystem, a Washington State Proviso was passed granting $200,000 annually for four years to develop a alternative to carbaryl.

As of yet, no other effective, low impact replacement for carbaryl has been found, prompting the conference.

The decision has caused no small amount of friction. "We're in a political situation, not a biological situation," said Sheldon.

"There's no proof carbaryl is not safe," said Chris Grue with the University of Washington. "We should be for science, we should be for information that leads us down a path for better resource management," he said, clearly frustrated.

"It frustrates me that the Toxics Coalition is not here (at the conference) and not being represented," said Miranda Wecker with the University of Washington. "There are a lot more things that are a lot more damaging than carbaryl." Part of the settlement was an agreement that the Toxics Coalition would assist in finding a suitable alternative to carbaryl.

But, Grue warned, it is prudent to search for alternatives to carbaryl anyway. It is a chemical the government is considering banning. "It may be off the market, completely banned," he said. Companies would stop making the product, even for special use exceptions, because there would be no profit.

So the question became, again, how to control the shrimp without damaging the bay. The problem was analyzed from every angle over the two-day period.

"We are working not only on an IPM (Integrated Pest Management) plan but also an integrated research plan," said Steve Booth with the Pacific Shellfish Institute.

Darryl Felder from Louisiana State University spoke about the life history of the shrimp.

"You can never talk about the animal without talking about the burrow," he said. The ghost shrimp are far more damaging because they burrow continuously.

They discussed and explored possible vulnerabilities in the shrimps' life cycle.

John Colt with NOAA explained the problems they were experiencing trying to keep the shrimp in the lab so they could be studied.

"We basically can't keep these things alive very well," he said, prompting a cheer from the crowd.

Armand Kuris from the University of California at Santa Barbara talked about various biological controls - parasites, diseases, and predators of the shrimp. One of the parasites, a nematode or worm, has a fish as its final host. The shrimp is an intermediary host, and has to be eaten by the fish for the worm to finish its life cycle.

"There's a fin fish that is helping to protect you in a big way," he said. If they could discover just which fish it was, the fish could be protected and encouraged to multiply.

Kim Patten with WSU described experiments with other organic substances that might be toxic to the shrimp. They had some success with habanero hot pepper extract, "which is really, really hot," he said, not the standard tabletop sauce. But some of the products were simply too expensive at this point to be practical.

Mechanical means of killing the shrimp, such as with water jets, compressing the ground and smashing the shrimp, or discing the infested areas was also explored. But no effective technique had been found, and was considered high impact, highly disturbing and disruptive to the mudflats.

Everyone agreed there was no one simple solution. No one wanted to eradicate the shrimp, but it would take a variety of techniques to control them.

"If we could find an economic use for these, we could wipe them out in 10 years," joked one participant. Unfortunately, the shrimp are notoriously bad tasting, and difficult to harvest for bait.

"This is a bay scale management issue," said Kuris.

"This is an act of God business out here," said Barry Griffin with Netsystems, explaining the precarious nature of the industry. "We're looking around desperately for another simple answer. Well, maybe it's a complex answer.

In the end, everyone agreed the purpose of the conference was not to just save the oysterbeds, but to save the bay. The oytergrowers' passion for protecting it is clear.

"I still love the bay," said Fritz Wiegardt. " I hope those of you who are new here can sense that we feel it's unique."

"We've got 20,000 acres of wasteland out there," said Wilson.

"We've got to find something that works not just on oyster ground but on shellfish ground," said Brian Sheldon. He called on the Department of Natural Resources to manage their tidelands as well to help restore balance to the bay.

Dick Sheldon's impassioned plea for the bay caused thunderous applause. "Willapa is a special place, and I don't want to see it screwed up by us doing something worse than we're doing now."

At the end of the conference participants, over and over, described it as "the best they've ever taken part in." Although no "silver bullet," was discovered, all agreed the conference was "a good start" for finding a solution. Preparations have begun for another burrowing shrimp conference next year.

Jim Liou with the University of Idaho summed up the feelings of determination in the group. "We've got a problem to solve. We'll put our resources together, put our differences aside and solve this problem."

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