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An Interview with Brett Dumbauld, Research Scientist Brett Dumbauld is a research scientist who heads the Washington Department of Fish and Wildlife's Nahcotta Field Station on the Long Beach Peninsula. His duties range from supervising the sales of oysters from state beds to controlling the northward advance of the European green crab, an exotic predator that could pose a serious threat to Washington shellfish. Brett is married and has two children, a dog and two birds. They live in Ocean Park.

Q: What is your educational and professional background? A: I grew up in Salt Lake City, Utah and attended the University of Utah for a couple of years. The rest of my education was at the University of Washington. I'm a fisheries research scientist. I've been with the department since 1991. I got my Ph.D degree at the School of Fisheries at the University of Washington and was working for the Department in Willapa Bay before I actually finished my degree in 1994. I was working on the ghost shrimp -- carbaryl issue in Willapa -- the oyster growers spray a pesticide called carbaryl or Sevin. It is a nervous system toxin that is toxic primarily to shrimp and other arthropods although it does kill some mollusks. Since they spray it in the estuary, it is a big issue. They've been doing that since the 1960's to control ghost shrimp and that is what I've focused a great deal of my work on. Ghost shrimp cause the oysters to sink in the mud and die. The oysters get covered up by sand and mud and suffocate and die so the growers spray to kill the shrimp. The department was primarily interested in the effects of the spray on Dungeness crab because it kills juvenile crabs that are on the beds. My doctoral research dealt with the life history of the shrimp, looking at how we might get around spraying the pesticide or do it more effectively. The shrimp recruit to the estuaries on an annual basis. So we studied the life history of the shrimp and the effects of the carbaryl on non- target organisms. We also examined lowering the concentration range of the carbaryl and modeling that versus shrimp kill to see whether less pesticide could be used. The shrimp problem continues to be of great interest to me and we continue to seek effective alternatives to control shrimp. We haven't really found anything other than carbaryl to be effective for adult shrimp yet, although we have found some techniques that might be integrated with carbaryl to make it more effective based on the life history of shrimp. Q: What do shrimp do to make the oysters sink? A: They are a burrowing animal. They dig a gallery or burrow in the mud up to 60 centimeters deep, and in the process, because they kick up sediment into the water column, the oysters either sink into the sediment and suffocate or get covered with mud and die. Particularly vulnerable are juvenile oysters, which are attached to a larger shell and can't move and stay above the surface of the sediment. Ghost shrimp and burrowing shrimp are incredibly abundant in the coastal estuaries of Grays Harbor and Willapa Bay. Q: What are the principal duties you have now that you work for the department? A: The Willapa Bay Field Station--there have been people from the department here for a long time. The primary duties, and the reason the lab is still here, particularly with the latest budget crisis, have revolved around the state's oyster reserves which were set aside at the turn of the century. Some of the first territorial laws of the state set aside the oyster reserves because oysters were incredibly important then as they are now. The reserves were set aside to preserve the stocks of the native or Olympia oyster--probably called the Shoalwater oyster from Willapa Bay. Native oysters prefer the low intertidal or subtidal environment, so the reserves tend to be located in that part of the bay where they grew best. Reserve laws have changed over time and now we largely manage the reserves for the Pacific oyster, but we have a plan to go back and look at the native oyster again. We have an annual oyster sale. We sell oysters to the highest bidder. Buyers could be anybody, but tend to be a growers because you sign a contract to pick all of the oysters on a given area of the reserve. The oysters harvested are what we call a transplant oyster since they generally require another year until harvest. Growers move then to private lands near the mouth of the bay for a year or so until they fatten up and become a marketable oyster. There are some areas on the state reserves where you can harvest a marketable oyster. I oversee the oyster reserve program which is one of the primary functions of the field station. The history of the lab is tied to the reserves and the oyster industry so the carbaryl issue is really important. Although we no longer have regulatory authority, most of that has been given to the Department of Ecology, I'm still involved from a research standpoint and I'm the only remaining contact in the department who deals with the issue. Click on photo for full image Q: Does the department spray carbaryl? A: The oyster reserves were never treated until a couple of years after I got here. There are ghost shrimp and burrowing shrimp on certain areas of the reserve and some of the growers, and certainly I, would argue you could treat those and raise more oysters on that ground because there are abundant shrimp there. So we did , but to date most of that treatment has been tied into experimental work and we haven't done it just to raise oysters. The reserves tend to be on the south end of the bay where the shrimp problem isn't as bad. Getting back to our duties at the field station. We have a broader project called the coastal estuarine habitat project which doesn't fit nicely into the Fish Management program, but all of the fish and shellfish resources we manage in the estuary rely on habitat and all of the issues, such as carbaryl-ghost shrimp one, are really habitat issues. So eelgrass, oysters, dredging and all the projects that influence what goes in the bay are part of this project. As issues arise a bunch of smaller projects sort of feed into this as they come along with some outside money and some agency money. Spartina is probably the classic example and currently the most serious habitat issue. Spartina is an introduced marsh grass that greatly modifies the intertidal estuarine habitat and has been the focus of a great deal of work. We implemented the first Spartina control program on agency lands and examined the impacts of the grass on clams and oysters. The control program now resides in the Lands Program and they do Spartina management on a large scale. They pull, spray and mow the grass. I still try and stay involved in the planning aspect and conduct some research. There is a project to introduce a leaf hopper bug that kills Willapa Spartina. The project is sponsored by a local effort called the Coastal Resource Science Center group. I've been involved as a technical advisor on this project. We hope the bug will provide another management tool. Dredging is another issue in the coastal estuaries. Dredging kills Dungeness crab and the Army Corps of Engineers has been required to conduct several projects to examine the impacts and investigate ways to mitigate for these losses. Currently they mitigate by putting oyster shells in intertidal environment to create habitat for juvenile crab and ostensibly creating enough juveniles to mitigate for the loss of adult crabs. I was active in some of the preliminary studies for the Corps when I was at the University of Washington and remain interested. We managed a smaller project this summer to mitigate for some dredging in Willapa Bay by putting shell on the oyster reserves. Q: The state discovered it had green crabs while doing Spartina control. Tell me how green crabs were found. A: It was an odd event. Andy Cohen, a researcher from California who has published green crab work and has studied invasive species was here visiting after a conference in eastern Washington. He and Janie Civille, an employee from the Department of Natural Resources (DNR), were out looking at some of the Spartina problems and found a molt of a green crab on the tideflat. The locals hadn't seen any, but it was a foreboding of what was to come. Then a second DNR staff person was mowing Spartina and found the first live green crab. It turned out to be the largest green crab we have found to date. We had been looking in the wrong place and when we began looking for them in the Spartina and low saltmarsh by setting traps, it was relatively straight forward to go out and capture them. Although the numbers have gone down in the winter because they aren't coming to the traps, if you set the traps in the right place, you'll find them. Spartina happens to be the right place in Willapa. We found 99 percent of the green crabs in the Spartina this summer. Spartina is definitely providing the habitat for them in Willapa. We think one of the reasons for this is that just beyond the Spartina on the mudflats, oysterbeds, and in the channels you find our native crab--Dungeness and rock crab--which are larger. The larger native crabs seem to hold their own. Some initial thought that these green crabs were larger than life killer crabs--so voracious that they would take out our Dungeness crab, proved to be wrong. Researchers have done some work showing Dungeness and rock crab of equal size can hold their own against green crab. Still we don't know what might happen if the Dungeness population dropped for some reason, and all we had were large green crabs. Adult Green Crab © Gregory C. Jensen Q: There must be other natural predators for green crabs? A: Fish and birds certainly prey on the small ones. The situation is different than it is in Europe where the green crab are native. There aren't as many of the larger crab present in Europe and even on the east coast of the United States their distribution is apparently limited by the native blue crabs. You don't find many green crab in the Chesapeake where the blue crab are real abundant yet north of that, where you have fewer and less aggressive crabs, the green crab do real well. Our data sort of documents that is what is going on in Willapa, at least so far. If the pattern holds and crab are limited to Spartina, it may limit their effects on oysters and clams too. Oysters tend to be found at lower tidal elevations and are already affected by Dungeness crab as predators, maybe the green crab won't affect them. I would argue it is a little too early to tell. We are looking at a pretty low level infestation so far. We are getting two green crabs per trap for 24 hours of fishing. In California, where they are abundant, you'd get 50, or so I'm told. Q: Are you suggesting green crabs may not be a threat to oysters and clams? A: I'm holding judgment on that. I doubt green crab are having much of an effect now because they seem to be found in the Spartina and their abundance is relatively low. As they become more abundant they could move and affect oysters and clams. There is some indication green crab move seasonally. Q: How will you control green crabs? A: WDFW requested emergency funds from the governor to look at monitoring and control statewide. We will be looking at ways to control them on the coast. We have a couple thoughts on that. The first is trapping on a large scale. We know we can catch green crab in traps and traps have few environmental impacts because you can throw everything else back, although you wouldn't want catch juvenile salmonids in an intertidal trap. The second is chemical control. We know we can use carbaryl to kill ghost shrimp, although it has other potential environmental impacts. We know what these are, though, and they could be minimized, particularly in the upper marsh where green crab are present. We are going to look at poison bait first, initially in a trap, so we can determine effectiveness and also see what other animals are affected. We have some other ideas like biological control, but they are further down the road. Then there is the question of how to do it. Do we do it as an agency or do we set up a bounty program and let other people implement the control? Both have advantages and disadvantages. Q: If there are huge numbers of green crabs to the south won't they keep moving up? A: Good point and a big problem. It has to be a multi-state effort and right now Oregon ... has sort of resigned itself to having green crab, at least that's my read. That doesn't bode well, because it appears they got here when crabs to the south released their larvae which floated in the nearshore coastal ocean and we had a natural recruitment event. It could have been an unusual event and even related to El Nino. We can only hope that it was a one-time event and it won't happen for a period of time. The problem is we now have the crabs here and they have the potential to breed. In fact some of the females we held here at the lab, now have eggs. If we don't limit the breeding population, they will continue to spread even faster and further up the coast. We are particularly concerned about Puget Sound. The environment looks pretty good for them here in Willapa and unfortunately we have our work cut out for us.