Progress 06/01/07 to 05/31/10

Outputs
OUTPUTS: Activities: We assessed bio-rational reduced risk controls for burrowing shrimp. Forty seven chemistries were screened, between 2005 and 2007, for efficacy in replacing carbaryl for control of burrowing shrimp. Based on efficacy, ease of application, cost, and registration potential, one compound, imidacloprid, was selected to focus on for additional work. Between 2006 and 2010, imidacloprid efficacy was evaluated as a function of rate, season of application, timing (hours exposure prior to tidal flushing), sediment type and vegetation coverage, and application methods (broadcast, subsurface injection and in-water application of granular). Four sub-surface pesticide delivery systems were made and evaluated: a shanking system, a tine harrow system, and two spikewheel systems. We developed and assessed mechanical controls for burrowing shrimp. We evaluated compaction methodology in the field and lab. Multiple large-scale crushing events were implemented in the field. Laboratory studies were done to evaluate the physics, mechanics, and impacts of substrate liquefaction on burrowing shrimp Research was conducted to assess sediment cementation using quicklime, fly ash, and cement kiln dust additives as a means of eliminating shrimp burrowing. IPM: We developed and tested underwater-subsurface video methodology to provide detailed records on what happens during a chemical or mechanical control episode. We evaluated how burrow counts change as a function of temperature and time at different burrow densities. We utilized the findings from the above studies to help fine-tune alternative pest-management strategies for the industry. Events: Five burrowing shrimp grower/researcher workshops (Winter 2006 through 2010) were held and there were six burrowing shrimp research sessions at the Pacific Coast Shellfish Grower Association (PCSGA) annual meetings (2005 through 2010). Products: A CD containing all the research studies on burrowing shrimp control was produced. Website information was produced containing results from many of these studies. Federal Experimental Use Permits were grant for large-scale trials in 2008 and 2010. Dissemination: Informational packages containing data on burrowing shrimp control and its nontarget impact were sent to EPA for evaluation. Meetings were held with EPA and state agencies regarding burrowing shrimp control and registration of imidacloprid. Other outreach activities included more than 25 separate presentations on this project during the annual grower workshops and PCSGA meetings. Results were included in the 2010 Pest Management Strategic Plan for Bivalves in Oregon and Washington. PARTICIPANTS: Kim Patten, extension professor. Scott Norelius, Research Assistant. Don Aasen, Dale Versteegen, Research Assistants; Jim Durfey, associate. Oregon State University, USDA, University of Washington, WSU Vancouver, San Jose State University and University of Idaho collaborated on research. Pacific Shellfish Institute, Willipa Grays Harbor Oyster Grower Association, Washington State Commission on Pesticide Registration collaborated on research. Project trained one graduate student, one undergraduate, and one high school science teacher. TARGET AUDIENCES: Target audiences were the shellfish industry of Willapa Bay and Grays Harbor. State and federal agencies with regulatory authority for pesticide use in aquatic environments (Washington Department of Ecology, Wsahington Department of Agriculture, Washington Department of Fish and Wildlife and EPA and NOAA/National Marine FIsheries were involved. PROJECT MODIFICATIONS: This project did not develop far enough to develop an IPM or marketing strategy as proposed in Objective 3.

Impacts
Results contributed to the database of efficacy and toxicological attributes of compounds with potential for registration for use against burrowing shrimp and to the species composition of the benthic community in Willapa Bay. As a consequence, one compound, imidacloprid, has moved forward towards registration. The package for registration was submitted August 2010. It is too early to confirm that a usable control tactic was developed and implemented, or if that tactic will have a major impact on shellfish aquaculture and the economy and ecology of Willapa Bay.

Publications

• Patten, K.D. 2010. Efficacy and non-target impacts of field and lab trials of two formulations of imidacloprid for burrowing shrimp control. Pacific Coast Shellfish Growers Association Conference. (abstract).
• Patten, K.D. 2009. Evaluations of formulations and rates of imidacloprid for burrowing shrimp control. Pacific Coast Shellfish Growers Association Conference (abstract).
• Booth, S., K.D. Patten, and B. Dumbauld. 2009. Experimental trials, regulatory tribulations and theoretical fuzziness in the development of an IPM program for burrowing shrimp. IPM Conference. (abstract).
• Hemberry, Christina. 2008. A soil modification to mitigate burrowing shrimp on commercial oyster grounds. MS Thesis, Civil Engineering, University of Idaho.
• K. Patten, D. Aasen, 2008. Efficacy and non-target impacts of imidacloprid for burrowing shrimp control. Pacific Coast Shellfish Growers Association Conference (abstract).
• K. Patten, D. Aasen, and D. Versteegen. 2007. Advances in chemical control of burrowing shrimp Pacific Coast Shellfish Grower Association Conference (abstract).
• Patten, K. 2007. Design and evaluate subsurface chemical delivery systems and deep penetrating harrow for management of burrowing shrimp populations. Coast Shellfish Grower Association Conference (abstract).
• Patten, K.D. 2007. Advances in chemical control of burrowing shrimp. Pacific Coast Shellfish Growers Association Conference (abstract).
• J. Durfey, C. Hilley and K. Patten. 2005. Subsurface shanking as a new technique for managing burrowing shrimp population in Willapa Bay. Pacific Coast Shellfish Grower Association Conference (abstract).
• K. Patten, D. Aasen, J. Durfey, C. Hilley and Spikewheel Co. 2006. Design and evaluate subsurface chemical delivery systems and deep penetrating harrow for management of burrowing shrimp populations. Pacific Coast Shellfish Grower Association Conference (abstract).
• K. Patten, J. Durfey, J. Raskauskas and S. Stern. 2005. An assessment of chemical controls and their methods of application for the management of burrowing shrimp in Willapa Bay. Pacific Coast Shellfish Grower Association Conference (abstract).
• J. Durfey, C. Hilley and K. Patten. 2005. Subsurface shanking as a new technique for managing burrowing shrimp population in Willapa Bay. Pacific Coast Shellfish Grower Association Conference (abstract).
• K. Patten, J. Durfey, J. Raskauskas and S. Stern. 2005. An assessment of chemical controls and their methods of application for the management of burrowing shrimp in Willapa Bay. Pacific Coast Shellfish Grower Association Conference (abstract).

Progress 01/01/09 to 12/31/09

Outputs
OUTPUTS: Forty-seven chemistries were screened between 2005 and 2007 for efficacy in replacing carbaryl for control of burrowing shrimp. Based on efficacy, ease of application, cost, non-target impact and registration potential, one compound, imidacloprid, was selected as the focus for additional work. Between 2006 and 2009, imidacloprid efficacy was evaluated as a function of rate, season of application, timing, sediment type, vegetation coverage, formulations and application method. Under most conditions, imidacloprid provided reasonable efficacy at 0.5 lbs ai/ac with the granular formulation being better than the DF formulation. Rates up to 2 lbs ai/ac of the DF were required to achieve efficacy in silty sediment, while the granular formulation worked better at lower rates in eelgrass or when the site was covered with water. Benthic samples were gathered following treatment with alternative insecticides. The impact to the benthic infauna following treatment with alternative compounds, and using alternative delivery systems, was minimal relative to untreated plots. This was according to four indicators of community composition and analysis of the relative ubiquity of individual species, at both 1 and 6 months after treatment. Results provided preliminary data towards a more comprehensive study of imidacloprid. Pacific oyster larvae and juveniles, juvenile Manila clams, and juvenile and mature Dungeness crabs were tested for their dose responses to imidacloprid. There was no consistent treatment effect that would suggest nontarget impact from the use of imidacloprid for burrowing shrimp control in Willapa Bay. PARTICIPANTS: Partners were Chris Grue, U.W.; Brett Dumbauld, USDA/ARS; Steve Booth and Dan Cheney, Pacific Shellfish Institute; Steve Bollens, WSUV, Doug Walsh, WSU; and Vince Hebert, WSU. Organizations: Pacific Shellfish Industry, Willapa Grays Harbor Oyster Growers Association, Pacific Coast Shellfish Growers Association, Washington State Department of Ecology. Training or professional development: A shrimp conference was held annually, and PI attended PSGA and other professional meetings. High school students and college students were hired for summer work experiences. TARGET AUDIENCES: Shellfish growers, state and federal regulatory agencies, Department of Ecology. PROJECT MODIFICATIONS: Nothing significant to report during this reporting period.

Impacts
Loss of the use of carbaryl in 2012 without alternatives will permanently cripple the existing oyster industry in Willapa Bay/Grays Harbor, WA and devastate rural coastal economies already affected by declines in timber, fishing and other resource-based industries. Our research has found both a potential replacement chemistry for carbaryl and a new method of application that minimizes nontarget impact and reduces the rates of insecticide needed to achieve efficacy. Once these findings are fully implemented by the industry in 2011, they will have a dramatic impact on assuring the continued survival of the industry.

Publications

• No publications reported this period

Progress 01/01/08 to 12/31/08

Outputs
OUTPUTS: Forty-seven chemistries were screened, between 2005 and 2007, for efficacy in replacing carbaryl for control of burrowing shrimp. Based on efficacy, ease of application, cost, non-target impact and registration potential, one compound, imidacloprid, was selected as the focus for additional work. Between 2006 and 2008, imidacloprid efficacy was evaluated as a function of rate (0.1 to 4 lbs ai/ac), season of applications (April to October), timing (0.1 to 3 hours exposure prior to tidal flushing), sediment type (sand to silt), eelgrass coverage (none to thick), and application methods (broadcast & subsurface injection. Under most conditions, imidacloprid provided reasonable efficacy at 0.5 lbs ai/ac. Rates higher than that were required when conditions were not favorable for efficacy, such as thick eelgrass. Four sub-surface pesticide delivery systems were made and evaluated between 2005 and 2007: a shanking system, a tine harrow system, and two spikewheel systems. The shanking and tine-harrow systems were problematic in terms of ease of application, calibration, and accuracy. The spikewheel systems provided better accuracy and ease of use. Results from two years of spikewheel application (2007 to 2008), however, have not been consistent enough to be considered commercially viable. Benthic samples were gathered following treatment with alternative insecticides. The impact to the benthic infauna following treatment with alternative compounds, and using alternative delivery systems, was minimal relative to untreated plots. This was according to four indicators of community composition and analysis of the relative ubiquity of individual species, at both 1 and 6 months after treatment. Results provided preliminary data towards a more comprehensive study of imidacloprid. Pacific oyster larvae and juveniles, juvenile Manila clams, juvenile and mature Dungeness crabs, Saddleback Gunnel, Japanese oyster drill, Nereid polychaete, staghorn sculpin and threespine stickleback were tested for their dose response to imidacloprid. There was no consistent treatment effect that would suggest nontarget impacts from the use of imidacloprid for burrowing shrimp control in Willapa Bay. Laboratory and field studies were conducted to modify estuarine sediment, using III Portland cement, quicklime, fly ash, and cement kiln dust additives to eliminate shrimp burrowing. PARTICIPANTS: Brett Dumbauld, USDA/OSU Steve Booth, Pacific Shellfish Institute Chris Grue, University of Washington TARGET AUDIENCES: Shellfish growers and regulatory agencies. PROJECT MODIFICATIONS: Nothing significant to report during this reporting period.

Impacts
Loss of the use of carbaryl in 2012 without alternatives will permanently cripple the existing oyster and hardshell clam industries in Willapa Bay/Grays Harbor and devastate rural coastal economies already affected by declines in timber, fishing and other resource-based industries. Our research has found both a potential replacement chemistry for carbaryl and a new method of application that minimizes non-target impacts and reduces the rates of insecticide needed to achieve efficacy. Once these findings are fully implemented by the industry in 2011, they will have a dramatic impact on assuring the continued survival of the oyster and hardshell clams industries.

Publications

• Patten, K.D. 2008. The use of pesticides to retain the resiliency of estuaries confronted with invasive species; is it justified Pacific Estuary Research Conference. Newport, Oregon. http//www.pers-erf.org/PDF/Program_PERS-08.pdf

Progress 01/01/07 to 12/31/07

Outputs
OUTPUTS: Two alternative harvest systems for burrowing shrimp were developed and evaluated. Neither system, suction extraction or air bubbles, appears to selectively remove shrimp from the sediment. Both were problematic in terms of their application. Without considerablly more development money and effort, it is unlikely that a device can be constructed that will selectively extract burrowing shrimp without also causing considerable damage to the sediment. No additional effort in this area is recommended. Additional expenditures in this line of research would most likely not be fruitful. Efficacy of imidacloprid broadcast applied was assessed across time and conditions. 0.5 lbs ai/ac provided excellent control from May to October when broadcast- applied on bare ground. Efficacy when applied to ground covered by eelgrass was reduced. A barge was built to allow for subsurface spikewheel injection. To deliver uniform rates regardless of rate of travel, we utilized a roller pump attached to a chain drive to a spikewheel. Comparisons of this pumping system to a 12V 5 GPA diaphragm pump were made. Data from the roller pump were not consistent or as efficacious as that we had obtained from a diaphragm pump. Three studies were conducted to evaluate efficacy as a function of wheel spacing. The efficacy of imidacloprid was not reduced going from 6 wheels/6 ft to 4 wheels/6 ft but carbaryl was. The pesticides imidacloprid (0.1 to 0.5 lbs ai/ac), carbaryl (2-8 lbs ai/ac), Pyganic (64 and 128 oz/ac), habanero extract, methoprene, Ecozone and sulfur (20 to 80 lbs ai/ac) were tested with spikewheel injection. Only imidacloprid (0.5 lbs ai/ac) and carbaryl (3-8 lbs ai/ac) provided reasonably consistent efficacy across the test periods and range of conditions tested. The toxicity of imidacloprid to young clams, oysters, fish and crab was evaluated. For small hardshell clams there was no evidence that up to 72 hours exposure to imidacloprid at rates 1000 fold what they might experience for only a few hours (<1 ppm) caused mortality. For oyster larvae two of the studies suggested that imidacloprid could affect oyster larvae at concentrations between 1 ppm and 10 ppm for 1 hour. Additional work should be done to refine the data on risk of oyster larvae from imidacloprid. It is unlikely that the water column where oyster larvae are swimming would be ever be above 0.1 ppm. For fish there was no effect of imidacloprid on Threespine Stickleback or Staghorn sculpin under exposure conditions that would occur in a vernal tide pool. This contrasts to carbaryl which resulted in 89% mortality of stickleback. Juvenile Dungeness crab (2-3" carapace) were not affected by imidacloprid in vernal tide pools, even at rates ten-fold of what they could be normally exposed to. PARTICIPANTS: Jim Durfey TARGET AUDIENCES: Pacific coast shellfish industry

Impacts
Loss of the use of carbaryl in 2012 without alternatives will permanently cripple the existing oyster industry in Willapa Bay/Grays Harbor and devastate rural coastal economies already affected by declines in timber, fishing and other resource-based industries. Our research has found both a potential replacement chemistry for carbaryl and a new method of application that minimizes non-target impact and reduces the rates of insecticide needed to achieve efficacy. Once these findings are fully implemented by the industry in 2011, they will have a dramatic impact on assuring the continued survival of the industry.

Publications

• Patten, K.D. 2007. Shorebird and waterfowl usage of Willapa Bay, Washington, in response to invasive spartina control efforts. Journal of Field Ornithology. 78:395-400.

Progress 01/01/06 to 12/31/06

Outputs
Numerous pesticides were screened in the field for efficacy, using broadcast application or Spikewheel injection from a barge. Only imidacloprid and low rates of carbaryl provided consistent efficacy across different application methods. None of the other products evaluated appeared very promising. Numerous replicated trials were conducted comparing the efficacy of carbaryl in burrowing shrimp control as a function of the duration of time that the tide had pulled off the site. Carbaryl rates masked timing effects. In one study, the main effect of tidal application time was significant; in another study, which was only the 4 lb ai/ac rate, there were no differences. At the low rate of carbaryl, application just as the water is pulling off the tideflat provided the best control. Rate-dependent efficacy of carbaryl was studied on two different types of sediment at two sites. There appeared to be minimal variation in efficacy as a function of sediment type. Sediment cover with eelgrass had a very significant effect on insecticide efficacy, reducing it by 23 to 53% depending on the insecticide and insecticide rate. Averaged across eight separate experiments, carbaryl at 4 lbs ai/ac was least affected by eelgrass cover (23% reduction); both naturally extracted pyrethrins and imidacloprid were the most affected (50% reduction in efficacy). For a given rate of imidacloprid Spikewheel application provided better efficacy than broadcast. Spikewheel injection also provided excellent efficacy when the sediment was covered with eelgrass. For imidacloprid, efficacy was achieved at both the 8" wheel spacing and 16" wheel spacing. Research to find alternative mechanical control methods to harvest shrimp using high volume subsurface air injection or suction were not successful. The predation of mature shrimp in burrows by mature crab was measured and was not significant.

Impacts
Loss of the use of carbaryl in 2012 without alternatives will permanently cripple the existing oyster industry in Willapa Bay/Grays Harbor and devastate rural coastal economies already affected by declines in timber, fishing and other resource-based industries. Our research has found both a potential replacement chemistry for carbaryl and a new method of application that minimizes non-target impact and reduces the rates of insecticide needed to achieve efficacy. Once these findings are fully implemented into the industry, they will have a dramatic impact on assuring the continued survival of the industry. An additional three to four years of work will be required to achieve that end.

Publications

• No publications reported this period

Progress 01/01/05 to 12/31/05

Outputs
Chemical screening: Numerous pesticides were screened in the lab and in the field for efficacy. Lab screening consisted of acute (1 hour) toxicity testing and assessing for mortality after 24 hours. Bifenthrin, cypermethrin, deltamethrin and carbaryl were effective at ultra low rates (0.001 to 0.1 ppm) and natural pyrethrins were effective at 1 ppm. All other products required >500 ppm exposure for mortality or provided no shrimp mortality at all. Pesticides were also screened in the field for their efficacy with subsurface application methods. Treatments were shanked in at the 4-6 ft. depth. Carbaryl and cypermethrin were the most effective compounds tested and the only products that were able to achieve burrow counts below the threshold limit of 10 burrows/m2. Other compounds (natural pyrethrins) looked promising and significantly reduced burrow counts. Chemical control improved efficacy of carbaryl: Our previous studies have indicated that carbaryl efficacy for burrowing shrimp is dependent on sediment type, vegetative cover and dry time. In 2005 we clearly documented that a cover of Japanese eelgrass over a shrimp bed significantly reduced carbaryl efficacy. We conducted several studies on the relationship between dry time and carbaryl efficacy. Results varied considerably by location on the tide flat and there was no clear trend (data not shown). We conducted several studies to evaluate the effects of surfactants and of increasing the density of the spray solution (corn syrup and salt) on carbaryl efficacy. None of our treatments increased carbaryl efficacy. Mechanical control field treatments: We have evaluated compaction methodology for the past two years. The results indicate that this approach, even with multiple crushing events, will not work. In 2005 we obtained our final follow-up data on our large-scale crushing plots. These results confirm previous years data.

Impacts
New options for control were developed, however these will required several years before their impacts will be realized.

Publications

• No publications reported this period

Progress 01/01/04 to 12/31/04

Outputs
We evaluated mechanical and chemical control alternatives for burrowing shrimp in Willapa Bay. Low-risk insecticides for alternative chemical control were screened. Poncho and organic elemental sulfur showed some promise. Shrimp control was linearly related to the rate of carbaryl. The use of stickers did not significantly improve shrimp control using 2# ai/ac of Sevin, although a few products appeared to slightly enhance efficacy. Both Poncho and Sevin were affected by vegetative cover. A large-scale crushing experiment was conducted. There were three sequential crushing events in zones of varying density. Shrimp density was reduced after the first crushing events across all zones. Shrimp density at the end of the season in the medium and high zones never went below a level considered adequate for oyster production. The depth of shrimp in the sediment was monitored as a function of tide and diurnal effects. Average depth was 38 cm. Shrimp were slightly deeper during low tides and during daylight hours. Shrimp burrow density varied slightly during the year, deceasing in January when sediment temperatures were less than <12 C. There was a linear relationship between sinking rate and burrow density for both oyster shells and petri dishes filled with cement. Attempts were made to develop a methodology for removing shrimp using scented surface traps. Although shrimp were occasionally caught, success was rare. We also lead a strategic planning process for the Southwest Washington Shellfish Growers concerning the invasive species that are severely taxing the productivity of oyster beds in Willapa Bay and Grays Harbor. It was concluded that growers are frustrated and anxious over the pace of research progress leading to alternative controls for burrowing shrimp. They are concerned about water quality issues from development in the area, and need more assistance in both packaging and marketing their unique products. Value-added research is needed.

Impacts
Results of these studies will provide future direction for mechanical and chemical control of burrowing shrimp in subsequent years.

Publications

• No publications reported this period