Location: Forage Seed and Cereal Research2013 Annual Report
1a. Objectives (from AD-416):
Objective 1: Develop effective population control strategies for burrowing shrimp utilizing data on age structure, larval recruitment, and movement of these pests and establish protocols for identifying sources of juvenile mortality that constrain oyster aquaculture production in West Coast estuaries. Sub-objective 1.1. Determine whether annual recruitment patterns affect population dynamics of burrowing shrimp populations in West Coast estuaries and apply this to control strategies for oyster culture. Sub-objective 1.2. Evaluate the utility of imadocloprid and selected biological control measures to control newly recruited juvenile shrimp. Sub-objective 1.3. Quantify selected causes of mortality of juvenile oysters at a landscape scale in Willapa Bay, Washington. Develop a field protocol for evaluating juvenile oyster mortality and test the protocol in additional estuaries. Objective 2: Quantify utilization of eelgrass, shellfish, and burrowing shrimp dominated habitat by fish and invertebrates at the estuarine landscape scale and quantify the influence of shellfish aquaculture practices on existing estuarine habitats. Sub-objective 2.1. Quantify fish and invertebrate use of intertidal habitats including oyster aquaculture in Willapa Bay, Washington and evaluate the functional value of these habitats for juvenile English sole. Sub-objective 2.2. Quantify the effects of oyster aquaculture on aquatic vegetation and utilize habitat maps to examine this interaction at the estuarine landscape scale and over inter-annual time frames.
1b. Approach (from AD-416):
Conduct research in marine/estuarine ecology to develop new and sustainable approaches to controlling bivalve shellfish pests and predators such as burrowing shrimp, crab, and drills. Using a systems approach, examine key aquaculture management practices and their impacts on ecological components of complex, dynamic estuarine environments. Establish a clear understanding of the life history, ecology and biology of key pests and predators that impact survival and production of shellfish. Identify and evaluate potential control agents for efficacy in controlling these pests in an integrated pest management system. Develop a multidisciplinary approach in collaboration with USDA ARS, Oregon State University, and EPA scientists located at the Hatfield Marine Sciences Center, Newport, OR, and elsewhere as needed. Work with outreach and extension personnel groups to transfer technology to shellfish growers. FY03 Program Increase $223,537. 1 SY. FY04 Program Increase $120,783. Replacing 5358-63000-001-00D (7/05). Replacing 5358-63000-002-00D (11/09).
3. Progress Report:
Substantial progress has been made on Objective 1. Survey results revealed that populations of two species of burrowing shrimp are declining in estuaries along the US West coast. These shrimp act as pests and cause substantial problems for the shellfish aquaculture industry. Results also suggest that shrimp abundance is directly linked to inter-annual variation in recruitment, since shrimp larvae are flushed from and then must return to these estuaries from the coastal ocean. Substantial recruitment of ghost and mud shrimp occurred to Oregon estuaries in 2010 and 2011 respectively, but not to our long term monitoring sites in Washington estuaries. Recruitment patterns were reversed in 2012 with fairly substantial recruitment of ghost shrimp to Willapa Bay and lower levels in Oregon estuaries. We are actively working with the integrated pest management coordinator hired by the shellfish industry to establish an industry program to track shrimp recruitment to Willapa Bay. Although to date, we have been unable to directly relate recruitment patterns to ocean conditions, we are actively pursuing this research and it is already clear that the shellfish industry will experience years when it is more critical to control shrimp than others. This type of information can be incorporated into integrated pest management plans to maintain sustainable aquaculture activities in these estuaries. A tool for consistently measuring juvenile oyster survival and growth was developed and tested in Willapa Bay. We observed a gradient in both growth and mortality from the mouth to the head of the estuary and a significant difference between oysters deployed off and on-bottom due to siltation and predation. Substantial progress is also being made towards Objective 2. Results of surveys conducted with underwater video and fish traps suggest that most fish including juvenile English sole, shiner perch, and sculpins are found in greater abundance in structured intertidal habitats (both eelgrass and oyster aquaculture) than in open unstructured mudflat. Abundance is also higher during daytime flood tides. Experiments to examine mortality of juvenile English sole in these three intertidal habitats revealed that predation pressure was high in all three habitats with staghorn sculpin and crabs being the dominant predators. We have quantified the spatial extent of both aquaculture and eelgrass habitats in Willapa Bay in order to extend these results to the estuarine landscape scale. Since eelgrass is widely viewed as essential nursery habitat for commercially valuable fish like English sole and salmon, this research will be useful for permitting decisions regarding both current and proposed expansion of sustainable aquaculture operations in West Coast estuaries.
1. Burrowing Shrimp Recruitment Monitoring Tool. The burrowing activities of two species of shrimp cause shellfish to sink under the mud and die in West Coast estuaries. The aquaculture industry has addressed this problem by annually treating some of their beds with a pesticide, but are searching for alternative control measures and attempting to implement an integrated pest management program. ARS researchers in Newport, Oregon, discovered that shrimp population abundance can be traced to distinct years when shrimp pelagic larvae recruit to each estuary. Although it is not yet clear what influences inter-annual trends in mortality and abundance of these larvae, their abundance after settlement can be used to forecast the need for treatment of older shrimp on aquaculture beds, since the researchers have also documented little movement of larger adult shrimp from place to place. This accomplishment will enable researchers and producers to develop simple monitoring techniques that can be used to track recruitment and be adopted in their integrated pest management program.