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United States Department of Agriculture

Agricultural Research Service

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Research Project: Quantifying Habitat Utilization and Reducing Juvenile Oyster Mortality in Pacific Shellfish Production

Location: Forage Seed and Cereal Research

2012 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, Oregon, and elsewhere as needed. Work with outreach and extension personnel groups to transfer technology to shellfish growers.


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 in Oregon, estuaries in 2010 and 2011 respectively, but not in our long term monitoring sites in Washington estuaries. Recruitment appears to be lower again in 2012, but we were alerted to and, in collaboration with the integrated pest management coordinator hired by the industry, documented the presence of two year old ghost shrimp (2010 recruits) outside our monitoring location in Willapa Bay. Although we have been unable to directly relate recruitment patterns to ocean conditions, this research suggests that the industry should continue to monitor shrimp recruitment because it relates directly to the abundance of older shrimp and that they 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. 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. No detectable difference however was observed in crab abundance between structured and unstructured habitats or day and night flood tides. Experiments to examine growth and mortality of juvenile English sole in these three intertidal habitats are underway and we have quantified the spatial extent of aquaculture and eelgrass in Willapa Bay. Since eelgrass is widely viewed as essential nursery habitat for commercially valuable fish like English sole, this research will be useful for permitting decisions regarding both current and proposed expansion of sustainable aquaculture operations in West Coast estuaries.


4.Accomplishments
1. Burrowing shrimp population assessments. Two species of burrowing shrimp cause significant problems for the U.S. West coast shellfish aquaculture industry and growers in Washington state have used a pesticide to control them for 60 years. The industry is currently seeking alternative control measures as part of an integrated pest management program. ARS researchers in Newport, Oregon, implemented an annual monitoring program in several estuaries in 2005 and mapped the distribution of these shrimp in large portions of two estuaries from 2006 – 2012. Results indicate that populations of both species have declined markedly over this 6 year period and that these declines are tied to inter-annual fluctuations in larval recruitment. ARS researchers are collaborating with colleagues at Oregon State University to further define mortality sources and potentially predict population trends and working with industry to incorporate this information directly into integrated pest management plans to sustain aquaculture activities in these estuaries.


Review Publications
Coen, L.D., Dumbauld, B.R., Judge, M.L. 2011. Expanding shellfish aquaculture: A review of the ecological services provided by and impacts of native and cultured bivalves in shellfish dominated ecosystems. In: Shumway, S.E. editor. Shellfish Aquaculture and the Environment. Hoboken, NJ: Wiley-Blackwell. p. 239-318.

Last Modified: 9/10/2014
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