Location: Dairy Forage Research2009 Annual Report
1a. Objectives (from AD-416)
The yellow perch (Perca flavescens) is an important social and economic species in the Great Lakes; however, populations have plummeted. Given strong consumer demand, and high (historically) fillet value ($12.00/lb.- $15.00/lb retail), there is an urgent need to develop a sustainable yellow perch aquaculture industry that can deliver a high-quality cultivar year-round. Due to strong consumer demand, research efforts will focus on improving yellow perch production using state-of-the-art genetic and physiological approaches. Our long-term goal is to produce a genetically defined broodstock of yellow perch that will enable development of superior germplasm for release to stakeholders. Initial efforts for this project plan have yielded genetic information on genetic structure among various U.S. perch populations, and have identified new genes and genetic sequences that have been used to 1) direct genetic selection to improve cultivar traits, and 2) be used for pedigree tracking to further improve/support future selective breeding efforts. The new technologies and resources that are developed from this program will continue to support innovation and improvement in perch aquaculture. An additional component of study in this SCA stems from the recent emergence of viral hemorrhagic septicemia virus (VHSV) in the Great Lakes region of North America that has led to dramatic multi-species epidemics. The virus has been isolated from over 25 Great Lakes fish species. This disease poses a serious threat to yellow perch production in this region and to the scientific efforts of the ARS-GLWI program. Additional work is needed to maintain pathogen-free stocks of cultured yellow perch. To accomplish this, it is necessary to develop a disease-challenge model to understand the infection and virulence of VHSV in yellow perch and develop rapid methods for detection of VHSV in this species.
1b. Approach (from AD-416)
The aquaculture “tool box” for yellow perch early life stage production has been established, however several parameters need additional research to advance the technology and make it more cost-effective. The aims (outlined below) of this work is to test commercially-available micro-diets as substitutes for the food constituents presently used, which include Green Tank Water (GTW), Brine Shrimp Nauplii (BSN), and Beef Liver and Heart mixture (BLHM). The goal of the proposed research is to reduce the cost of the first-feeding technology and improve survival of yellow perch. Aim 1: Improve survival & quality of first feeding larvae by reducing dependence upon “Green Tank Water”. Introduce fish starter diets within the first-feeding window (1-2 days post hatch). The aim is to decrease dependence on the use of processed mammalian tissue diets, such as beef liver and heart. Diets will be progressively replaced with available commercial larval starter diets. Aim 2: Evaluate performance measures of genetically-defined broodstock progeny (first-feeding, swim bladder inflation, development, survival and growth and condition) that are reared under either a control dietary regimen or substituted dietary regimens. Aim 3. Continue development of genetically defined perch broodstock: The top 25-35% performing fish/strains (from the performance trial performed in 2007) have been separated, pit-tagged, and genotyped with appropriate microsatellites for a particular strain. These fish have been held (2008-2009) under photoperiod and temperature cycling to mimic their geographic origin and have begun to spawn (February-March 2009). One strain has already spawned and parental crosses performed in February 2009. These new fish will undergo another 12-month performance trial and will be sampled for tissues for deep sequencing and microarray analyses to identify biochemical pathways associated with fast growth. Aim 4. Expressed sequence tag and microsatellite development: The new larval perch library has been developed and test sequenced. This past year the techniques were worked out to produce primary cell culture of granulocytes (presumably macrophages) from the perch head kidney and a cDNA library has been made from plated perch macrophages stimulated with LPS. EST clones from this library will be sequenced for immune gene discovery needed to characterize the innate immune system in yellow perch. We will continue to mine all of the ESTs from all libraries for microsatellites and for SNPs which will add genotyping capabilities. For microsatellites, we will test new ones to determine their appropriateness for use in pedigree tracking. Overall, greater than 25,000 ESTs clones have been sequenced and annotated and this work will continue.
3. Progress Report
This project is a continuation of project number 3655-31320-001-01S, which terminated on April 30, 2009. This is a new project and, as yet, there are no results to report. However, we have established an inter-agency agreement with the U.S. Geological Survey, Western Fisheries Research Center, Seattle, WA, to develop a disease-challenge model to characterize the disease process in yellow perch infected with the Midwest strain of viral hemorrhagic septicemia virus (VHSV). To facilitate this, we have sent fish from our three yellow perch broodstock strains for disease-challenge trials. Following exposure to VHSV, tissue samples will be collected from surviving and non-surviving fish to characterize the disease pathology in yellow perch. In addition, survivors and non-survivors from the disease trials will be genotyped to determine their pedigree and identify strains/families which show greater resistance to this disease.