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Abstracts
Workgroup: Genetics and Oyster Populations
Breeding and Evaluation of Oyster (Crassostrea virginica) Strains Selected for Resistance to MSX, Dermo and JOD
Principal Investigator(s):
Ximing Guo, Rutgers Universit, xguo@vertigo.hsrl.rutgers.edu
Co-Investigator(s):
Susan Ford, Rutgers University; Gregory DeBrosse, Rutgers University; Roxanna Smolowitz, Marine Biological Lab
Funding Period: 10/1/99-9/30/01
The Northeastern region has a major oyster aquaculture industry that is seriously threatened by three diseases: MSX, Dermo and JOD. We proposed to produce and evaluate the Rutgers NEH strain (selected for MSX- and Dermo-resistance), Flower's FMF strain (selected for JOD), their hybrids, along with a global control (ME, susceptible, from Maine ) and local controls that would normally be used by the participating growers. The goal of this study was to breed and evaluate oyster strains for disease resistances and superior growth, and to identify the best performing strain for the NE oyster industry.
The first four groups, NE1-4, were produced at the Rutgers's Cape Shore Facility in June 2000. For each group, two bags of two thousand seed each were deployed at four sites in July 2000: Cotuit Harbor in MA, Milford in CT, Cape Shore and Cape May in NJ. Oysters are cultured in on-bottom or suspended cages. In addition to monthly checks, experimental oysters were sampled five times: 09/00, 12/00, 03/01, 05/01 and 08/01. At each sampling, thirty oysters from each replicate (60/group) were taken for disease analysis and size measurements. No significant levels of JOD were detected. Infection by MSX and Dermo was evident at all four sites. The oysters were about 15 months old as of September 2001, and there was no major mortality due to infection by MSX and Dermo. The disease-caused mortality is expected to start in late 2001 and peak in fall of 2002. Analysis of size data revealed considerable heterosis in growth. The hybrid group (HYB) was larger than both parental stocks by 9 - 19% in shell height and 21 - 40% in total body weight. This project is funded for a third year, and evaluation will continue.
IMPACTS and/or BENEFITS:
Rutgers strains have shown strong resistance to MSX and recently some resistance to Dermo, but not been exposed to JOD. The FMF strain has shown superior growth and markedly improved survival in the face of JOD, but not much resistance to MSX and perhaps neither to Dermo. The hybrids may combine disease-resistance and superior growth from the two selected strains. This study covers the first two years of a three-year project, and most of the disease-inflicted mortality has not occurred. The oysters are only about 15 months old, and it is still too early to make any conclusions. Results so far suggest that the hybrid strain may exhibit heterosis in growth. Fast growth reduces not only culture duration and cost, but also exposure to mortalities. The project is on-going, and oysters will be evaluated to 27 months of age.
PROJECT PUBLICATIONS: (on-going)
Guo, X., S. Ford, G. DeBrosse and R. Smolowitz, 2000. Breeding for a superior eastern oyster for the Northeastern region. J. Shellfish Res., 19(1):572. (abstract)
Guo, X. and J. Kraeuter, 2000. Aquaculture and breeding technology. The Jersey Shoreline, 19(3):1-4.
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