Location: Aquatic Animal Health Research
Project Number: 6420-32000-024-13
Start Date: Aug 01, 2010
End Date: Jul 31, 2015
The Rathbun Fish Hatchery (RFH) produces 200,000 walleye fingerlings (200 mm or larger) for sport fisheries. These fish are produced in a three-phase culture system, corresponding to Phase 1: pond culture of 3 day post hatch fry to 30 days post hatch, final size 45 mm; Phase 2: tank habituation of fingerlings to feed which lasts 30 days, final size 90 mm; and Phase 3: outdoor grow out of fingerlings which lasts 90 days, final size 200 to 250 mm. Columnaris disease, caused by F. columnare, commonly occurs during Phase II culture but also during Phase III. The experimental approach for the first year of study is as follows: At 3 days post hatch (dph), groups of 5000 fry will be vaccinated or sham-vaccinated in triplicate and stocked into ponds for Phase 1 culture. At approximately 30 dph, ponds will be harvested for Phase 2 culture. At pond harvest, each pond will be split into two groups of fingerlings. One group will be sham vaccinated, and the other will be vaccinated. The treatments will consist of: 1. Fry sham vaccinated, fingerling sham vaccinated. (3 replicates) 2. Fry sham vaccinated, fingerlings vaccinated. (3 replicates) 3. Fry vaccinated, fingerling sham vaccinated (3 replicates) 4. Fry vaccinated, fingerlings vaccinated. (3 replicates) For Phase 3 culture, fish will be maintained in the above treatment groups. Several performance variables will be collected to assess the efficacy of the vaccine, including: mortality related to F. columnare (identified by microscope and by re-isolation of F. columnare from kidney samples), survival of walleye at the end of Phase 2 and 3 culture, and growth of walleye at the end of each culture phase. Additionally, blood samples will be collected at the end of Phase 1 culture and at one or more sampling periods during Phase 2 and Phase 3 culture to determine if walleye generated a specific antibody response following vaccination. Pending the results of the first year of study, the research approach will be modified as necessary.