Fish escape prompts worry about disease

The Fish Site
by The Fish Site
15 May 2006, at 1:00am

OKLAHOMA - State biologists said Friday that 60 adult winter steelhead being held as broodstock at Cole Rivers Hatchery recently escaped a holding pond where they were placed after other fish from the same pond tested positive for a virus. Cole Rivers is about 30 miles northeast of Medford on the Rogue River. Infectious hematopoietic necrosis virus is common to native fish populations in the Rogue River system. The problem occurred when dam boards that were placed to help regulate water levels in the hatchery pond and block fish movement floated up enough to allow the fish to escape. Adult steelhead entered the hatchery water supply lines, creating a concern that other fish in the hatchery could be exposed to IHNV. More than half the steelhead have been recovered, and hatchery staff members continue working to complete the recovery. The fish tested positive for IHNV during routine fish health testing but were not sick or dying from the virus. Hatchery officials are working to determine if IHNV was spread elsewhere in the hatchery and are making structural changes to prevent future escapes. "We are seeing no signs that the hatchery fish are infected with IHNV, but because they have been exposed, we must take steps to recognize the potential risks and protect both wild and hatchery fish stocks," said Dan Van Dyke, a district fish biologist. Source: Statesman Journal