Conservation Aquaculture (Re-building small populations)
The chips are down for burbot, a freshwater cod, in northern Idaho’s Kootenai River.

University of Idaho aquaculture expert Ken Cain wants to learn how to raise burbot in captivity to help restore their fortunes through a project funded by the Kootenai Tribe of Idaho. Cain’s team of researchers at the UI Aquaculture Research Institute and the Department of Fish and Wildlife received $45,000 from the tribe to begin developing spawning and feeding techniques for the fish. Tribal leaders want to apply Cain’s findings to conserve and restore populations of burbot, a coldwater fish found in northern Idaho’s Kootenai River. The tribe helped lead efforts to restore the river’s white sturgeon as well. Burbot once provided a valuable tribal, sport, and commercial fishery in the Kootenai River. In recent years biologists documented dramatic declines of the burbot population.
Overfishing, habitat destruction, and altered water flows and temperatures following construction of Libby Dam in 1972 are implicated as factors. Belgian researchers hope to establish a similar burbot conservation program. Resolution of the problem will take time, Cain said. “This research addresses many unknown questions,” he said. “Nobody in the U.S. has cultured this species before and only limited information on the biology of this species is available.” UI scientists are adapting techniques recently developed to culture marine cod. The Kootenai Tribe hopes to implement a conservation aquaculture program for burbot similar to the white sturgeon program begun in the early 1990s.

In January of 2004, 20 adult burbot collected from Canada’s Duncan River at the north end of Kootenay Lake, B.C., were transferred to UI tanks The chilled 35-degree water is recirculated and mimics the burbot’s natural spawning requirements. Lighting in the lab also mimics spawning-season day length. Ultrasound exams showed 13 were females, which were then divided into three treatment groups. Burbot in two groups were injected or implanted with small amounts of hormones. Male burbot play their part by fertilizing the eggs. Cain’s team is also working to freeze sperm in case burbot numbers continue to dwindle and they are unable to catch adult male fish in the future. Cain said all 13 females have spawned, adding, “We have now met our first goal, which was to fertilize and incubate the eggs.” The eggs are only about as thick as a grain of rice, and females can spawn up to three million of them. The team is testing several different types of incubators and will soon shift focus to rearing larval and juvenile fish.

Our second goal is to begin feeding larval fish and show that we can get them to a size large enough for tagging, which would be important for a program that releases captive-reared fish into the wild,” Cain said. The researchers hope to eventually write a technical manual about how to implement a burbot conservation program at tribal facilities in Bonners Ferry. “In addition to conservation aquaculture, the long-term implications for commercial foodfish aquaculture are pretty high,” Cain said. “If we can successfully rear this freshwater cod, there is the potential to produce this species for food as well.”

As a PhD candidate in the Department of Fish and Wildlife at the College of Natural Resources, John Drennen's research is focused on transmission, diagnostics, and immunity of white sturgeon iridovirus (WSIV).  This virus appears to be endemic in most wild white sturgeon populations in the Pacific Northwest and is a threat to conservation aquaculture programs involved in re-establishing endangered populations, such as the Kootenai River white sturgeon.   This virus also limits the success of commercial farming operations that grow these fish for meat and caviar production.   Little is known about this host-pathogen relationship.  However, his research is providing useful information on stocking densities to minimize WSIV disease epizootics, non-lethal sampling approaches to identify infected individuals, how this virus is transmitted within the environment, and the immune response of white sturgeon against this virus for possible vaccination strategies.  John’s research has been directly funded by the Kootenai Tribe of Idaho (KTOI) and Bonneville Power Administration and should be completed by May 2006.  John’s major Professor is Dr. Ken Cain who leads the department’s interest in the continued collaborative efforts with the KTOI.