Idaho Department Of Fish And Game Research Articles

Twenty Years of Disk Diffusion Testing Indicate No Meaningful Loss of Antibiotic Susceptibility for Multiple Pathogens Isolated from Hatcheries Operated by the Idaho Department of Fish and Game

AbstractAntibiotic use in animal production, including aquaculture, has become a controversial subject in recent years. It is unclear whether antibiotic use by fish hatcheries or farms is functionally related to the development of resistance in important human pathogens. Nevertheless, antimicrobial resistance is relevant to aquaculture because it may reduce the effectiveness of the limited treatment options available for fish health management. We used linear regression models to explore possible temporal trends in antibiotic susceptibility of several bacterial fish pathogens over a 20‐year period at 12 Idaho Department of Fish and Game (IDFG)‐operated hatcheries. Observed antibiotic susceptibility was variable among hatcheries and among pathogens. Predicted susceptibility was generally unchanged or increased on average over the study period, suggesting no significant loss in susceptibility to the antibiotics tested. Collectively, our results indicate that fish health management, including occasional antibiotic treatment, has not substantively influenced antibiotic susceptibility of pathogens at IDFG‐operated hatcheries.

Two Idaho Chapter AFS Members Die in Helicopter Crash

Danielle JoAnne Schiff, 34, and Lawrence T. Barrett, 47, fisheries biologists with Idaho Department of Fish and Game (IDFG), died in a helicopter crash on August 31, 2010. The helicopter was en rou...

Management of Bacterial Kidney Disease in Chinook Salmon Hatcheries Based on Broodstock Testing by Enzyme‐Linked Immunosorbent Assay: A Multiyear Study

AbstractFrom the mid‐1980s through the early 1990s, outbreaks of bacterial kidney disease (BKD) caused by Renibacterium salmoninarum continued in Chinook salmon Oncorhynchus tshawytscha in Idaho Department of Fish and Game (IDFG) hatcheries despite the use of three control methods: (1) injection of returning adult fish with erythromycin to reduce prespawning BKD mortality and limit vertical transmission of R. salmoninarum, (2) topical disinfection of green eggs with iodophor, and (3) prophylactic treatments of juvenile fish with erythromycin‐medicated feed. In addition, programs to manage BKD through measurement of R. salmoninarum antigen levels in kidney tissues from spawning female Chinook salmon by an enzyme‐linked immunosorbent assay (ELISA) were tested over 13–15 brood years at three IDFG hatcheries. The ELISA results were used for either (1) segregated rearing of progeny from females with high ELISA optical density (OD) values (usually ≥0.25), which are indicative of high R. salmoninarum antigen levels, or (2) culling of eggs from females with high ELISA OD values. The ELISA‐based culling program had the most profound positive effects on the study populations. Mortality of juvenile fish during rearing was significantly lower at each hatchery for brood years derived from culling compared with brood years for which culling was not practiced. The prevalence of R. salmoninarum in juvenile fish, as evidenced by detection of the bacterium in kidney smears by the direct fluorescent antibody test, also decreased significantly at each hatchery. In addition, the proportions of returning adult females with kidney ELISA OD values of 0.25 or more decreased 56–85% for fish reared in brood years during which culling was practiced, whereas the proportions of ELISA‐negative adults increased 55–58%. This management strategy may allow IDFG Chinook salmon hatcheries to reduce or eliminate prophylactic erythromycin‐medicated feed treatments. We recommend using ELISA‐based management of BKD in Chinook salmon hatcheries where it is a concern.

Integrating Conservation Genetic Considerations into Conservation Planning

Abstract Bull trout (Salvelinus confluentus) is a species of conservation concern–listed as “threatened” under the Endangered Species Act–throughout its native range in the western United States. The authors were assembled by the Clark Fork River Aquatic Implementation Team, composed of biologists representing Montana Fish, Wildlife and Parks (MFWP); Idaho Department of Fish and Game (IDFG); and Avista Corporation, to provide a conservation genetics perspective and to assist those managers charged with stewardship of the bull trout populations occupying the Lake Pend Oreille (ID)–Iower Clark Fork River (ID, MT) drainage. More specifically, we were asked to assess the risks to bull trout from alternative conservation strategies and to recommend a plan of action aimed at promoting the species' long-term viability and functional recovery. We describe here a case study of one application of the expert advisory panel approach within the context of a restoration program and of the underlying perspectives this p...