Ask the Conservation Officer (CO)

by Gary Hompland, Regional Conservation Officer Question: "I used to fish for walleye at Salmon Falls Creek Reservoir. How are they doing lately?" Answer: The walleye population in Salmon Falls Creek Reservoir is doing well. You may have missed it in the news, but earlier this year Mark Abel of Sun Valley caught a new Idaho walleye record (17.6 pounds) at Salmon Falls Creek Reservoir. Biologists and walleye club volunteers spent a considerable amount of time this summer sampling various locations of the reservoir with nets to examine the walleye population. Biologists were striving to sample across all age classes of fish to examine overall population health. In a second sampling effort young-of-the-year walleye were collected using electro-fishing equipment. These young-of-the-year walleye are marked in the hatchery using oxytetracycline (OTC). The OTC discolors small bones called otoliths located behind the gill covers in the head of a hatchery produced walleye. The otoliths are removed from young of the year walleye captured using electro-fishing gear. When "read" by experts, the otoliths of the hatchery fish treated with OTC fluoresce under a black light. Biologists use OTC to identify fish of hatchery origin. OTC is used because it is an efficient method of marking large numbers of walleye fry, it is undetectable by anglers, causes the fish no harm, and is long lasting. Comparing OTC marked hatchery walleye to walleye without OTC marks biologists can evaluate the Department's walleye hatchery stocking program. If the percentage of hatchery young of the year fish to wild young of the year walleye is high, then biologists know the stocking program is important in supporting the walleye fishery. Biologists are just beginning to get results of the hatchery walleye evaluation. The use of OTC marked hatchery walleye fry is expected to continue for several more years. If you have any further questions you may call the Magic Valley Regional Office of the Idaho Department of Fish and Game at (208)324-4350 or e-mail us at the Fish and Game web site at http://fishandgame.idaho.gov.