Ask the Conservation Officer (CO)

by Gary Hompland, Regional Conservation Officer Question: "I was talking to a fellow angler about the markings to determine cutthroat trout from other species. We both thought the red slashes along the bottom of the jaw or "throat" was the most definitive markings. Now I'm hearing that is not true. Can you clear this up for us, how do you identify a cutthroat trout from a cutthroat hybrid?" Answer: As it turns out you are not alone. The current fishing rules brochure has a pretty good discussion in the fish identification section. Cutthroat trout are the state fish of Idaho and populations throughout the state appear to be declining from historical levels. This could be due to hybridization with rainbow trout and habitat degradation. In areas we have historically stocked fertile hatchery catchable rainbow trout there has been some concern about hybridization. In other areas the Department historically produced and stocked cutthroat hybrids in hatcheries to support sport fisheries. Stocking of hybrids in areas where they may impact pure cutthroat populations ceased several years ago. Hatchery rainbow trout produced in Department hatcheries use pressure and heat at egg fertilization to produce sterile hatchery catchables. The sterile fish prevent any potential for hybridization with cutthroat trout. Special rules and bag limits for cutthroat and cutthroat trout hybrids apply throughout Idaho. While reduced bag limits apply to cutthroat trout, cutthroat hybrids are considered similar to rainbow trout. In order to comply with reduced cutthroat trout bag limits an angler must be able to identify cutthroat trout from cutthroat hybrid trout. Cutthroat hybrids exhibit many of the characteristics of both cutthroat and rainbow trout. They both possess the red slashes on the underside of the jaw. Both rainbow and cutthroat hybrids tend to be spotted evenly from the head to the tail, above and below the lateral line. One difference is hybrids in the Snake River have conspicuous white fin tips. The Yellowstone cutthroat that occupies the Snake River drainage has spots concentrated near the tail and above the lateral line. Its color can be variable but its sides may be yellow brown with red or pink along the belly. The color of the back ranges from steel gray to olive green. For management plans to successfully improve cutthroat trout populations, anglers must be able to identify cutthroat trout from all the other trout species. 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.