Idaho has about 120 fish species within its lakes, streams, and reservoirs. Of those, only about 40 species are native, meaning they were in Idaho naturally. The remaining 80-plus species were intentionally introduced, mostly to provide recreational fishing opportunities. Managing these fisheries means balancing recreational angling with the conservation of native fish.
Native fish in Idaho - Chinook salmon, steelhead, cutthroat trout, and sturgeon, amongst others - support some of the state’s most popular fisheries. Introduced fish have created many outstanding and extremely popular fisheries, as well. Unfortunately, through predation, competition, or hybridization, introduced fish sometimes cause serious problems for native fish populations. In those cases, fishery managers are faced with the challenge of balancing native fish conservation with non-native sport fishing opportunities.
Though we may tend to think these challenges are relatively new, our predecessors recognized them years ago. The first Statewide Fishery Management Plan was created in 1981, marking the first time statewide policy regarding native and non-native fish management was established. Not only did the plan acknowledge the potential conflicts between native species and non-native sport fisheries, it emphasized the importance of native fish conservation, establishing a statewide policy that stated, “nonnative salmonids and warmwater game fish will not be introduced into waters where they adversely affect goals and objectives set for native, coldwater or anadromous programs.”
Idaho citizens hold wide ranging values and opinions about whether native fish or recreational fisheries should take priority, so it’s not surprising that thirty-three years later, fishery managers and policy makers still work to strike an appropriate balance. Fortunately, a better understanding of native fish distribution, innovative management techniques and fishing regulations have helped insure popular recreational fisheries don’t come at the expense of native fish populations.
One recent development helping minimize the risk of non-native fish is the production of sterile fish. Cutthroat trout, Idaho’s state fish, are native to many lakes and rivers throughout the state. Because they are closely related to rainbow trout, the two species can easily cross-breed, or hybridize, damaging or even eliminating genetically pure cutthroat populations. By stocking rainbow trout that can’t reproduce, managers insure hatchery raised rainbows won’t crossbreed with their wild cousins. Virtually all rainbow trout stocked in Idaho where wild cutthroat exist are now sterile.
Another benefit to using sterile fish is the assurance introduced populations can’t reproduce and take over a water body. Because sterile fish populations are entirely dependent on stocking, their numbers are controlled by fishery managers, and the decision to stock them is ultimately reversible. Sterile tiger muskies, lake trout, brook trout, and grass carp have all been stocked into Idaho lakes and ponds to provide fishing opportunities (or control vegetation in the case of grass carp) without the risk of reproduction.
Catch-and-release regulations are another management tool for supporting many native fish populations. For example, sturgeon, wild salmon, and cutthroat trout became scarce in many areas where angling effort was high. Catch-and-release regulations has helped restore populations and fishing opportunity.
While eliminating harvest has pleased many anglers, others enjoy a fish dinner. One way of providing harvest opportunity for trout without harming native fish populations is the use of “catch-out ponds.” Historically, hatchery trout were stocked into many streams to supplement the population and provide harvest opportunity. Time has shown the vast majority of trout stocked into streams are never caught by anglers. For that reason, IDFG stocks trout into ponds, often adjacent to wild trout streams. Though not a strategy for fish like sturgeon, these catch-out ponds are one way to meet diverse angler demands, providing trout harvest opportunities without overharvesting wild, native populations
Finally, there are times when non-native fish threaten to eliminate important native fish populations and we simply can’t have both. In those cases, aggressive control of a non-native fish population may be the only answer. Lake Pend Oreille is one such example.
Idaho’s largest and deepest lake, Pend Oreille once provided the most productive fishery in the state and had produced world record bull and rainbow trout. The fishery was based on kokanee salmon, trophy rainbow trout, and native cutthroat and bull trout. While not native to Pend Oreille, kokanee had become the primary food source for native bull trout. Unfortunately, a non-native population of lake trout began to take over the lake in the late 1990’s threatening the well-balanced fishery.
In response to the dramatic declines in kokanee abundance and the threat to native bull and cutthroat trout due to lake trout, a large-scale suppression effort was initiated in 2006. The two-pronged effort included a financial incentive to encourage anglers to harvest lake trout, and an extensive netting effort to remove lake trout. After eight years of suppressing the lake trout population, it has been reduced by approximately 80 percent. Kokanee populations have come roaring back, allowing IDFG to re-open the kokanee fishery in 2013. Through effective control of non-native lake trout, not only have the kokanee and trophy rainbow trout fisheries been restored, but the future of native cutthroat and bull trout is secure.
Idaho Fish and Game’s formal policy for managing native and non-native fish began in 1981 with the first statewide fishery management plan, and it has been evolving ever since. Policies are reflections of societal values. As long as public values are diverse and changing, policies will continue to be modified and adjusted. One thing seems fairly certain -- IDFG will continue to use technology, innovative management approaches, and public input to balance native fish conservation with recreational angling long into the future.