Fish like carp, yellow perch, suckers, shiners, sunfish and even certain game fish can severely affect a sport fishery. So, when people move live fish from one body of water to another, the future of their own fishing is at stake. Some of the earliest fisheries management in the United States centered around the introduction of game fish. Those introduced trout are the foundation for Montana's internationally famous fishing. Our waters have also been planted with northern pike, walleye, bass, crappie, sunfish, golden trout, salmon, yellow perch and carp, among others.
Some introductions are planned management plants that benefit certain waters.
But sometimes anglers have illegally introduced species by using live bait, dumping bait buckets, and even intentionally stocking rivers and lakes. One example of a drastic change caused by an introduction is that of the Mysis shrimp into Flathead Lake which caused the collapse of the kokanee fishery in the lake, in addition to the potential for other, unknown changes. You can be arrested and fined for any such activity in the state of Montana. There are important reasons for this law. The result is less fishing opportunity and higher costs for anglers.