Biologists with the Idaho Department of Fish and Game (IDFG) and Coeur d’Alene Tribe are resuming efforts to give cutthroat trout a better chance of survival in Coeur d’Alene Lake.
The goal is to remove northern pike from Windy Bay while cutthroat trout are migrating to reduce the occurrence of northern pike preying on the trout before they have a chance to spawn in Lake Creek, which enters the lake in Windy Bay. As in the previous two years, pike in Windy Bay will be caught with gill nets, transported, then released in Cougar Bay where pike are less likely to prey on native cutthroat trout and are more readily available to anglers. Transport of fish will continue until catch rates in Windy Bay decline to the point where it is no longer cost effective.
“The idea is to reduce the threat to cutthroat trout, while creating more opportunities for anglers to fish for and catch pike in other parts of the lake,” said Andy Dux, Regional Fishery Manager for IDFG. Both the Tribal and IDFG fishery management plans place a priority on cutthroat trout conservation. IDFG’s plan also calls for providing diverse recreational fishing opportunities in Coeur d’Alene Lake.
Biologists will begin sampling next week. They are interested to see if pike previously tagged and released in Cougar Bay have returned to Windy Bay. The hope is that the pike have remained on the north end of the lake where fishing pressure is high. At the end of the three-year project, the findings will help to determine if this strategy can be used to reduce the predation threat on cutthroat trout in Windy Bay into the future.
The project has produced encouraging results so far. In 2015, fisheries staff captured 311 northern pike in Windy Bay over a 7 week period. In 2016, just 161 were removed.
“It’s gotten much more difficult to catch pike in Windy Bay, so this leads us to believe that the vast majority of pike in the bay have been removed,” said Angelo Vitale, Fisheries Program Manager for the Coeur d’Alene Tribe.
Since the project started, approximately 74% (345 total fish) of the captured fish survived and were transported to Cougar Bay. By-catch of other fishes, including cutthroat trout, has been minimal.
In order to examine information regarding movement patterns and harvest rates by anglers, staff tagged all fish before releasing them. Tag returns provided an estimated harvest rate by anglers of 34% in 2015 and 17% in 2016, meaning that anglers have caught a fair number of the transported fish. Importantly, most of the fish were caught near Cougar Bay and less than 1% have been documented moving back to Windy Bay.
Biologists with the Tribe are monitoring the number of cutthroat returning to spawn in Lake Creek. They are hopeful that the run size will see a boost following two years of reduced predation in the lake. “Cutthroat generally spend two to three years in the lake before they spawn, so we hope we start to see a return on our investment of time and effort beginning this year,” said Vitale. In recent years, cutthroat numbers in Lake Creek have averaged around 300 spawning adults and as many as 8,000 juveniles that move between the stream and lake each year.