Biologists with the Coeur d’Alene Tribe, in cooperation with Idaho Department of Fish And Game, were to resume gill netting efforts this week in Lake Coeur d’Alene to reduce pike predation on native, lake-run cutthroat trout in select areas.
The aim is to reduce northern pike numbers in Windy Bay, Benewah, Chatcolet, Round and Hidden Lakes.
Netting in 2020 is scheduled to occur from this week to May 24 and Oct. 1 to Nov. 31. In order to minimize impacts to recreational anglers, netting is suspended all weekends and during the summer from Memorial Day weekend through September.
Spring netting targets shallow, shoreline habitat where pike prefer to spawn. Fall netting is used primarily to monitor the pike population response.
Northern pike were illegally introduced in Lake Coeur d’Alene during the 1970’s. In the spring, pike congregate in shallow areas to spawn, including near the mouths of tributaries where migratory westslope cutthroat trout must pass in order to spawn in streams. This creates a “predator trap” that is believed to reduce cutthroat populations in some watersheds.
Fish and Game biologists work closely with the Tribe to ensure there are no impacts to other gamefish populations, such as the popular largemouth bass fishery. Largemouth bass made up just over 7% of the total catch in 2019 and 83% were released alive.
“Bass mortality was low and netting modifications were made that should lead to even less mortality this year. As a result, we are optimistic that the bass fishery won’t suffer from pike removal,” said Andy Dux, Regional Fishery Manager for Fish and Game.
Fish and Game biologists conducted a bass survey on Chatcolet and Benewah lakes last year. That survey will be repeated in the future to monitor how bass respond to pike removal.
Biologists are starting to see positive results for cutthroat trout in Lake Creek, the main tributary to Windy Bay where pike suppression efforts began in 2015. Nearly 500 adult cutthroat ascended Lake Creek in 2019, the largest spawning run observed in more than 20 years.
Jon Firehammer, fisheries research biologist for the Coeur d’Alene Tribe, reported that cutthroat returned to the Lake Creek watershed at rates four times higher compared to the ten years prior to the start of the suppression program. “These responses are undoubtedly due to a reduction in predation and a more favorable environment in the lake for cutthroat,” Firehammer said. Consistently higher rates of survival are projected to rebuild the population of cutthroat in the watershed.
Netting was expanded to Benewah, Chatcolet, Round and Hidden Lakes in 2019 to help cutthroat that spawn in southern tributaries such as Benewah Creek and the St. Joe watershed. Native bull trout also stand to benefit since they use the area as part of their migration between the lake and the upper St. Joe watershed.
Suppression efforts in these southern lakes are challenging given the expanse of spawning habitat available to pike and their greater numbers. The Tribe’s work in 2019 was largely exploratory, testing different types of nets and using radio transmitters to track pike as they made their seasonal movements. Overall, 1,409 pike were removed during the first year of expanded operations. Within the four southern lakes, biologists estimate this represents 50-60% of the pike population that is susceptible to netting.
“The tracking work we did was important as it indicated that locations outside our target area for netting likely serve as important spawning centers. Many pike moved out of the lake and up the St. Joe River in early spring. So it is a more complex dynamic to get our hands around,” said Angelo Vitale, Fisheries Program Manager with the Tribe. The tracking work will continue in 2020 to help inform the approach to pike management.
Many of the pike that were removed from the lake were donated for consumption and were distributed from the Blue Goose Sporting Goods store in St. Maries. “Making pike available for consumption last year was appreciated by many community members, so we are pleased that the Tribe is continuing that program,” said Dux.
In coming years, the Tribe will evaluate the effectiveness of the southern lakes netting program by monitoring changes in the pike population and the survival of juvenile cutthroat trout and the number of adult cutthroat that return to spawn in Benewah Creek.
In 2017, the Tribe and Fish and Game conducted a public opinion survey of Lake Coeur d’Alene anglers. Survey results showed strong public support for northern pike suppression in Windy Bay. In addition, there was strong support for localized suppression in the southern end of the lake if efforts in Windy Bay showed promise for improving cutthroat trout abundance.
“Survey results were supportive of this type of work and the intent is to strategically target areas where suppression of northern pike can provide the greatest benefit to native cutthroat trout,” said Vitale.
The Tribe and Fish and Game are planning to host a community meeting in Plummer later this spring to discuss these efforts. A date has not yet been set given the concerns and uncertainty associated with the coronavirus outbreak but an announcement will be made in the coming weeks.