Coeur d’Alene Lake, a large, deep natural lake in northern Idaho, acts as the primary reservoir for the Coeur d’Alene River and is fed by the St. Joe River. Its connection to these major river systems and its considerable size support a complex ecosystem hosting a variety of fish species. The lake’s deep, cold waters and its shallower, vegetated bays provide habitats for fish ranging from large apex predators to small plankton feeders. This natural setting, combined with decades of fisheries management, has resulted in a varied fish community.
Prized Game Fish for Anglers
Recreational anglers often target several non-native species that have been stocked to create a trophy fishery in the lake. The landlocked Chinook Salmon are among the most sought-after, with some specimens capable of exceeding 20 pounds. Fishing for Chinook is best accomplished by trolling with downriggers in the open water, where they roam in search of prey like Kokanee Salmon. During the summer months, these large salmon typically hold deep, often between 60 and 100 feet down, before moving to shallower depths as the water cools in the fall and winter.
Kokanee Salmon, a smaller, landlocked form of Sockeye Salmon, are another popular target, typically averaging between 12 and 16 inches in length. These fish are plankton feeders and are usually caught in schools over deeper water, with peak fishing activity occurring from late spring through early fall. Anglers target Kokanee by trolling small spoons or spinners behind dodgers, often at depths between 40 and 80 feet during the summer. Current regulations allow for a daily bag limit of 15 Kokanee.
The lake also offers excellent fishing for black bass species, namely Largemouth Bass and Smallmouth Bass, both of which are non-native introductions. Smallmouth Bass prefer rocky shorelines and points, while Largemouth Bass are generally found in the shallower, vegetated bays and sloughs. Anglers may use jerkbaits or other lures to find these fish, which are managed under a combined daily limit of six. Rainbow Trout, which include both hatchery-stocked fish and wild strains, are active year-round and range from 12 to 18 inches. They can be caught by trolling or casting near inlets and drop-offs, with the best fishing typically in the cooler water temperatures of spring and fall.
Native Fish and Conservation Focus
The native fish populations in Coeur d’Alene Lake and its tributaries are a central focus of conservation efforts by management agencies and the Coeur d’Alene Tribe. The Westslope Cutthroat Trout is the primary native trout species and is distinguished by its adfluvial life history. This means the adults live in the lake but migrate into tributaries to spawn. These trout populations have seen declines due to habitat degradation and the introduction of non-native species.
Management strategies are designed to protect the genetic integrity of this species and restore its habitat. A special rule is in place that prohibits the harvest of Westslope Cutthroat Trout. Conservation work often involves improving access to spawning and rearing habitats, such as replacing stream barriers like culverts that impede the fish’s natural migration.
The Mountain Whitefish is another native species often present in the deeper, cooler waters of the lake. While often overlooked by anglers, the Mountain Whitefish is important to the aquatic food web and is a key indicator of the lake’s ecological health. Other native species include the Northern Pikeminnow and the Largescale Sucker.
Non-Native and Invasive Species
A significant ecological concern in Coeur d’Alene Lake is the presence of species that pose a threat to native and stocked fish populations. The Northern Pike, which was illegally introduced in the 1970s, is the most impactful invasive predator in the system. This voracious fish preys heavily on other fish species, including the native Westslope Cutthroat Trout and the stocked Kokanee Salmon. Pike congregate in shallow, vegetated areas, especially near the mouths of tributaries, which creates a “predator trap” for juvenile cutthroat trout migrating to the lake. To mitigate this impact, management agencies and the Coeur d’Alene Tribe conduct active suppression efforts, primarily using gill netting in areas like Windy Bay and the southern chain lakes. Regulations encourage the harvest of Northern Pike by anglers, as there are no bag, length, or possession limits on the species.
The non-native Yellow Perch is another established species that is common in the lake. They compete with native species and prey on young trout. Yellow Perch are frequently consumed by Northern Pike, and this heavy predation on perch may unintentionally act as a “predation buffer” for other more vulnerable species, such as the native cutthroat trout.