Changing Fish Population Casts New Identity On Sprague

Perch, crappies and walleyes are becoming the dominant fish species at Sprague Lake as fish populations continue to change at the popular fishing hole. They’re apparently displacing bluegills, trout and possibly smallmouth bass.

Carp dominated the lake’s fish population when the Fish and Wildlife Department treated the lake with rotenone a few years ago. The rotenone killed hundreds of tons of carp, as well as thousands of stunted perch, crappies, bass and catfish. Carp are back, and their numbers are increasing slowly.

For the first few years after rehabilitation, big, fiesty rainbows and Lahontan cutthroat overshadowed the slowly increasing populations of bass, walleyes, bluegills and catfish.

Northwest fishermen converged on the lake each year to catch 14- to 22-inch trout. Even national magazines touted the trout fishing. As a result, Sprague became more popular than most lakes managed specifically for trout. But the terrific fishing lasted only a few seasons.

As bass and walleyes grew, they gobbled up the tiny Lahontan and rainbow fry released each year. Consequently, the department had to stop planting fry and start releasing catchable-size trout. However, raising trout to catchable size is costly, and because the department has limited numbers of catchable-size trout at its hatcheries, it could plant only a few thousand in Sprague each year. Naturally, great trout fishing ended.

The lake proved to be ideal habitat for bluegills. Almost unbelievable numbers of chironomids provided food for the young bluegills. Millions of chironomids hatched each year, often plastering windshields of cars traveling along Interstate 90 just north of the lake. As a result, the bluegills grew fast, many measuring more than 10 inches, big for the species.

Meanwhile, perch and crappies, which hadn’t been released by the department, began showing up. Some anglers figured “bucket biologists” planted the species after the lake was treated with rotenone.

Inasmuch as carp are now showing up in the lake, that theory may be fallacious. It’s highly unlikely that anyone would release carp into the lake. Most likely, the rotenone didn’t kill all the carp, perch and crappies.

Anglers loved the bluegills, especially during the winter months. The fishing peaked during the winter of 1992-93, with many ice fishermen filling 5-gallon buckets with 7-11-inch bluegills. Between 100 and 200 anglers fished through the ice in the east end of the lake every weekend.

Then the population crashed. Some anglers attributed the big drop in bluegill numbers to over-fishing and called for setting daily limits on bluegills. However, a bacterial disease may have been more responsible for the crash.

Fisheries biologist Bob Peck of Spokane said some of the bluegills that were recovered during the population decline had fungus infections on their skins.

Enough bluegills survived the crash to provide fair and sometimes good fishing the last couple of years, leading some to conclude the population didn’t drop as much as some had thought. Most fishermen now assume the bluegill population is far smaller than in recent years.

Whatever the cause of the crash, perch and crappies began moving into the niche left by the bluegills. Perch apparently have been more successful than the crappies, but indications are that crappies are increasing steadily.

Perch that escaped rotenone treatment spawned and the population exploded. Those spawners, with little competition for food for a couple of years, grew fast, some measuring more than 12 inches. Their progeny also grew fast and now are 8-10 inches long. This winter, nearly all perch caught by anglers are 4-6 inches long. Larger perch appear numerous enough to provide good fishing at times, but they’re often difficult to find.

It’s impossible to assess the crappie population. A few anglers filled buckets with 7-11-inchers in December and some have caught good-sized crappies through the ice. The most productive crappie fishing is usually in April and May. If anglers find large schools during those months, Sprague may once again become one of the most productive crappie lakes in the state.

For some unknown reason, smallmouth bass haven’t done as well as their largemouth cousins. Bass anglers and other fishermen who hooked good number of smallmouths three years ago say they haven’t hooked nearly as many the last couple of years.

The walleye population, on the other hand, has exploded and there are thousands of 18- to 25-inchers. Walleye fishing could be terrific this year.

As for carp, is anyone interested in fishing for them?

, DataTimes MEMO: You can contact Fenton Roskelley by voice mail at 459-5577, extension 3814.

The following fields overflowed: CREDIT = Fenton Roskelley The Spokesman-Review