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Idaho Fish and Game

Big Toothy Guy Takes Bum Rap

Cascade Reservoir's tiger muskies have a perfect alibi in the continuing investigation into the demise of that lake's famous perch population; they were not even on the scene when the perch met their demise. Frustrated perch anglers have been blaming tiger muskies for eating their favorite fish and cussing Fish and Game for having planted the hybrid predators in Cascade. Fish and Game biologists and the Bureau of Reclamation have joined forces to investigate the mystery of the perch collapse. The researchers are not ready to name a suspect yet. But the tiger muskies - despite their size, voracious appetite, and fearsome appearance - didn't do it. McCall-based fisheries biologist Paul Janssen pointed out that tiger muskies were first stocked in Cascade in July 1997 when 600 11-inchers were released. Another 7,500 tiger muskies of about seven inches were planted in September 1997. Perch fishing began to decline in the early 1990s and had totally collapsed by 1995. Most of the tiger muskies were too small to eat adult perch until at least the late summer of 1998 and so could not have been implicated in a perch crash until 1999, four years after the huge population of perch actually disappeared. Even if the tiger muskies had been stocked into the middle of the several million perch that were swimming in the lake in the late 1980s, there were too few of them to have done the dirty deed. Another factor that clears the reputation of tiger muskies is that they really do not find the spiny-ray perch as much to their liking as they do soft-ray species including northern pikeminnow (historically known as squawfish) and suckers, two fishes Cascade holds in great abundance. One good reason for planting tiger muskies in Cascade is their appetite for suckers and pikeminnow. Tiger muskies prefer to live in the weedy margins of lakes while perch use all the water. It is unlikely that they would hold down a resurgence of perch in the 30,000 acres of Cascade. While tiger muskies could not have been the villain in the perch story, the much more numerous pikeminnow might be a suspect. The large population of pikeminnow persisted through the perch collapse and are still in a position to hold back perch recovery. Biologists want to have their case nailed down before naming the cause or causes of the perch problem. In the study begun in 1997, biologists have found virtually no survival of first-year perch. Virtually none of the adult perch lost since the early 1990s have been replaced. Besides the tiger muskie, research has eliminated several other suspected causes of perch decline, Janssen noted. Actions to improve fishing in Cascade are likely to begin soon, he added.