Research shows healthy fish population in Lake Elmo

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BILLINGS — When Montana Fish, Wildlife and Parks biologists and fisheries technicians pulled research nets out of Lake Elmo earlier this week, they found data that was satisfying, if not surprising.

Early analysis of statistics shows that the fish species most preferred by anglers are doing well in size, number or both. And some of the controls in place for the less-desirable species apparently are working.

The fisheries workers put three live traps and two gillnets in the Billings Heights reservoir and left them overnight earlier this week. The live traps are a series of funnel-shaped nets. Fish of all sizes can swim in, but cannot find their way back to freedom. Gillnets are long, rectangular nets, similar to volleyball nets, that are stretched out at a specified depth in the lake. As fish try to squeeze through the holes in the net, they get hung up and cannot back out because their backward-pointing fins, gill covers and scales catch in the netting.

Biologists put the nets at the same places in the 64-acre lake on about the same date each spring and fall so the data they collect are consistent and comparable.

This year, yellow perch and white suckers were again the most common species caught in nets. Workers pulled 120 yellow perch out of the nets, compared with 70 during the same week in 2007. Those numbers would indicate that the yellow perch population in Lake Elmo has not quite doubled in the past year.

While the number of yellow perch has grown, the size and weight of the fish has not. The average yellow perch this fall was 6.6 inches long and weighed .11 lbs. That is down .2 inches and .03 pounds from a year ago.

Ken Frazer of Billings, the FWP’s regional fisheries biologist, said an early look at the statistics indicates that Lake Elmo may be reaching its capacity for yellow perch. Competition for food could keep the yellow perch from growing in size. He encouraged anglers to keep any yellow perch they catch from Lake Elmo, even if they are small. Fewer fish, he said, could mean less competition for food and, therefore, bigger fish.

White suckers, meanwhile, also have increased slightly in number – from 64 in 2007 to 75 this week. But this year, Frazer said, workers did not find any white suckers smaller than 11.3 inches long. He believes the smaller suckers are falling prey to tiger muskies that were planted in the lake to control the white suckers.

Tiger muskies are a sterile cross between a northern pike and a muskellunge. They are voracious predators that prefer white suckers over perch, trout, salmon, bass or panfish. FWP planted 65 foot-long tiger muskies in Lake Elmo in 2006 and nine more last spring. Those fish should be large enough now to eat white suckers up to a foot long, he said.

As tiger muskies eat away at the white sucker population, more food will be available for trout, bass and other game species, Frazer said. Those more desirable fish should grow bigger and more numerous in the lake.

Fisheries workers found other encouraging evidence this fall:

n                     While they found slightly fewer channel catfish in 2008, the average length was up considerably from 11.6 to 15.4 inches. And the 2008 captures averaged 1.54 pounds – more than a pound heavier than those weighed in 2007.

n                     One net contained three-inch-long smallmouth bass. Since FWP does not plant smallmouth bass in Lake Elmo, their presence indicates natural reproduction.

n                     They found more white crappie, bluegills and pumpkinseeds than in 2007.

Other species captured in nets this fall included rainbow trout, Yellowstone cutthroat trout, carp, longnose sucker and shorthead redhorse.

About 9,600 rainbow trout and 1,020 Yellowstone cutthroat trout from Montana hatcheries were planted in Lake Elmo this year. They averaged 7-8 inches long. Some small channel catfish and largemouth bass also were planted in Lake Elmo from the FWP hatchery in Miles City.

 

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