A wild fish journey: From the Bob to the hatchery and back

Some wild fish are about to take a long journey out of the Bob Marshall Wilderness this summer.

Montana Fish, Wildlife and Parks biologists will use fly rods to catch about 300 juvenile westslope cutthroat trout from streams in the upper Youngs Creek drainage. The young fish will then be carried in coolers on the back of mules for the 12-mile journey out to the Lodgepole Creek trailhead.

The fish will be kept cool and oxygenated using ice and bottled oxygen, biologist Matt Boyer explained. Catching the fish doesn’t take long, he said. Fish densities are so high in those headwater streams that biologists can catch what they need in a day or so.

The young cutthroat will then be transported to the FWP hatchery at Sekokoni Springs near Blankenship where they’ll be raised to maturity as brood stock. The resulting offspring eventually will be used to re-stock lakes as part of the South Fork Westslope Cutthroat Trout Project.

Ongoing for several years, the project aims to rid 21 headwaters lakes in the South Fork drainage of non-native Yellowstone cutthroat and rainbow trout. Many of the wilderness lakes already have already been rehabilitated.

The South Fork of the Flathead River is one of the few remaining pure westslope cutthroat trout drainages in the U.S. The fear is that non-native fish from the headwater lakes could eventually dilute the genetic integrity of the South Fork fish. Cutthroat can cross-breed with rainbow and Yellowstone cutthroat trout.

FWP plans to use the Youngs Creek fish to restock the headwaters lakes once the non-native fish have been removed. The method has proven to work.

From 2009 to 2012, biologists caught 300 fish a year from the upper reaches of the Danaher Creek. Those fish took an even longer journey — 25 miles in a single day out to the trailhead by mule.

Still, the project had a 99 percent survival rate. The fish were raised to adulthood in the hatchery, which is exclusively set up as a cutthroat trout facility. The resulting offspring were planted in the Necklace Chain of Lakes in the Bob Marshall Wilderness last year and will be planted in Lick Lake later this year.

To rear wild fish in a hatchery, biologists had to teach the fish to eat food pellets. Only 30 to 40 percent of the native fish caught from Danaher Creek would eat the pellets, hatchery manager Scott Relyea said.

Relyea supplemented the feed with mealworms, which the native fish would eat, but the mealworm diet made them grow slowly. To transition the fish to pellets, he coated the feed with a freshwater shrimp oil. Over time, the wild fish took a liking to it, and eventually all would eat pellets.

Biologists also take pains to ensure cross-breeding in the hatchery population. The eggs are gathered from the females, the milt from the males and then they’re combined with a hormone agent that stimulates the sperm. Three males are used to fertilize each female’s eggs. The eggs are then raised in dishes until the fry hatch under controlled water temperatures. The temperature of Sekokoni Springs water runs in the low to mid-50s — ideal for westslope cutts.

The Youngs Creek project is supported by $66,000 in Bonneville Power Administration funding for the Hungry Horse Dam mitigation and is also done in cooperation with the staff at the Spotted Bear Ranger District. An environmental analysis of the four-year project is available online at http://fwp.mt.gov under Public Notices. Hard copies are available at the FWP office, in Kalispell and Flathead County libraries.

Comments can be made to FWP Fisheries Biologist Matt Boyer at 751-4556 or mboyer@mt.gov. The comment period runs through July 4.