Friday, June 27, 2003
In August 1988, the Big Hole River was not a good place for the only fluvial, or river dwelling, population of Arctic grayling in the lower 48 states. The river was virtually dry in places.
The drought of 2000-2002 was worse.
Unlike 1988, however, the Big Hole continued to flow at low levels during this drought because irrigators, anglers and others worked together to keep it flowing. Nevertheless, both of these severe drought episodes impacted the Big Hole River population of Arctic grayling.
The drought took a population of grayling that numbered 96 fish per mile in 1997 down to the point that we could not get accurate estimates in the fall of 2002 in some reaches. But some grayling sought refuge in Big Hole tributaries where, with acceptable temperature and flow, we saw grayling numbers as high as 90 fish per mile.
For grayling survival, habitat is everything. To protect fish habitat in tough times, public involvement is essential. The Big Hole Watershed Committee, local landowners, Trout Unlimited, anglers, recreationists and municipalities have worked together the past couple of years to keep water in the Big Hole.
For example, in 1988 a stock water wells program came on line that now provides ranchers an alternative to diverting water from the river. The local group also used voluntary irrigation cutbacks and angling closures to protect fish during stressful low flows.
In the past, the Big Hole grayling populations were connected with other grayling populations from the Jefferson, Beaverhead, and Ruby Rivers. Those fish disappeared following settlement by Europeans in the late 1800s-early 1900s and the Big Hole Arctic grayling now stand alone, increasing their vulnerability to drought and other random events.
To our advantage, we’ve learned a lot about grayling as we’ve worked to preserve the Big Hole population. For instance, since low numbers of grayling in traditional areas were partially offset by high numbers in refuges in tributaries, we can work to maintain these natural refuges to help grayling survive in low flow times.
Grayling also have the ability to recover rapidly under the right set of habitat conditions. Grayling produce two to three times as many eggs as a similar sized trout. During good conditions in the mid-1990s, the grayling population increased from 22 per mile in 1989 to 96 per mile in 1997.
While maintaining the grayling population in the Big Hole River is critical, establishing new populations is essential for the long-term security of the species. Grayling have been introduced into some Missouri River tributaries recently to expand the grayling’s present range.
Plants in the upper Ruby River have shown encouraging results with natural reproduction from stocked grayling documented in 2000 and 2002. In 2003, additional grayling plants in the upper Ruby River will hopefully increase the numbers of spawning age grayling to reproduce in future years. Remote stream incubators will also be used to imprint fry on potential spawning sites.
With improved snowpack in 2003 and the continued cooperative efforts, grayling should experience improved conditions compared to the past three years. Hopefully, we are over the hump and we will see improved recruitment and abundance in 2003.