Bull trout stream tally holds steady

Bull trout reproduction has improved in parts of Montana that are the country's stronghold for the species, according to recent field surveys conducted by Montana Fish, Wildlife and Parks.

State biologists recently counted "redds," distinctive stream-bottom spawning beds, in selected sections of 19 Northwest Montana streams.

Despite several years of drought, this year's counts exceeded recent counts in the Swan River drainage, the South Fork Flathead drainage, and the greater Flathead River Basin.

Tom Weaver, the lead bull trout biologist with Fish, Wildlife and Parks, attributed the increases largely to a generational recovery since bull trout redd counts collapsed in the mid-1990s.

"Based on redd numbers observed a generation ago, the current count is just about what we expected," Weaver said of redd counts in the Flathead River Basin.

"During the six-year period between 1992 and 1997 we found the lowest numbers of redds on record," he said. "The absolute lowest number was in 1996 when we only counted 83 redds in our index sections."

The offspring from 1996 were the first-time spawners that made up the bulk of last year's spawning run.

This year's count in eight established "index sections" was 136 redds, six higher than last year.

In 25 years of monitoring the same index sections, the highest count was 600 redds in 1982.

"We believe that the recent low counts are largely the result of the weak year classes observed during the mid-1990s, but the good news is the current generation appears to be more abundant than the previous one," Weaver said. "If this holds true, we should begin to see increasing redd numbers next fall."

Spawning and rearing habitat is in fair shape in most of the bull trout streams, Weaver said.

Habitat quality is largely dependent on flushing streamflows that clean fine sediments out of spawning and rearing areas.

"In general, we have lacked good flushing flows during the spring runoff in recent years and sediment levels are creeping back up as they did in the late 1980s and early 1990s," Weaver said. "This pattern appears widespread in the Flathead, and Coal Creek is chronically in the worst shape."

The index section on Coal Creek, a tributary of the North Fork Flathead River, had just three redds this year, compared to one last year and none the previous two years.

State biologists also monitor the abundance of juvenile bull trout in designated rearing streams in the Flathead's Middle Fork and North Fork drainages. Similar to the redd counts, juvenile densities declined to the lowest levels on record during the mid- to late 1990s, but have increased annually since 2000.

This year's monitoring efforts were not completed in some index streams because of unusually high streamflows during the late summer. But juvenile numbers appeared to be consistent with recent years, Weaver said.

The state has been monitoring bull trout reproduction in the Swan River Basin for the last 23 years.

This year's count in three streams came up with 435 redds, compared to 425 last year and 430 the year before.

For 12 years, the state has monitored bull trout reproduction in the South Fork Flathead Basin, which is biologically separated from the greater Flathead Basin by Hungry Horse Dam.

Surveyed streams around Hungry Horse Reservoir have averaged 76 redds for the last 12 years, and this year's count was 98.

Four tributaries to the South Fork Flathead River, upstream from the reservoir, are also surveyed every three years. This year's count was 479 redds, compared to the 2001 count of 470.

Reporter Jim Mann may be reached at 758-4407 or by e-mail at jmann@dailyinterlake.com