Montana Fish, Wildlife & Parks: Bull Trout Redd Counts Completed In The Flathead System

Montana Fish, Wildlife & Parks field crews completed the 2009 bull trout redd (nest) counts between September 29 and October 30. The index sections in tributaries for all three major populations (Flathead, Swan, and Hungry Horse Reservoir) were surveyed this year, under good conditions. The same stream sections are counted each year and represent a portion of the total bull trout spawning-run. According to FWP Fisheries Biologist Tom Weaver, the Middle and North Fork Flathead redd counts were about average for the past decade, while counts in the South Fork Flathead and Swan drainages were below average for the past decade.

Flathead Lake population: This was the 30th year of index counts for the Flathead Lake bull trout population. These fish spawn in tributaries to the North and Middle forks of the Flathead River. The 2009 index count of 187 redds in the eight standard stream sections is about equal to the average (192 redds) over the last decade. (See accompanying table).

The total count for the four Middle Fork index tributaries (102) was above average while the count in North Fork tributaries (85) was below average.

Swan Lake population: This was the 28th year of bull trout redd counts in the Swan Drainage. Adult bull trout in Swan Lake spawn in tributaries to the Swan River upstream from the lake. The four annual index stream sections had a total of 366 redds this year, which is well below the average (447 redds) for the past decade (see accompanying table). Biologists are closely monitoring the status of the lake trout population in Swan Lake. Information clearly shows that lake trout have been reproducing for several years and that considerable numbers of large, mature fish are present. If lake trout continue to prosper, changes to the fish species mix in Swan Lake and impacts to the bull trout population are likely to occur. Lake trout have now been noted in Lindberg Lake as well.

Hungry Horse Reservoir population: This was the 17th year of monitoring for the South Fork Flathead/Hungry Horse Reservoir population. The 2009 total of 66 redds is well below the average over the past decade (96 redds). The four Wilderness tributary index sections were not surveyed this year.