Last week, Montana Fish, Wildlife and Parks released the numbers for 2010 bull trout redd counts in the Flathead watershed. Those numbers continue to show that native fish face serious obstacles to their continued survival in our home waters.
Most news stories got the headline correct. The Daily Inter Lake article said “‘Redds’ count down in Swan River drainage”, the Beacon’s coverage, though brief, was to the point “Survey Finds Fewer Bull Trout Spawning Beds”. Both stories focused on the drastic decline in spawning bull trout in the Swan River drainage. Redd counts in the Swan have declined 50 percent just since 2007 and are down to nearly half of the 15-year average. What I found curious in all the coverage was that most stories quoted the FWP story line that “non-native lake trout may be the reason for the decline.” May be…?
Lake trout were first discovered in Swan Lake in 1998, but evidence shows that they were likely present considerably longer. Last year, lake managers netted just over 5,000 lake trout from Swan Lake. At that time they boasted that they felt they had removed over half of the invasive population. This year, the removal effort so far has netted more than 10,000 lake trout blowing away that previous population estimate. The declines in spawning of native bull trout in the Swan have not approached these low numbers in over two decades and there has never been a sustained decline on the order of what is occurring now. The only significant change is the lake trout invasion.
The redd count numbers also reveal a continued decline of spawners in the North Fork Flathead. Redd counts within the North Fork index reaches are down by more than 40 percent since 2006 with only 54 redds found this year. Due to higher than average redd counts in the Middle Fork reaches, FWP was able to claim in their news release “Bull trout counts steady in the Flathead…” However, there are disturbing reasons for the steady decline in North Fork redd counts.
An article in the Missoulian on Nov. 7 reveals some of what is happening in the North Fork; “Glacier Park’s nonnative fish on path to wipe out bull trout”. The article quotes Clint Muhlfeld, USGS fisheries biologist in Glacier National Park;
“Of the 12 lakes in Glacier National Park that are connected to Flathead Lake – all of them home to previously healthy populations of bull trout – 10 have been invaded by lake trout, said aquatics ecologist Clint Muhlfeld, whose research at the U.S. Geological Survey’s Glacier National Park field station is meant to inform conservation and management programs. Bull trout are now functionally extinct in eight of those dozen lakes, Muhlfeld said, and research indicates their future is threatened in a ninth lake; a 10th lake is in the early stages of invasion.”
Our native bull trout are EPA listed as a Threatened Species and face serious challenges throughout the Flathead watershed. Studies have found that the No. 1 threat to our native fish is predation by invasive lake trout. A bloated half-million plus population of predatory lake trout in Flathead Lake is gobbling up our native fish and forcing lake trout immigrants out of the lake and into the surrounding watershed where they menace the few remaining strongholds of native fish. Quoting these redd count numbers as representing “steady” or “average” bull trout populations only serves to cloud the significant perils facing native fish in the Flathead.
For more information on native fish issues in the Flathead, please visit the Flathead Valley Trout Unlimited website www.flatheadtu.org