A two-pronged effort to reduce lake trout populations in Idaho’s Lake Pend Oreille is showing success – the reservoir’s kokanee population is rising and the catch rate for predatory lake trout falls with every passing year.
A sport reward/commercial netting strategy that has been implemented from 2006 through this summer has resulted in a total of 124,944 of the big lake trout have been removed from the lake. Sport fishing continues and this fall netters will spend five weeks trying to plunder areas where lake trout are known to spawn.
The harvest since 2006 includes 61,928 fish by angling and 63,016 by netting.
The lake trout were introduced to Pend Oreille in 1925 but did not seem to pose a problem until around the turn of the century. The big predators are considered the primary cause of a decline in the kokanee population that has gone from weak to almost non-existent. A record low count of only 5,000 wild female spawners was estimated in 2007.
Experts say said the lake trout can grow from 2-3 pounds to over 20 pounds in a five-year span.
But with the continue removal of lake trout the tide seems to have turned. The spawning kokanee population has increased every year since 2007 and that trend is expected to continue.
The bigger lake trout are becoming so scarce that the contracted operation has shifted to smaller mesh nets that target younger lake trout that tend to mill along the deep lake’s northwest shore.
Even that netting is showing declining success. In 2009 and 2010 the netters averaged 11.5 and 10.1 fish per box net, respectively, according to Andy Dux of the Idaho Department of Fish and Game. In the spring of 2011 that average dropped to 4.5 fish.
Beginning in May of 2006 a $15 bounty was offered to anglers for lake trout of any size and any rainbow 13 inches or larger. The professional netters were hired to focus on the lake trout.
Angler success is also dropping. The total catch of lake trout between 2006-2008 ranged from 11,000 to 18,000 per year. This year the catch is expected to be about 4,000, Dux said.