Identifying Movement Patterns and Spawning Areas of Invasive Lake Trout in Yellowstone Lake

Although the lake trout Salvelinus namaycush suppression program in Yellowstone Lake has been successful at removing large numbers of these predaceous invaders, the number of lake trout captured continues to increase.  It is apparent that targeted removal of adult lake trout can have positive effects on population suppression, and capture of adult lake trout can be increased by focusing removal efforts on regularly used travel corridors or spawning areas.  Furthermore, destroying lake trout embryos on spawning grounds could be applied synergistically with methods that target free-swimming individuals (e.g. gill nets) in order to maximize suppression of lake trout.  Efforts to increase direct removal with gill nets and utilize techniques for destroying lake trout embryos and larvae require knowledge regarding lake trout movement patterns and accurate information concerning the location of spawning areas.  To this end, we initiated a collaborative effort of federal and academic scientists with additional funding support from a consortium of four NGOs to identify movement patterns and spawning areas of invasive lake trout in Yellowstone Lake. This pilot study included implanting acoustic transmitters in 141 lake trout and deploying 40 acoustic receivers in 2011.  Data were downloaded from the receivers three times in September and October.  Preliminary analysis has provided evidence concerning movement corridors and distribution patterns that confirm previous hypotheses and yield intriguing insights.