Locating Spawning Habitat of Invasive Lake Trout in Yellowstone Lake

The lake trout suppression program in Yellowstone Lake has primarily relied on removal with gill and trap nets; however, new strategies to maximize program effectiveness include destruction of lake trout embryos on spawning grounds.  Such methodologies require knowledge of movement patterns and spawning areas.  An acoustic telemetry study was initiated in 2011, to collect critical movement and distribution information concerning this invasive species.  Two hundred seventy-nine adult lake trout (weight > 500 g) were implanted with acoustic transmitters.  A subset of acoustic transmitters was equipped with depth/temperature sensors to gain further insight on lake trout spawning behavior.  Fifty-two receivers were deployed in Yellowstone Lake with an additional 11 receivers positioned at Carrington Island to 2-D position lake trout at known spawning location. We present data collected from receivers near Carrington Island, to examine the timing of spawning activities around the island, and examine lake trout detections at individual sites throughout Yellowstone Lake.  Lake trout were consistently detected near the surface at Carrington Island.  Shallow depths (< 3 meters) were only consistently observed at six other sites around the lake.  Temperature data from the receivers also suggest a potential spawning window from early September to early October.