West Grand Lake Trout Spawning Study
Georgia Pacific Corporation
Woodland, ME
West Grand Lake, Maine is a 14,000-acre impoundment in a remote area of eastern Maine containing an important wild lake trout
fishery. A Georgia-Pacific dam which releases flow to Grand Lake Stream for downstream power generation controls the water
elevation of West Grand Lake. During project relicensing, it became necessary to investigate the potential of dewatering
lake
trout redds as a result of project operation, as lake trout spawning depths and habits can vary tremendously among lakes,
and little was known about the spawning habits on this large, deepwater lake. This presented a significant technical challenge,
as spawning sites and depths would have to be definitively located in a large lake in late fall, based on a reasonably robust
sample size. (A related study conducted by Kleinschmidt involved an IFIM model of Grand Lake Stream to assess potential impacts
to landlocked Atlantic salmon spawning resulting from changes in flow brought about by any proposed lake-level re-regulation).
Kleinschmidt used an innovative combination of radio telemetry and mobile hydroacoustics to track spawning lake trout to their redd sites. Although similar studies had been conducted before on smaller water bodies with small numbers of fish, Kleinschmidt’s study was the most comprehensive and conclusive movement study of lake trout conducted to date. Kleinschmidt located and trapped pre-spawning adult lake trout from 60-80 ft depth in cooperation with the Maine Department of Inland Fisheries and Wildlife.
Approximately 20 fish were collected, anesthetized, surgically tagged, re-equilibrated, released at capture depth, and tracked for approximately a six-week period until spawning aggregations formed. Fish were tracked nocturnally lake wide, with locations marked using GPS. Hydroacoustic surveys were conducted to verify which telemetered fish were congregating with other similarsized targets in spawning clusters, and to search for other trout aggregations throughout the lake.
Several large spawning sites were located, along with additional secondary potential sites, each sharing common depth, substrate and wind/wave exposure characteristics. Following postspawning dispersal, diving inspection of key GPS locations confirmed the presence of egg deposition and revealed the depth range at which eggs were laid.
These data conclusively showed that lake trout in this water body spawned at depths both similar to and also greater than reported elsewhere in Maine, and continuation of the existing project operation would not impact this resource.