North American Journal of Fisheries Management
American Fisheries Society
lake trout, spawning, Lake Tahoe, egg incubation, deepwater, macrophyte beds
Although most populations of lake trout Salvelinus namaycush spawn over rocky shoals, use of these substrates by lake trout has not yet been found in Lake Tahoe. Large cobble substrate exists at depths less than 20 m, and steep, fractured, rocky substrate can be found in isolated areas from the surface down to at least 100 m, but no evidence of spawning activity in these areas has been found. Instead, at least a portion of the population spawns on deepwater mounds (40–60 m deep) over beds of the macrophyte Chara delicatula. This is the first known report of lake trout spawning over macrophyte beds. We hypothesize that this population originated from a deep-spawning stock and that the macrophyte beds on these mounds may provide some of the best deepwater incubation habitat in the lake, Although egg predation by intermediate sizes of lake trout (375–500 mm fork length) was substantial, the mounds appeared to be a refuge from the potentially more effective invertebrate and small vertebrate egg predators. The oxygen and temperature regime within the macrophytes was suitable for egg development, and the eggs that infiltrated deeply among the plant strands were anchored against currents and were presumably protected from further predation by lake trout.
Beauchamp, D.A., B.C. Allen, R.C. Richards, W.A. Wurtsbaugh, C.R. Goldman. 1992. Lake trout spawning in Lake Tahoe: Egg incubation in deepwater macrophyte beds. N. Am. J. Fisheries Manag. 12:442-449.