A Comparison of Lake Trout Spawning, Fry Emergence, and Habitat Use in Lakes Michigan, Huron, and Champlain

Restoration of self-sustaining populations of lake trout is underway in all of the Great Lakes and Lake Champlain, but restoration has only been achieved in Lake Superior and in Parry Sound, Lake Huron. We evaluated progress toward restoration by comparing spawning habitat availability, spawner abundance, egg and fry density, and egg survival in Parry Sound in Lake Huron, in Lake Michigan, and in Lake Champlain in 2000-2003. Divers surveyed and assessed abundance of spawners at 5 to 15 sites in each lake. Spawning adults were sampled using standardized gill nets, eggs were sampled using egg bags, and fry were sampled using emergent fry traps and egg bags left on spawning reefs overwinter. Spawning habitat was abundant in each lake. Adult lake trout abundance was low in Lake Michigan and Parry Sound, and very high at one site in Lake Champlain. Egg deposition was lowest in Lake Michigan (0.4-154.5 eggs
- m−2, median = 1.7), intermediate in Parry Sound (39-1,027 eggs
- m−2, median = 278), and highest in Lake Champlain (0.001-9,623 eggs
- m−2, median = 652). Fry collections in fry traps followed the same trend: no fry in Lake Michigan, 0.005-0.06 fry
- trap−1 day−1 in Parry Sound, and 0.08-3.6 fry
- trap−1 in Lake Champlain. Egg survival to hatch in overwinter egg bags was similar in Lake Michigan (7.6%) and Parry Sound (2.3-8.9%) in 2001-02, and varied in Lake Champlain (0.4-1.1% in 2001-02, and 1.8-18.2 in 2002-03). Lake trout restoration appears unlikely in northern Lake Michigan at current adult densities, and failure of restoration in Lake Champlain suggests that there are sources of high mortality that occur after fry emergence.