Use of Egg Traps to Investigate Lake Trout Spawning in the Great Lakes

Contribution of lake trout stocked as fry to an adult population in Lake Superior

“…This reef is located about 0.15 km to 0.5 km offshore, and encompasses about 0.1 km 2 . Prior to stocking, the reef was examined by scuba divers to ensure that it was composed of rocky substrate with prevalent interstitial spaces, which characterize good spawning habitat (Fitzsimons, 1995;Marsden et al, 1995;Schreiner et al, 1995). Although this emergent reef is located fairly near shore, the bottom slopes steeply, and the offshore side of the exposed portion drops quickly to >15 m in depth.…”

“…Wherever fry stocking is proposed, visual examination of potential stocking reefs is recommended to identify appropriate spawning habitat characteristics (Marsden et al, 1995;Schreiner et al, 1995). Delivery of fry directly to the reef surface where they will actively seek refuge (Negus, 1998) can prevent drifting to unsuitable areas.…”

The significance of man-made structures for lake trout spawning in the Great Lakes: are they a viable alternative to natural reefs?

“…In contrast, spawning by contemporary lake trout stocks appears restricted to cobble substrates in relatively shallow (< 15 m) water Wagner 1981;Peck 1986;Fitzsimons 1994aFitzsimons , 1995Casselman 1995;Holey et al 1995;Kelso et al 1995;Schreiner et al 1995). The difference between historic and contemporary accounts may result from incorrectly inferring where spawning occurred.…”

“…In southern and central Lake Michigan, where cobble substrates are rare nearshore, man-made structures have been the only sites where substantial numbers of lake trout eggs and fry have been collected Wagner 1981;Marsden 1994;Holey et al 1995). In Lakes Superior and Ontario also, studies have indicated that the highest density of lake trout eggs occurs on man-made structures in areas where natural cobble substrates are rare (Marsden 1994;Schreiner et al 1995;Fitzsimons 1995).…”

“…Although lake trout were observed in the area of each reef, the only evidence of spawning was at the Tawas reef site in Lake Huron. Lake trout spawning has also been noted on other man-made structures, including water intakes, breakwalls, and artificial reefs in all of the Great Lakes with the exception of Lake Erie Wagner 1981;Nester and Poe 1984;Peck 1986;Fitzsimons 1994aFitzsimons , 1995Marsden 1994;Schreiner et al 1995). Clearly, under certain circumstances, artificial reefs that attract lake trout and have the potential to improve lake trout reproduction can be constructed.…”