Estimates of egg deposition and effects of lake trout (Salvelinus namaycush) egg predators in three regions of the Great Lakes

• Published in: Canadian journal of fisheries and aquatic sciences Vol. 62; no. 10; pp. 2254 - 2264
• Main Authors: Jonas, Jory L, Claramunt, Randall M, Fitzsimons, John D, Marsden, J Ellen, Ellrott, Brian J
• Format: Journal Article
• Language: English
• Published: Ottawa, Canada NRC Research Press 01.10.2005; National Research Council of Canada; Canadian Science Publishing NRC Research Press
• Subjects: Animal, plant and microbial ecology; Applied ecology; Biological and medical sciences; Competition; Cottus; Effects; Eggs; Environmental aspects; Estimates; Exploitation and management of natural biological resources (hunting, fishing and exploited populations survey, etc.); Fish; Fish populations; Freshwater; Fundamental and applied biological sciences. Psychology; Lake trout; Lakes; Mortality; Orconectes propinquus; Orconectes rusticus; Predation; Predation (Biology); Predators; Salvelinus namaycush; Spawning; United States; Great Lakes; Canada, Ontario, Parry Sound; North America, Huron L; North America, Champlain L; USA, Michigan L; Freshwater environment; Salvelinus namaycush; Aquatic environment; Vertebrata; Egg; Pisces; Great Lake; Predator; Great Lakes
• ISSN: 0706-652X; 1205-7533
• DOI: 10.1139/f05-141

Excessive mortality from spawning through the first year of life is likely responsible for recruitment failures in many lake trout (Salvelinus namaycush) populations. We evaluated relationships between interstitial predator species and lake trout egg deposition in three regions of the Great Lakes. The introduced crayfish Orconectes rusticus dominated the nearshore zone in northern Lake Michigan, whereas other sites in Lake Michigan and Parry Sound were dominated by native Orconectes propinquus. In Lake Champlain, sculpin (Cottus spp.) were the most common interstitial predator, yet densities were comparable with those in Lake Michigan. Predator densities in Lake Michigan (mean ± standard error = 15.5 ± 0.4 predators·m –2 ) were twice those in Lake Champlain or Parry Sound (6 ± 1 predators·m –2 ). Densities of eggs were higher in Lake Champlain (2994.1 ± 398.3 eggs·m –2 ) and Parry Sound (454.7 ± 36.3) than in Lake Michigan (7.5 ± 1.3; Kruskal-Wallis, P ≤ 0.05). Ratios of eggs to predator provide simple measures of the effectiveness of lake trout rehabilitation efforts. The average ratio calculated from 10 successful spawning locations is 190 eggs·predator –1 ·m –2 . Ratios may help establish target egg densities for restoration efforts and the concentration of spawning adults required to allow survival to the fry stage.