"Egg Hatch and Swim-up Survival for Two Salmonid Species Using Remote Site Incubators"

Remote Site Incubators (RSIs) were developed for the incubation of salmonid eggs directly at a field site to enhance success and imprinting of young. They have been successful in the re-establishment of Arctic Grayling in Montana and are being tested for possible reintroduction of this species in the Manistee River, MI.  Arctic Grayling were historically native to the Manistee River watershed but were extirpated by the 1930s.  Rainbow and Brook Trout eggs, obtained from state hatcheries, were reared in a laboratory using flow through lake water to assess egg and fry survival to test RSI applications. Dead eggs and fry were removed daily and observations of developmental stages recorded. Rainbow Trout eggs were evaluated at high (n ~1600, 3.5 eggs/cm²), medium (n ~1200, 2.7 eggs/cm²), and low (n ~800, 1.7 eggs/cm²) egg densities with an average percent survival to hatch of 86% and swim up of 72%. Brook Trout eggs at medium (2.7 eggs/cm²) and low (1.8 eggs/cm²) densities were just reaching hatch in late February 2016. In Montana, RSIs achieved success with 67% survival of Arctic Grayling and our hatch and swim up rates suggest that RSIs can be used for similar future reintroductions to suitable Michigan streams.