Dynamics of Reproduction by Hatchery Lake Trout on a Man - Made Spawning Reef

Acoustic estimates of abundance and distribution of spawning lake trout on Sheboygan Reef in Lake Michigan

“…However, gill net data from 1999-2001 indicate that Sheboygan Reef had the highest catch per effort of any Lake Michigan location sampled regularly during the spawning season (Bronte et al, 2007). Mean density observed in this study (5.8 fish/ha) fell in the middle of the range of mean densities estimated from mark-recapture studies in five inland Ontario lakes (0.69-11.1 fish/ha, Janoscik, 2001), but were much lower than the density of ∼8600 fish/ha calculated from mark-recapture spawner abundance estimates at Presque Isle Harbor, Lake Superior (Peck, 1986). It is also unclear if the density we observed was consistent throughout the spawning season.…”

“…Fish distribution and abundance at Sheboygan Reef were sampled acoustically during the day (10:00-16:00, 20 October 2005) with a 129 kHz, Biosonics DT-X, split-beam echosounder with a hull-mounted transducer operated from the Michigan Department of Natural Resources S/V Steelhead. Sampling was conducted during the day because spawning generally occurs at dusk and dawn (Royce, 1943;Peck, 1986) and we assumed that spawning lake trout would be farther above bottom when they were not actively spawning (more acoustically detectable during the day). The acoustic system was coupled with a laptop computer, which recorded acoustic and differential GPS data.…”

Feeding rate of slimy sculpin and burbot on young lake charr in laboratory reefs

“…This density is lower than the 200-500 me2 reported by Royce (1951) and Martin (1956) in smaller lakes, but approximates the larval lake charr densities (up to 50me2) in Lake Superior reported by Peck (1986). Six to twelve sculpins were used per treatment and some tests were repeated twice to examine the effects of training.…”

“…Much of the work on lake charr spawning reefs has dealt with physical characteristics associated with good habitat for incubating young lake charr (DeRoche 1969, Peck 1986, Nester & Poe 1987. Our study points to the need for assessing the biological component of spawning reefs as well.…”

“…This temperature lies within the thermal range in the Great Lakes from fall to spring, but is higher than that during the midwinter incubation period. Winter temperature ranges have been reported to be 4-7" C in December and 1-2" C in March in Lake Michigan (Eck & Wells 1986), and 5-11°C in October and November, 2-5°C in December, and l&C in March and April in Lake Superior (Peck 1986). For consistency we held the water temperature at 6-7" C for all of our tests.…”