Michigan Department of Natural Resources
Fisheries Research Report No.1892,1981
Dispersal of Lake Trout Fry From an Artificial Spawning Reef in Lake Superior
James W. Peck
Abstract.-Dispersal of lake trout fry from a spawning area in Presque Isle Harbor during May-July 1976 was determined from weekly sampling with a 5-m otter trawl. The eight sampling stations were located 0-3000 m from the spawning area at depths of 2-36 m. Most fry were caught on sand and rock bottom at depths of 2-12 m and water temperatures of 6-15 C. Many lake trout fry remained in Presque Isle Harbor until the end of July. They did not migrate immediately to deep water as has been reported by other scientists. Abundance was greatest at stations within 500 m of the spawning area until mid-June then shifted to stations 900-3000 m away but at depths comparable to the spawning area. Average total length of fry increased from 26 mm to 36 mm (4 May-12 July) at stations on and near the spawning area and from 26 mm to 45 mm (17 May-26 July) at stations 900-3000 m away. Water temperatures in excess of 15 C, random dispersal, and a preference for deep water 12 weeks after hatching were judged to be responsible for dispersal of lake trout from Presque Isle Harbor, with the latter factor appearing to be most responsible. Sampling for fry to assess success of natural reproduction would be most easily done on and near the spawning area during May-July.