Collecting Gear for Lake Trout Eggs and Fry

Abstract

Various types of gear for sampling eggs and fry of lake trout (Salvelinus namaycush) were tested in Lakes Superior and Michigan during 1973-79. One type consisted of pails set in spawning substrate before lake trout spawned. Some were lifted soon after spawning to determine number of eggs deposited; others were left until spring when traps mounted atop the pails caught fry that hatched from eggs previously deposited in the pails. For collecting on lake trout spawning grounds, centrifugal pumps, which sucked up water and organisms from spawning substrate, were effective both for eggs and sac fry. Pyramidal wire-mesh traps, set on lake trout spawning areas, were very effective in catching fry in May and June. Plastic minnow traps also caught fry on spawning areas. Two versions of a 1.2-m beam trawl equipped with “ticklers” were moderately effective for fry on rough-bottomed spawning areas and on nearby smooth, hard bottom during May-July. A 5-m otter trawl, fished at night near spawning grounds, was effective for collecting fry on moderately smooth bottom in July and July.