Design and Use of Mesh Bags to Estimate Deposition and Survival of Fish Eggs in Cobble Substrate

Abstract

Abstract A sampler is described and evaluated for use in early life history studies of demersally spawning fishes that broadcast eggs over rocky substrate. The sampler was designed to be buried in substrate and to collect spawned eggs under natural environmental conditions (including natural water flow). Each sampler consisted of a metal ring (32-cm inside diameter) with a 51.5-cm-deep nylon mesh bag attached (mesh size = 0.16 cm). Egg deposition in the substrate per unit area, survival of embryos at various developmental stages, and predator density in the substrate were estimated based on data from 135 bags buried by scuba divers on a spawning reef used by lake trout Salvelinus namaycush in Lake Ontario. None of the bags were dislodged during storms. Bags were easier to construct, bury, and retrieve than many other devices previously described.