Center for Systems Integration and Sustainability

Journal or Book Title: Journal of Great Lakes Research

Keywords: Lake Ontario; Salvelinus namaycush; reproduction; early life history

Volume/Issue: 20(2)

Page Number(s): 385-389

Year Published: 1994

Biologists in the Great Lakes have used circular egg traps to study lake trout (Salvelinus namaycush) reproduction for the past several years; however, interpretation of egg trap data beyond the presence or absence of eggs has been speculative. The main objective of this study was to determine if trap data could be used to index egg abundance in spawning substrate. In 1990 and 1992 the number of eggs captured in traps on a reef in Lake Ontario was compared to the egg abundance in cobble substrate adjacent to each trap. Linear regression models indicated that the relationship between eggs captured in traps and egg abundance varied significantly, both among depth transects within years and between years (P<0.05). However, within a given year, egg capture in traps generally increased as egg abundance increased. Wind-induced waves and water currents probably affected the proportion of eggs that were dislodged from the substrate and drifted into traps or off the reef and caused much of the variation observed in the eggs * trap 1 - egg abundance relationship. Different substrate size and interstitial depth may also explain some of the within year variation among trap sites. Trap data should not be used to compare egg abundance among different Great Lakes spawning areas unless data interpretation includes sources of variation such as water currents and substrate type. Comparison of trap data among years for the same spawning area should only be made among years with similar water currents.

Type of Publication: Journal Article