Egg size and lipid content of lake trout (Salvelinus namaycush) in the wild and in captivity

Abstract

Egg quality influences early life survival in fishes, but drivers of egg quality variation remain poorly understood. I examined egg quality of a long-lived, iteroparous salmonid (lake trout (Salvelinus namaycush)) with respect to maternal traits and environmental conditions in wild and captively reared populations. Variation was stronger and more consistent for egg size than for lipid content. Among females, egg size was most strongly related to maternal age, in both wild and captive populations, and faster-growing females tended to produce larger eggs. Among wild populations, maternal growth was more strongly associated with indices of ecosystem size or productivity than climate, whereas the opposite was observed for egg size. Egg size and, to a lesser extent, maternal growth in captive populations were positively correlated with egg size and growth, respectively, in their wild source populations. However, captive females grew faster and produced larger eggs at age, but smaller eggs at length, than their wild counterparts. Lake trout egg quality variation has both maternal and environmental components, and captive rearing appears to alter the ontogenetic progression of egg size.