Rapid early development and feeding benefits an invasive population of lake trout

Lake trout (Salvelinus namaycush) were discovered in Yellowstone Lake in 1994 and their population expanded dramatically despite intensive suppression. The lake is species-depauperate, with no major lake trout embryo predators. We hypothesized that without this predation threat, lake trout free embryo feeding and growth may be greater than in their native range, leading to increased survival of age-0 individuals and rapid population growth. We compared length, developmental rate, and feeding patterns of lake trout free embryos captured at a spawning site in Yellowstone Lake with free embryos captured in their native range in Lake Champlain, Vermont. More embryos were feeding, contained more food, and were significantly longer at the same developmental stages in Yellowstone Lake. With an abundance of available food and minimal threat of predation, free embryos remained on the spawning site in Yellowstone Lake later into the summer than in Lake Champlain and achieved a greater maximum length before they dispersed. Greater food consumption and associated growth likely leads to high survival of lake trout free embryos in Yellowstone Lake, contributing to rapid population growth.