A Conundrum: a burst in lake trout reproduction in west Lake Ontario while it declined in the east

Session: Poster Session

Stacy Furgal, U.S. Geological Survey, Great Lakes Science Center, [email protected]
Brian Lantry, U.S.G.S., Lake Ontario Bio Station, [email protected]
John Farrell, SUNY-ESF, [email protected]
Brian Weidel, U.S. Geological Survey, Great Lakes Science Center, [email protected]
J. Marsden, University of Vermont, Rubenstein School of Environment and Natural Resources, [email protected]
Dimitry Gorsky, U.S. Fish and Wildlife Service, [email protected]
Michael Connerton, SUNY ESF, [email protected]
Jeremy Holden, OMNRF, [email protected]

Abstract

Despite years of stocking efforts, lake trout (Salvelinus namaycush) in Lake Ontario have yet to reestablish a self-sustaining population. During the 1980s, surveys at Stony Island Reef (SIR) in eastern Lake Ontario documented substantial egg deposition and production of swim-up fry. Agency bottom trawl assessments in the same area confirmed survival of naturally reproduced individuals to the juvenile stage. Beginning in 2014, results of long-term bottom trawl assessments showed increased production of natural recruits from sites in western Lake Ontario while simultaneously recording decreased production near Stony Island.  In this study, we examined several factors associated with spawning success at SIR including: habitat condition, egg deposition, adult and juvenile CPUE from assessment data, and telemetry data for stocked juveniles. Assessment survey results indicated decreased adult and juvenile abundance; telemetry studies revealed high initial post-stocking survival but later high juvenile emigration rates; and sampling on SIR indicated degraded spawning habitat and egg deposition rates near zero. These findings indicate that substantial changes in lake trout habitat may limit lake trout reproduction at SIR and emphasize the need to examine other critical nearby eastern Lake Ontario spawning habitat.