Book Description

Variability in annual recruitment for many fishes is correlated with survival during the larval phase. Yellow perch in Lake Michigan have experienced sustained recruitment failure since 1990 and this has been blamed on low larval survival. Direct examination of factors important to larval yellow perch survival in Lake Michigan is complicated by the large size of the lake (52,000 km2) and the short length of the pelagic larval period (30-40 days). Individual-based modeling is a valuable indirect method for assessing the importance of multiple factors to larval survival. I used an individual-based modeling approach combined with field data collection to test four hypotheses regarding factors limiting survival of larval yellow perch in Lake Michigan. I tested whether larval survival is limited by prey community composition, size-selective predation, advection of larvae into offshore habitat or an interaction of these factors. I sampled larval and zooplankton abundance in Lake Michigan along a transect from 1 - 32 km from shore in 2000 and 2001. I conducted laboratory experiments to quantify larval vulnerability to predation by three typical predators as a function of both predator and prey size. I also conducted laboratory experiments to quantify larval selectivity for different zooplankton prey as a function of larval size and prey community composition. I used the results of these experiments to develop an individual-based model specifically to describe growth and survival of larval yellow perch. Field data suggest that larval yellow perch are being transported from the nearshore to the offshore zone of Lake Michigan, but the timing of this transport varies between years. Model simulations in which the offshore prey community and the timing of larval advection were both varied suggested that larval survival will be highest in years when advection occurs within two weeks of peak hatch, allowing larvae to exploit offshore prey resources early during ontogeny. The.