Altered yellow perch stock-recruit relationships in Saginaw Bay, Lake Huron

In Saginaw Bay, a large productive embayment of Lake Huron, yellow perch (Perca flavescens) experienced a multi-decadal decline in adult abundance despite increasing fall age-0 abundance, suggesting a shift in recruitment dynamics. To assess the relative influence of ecosystem changes in altering yellow perch stock-recruit relationships, we compared candidate models, assuming either stationary or nonstationary dynamics, to evaluate potential shifts in the age at which year-class strength is set and the importance of environmental and biotic factors in explaining yellow perch age-0 and age-1 relative abundance (1970-2022). Results indicate that the age when year-class strength is established may have shifted from age-0 to age-1 in the early-2000s. Models incorporating nonstationarity best explained annual variation in yellow perch age-0 (~83%) and age-1 (~65%) relative abundance. High age-0 production was attributed to reduced competition and predation following the 2003-2004 collapse of alewife (Alosa pseudoharengus). However, increasing walleye (Sander vitreus) abundance, coincident with alewife declines, may have increased predation on age-1 yellow perch, leading to declines in age-1 relative abundance.