“Optimal” P loading in large lakes affects fish communities: Do you prefer walleye or yellow perch?

In the Laurentian Great Lakes, recruitment of yellow perch (Percajlavescens) and walleye (Sander vitreus) is high1y variab1e. Suggested factors to exp1ain this resu1t include spawning stock size, zoop1ankton availability to juveni1es (DETIMERS et al. 2003, HoXMEIER et al. 2004, FULFORD et al. 2006), predation (HARTMAN & MARGRAF 1993), spring warming rate (BuscH et al. 1975, CLADY 1976), and temperature (HO KANsoN 1977, HENDERSON & NEPZY 1988). Recruitment of other taxa found in the smallest ofthe Laurentian Great Lakes, Lake Eri e, a1so varies, inc1uding species such as, white bass (Morone chrysops), gizzard shad (Dorosoma cepedianum), rainbow sme1t ( Osmerus mordax), andemera1d (Notropis atherinoides) and spottai1 shiners (N. hudsonius; ODW 2006). The abundances of walleye and yellow perch have increased significantly since 1970 as phosphorus (P) 1oading to the 1ake has decreased. Because P 1oading and young-of-the-year (YOY) fish abundances have been measured since 1969, Lake Eri e allows us to test whether P-1oading affects fish recruitment.