| Patterns of activity in walleye (Sander vitreus) and its prey were investigated in nine lakes in the region of Sudbury, Ontario, Canada. Four lakes contained only small-bodied prey, yellow perch ( Perca flvenscens); the other five lakes contained yellow perch and a larger-bodied alternative prey, lake herring (Coregonus artedi). Stomach contents revealed that walleye of all sizes consumed lake herring when available, but herring was most important to larger walleye.; Bioenergetic modeling confirmed walleye were less active in lakes with herring, and prey consumption rates were actually lower when a larger-bodied prey was available. The result of spending less energy foraging while consuming larger prey was that walleye, particularly large females, exhibited significantly more efficient growth.; Empirical patterns, modeled energy budgets, and physiological indicators all concur that both walleye and yellow perch are less active in the presence of larger prey, lake herring. The lowered active costs for walleye in lakes with herring are a result of foraging less often on larger prey, leading to trophy growth. (Abstract shortened by UMI.)... |
