Walleye (Stizostedion vitreum) from two northern Minnesota spawning stations (Pike River, Hudson Bay drainage, and Little Cutfoot Sioux Lake, Mississippi River drainage) simultaneously stocked as fry into five southern Minnesota lakes had different survival rates. One year after stocking, Pike River walleye were more abundant than their original proportion of 46.5% of the stocked fish, but by the end of their second summer, neither population had a clear survival advantage. In the three lakes where walleye were consistently sampled, natural-origin walleye that descended from previous stockings significantly increased in percent of all sampled walleye over the study (P = 0.001). The unmarked and untagged stocked fish (N = 566) were assigned to their source population by comparing their genotypes at nine microsatellite DNA loci to the known genotypes of the parent pairs crossed in a hatchery (parentage assignment). Fish not assigned to a parent pair were considered to be the product of natural reproduction (N = 177) by previously stocked fish. Simulations indicated that natural-origin walleye were sufficiently excluded from assignment to stocked fish parent pairs so as not to bias the comparison. Parentage assignment is a powerful population discrimination tool if genotypes are known for all parent pairs from all but one putative source.

Catch rates of Yellow Perch Perca flavescens in standard gill-net surveys conducted by the Minnesota Department of Natural Resources have declined since 1970, but it is unclear whether this trend was due to reduced abundance or to changes in size structure affecting catchability. Because the minimum capture length of standard gill nets may limit effective sampling of some populations, the objectives of this study were to determine if length-based metrics could be used to characterize populations and their susceptibility to standard gill nets, if these metrics were correlated with a suite of abiotic and biotic variables, and if temporal trends in these metrics were evident. Data were collected from a broad size distribution of Yellow Perch sampled with standard gill nets, boat electrofishing, and small-mesh gill nets in 17 lakes. Estimated length at 50% maturity (L50) for females varied up to 100 mm across lakes, with values as small as 70 mm documented in some populations. Female L50 from supplemental gears was significantly positively correlated with the average length of the 15 largest fish (L max ) from all gears, and both of these metrics were positively correlated with standard gill-net catch. Exploratory analysis of female L50 indicated that this metric was positively correlated with latitude and lake size and negatively correlated with water clarity. Additionally, a statewide analysis of L max conducted with standard gill-net data from over 1,000 lakes found significant declines during the past 25 years, indicating that populations in Minnesota have likely shifted towards a smaller size structure, reducing catchability in standard gill nets. These results indicate that standard gill nets were ineffective for sampling some Yellow Perch populations and that length-based metrics such as L50 and L max can be used to infer catchability in standard gear and to monitor populations through time.Yellow Perch Perca flavescens are a percid species of management interest in the Upper Midwest region of the United States, occupying diverse lentic systems from the Great Lakes to glacial ponds. Yellow Perch fulfill dual ecological roles as a primary forage species for top predators, such as Walleye Sander vitreus (Johnson and Hale 1977) and Northern Pike Esox lucius (Pierce 2012), but are also piscivorous and targeted for harvest at larger