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Conservation and management issues related to genetic diversity and stock structure of native populations of Muskellunge Esox masquinongy have largely been unexplored. In Lake Huron's North Channel and Georgian Bay, Muskellunge populations have been impacted by historical commercial fisheries, recreational fisheries, loss of spawning habitat, historical water quality issues, and ecosystem changes. To determine the spatial genetic structure of native Muskellunge in Lake Huron and Georgian Bay, spawning adults were sampled from 10 sites in the North Channel and eastern Georgian Bay. Genotyping with 20 microsatellite DNA loci showed substantial spatial genetic structure, with significant pairwise divergences among spawning sites. Individual‐ and population‐based analyses revealed hierarchical population structuring, with strong patterns of spawning site fidelity and isolation by distance; very low levels of dispersal and gene flow over historical and contemporary timescales were indicated. Estimation of effective population sizes highlighted the limited genetic resources that are present in these localized populations. The present results show that Muskellunge in Lake Huron and Georgian Bay consist of multiple small populations with limited ranges and high site fidelity and should be managed accordingly. Received February 28, 2016; accepted July 1, 2016 Published online October 11, 2016

We used allozymes and mitochondrial DNA (mtDNA) restriction fragment length polymorphisms to determine if spawning populations of walleyes Stizostedion vitreum from the Lake Erie-Lake Huron corridor are genetically differentiated and to estimate their contributions to a commercial fishery in southern Lake Huron (operated by Purdy Fisheries) in 1994 and 1995. Both types of genetic markers detected significant differentiation among walleyes collected from different sites, suggesting that fish from Lake Erie, Lake St. Clair, and Lake Huron are not a single, genetically homogeneous population. The combined use of both marker systems detected the greatest differentiation in pairwise comparisons of samples. Although some exceptions were detected, both marker types suggest a relationship between geographic proximity and genetic differentiation. The fish from Purdy Fisheries caught throughout 1994 had highly significantly different haplotype frequencies (mtDNA) but not allele frequencies (allozymes) from those caught throughout 1995. The estimated contributions of walleyes from different spawning sites to the catch from Purdy Fisheries varied little between years. Most estimates were significantly greater than zero, indicating that all sites contributed at some level and none should be ignored in management considerations. The mixed-stock analysis was robust when factors affecting bias and precision were evaluated. * Corresponding

Liskauskas, A. I>., and M. M. Ferguson. 1991. Genetic variation and fitness: a test in a naturalized population of brook trout (Saiveliwus dontina%is). Can. 1. Fish. Aquat. Sci. 48: 21 52-21 62.The relationship between enzyme heterozygosity and several components sf fitness (sine and survival) was examined in a naturalized popeslation of brook trsut (Salvelinus dontinalis) from Algonquin Provincial Park, Ontario. Significant differences in allele frequency and the number of heterozygous loci per individual were Pound among five age classes spanning most of the life history stages sf brook trsut in this population. A young sf the year (YOY) cohort sampled after a period of high natural mortality had significantly greater numbers of heterozygous loci per individual than YOY sampled shortly after emergence from redd sites. A positive association between heterszygasity and size was only found in YOY sampled in June and not in the other age classes in which sexual maturity was not a complicating factor. The association between heterozygssity and size was affected by the onset of sexual maturity. Significant negative regressions between rnultilocus or single lscus heterozygosity and size were found in mature males whereas heterozygosity was positively associated with size in females. These dissimilarities may Re the result sf differences in growth rates prim to sexual maturation and differential allocation of energy towards gametic and somatic tissue.On a &$lie la relation entre 11h6t6rog6nie des enzymes et plusieurs cornposantes de la condition physique (taille et taux de survie) dans une population acclirnat6e d'omble de fontaine (Salvelinus fmtinalis) d e e parc provincial Algsnquin (Ontario). O n a releve des differences significatives de la frbquence allelique et der nsmbre de loci hetersaygotes par poisson chez cinq classes dt3ges englobant la presque totalit6 du cycle vital de I'ornble de fontaine csmposant cette population. L16chantillonnage d'une c~h o r t e d'ombles de rnsins d'un an aprPs une periode de mortalit6 naturelle etev6e a revel6 un nsmbre laettement plus &lev$ de loci h6terozygetes par poisson comparativement aux ornbles du mGme 2ge echantillonnks peu apr6s avoir quitt6 les sillons. Une association positive entre Ith6tersgt5nie et la taille n'a et6 relevee que chez ies ambles de rnoins d'un an echantillsnn6s en juin et non chez les autres classes d'dges oO la maturite sexuelle nt6tait pas un facteur coniplexant. L'approche de la maturit6 sexuelle infiuait sur l'association eotre 11h6t6rsg6nie et la taille. On a aussi relev6 des r6gressions negatives significatives entre, d'une part, Bth6t6rog6nie A plusieurs loci et Ith6t6rsgt5saie A un seui lscus et, d'autre part, la taille des rn2les matures, tandis que 11h6t6rog6nie msntrait une association positive avec la taiile des femelles. Ces differences peuvent Gtre le resultat de variations du taux de croissance avant la rnaturite sexuelle et une repartition differentielle de I'energie pour Itelaboration de tissus ssmatiques et de gamPtes.

The spatial and temporal distributions of mitochondrial DNA (mtDNA) haplotypes in walleyes Stizostedion vitreum captured from spawning stocks were examined to assess genetic population structure in eastern Lake Huron, Ontario. We also assessed mtDNA variation in pondreared fish relative to that in their parental sources to determine whether cultured fish have the potential to influence mtDNA structure within and among stocks. Restriction fragment length polymorphisms in two polymerase-chain-reaction-amplified fragments totaling 7.6 kilobases and sequencing 310 base pairs of the control region were used to assess mtDNA variation in both archived scales and contemporary samples collected from 1965 to 1998. Although many stocks in eastern Lake Huron differed significantly in pairwise comparisons of contemporary haplotype frequencies, fish from eastern Georgian Bay and the French River complex exhibited low mtDNA differentiation. Low nucleon diversity (h) and the absence of low-frequency haplotypes (Ͻ0.15) were observed in some stocks, particularly those examined in eastern Georgian Bay. There appeared to be a loss of mtDNA variation in two stocks, which exhibited a general reduction in h, loss of low-frequency haplotypes, and a significant change in haplotype frequencies over a 28-year and a 33-year period, respectively. Cultured walleyes from rearing ponds had reduced h, lower numbers of haplotypes, and significantly different haplotype frequencies compared with their parental sources. * Corresponding author: michael.gatt@mnr.gov.on.ca 1 Present address: Peterborough District Office, Ontario Ministry of Natural Resources,