Many populations of lake sturgeon Acipenser fulvescens have decreased in size throughout the Great Lakes basin. To implement management strategies such as stocking, it is important to understand the genetic structure of lake sturgeon spawning populations. Lake sturgeon from 27 spawning locations (25 from the Great Lakes basin and 2 from the Hudson Bay drainage) were analyzed using 12 microsatellite loci. Population structure was detected at different spatial scales. At the largest scale, consistent genetic breaks were observed among three clusters of spawning populations: (1) Hudson Bay–northern Lake Superior, (2) southern Lake Superior, and (3) the rest of the Great Lakes. These clusters were identified using a Bayesian approach that does not define the populations a priori. Within each of the three clusters, sublevels of genetic structure were detected. These sublevel clusters accounted for 8.82% of the genetic variation (P < 0.000), while differences among populations within the clusters accounted for 3.72% of the genetic variation (P < 0.000). At the smallest scale, significant genetic differentiation was detected between most sampled locations through pairwise genetic differentiation index (FST) tests and pairwise contingency tests. Lake sturgeon showed greater genetic differentiation in Lake Superior than elsewhere, which could be due to the lake's bathymetry. The lower genetic resolution observed elsewhere in the Great Lakes could be due to more recent colonization events. The results can be used to delineate management units and to select appropriate donor populations for supplementation or reintroductions.

Four Lake Trout Salvelinus namaycush morphs were identified from Isle Royale, Lake Superior; the morphs differed in shape, traits linked to feeding and locomotion, buoyancy, and physical habitat use. Lean, humper, and siscowet Lake Trout generally conformed to previous descriptions, and we report, for the first time, quantitative evidence of a fourth morph, previously described anecdotally as the “redfin.” Jackknife classification of individuals to morphs based on body shape were 94% correct. High variation within and low variation among morphs led to moderately low percent agreement among visual identifications and high uncertainty in Bayesian model groupings of morphs. Eight linear measures of phenotypic traits linked to feeding (i.e., head and eyes) and locomotion (i.e., fin lengths and caudal peduncle shape) varied among morphs, consistent with specialized adaptations for trophic and physical resource use. Habitat differed among morphs with leans being most abundant in the 0–50‐m depth stratum and siscowets most abundant in two deeper strata (50–100 and 100–150 m). Differences in capture depth and percent buoyancy reflected physical habitat and known trophic resource partitioning among morphs. While the historical fingerprint of morphological and ecological diversity in Lake Superior Lake Trout persists, it is unknown whether the contemporary low level of differentiation is due to ecological release without subsequent reorganization or to a complete breakdown of differentiation. Received July 11, 2013; accepted February 7, 2014

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Coaster brook trout are a migratory form of brook trout Salvelinus fontinalis that spend part of their lives in the Great Lakes. Over the last century the abundance of coaster brook trout in Lake Superior has declined dramatically, and only remnant stocks remain. Recently, the rehabilitation of coaster brook trout in Lake Superior has become a goal of fish management agencies. The specific goal agreed upon by all of the agencies involved is to maintain widely distributed, self‐sustaining populations in as many of the historical habitats as practical. We discuss realistic expectations for rehabilitation and emphasize the need for management agencies, academia, and angling organizations to work cooperatively. We first present a brief history of coaster brook trout in Lake Superior, then discuss habitat requirements and protection, the regulations required for rehabilitation, stocking, species interactions, and the role that human dimensions play in rehabilitation. The management issues that must be addressed are implementation of a basinwide survey to identify remnant stocks and critical habitat, restrictive harvest regulations, watershed rehabilitation, critical biological review, and the formulation of expectations before experimental stocking programs are initiated, along with coordinated, basinwide information sharing and cooperative management among agencies similar to that undertaken during the rehabilitation of lake trout Salvelinus namaycush in Lake Superior. Future research needs include basic coaster biology and life history, habitat use in streams and the lake, interaction with other species in the Lake Superior fish community, and interaction between stream‐resident and coaster brook trout. Successful rehabilitation will require a shift from a harvest fishery to one with minimal or no harvest of coaster brook trout in the Lake Superior basin. Coaster brook trout rehabilitation will take time and will proceed at different rates at different locations, depending on the presence of remnant stocks, quality of habitat, angling pressure, and political will.

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We evaluated a pilot aquatic invasive species (AIS) early detection monitoring program in Lake Superior that was designed to detect newly introduced fishes. We established survey protocols for three major ports (Duluth-Superior, Sault Ste. Marie, Thunder Bay) and designed an adaptive cycle for routine evaluation of survey performance. Among the three ports, we found both similarities (species richness) and differences (introduced species detectability, species detection efficiency) with respect to AIS survey performance. Despite those differences, our analysis indicated potential for increasing detection efficiency at all three ports by exploiting differences in fish assemblages and sampling gears to increase rare species encounters. Using this information in the adaptive cycle, we demonstrate the ability to improve AIS detection efficiency. Our pilot monitoring program with its adaptive cycle of assessment, refinement, and implementation provides a performance-based approach to increase AIS detection efficiency over the course of a survey and within practical resource constraints. Diseño de muestreo para la detección temprana de especies acuáticas invasivas en los puertos de los Grandes LagosSe evaluó un programa piloto de monitoreo para la detección temprana de especies acuáticas invasivas (EAI) en el lago Superior, mismo que fue diseñado para detectar peces recién introducidos. Se establecieron protocolos de muestreo en tres puertos importantes (Duluth-Superior, Sault Ste. Marie y Thunder Bay) y se diseñó un circuito adaptativo para evaluar de forma rutinaria el desempeño del muestreo. Con respecto al desempeño del EAI, se encontraron similitudes (riqueza de especies) y diferencias (capacidad de detección de especies introducidas y eficiencia en la detección de especies) entre los tres puertos. Pese a dichas diferencias, los análisis indicaron que existe potencial en los tres puertos para incrementar la eficiencia en la detección de especies si se aprovechan las diferencias entre ensambles ícticos y entre artes de pesca para el muestreo con el fin de incrementar el encuentro de especies raras. Al utilizar esta información en el circuito adaptativo, se corrobora la habilidad para mejorar la detección del EAI. Nuestro programa de monitoreo piloto, el circuito adaptativo de evaluación, su refinamiento e implementación representan un enfoque basado en el desempeño, cuyo objetivo es incrementar la eficiencia en la detección de EAI en el curso de un muestreo y con limitaciones realistas de recursos. Modèle d'Échantillonnage pour la Détection Précoce des Espéces Aquatique Invasives aux Ports des Grands LacsNous avons évalué un programme pilote de surveillance de la détection précoce d'une espèce aquatique invasive (EAI) [Aquatic invasive species (AIS)] dans le Lac Supérieur, conçu pour détecter les poissons nouvellement introduits. Nous avons établis des protocoles de surveillance pour trois ports majeurs (Duluth-Superieur, Sault Ste. Marie, Thunder Bay), et créé un cycle adaptatif pour l'évaluation habituelle des ré...

Brook trout Salvelinus fontinalis from Isle Royale, Michigan, three Minnesota tributaries of Lake Superior, and Lake Nipigon in Ontario were analyzed for genetic variation at 12 microsatellite DNA loci. Analysis of molecular variance, genetic distance measures, and cluster analysis were used to examine the diversity, gene flow, and relatedness among the samples. The diversity estimates for the samples from Isle Royale were similar to those for the samples collected from Minnesota tributaries of Lake Superior, and all estimates were lower than those reported in other studies of brook trout from eastern North America. Genetic differences were detected among the brook trout at Isle Royale, Lake Nipigon, and the Minnesota tributaries of Lake Superior. Further, the population in Tobin Harbor at the eastern end of Isle Royale was distinct from the populations from tributaries at the southwestern end of the island. The Minnesota tributary population formed a group that was genetically distinct from those from Isle Royale and Lake Nipigon. The Isle Royale population should be managed to preserve the genetic and phenotypic variation that distinguishes it from the other brook trout populations analyzed to date.

Lake Sturgeon Acipenser fulvescens rehabilitation efforts in Lake Superior are guided by a rehabilitation plan that sets goals and criteria for a self-sustaining population, including a minimum of 1,500 mature adults, roughly equal sex ratio, and annual exploitation rates &lt; 5%. The Bad and White rivers, Wisconsin host a genetically unique Lake Sturgeon population that is utilized by state-licensed recreational anglers and tribal subsistence fishers. Our objectives were to 1) determine if the Bad River population meets rehabilitation plan targets for a self-sustaining population, 2) assess harvest of Lake Sturgeon by recreational anglers and tribal subsistence fishers for compatibility with rehabilitation goals, 3) determine population trajectory from annual spawning runs, and 4) describe population demographics given the unique physical features of Lake Superior. We sampled Lake Sturgeon in the Bad and White rivers with gill nets over a 17-y period (2001 to 2017). The observed sex ratio in spawning runs was 2.2:1 (male : female), but calculated at 1.6:1 for the entire adult population on the basis of abundance estimates. Weight–length relationships converted to a standardized modified form factor indicated lower condition and possibly lower female fecundity compared with other large North American populations. Annual spawning run size estimates over time indicated that the population trajectory was stable to slightly increasing, and during 2016 was 739 and 241 individuals in the Bad and White rivers, respectively. Total population size (including nonspawners) exceeded 1,500 individuals, which met Lake Superior rehabilitation criteria for a self-sustaining population. Estimates of 1,426 males and 882 females were considered conservative because 472 unknown-sex fish could not be accounted for in return time and abundance models. Spawning return times were 2 or 3 y for males and 4 to 6 y for females, longer than many other populations. Exploitation by recreational anglers and tribal subsistence fishers was 1.3% or lower and met the rehabilitation plan target of &lt; 5%, but we recommend exploitation not exceed 3.1% to maintain a self-sustaining population. These findings help gauge rehabilitation progress in Lake Superior and better describe the demographics of a remnant self-sustaining Lake Sturgeon population in Lake Superior.