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K. S. Layton, Kara; Dempson, J. Brian; Snelgrove, Paul V.R.; Duffy, Steven J.; Messmer, Amber M.; Paterson, Ian; Jeffery, Nicholas W.; Kess, Tony; Horne, John B.; Salisbury, Sarah J.; Ruzzante, Daniel E.; Bentzen, Paul; Côté, David; Nugent, Cameron M.; Ferguson, Moira M.; Leong, Jong S.; Koop, Ben F.; Bradbury, Ian R. — 2020-01-17 <p>The resiliency of populations and species to environmental change is dependent on the maintenance of genetic diversity, and as such quantifying diversity is central to combatting ongoing wide spread reductions in biodiversity. With the advent of next-generation sequencing, several methods now exist for resolving fine-scale population structure, but the comparative performance of these methods for genetic assignment has rarely been tested. Here we evaluate the performance of sequenced microsatellites and a single nucleotide polymorphism (SNP) array to resolve fine-scale population structure in a critically important salmonid in northeastern Canada, Arctic charr (<i>Salvelinus alpinus</i>). We also assess the utility of sequenced microsatellites for fisheries applications by quantifying the spatial scales of movement and exploitation through genetic assignment of fishery samples to rivers of origin and comparing these results with a 29-year tagging dataset. Self-assignment and simulation-based analyses of 111 genome-wide microsatellite loci and 500 informative SNPs from 28 populations of Arctic charr in northeastern Canada identified largely river-specific genetic structure. Despite large differences (~4X) in the number of loci surveyed between panels, mean self-assignment accuracy was similar with the SNP panel and with the microsatellite loci (&gt;90%). Subsequent analysis of 996 fishery-collected samples using the microsatellite panel revealed that larger rivers contribute greater numbers of individuals to the fishery, and that coastal fisheries largely exploit individuals originating from nearby rivers, corroborating results from traditional tagging experiments. Our results demonstrate the efficacy of sequence-based microsatellite genotyping to advance understanding of fine-scale population structure and harvest composition in northern and understudied species.</p>

Emilie A. Geissinger; Gregory, Robert S.; Laurel, Benjamin J.; Snelgrove, Paul V.R. — 2020-01-27 To examine the consequences of size variation on overwintering success under contrasting food scenarios, we collected demersal age-0 cod from Newman Sound, Newfoundland and brought them to the laboratory for 114-day feeding trials at ambient overwinter sea temperatures. From January to April 2017, we reared two size-classes of juvenile cod under four daily ration levels (starvation, 2.5%, 5%, 10% dry body weight). We then used Fulton’s K condition factor to interpret how food availability and fish size interact to impact survival during the critical overwinter period. Size, weight, temperature, survial, and food consumption were measured throughout the 114-day experiment. This research is sponsored by the NSERC Canadian Healthy Oceans Network and its Partners: Department of Fisheries and Oceans Canada and INREST (representing the Port of Sept-Îles and City of Sept-Îles).

Van Wyngaarden, Mallory; Snelgrove, Paul V.R.; DiBacco, Claudio; Hamilton, Lorraine C.; Rodríguez-Ezpeleta, Naiara; Jeffery, Nicholas W.; Stanley, Ryan R.; Bradbury, Ian R.; Stanley, Ryan R. E.; Snelgrove, Paul V. R. — 2016-08-29 Understanding patterns of dispersal and connectivity among marine populations can directly inform fisheries conservation and management. Advances in high-throughput sequencing offer new opportunities for estimating marine connectivity. We used Restriction-site Associated DNA sequencing to examine dispersal and realized connectivity in the sea scallop Placopecten magellanicus, an economically important marine bivalve. Based on 245 individuals sampled range-wide at 12 locations from Newfoundland to the Mid-Atlantic Bight we identified and genotyped 7163 Single Nucleotide Polymorphisms; 112 (1.6%) were identified as outliers potentially under directional selection. Bayesian clustering revealed a discontinuity between northern and southern samples and latitudinal clines in allele frequencies were observed in 42.9% of the outlier loci and in 24.6% of neutral loci. Dispersal estimates derived using these clines and estimates of linkage disequilibrium imply limited dispersal; 373.1 ± 407.0 km (mean ± SD) for outlier loci and 641.0 ± 544.6 km (mean ± SD) for neutral loci. Our analysis suggests restricted dispersal compared to the species range (>2000 km) and that dispersal and effective connectivity differ. These observations support the hypothesis that limited effective dispersal structures scallop populations along eastern North America. These findings can help refine the appropriate scale of management and conservation in this commercially valuable species.