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Data from: Season and site fidelity determine home range of dispersing and resident juvenile Greenland cod (Gadus ogac) in a Newfoundland fjord
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Shapiera, Melanie; Gregory, Robert S.; Morris, Corey J.; Pennell, Curtis J.; Snelgrove, Paul V. R.; Gregory, RS; Morris, CJ; Pennell, CJ; Snelgrove, PVR — 2015-02-17 We used acoustic telemetry to track age 1 juvenile Greenland cod Gadus ogac in Newman Sound, Newfoundland, from October 2010 to November 2012, in 2 consecutive 1 yr experiments. Using single (Year 1) and reciprocal (Year 2) transplant study designs, we investigated seasonal dispersal, home range area, and potential homing behaviour between coves ~3.5 km apart. We tracked individuals moving at metre to kilometre scales, using a network of 26 to 32 hydrophones. We converted tag detections to position estimates in order to calculate seasonal home ranges and individual movement patterns. Home range increased significantly with season (pre-winter, winter, and post-winter) in both study years. Mean seasonal home range area ranged from 0.29 to 3.47 km2 in Year 1 and 0.43 to 1.72 km2 in Year 2. In contrast, fish size-at-capture, capture location, and release location had no significant effect on seasonal home range. Increased movement distance during the winter and post-winter season suggests a reduction in predation pressure on age 1 juveniles at these times, challenging previous assumptions about their vulnerability. We observed variable behaviour spanning residency to kilometre-scale dispersal movements, which represent greater distances than previously assumed. Similar proportions of control and transplant fish visited the other cove, indicating an absence of homing behaviour among dispersing individuals. Juveniles of marine fishes are often characterized as key life history transition stages between vulnerable larvae and older, larger individuals which are less susceptible to predators. Our results indicate that early juvenile life stages may be substantially more mobile than presupposed and contribute to population connectivity in temperate fishes in ways not well described previously.
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Data from: Oceanographic variation influences spatial genomic structure in the sea scallop, Placopecten magellanicus
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Van Wyngaarden, Mallory; Snelgrove, Paul V. R.; DiBacco, Claudio; Hamilton, Lorraine C.; Rodriguez-Ezpeleta, Naiara; Zhan, Luyao; Beiko, Robert; Bradbury, Ian R.; Beiko, Robert G. — 2019-01-02 Environmental factors can influence diversity and population structure in marine species and accurate understanding of this influence can both improve fisheries management and help predict responses to environmental change. We used 7163 SNPs derived from restriction site-associated DNA sequencing genotyped in 245 individuals of the economically important sea scallop, Placopecten magellanicus, to evaluate the correlations between oceanographic variation and a previously identified latitudinal genomic cline. Sea scallops span a broad latitudinal area (>10 degrees), and we hypothesized that climatic variation significantly drives clinal trends in allele frequency. Using a large environmental dataset, including temperature, salinity, chlorophyll a, and nutrient concentrations, we identified a suite of SNPs (285–621, depending on analysis and environmental dataset) potentially under selection through correlations with environmental variation. Principal components analysis of different outlier SNPs and environmental datasets revealed similar northern and southern clusters, with significant associations between the first axes of each (R2adj = .66–.79). Multivariate redundancy analysis of outlier SNPs and the environmental principal components indicated that environmental factors explained more than 32% of the variance. Similarly, multiple linear regressions and random-forest analysis identified winter average and minimum ocean temperatures as significant parameters in the link between genetic and environmental variation. This work indicates that oceanographic variation is associated with the observed genomic cline in this species and that seasonal periods of extreme cold may restrict gene flow along a latitudinal gradient in this marine benthic bivalve. Incorporating this finding into management may improve accuracy of management strategies and future predictions.
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Data for: High site-fidelity and low mortality of juvenile Atlantic cod (Gadus morhua) in subarctic coastal Newfoundland during their first winter
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Emilie A. Geissinger; Gregory, Robert S.; Laurel, Benjamin J.; Snelgrove, Paul V. R. — 2021-12-01 <p>This dataset contains capture-mark-recapture data of juvenile Atlantic cod (<i>Gadus morhua</i>) in subarctic coastal Newfoundland during their first winter. </p> <p>We evaluated size-structured overwinter mortality and movement using mark-recapture and condition metrics by marking 226 cod in two batches one week apart, in October 2016. We estimated fall and overwinter mortality, and documented movement of fish recaptured in May 2017 using Cormack-Jolly-Seber models. We applied fluorochrome markers – calcein (Sigma-Aldrich: C0875-25G) or alizarin red S (Sigma-Aldrich: A5533-25G) – to batch mark otoliths (Schmitt, 1982; Vigliola, 1997). A subsample of 60 otoliths from May 2017 recaptures was used for trace element analysis using secondary ion mass spectrometry (SIMS). See the ReadMe file for more information on the method of data collection. </p> <p>All R code is available at <a href="https://github.com/eageissinger/CHONe-1.2.1">CHONe-1.2.1 GitHub repository</a>.</p>
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Data from: Identifying patterns of dispersal, connectivity, and selection in the sea scallop, Placopecten magellanicus, using RAD-seq derived SNPs
Dryad
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.

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(Author: Snelgrove, Paul V. R.)

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