Migration patterns of Greenland halibut in the North Atlantic revealed by a compiled mark-recapture dataset

Marine fisheries are often allocated to stocks that reflect pragmatic considerations and may not represent the species’ spatial population structure, increasing the risk of mismanagement and unsustainable harvesting. Here we compile mark–recapture data collected across the North Atlantic to gain insight into the spatial population structure of Greenland halibut (Reinhardtius hippoglossoides), an issue that has been unresolved for decades. The dataset contains 168130 fish tagged from 1952 to 2021, with 5466 (3.3%) recaptured individuals. Our results indicate that fish tagged at <50 cm body length migrate at higher rates, suggesting that mark–recapture studies on adult individuals underestimate population-level migration rates. We find evidence for migrations across management units in the North Atlantic indicating two regional offshore populations: one in the Northeast Atlantic, where the West Nordic and Northeast Arctic stocks, currently managed separately, likely belong to a single population that spans from the Kara Sea to Southeast Greenland; and one in the Northwest Atlantic where migration was observed between the Newfoundland and Labrador stock and the Northwest Arctic stock in Davis Strait and Baffin Bay. Our findings indicate complex population structure with implications for international and domestic fisheries management of this long-lived species.publishedVersio

Fish community size spectra and the role of vessel avoidance in hydroacoustic surveys of boreal lakes and reservoirs

Hydroacoustic data were used to quantify vessel avoidance by fishes, and derive fish community size spectra in two shallow boreal systems in eastern Manitoba, Canada. Lac du Bonnet reservoir and adjoining lakes at Nopiming Provincial Park were studied during summer 2011 and 2012. The magnitude of boat avoidance varied between these relatively similar water bodies (p = 0.04), but was not significantly influenced by fish depth or survey speed. Length-frequency spectra were determined from acoustic surveys at Lac du Bonnet, and acoustic data were used to map bathymetry of the reservoir. Community abundance (spectra height) was greater in 2011 then 2012 (p < 0.05), and decreased through the summer. Spatial variation in spectra parameters appear to be related to physical habitat characteristics. I conclude that vessel avoidance should be quantified in situ, and that acoustic size spectra may be used to monitor differences in fish communities over time and among habitats

Spatiotemporal variation in maturation: A case study with American plaice (Hippoglossoides platessoides) on the Grand Bank off Newfoundland

Fisheries management usually does not explicitly account for spatial variation in life history traits within populations. However, for some stocks this spatial variation may be substantial. We develop a Spatiotemporal Generalized Linear Model and fit the model to a long time-series of maturation data for American plaice (Hippoglossoides platessoides) on the Grand Bank off Newfoundland and Labrador. The spatiotemporal correlation structure improves estimation of small-scale spatiotemporal variation in maturity across locations and times with limited or few samples. We test how American plaice maturity varies at three different spatial resolutions. We find improvements in model fit when decreasing spatial scales for higher spatial resolution due to high levels of spatial heterogeneity in American plaice maturity at age and size. Modeling variation in life history traits at the appropriate spatial and temporal scales is necessary for understanding population dynamics and developing appropriate fisheries management strategies.The accepted manuscript in pdf format is listed with the files at the bottom of this page. The presentation of the authors' names and (or) special characters in the title of the manuscript may differ slightly between what is listed on this page and what is listed in the pdf file of the accepted manuscript; that in the pdf file of the accepted manuscript is what was submitted by the author

Size metrics, longevity, and growth rates in Umbellula encrinus (Cnidaria: Pennatulacea) from the Eastern Canadian Arctic

Umbellula encrinus Linnaeus, 1758 is a deep-water sea pen commonly found in the Eastern Canadian Arctic. It can reach heights of >2 m, and it has often been caught as fishing bycatch. Here we characterized abundance/density, size metrics, longevity, and growth rates of U. encrinus colonies from Baffin Bay (between Greenland and Canada). No prevalent size classes were identified at most locations, except for Jones Sound and Cape Dyer, where small-size colonies dominated. Average number of growth rings in the internal skeleton (axis) of the examined colonies ranged between 2-68, with a maximum of 75. A bomb-The accepted manuscript in pdf format is listed with the files at the bottom of this page. The presentation of the authors' names and (or) special characters in the title of the manuscript may differ slightly between what is listed on this page and what is listed in the pdf file of the accepted manuscript; that in the pdf file of the accepted manuscript is what was submitted by the author

Migration patterns of Greenland halibut in the North Atlantic revealed by a compiled mark-recapture dataset

Marine fisheries are often allocated to stocks that reflect pragmatic considerations and may not represent the species’ spatial population structure, increasing the risk of mismanagement and unsustainable harvesting. Here we compile mark–recapture data collected across the North Atlantic to gain insight into the spatial population structure of Greenland halibut (Reinhardtius hippoglossoides), an issue that has been unresolved for decades. The dataset contains 168130 fish tagged from 1952 to 2021, with 5466 (3.3%) recaptured individuals. Our results indicate that fish tagged at <50 cm body length migrate at higher rates, suggesting that mark–recapture studies on adult individuals underestimate population-level migration rates. We find evidence for migrations across management units in the North Atlantic indicating two regional offshore populations: one in the Northeast Atlantic, where the West Nordic and Northeast Arctic stocks, currently managed separately, likely belong to a single population that spans from the Kara Sea to Southeast Greenland; and one in the Northwest Atlantic where migration was observed between the Newfoundland and Labrador stock and the Northwest Arctic stock in Davis Strait and Baffin Bay. Our findings indicate complex population structure with implications for international and domestic fisheries management of this long-lived species