University Events

Description: The School for Marine Science and Technology
Department of Fisheries Oceanography
Seminar Announcement

"Revisiting spatial stock structure in an era of climate change: a review of Atlantic halibut (Hippoglossus hippoglossus L) across the Northwest Atlantic"

Nancy Shackell
Research Scientist
Oceanography and Climate Section
DFO
Bedford Institute of Oceanography
Canada

Collaborators in alphabetical order: S.X. Cadrin, A. Czich, C. den Heyer, J.A.D. Fisher, K.T. Frank, D. Hennen, B. Hubley, M. Kersula, A. Le Bris, R. McBride, C. McGuire, K. Ransier, D. Robert, A. Seitz

Wednesday, March 3, 2021
2:30 pm to 3:30 pm
via Zoom

Abstract -

Associations between spatial dynamics, stock structure, and changing abundances in exploited marine fishes have largely been based on knowledge of stocks in decline. In contrast, stock structure is rarely re-visited for species expanding at their geographic range margins, or where stock boundaries were defined at low abundances prior to stock recovery. Here we review how these themes intersect in the rapidly expanding body of research on the large and enigmatic Atlantic halibut (Hippoglossus hippoglossus), which is managed as 3 stocks in the Northwest Atlantic. Halibut’s life history traits of slow growth and late maturity portended its collapse under high exploitation in the mid-19th century across its range. Despite these life history features, the Canadian Atlantic halibut fisheries value increased seven-fold over the past two decades. We show that halibut’s thermal habitat availability has increased in the northern part of the domain but climate change is not the sole factor in their expansion. There is evidence of weak genetic structure throughout most of its domain yet there is significant ontogenetic spatial structure with persistent core juvenile areas. Growth rates are faster in warmer water in southern parts of their range where females are more likely to mature at smaller sizes, suggesting phenotypic variation within one of the stock unit. Recent analyses of electronic archival tag data suggests skipped spawning in some individuals and clearly reveals spawning migrations in others. Conventional tagging studies conform to the typically right-skewed distributions where the median distance at recapture varies across the domain (3.2-89 km). The highest median distance occurs where halibut are at higher densities, suggesting density-dependent movement. The wealth of both conventional and electronic tagging studies in recent decades has shed new light on the diversity of migration patterns in halibut and the potential drivers of that diversity. Although it is clear that halibut are spatially structured, the spatial and economic scales of this species and its fisheries are raising new ecological and management questions about fisheries sustainability—questions that are increasingly suited to regional and international collaborations.

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Zoom Link: https://umassd.zoom.us/j/93401753807?pwd=MHJVMkFDV3RQUFZhQS9lNEdTNWJlUT09
Meeting ID: 934 0175 3807
Passcode: 464610
+1 646 876 9923 US
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For additional information, please contact Sue Silva at s1silva@umassd.edu