Bering Sea | Fishes and Fish Habitats DOCTORATE ORAL PRESENTATION Assessing spawning behavior at the northern latitudinal extreme of a commercially exploited demersal flatfish
Presenter: Austin Flanigan , aflanigan@alaska.edu, University of Alaska Fairbanks Dawn Wehde , dwehde@nsedc.com, Norton Sound Economic Development Corporation Tim Loher , tim.at.martingale@gmail.com, Martingale Marine Ecology Andrew Seitz , acseitz@alaska.edu, University of Alaska Fairbanks
The Pacific halibut in the Northeastern Pacific is a well-studied fish with decades of historical data. As such, many aspects of its biology have previously been assessed, including reproductive behavior. Current knowledge suggests that individuals spawn annually as far north as Pribilof Canyon from December to March, during which the directed commercial fishing season is largely closed. However, as conditions in the Bering Sea continue to warm, the latitudinal extent of the species appears to be shifting northward, with Pacific halibut now extending into the Bering Strait region. Pacific halibut at this northern extreme are understudied, with their spawning locations and timing unknown. To assess this, pop-up satellite telemetry tags were deployed at two Northern Bering Sea tagging locations (NBS) on Pacific halibut that had a high probability of being mature females. Recorded depth data and transmitted pop-off locations were used to assess spawning timing and location, respectively. Preliminary results indicate that NBS Pacific halibut spawn later than their southern counterparts: from January to May rather than December to March. Spawning also appears to occur farther north than previously documented, reaching as far north as the Russian shelf edge. Additionally, a large proportion of individuals never occupied spawning habitat, suggesting the presence of skipped spawning that violates the current assumption of annual spawning frequency. These findings indicate the presence of additional spawning habitat and behavior that is not accounted for in current stock assessment practice, and the potential for commercial exploitation during spawning. As such, these results will aid in estimating annual spawning stock biomass in the NBS and in considering adaptations to current management practices, such as shifting the winter fishery closure in the NBS to better represent the spawning season.
Alaska Marine Science Symposium 2023 51
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