Assessing spawning behavior at the Northern latitudinal extreme of Pacific halibut

While modern stock assessment practice often assumes spawning dynamics are consistent across a population’s range, recent studies have shown that these can vary latitudinally.  As a result, regional assessment of reproductive potential may be warranted for widely distributed species that are commercially exploited, such as the Pacific halibut (Hippoglossus stenolepis).  To characterize Pacific halibut spawning dynamics at the northern extreme of their range, we attached pop-up satellite telemetry tags to large females in the Northern Bering Sea (NBS), with tag reporting locations and recorded time series data being used to infer spawning behavior and identify occupied spawning habitat conditions, location, and timing.  Pacific halibut in the NBS spawned later and farther north than previously believed, where spawning habitat was occupied from January through May and reached as far north as the Russian continental shelf edge.  Additionally, 54% of mature individuals never occupied presumed spawning habitat, suggesting the presence of skip spawning behavior.  These findings indicate that current stock assessment practice may not accurately estimate Pacific halibut reproductive potential due to latitudinal variation in spawning dynamics.

Methods
The data was collected using satellite telemetry (PSAT's).  The data was processed primarily by summarizing and visualizing archived data.