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.