Further Updated progress report: A multi-stock model for North Pacific sei whales
Andre E Punt
The age-, sex-, and season-structured population dynamics model developed to conduct an assessment of North Pacific sei whales is updated based on the recommendations of the IA sub-committee in 2018. The model can now utilize minimum abundance estimates, account for differential probabilities of tag reporting as a function of number of hits, and better handle situations in which catches in some years are high relative to the estimates of available numbers. Preliminary base-case models are undertaken for single-stock, 3-stock, and 5-stock hypotheses. The base-case model for the 5-stock hypothesis cannot convergence as it appears to be over-parameterized so the (draft) sensitivity tests are based on the single-stock and 3-stock hypotheses. Several issues arising from the results require additional consideration by the IA sub-committee.