Further updated progress report: A multi-stock model for North Pacific sei whales
Andre E. Punt
International Whaling Commission
The age-, sex-, and season-structured population dynamics model developed to assess North Pacific sei whales is updated to allow for time-varying carrying capacity, distribution and natural mortality, and density-dependent distribution. The model can now utilize low abundance estimates, and tags for which the effective number of animals marked is unknown. Estimates of absolute abundance can be subject to additional variance related to changes in distribution among surveys. Base-case models are undertaken for single-stock and multi-stock hypotheses, along with a range of sensitivity tests. The results are summarized using numerical and graphical diagnostics.