Consolidated Mathematical Specifications and Base Model Results for 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 based on intersessional work and the discussions of the intersessional correspondence group on North Pacific sei whales. Compared to the version of the model presented to SC68A, the revised model includes options for time-varying carrying capacity, distribution and natural mortality, and density-dependent distribution, as well as natal homing, and dispersal. The model can now utilize low abundance estimates, and tags for which the effective number of animals marked is unknown. Estimates of absolute and relative 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 and the results are summarized using numerical and graphical diagnostics.