A statistical, age-structured, life-history-based stock assessment model for anadromous Alosa

We present a population dynamics model based on the life history of anadromous Alosa. The model is built around a catch-at-age array to which we have added an additional dimension to include previous spawning history. The previous spawning history determines the number of times that a fish is exposed to riverine impacts that contribute to overall mortality rates. The model is designed to incorporate the kinds of data typically collected for anadromous Alosa stocks, such as catch-at-age data, spawning escapement counts at fish ladders, larval and juvenile abundance indices, and turbine mortality estimates. We show how the model can be adapted to individual stocks and management questions and how the model parameter estimates can be obtained using maximum likelihood. We demonstrate this approach with examples for two alewife Alosa pseudoharengus populations in Nova Scotia.