Caitlin I Allen Akselrud1
1SAFS
November 10, 2015 9:00 (PST): FSH 203
Application of an age-length structured population dynamics model to data for Eastern Bering Sea Tanner crab (Chionoecetes bairdi)
Fishery stock assessments are frequently based on either age-structured population dynamics or length-structured dynamics. We have developed and implemented a model to account for both age and length dynamics for an individual fishery. An age-length assessment model is unique in its ability to capture the dynamics of fishing mortality and natural mortality on fish populations, which are functions of both length and age. By accounting for both factors, the age-length model should reduce estimation bias present in models that only account for age (or length) dynamics, and assist managers in achieving statutory goals for fishery management.
Simulation studies have showed that the age-length models can provide essentially unbiased estimates of biomass trajectories and have low sensitivity to the precision of the data. Here we evaluate these models using the actual data for the Eastern Bering Sea Tanner crab (Chionoecetes bairdi) fishery. The data include catches, fishing effort, and survey index, as well as length-composition and conditional age-at-length. Survey and fishery data (including several fleets) are available for each stock.