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Structural Considerations in Building a CASAL
R.I.C. Chris Francis, Brian Bull, Alistair Dunn, & David J. Gilbert
National Institute of Water and Atmospheric Research, Private Bag 14–901, Wellington, New Zealand.
Email: c.francis@niwa.co.nz
CASAL is a stock assessment computer program recently developed at NIWA. It was written in C++ using very general abstract base classes, allowing modifications and extensions to be easily added to the existing code. The major design requirement was for flexibility, so that it could be used for a wide range of fish stocks. The underlying population model may be age- or length-structured. It may relate to a single fishery on one stock, or to several fisheries operating on multiple stocks in more than one area. The annual cycle of the model may be broken up into an arbitrary number of time steps to allow the user flexibility in specifying the sequence of processes such as fishing and natural mortality, maturation, growth, age-incrementation, and migration. A range of data types is possible and model fitting is likelihood based (maximum likelihood or Bayesian). Some structural considerations that were important in building CASAL will be discussed.
Room 3 Thursday 4.00 pm
