Modelling catch and effort data using generalised linear models with random cruise effects: trawl fishery for mackerel icefish (Champsocephalus gunnari) in CAMLR Area 58.5.2

A set of procedures for modelling catch and effort data using generalized linear mixed models (GLMMs) including data analytic methods for examining the appropriateness of model structure and parameter values was presented in WG-FSA-SAM 03-12 using Dissostichus eleginoides in Subarea 48.3 of the CAMLR area as an example dataset. The application of these procedures to trawl catches of Champsocephalus gunnari in Subarea 58.5.2 is described. For the trawl catch and effort data it was found the precision of the standardised CPUE estimates was considerably poorer than that of the longline data for Subarea 48.3. It is concluded that CPUE was relatively stable from the start of the fishery until 2000, after which time there was a sharp increase in 2001 with a steady decline thereafter. The sharp increase in 2001 is most likely the result of the large abundance of 3 and 4 year-old fish in that year, which has since diminished through a combination of