Towards Spatially-Explicit Dynamics Models of Antarctic Toothfish (Dissostichus mawsoni) and Two of Its Main Prey (Macrouridae and Channichthyidae) on the Slope of the Ross Sea Region

We present spatially explicit models of the interaction of Antarctic toothfish and two of its prey species (macrouridae and channichthyidae) on the slope of the Ross Sea Region. Two models were developed, the first was a single area age-based population dynamics model of D. mawsoni, macrourid and icefish that included predator prey relationships and mortality from fishing for both the target and prey species. The second model expanded the first to a 20-area model that included ontogenetic movement of D. mawsoni as well as movement of the associated prey species. We compare two predation functions: the Michaelis-Menten equation (Holling type II and III) and a prey-switch predation function. Predicted population changes were evaluated against available abundance data for those species. Further, we propose that such multi-species models are useful for testing hypotheses about relative rates of predation and can be used to evaluate potential changes on macourid and icefish from the target D. mawsoni fishery. Such models can inform management decisions and provide a means of testing the utility of monitoring tools of fish species associated with the toothfish fishery.