Towards a Minimum Realistic Model for investigating trophic relationships between Antarctic toothfish and demersal fish in the Ross Sea, Antarctica

We report on progress towards developing a Minimum Realistic Model for investigating trophic relationships between Antarctic toothfish (Dissostichus mawsoni) and four groups of demersal fish in the Ross Sea, Antarctica. These demersal fish are known to form a part (in some cases a substantial part) of the diet of Antarctic toothfish of a size commonly taken by the Ross Sea fishery and are also taken as bycatch by the fishery: (1) macrourids (especially Whitson’s grenadier, Macrourus whitsoni); (2) icefish (especially Chionobathyscus dewitti); (3) deep sea cods (especially violet cod, Antimora rostrata); and (4) eel (moray) cods (Muraenolepsis spp.). Changes to the abundance of Antarctic toothfish due to fishing could affect these prey groups and the trophic relationship between these groups and toothfish. A Minimum Realistic Model is the most appropriate modeling approach to investigate what changes in the abundances of these four demersal fish prey/bycatch groups in the Ross Sea are possible, and what changes in the trophic relationships between Antarctic toothfish and these prey groups may occur. Feedback on the model is sought. Work on this model will continue through 2010 and 2011 and will be presented to CCAMLR in due course.