Factors influencing conversion factors in CCAMLR toothfish fisheries

Using Generalized Additive Mixed Models, factors recorded by SISO observers and influencing toothfish conversion factors (CFs) were examined. For both Dissostichus species, fish length, fishing location, timing and vessel were found to have signigicant effects on CFs. The relative effect of each factor differed between species, as well as the shape of their relationship with CFs, although models were limited due to the lack of overlap in observations between locations, months and vessels. Results of this analysis suggest that the accuracy of greenweight estimation (both at the fishery scale and at the local area scale) would benefit from stratifying sampling over the range of fish sizes, within fishing seasons, and among

locations.