The indices of exploratory toothfish fishery in the Ross Sea for the period of 2008-2015 are considered. The analysis was focused on CPUE toothfish (kg/1000 hooks), by-catch CPUE (kg/1000 hooks) and normalized target catch ratio. There was evidence of distinct differences in the mean (and distribution) in the CPUE toothfish and the by-catch CPUE.
Our analysis also show that target catch ratios significant varied across years and by SSMU and among longline gear types. The spatial-temporal heterogeneity in toothfish and non-target species distribution in the Ross Sea, but not the longline vessels and the flag States, should be considered as the primary cause of the observed variability in the target catch ratio in the Ross Sea. The observed influence of the longline gear types (Autoline, Trotline and the Spanish longlines) on CPUE and the target catch rations, apparently, point out varying catchability (or efficiency) among longline gears both in relation to toothfish and non-target taxa.
In order to improve the estimates of by-catch in the Ross Sea in the context of achieving the objectives of the CCAMLR Article II the following activities are proposed: investigations of spatial-temporal heterogeneity in tooth fish and non-target fish distributions through research programs the Ross Sea, as well as preparation of instructions for standardized-based fishery data collecting and recording onboard vessels.