The survivorship of rays discarded from the South Georgia longline fishery
Post-haulage survival experiments were conducted on 95 Raja sp. anon. cut off longlines at the sea surface by the Chilean fishing vessel Isla Sofía in May and June 2003 during the toothfish fishing season in Subarea 48.3. Capture depth had a consistently significant influence on the mortality of skates. There were some suggestions (not statistically significant) that wind speed (i.e. weather conditions) and the sex of rays also had some small influence on survivorship. Discard survivorship was 75% in waters shallower than 1 300 m (i.e. 1 200–1 300 m), 46% in waters 1 300–1 500 m, and 24% in waters between 1 500 and 2 000 m. These findings support CCAMLR’s recommendation that skates and rays be cut from the line at the sea surface, so as to maximise their chances of survival. Results from this experiment can also be used to calculate the expected skate mortality within the fishery, based on depth of capture. Further survival experiments should be conducted, particularly in shallow waters, where sampling in this study was restricted.