CCAMLR

This purpose of this document is to inform CCAMLR of work-in-progress in the Australian eastern tuna and billfish fishery (ETBF) of potential relevance to the conservation of Convention area seabirds. The research plan includes (a) a line weighting experiment on a chartered tuna vessel to determine the effect of line weighting regimes and bait type on the sink rate of longlines. This experiment was completed in April 2005. (b) a manipulative experiment testing the effectiveness of various combinations of line weighting and streamer lines as deterrent to fleshy-footed shearwaters. This experiment is scheduled for October and November 2005 when fleshy-footed shearwaters (the main seabird species taken in the fishery) are most abundant on fishing grounds. A summary of findings of the line weighting experiment is presented below. The experiment examined the effect of bait type, swivel weight and bottom length (distance between weighted swivel and hook) on the sink rate of branch lines used in Australia’s ETBF.

This document seeks the approval of CCAMLR for a research plan to improve the seabird by-catch mitigation effectiveness of the Spanish system of longline fishing. The plan also aims to reduce the amount of fishing gear (and ghost fishing) lost in benthic habitats by Spanish system vessels in the Convention area and, potentially, in other fisheries where Spanish system vessels operate. A step-wise approach will be taken using a chartered fishing vessel in Chile to trial various line weighting systems, including replacing with steel sinker weights the bags of rocks that are traditionally used by Spanish system vessels. The objectives are to (a) reduce the degree of lofting in hook lines between line weights that occurs with the CCAMLR line weighting regime to expedite sink rates in surface waters, and (b) reduce the incidence of line weight hook-ups on the seabed. A line weighting system that improves sink profiles (and reduces frequency of line breakage) will then be trialled in normal fishing operations in southern Chile to determine effectiveness (along with use of streamer lines) as deterrent to black-browed albatrosses. The operational effectiveness of the new regime will also be determined. Assuming the new regime is practical to use, the intention will then be to seek permission from CCAMLR to trial the improved mitigation measures against white-chinned petrels in sub Area 48.3 at a high risk time of year.

Soon after longlining on Patagonian toothfish (Dissostichus eleginoides) started in the Southern Ocean in the second half of the 1980’s, interactions of cetaceans with these fisheries became apparent. The two species primarily involved were orcas (killer whales) (Orcinus orca) and male sperm whales (Physeter macrocephalus). Both species took substantial number of fish from the line primarily during day light hours. Catch rates of longliners declined to less than 50% when orcas occurred close to longline vessels while the loss to sperm whales was much less obvious. They were seen diving close to the line down to 400 m where they apparently took fish. Their impact on catch rates was much less notable. Sperm whales became frequently entangled in the line and part of the line was lost in a number of cases. Other cetaceans were rarely seen in the vicinity of longline vessels. They became entangled in the line only occasionally and one whale (presumably a minke whale) died.

Information on CCAMLR fisheries of relevance to the work of WG-FSA is summarised. Where possible, summaries are in a format suitable for importing directly to the Fishery Reports. Additional fishery-related information can be found in WG-FSA-05/7, 05/8, 05/9 and 05/10 (summaries of observer data), SC-CAMLR-XXIV/BG/1 (catches in the Convention Area) SC-CAMLR-XXIV/BG/5 (summary of notification for new and exploratory fisheries), SCIC-05/10 (estimates of IUU catches) and CCAMLR-XXIV/BG/13 (implementation of conservation measures).