CCAMLR

The methods used for deciding the closure date for fisheries monitored by the Secretariat of CCAMLR, as described in Conservation Measures, have been difficult to implement because of the variation in catch rates shown by the fisheries. Non-fluctuating random and fluctuating random catch histories are simulated and the performance of four Models for making closure decisions is investigated under a variety of circumstances. The Model described in the existing Conservation Measures is shown to have a high probability of allowing large over- or under-shoots of the TAC. The most successful model determines the trend of catch rates using linear regression over the latest four reporting periods, and closes the fishery if these rates indicate that the TAC will be taken before the next report arrives at the Secretariat. The probability of large over-shoots of the TAC is reduced if reporting periods are small (5-days) and the reporting delay is minimal.

The incidence of entanglement in man-made debris by Antarctic fur seals (Arctocephalus gazella) at Bird Island, South Georgia, was monitored throughout the austral winter and summer of 1990/91 as part of an ongoing study by the British Antarctic Survey. A minimum of 8 seals were sighted entangled, 7 (88%) of which had their neck collars removed, during the winter months (April – October). During the summer pup-rearing period a minimum of 30 entangled seals were reported, 26 (87%) of which had their collars removed. This represents a reduction of 88% in the number of entangled seals reported in comparison to the same time period in 1988/89. Possible causes suggested for this observed reduction in entanglement include a reduction in fishing activity in the South Georgia area, a decrease in the amount of hazardous material jettisoned at sea or a possible increased mortality at sea of entangled seals. The most common type of neck collar material was polypropylene straps (50%) of the type used in packaging bands, followed by twine (16.7%) and fishing net fragments (16.6%). Apart from the increase in the incidence of twine, the proportions of the various neck collar materials were similar to those reported in 1988/89.