Catch rates and length composition data of the longline fishery for Dissostichus eleginoides at the Prince Edward Islands: 1996/97

The first reports of commercial catches of Patagonian toothfish Dissostichus eleginoides made in the vicinity of the Prince Edward Islands, a South African territory in the Indian Ocean Sector of the Southern Ocean, surfaced early in 1996. This generated both national and international interest in the fishery leading to a great influx of vessels to the area. By the end of 1996 up to 40 vessels had already landed catches of more than 23 000 tons in South Africa and Namibia. It is against this backdrop that permits were issued in October 1996 to five vessels, each with an allocation of 240 tons per year, to fish in the South African zone at the Prince Edward Islands. The sanctioned fishery was conducted according to CCAMLR guidelines and Scientific Observers were deployed on most of the trips.
From October 1996 to June 1997 sanctioned vessels at the Prince Edward Islands deployed around 3.7 million hooks and landed 2 100 tons of toothfish. Although catch rates were initially high at around 0.7 kg per hook at the end of 1996 a steady decline in CPUE to less than 0.4 kg per hook towards the end of the season was noticed. The length frequency distribution showed that fish caught at the Prince Edward Islands were generally smaller than those reported from the South American and South Georgia longline fisheries. A decrease in fish sizes was also noted since the inception of the fishery. Although probably related to the over-exploitation of the resource by unregulated vessels, a trend was also discerned that vessels were targeting shallower areas as the season progressed, possibly influencing the size of fish caught.
Intensive fishing for D. eleginoides over the past year at the Prince Edward Islands, mostly by unregulated vessels, was probably largely responsible for the sharp decline in catch rates. There are, however, indications that catch rates have stabilized during the latter half of the season, although any sound management of the fishery in the future will depend on the curtailment of the unregulated exploitation of the resource,