Fisheries Report No 78 - A Re-examination of the methods used for handling undersize Western Rock Lobsters

Authors

R. S. Brown, Fisheries Department, Western Australia
C J. Dibden, Fisheries Department, Western Australia

Publication Date

1987

Series Number

Fisheries Report 78

Publisher

Fisheries Department, Western Australia

City

Perth

ISBN

0 7309 16243

ISSN

0726-0733

Abstract

The fishery for the western rock lobster, Panulirus cygnus (George) is the most important single species fishery in Australia, and one of the major rock lobster fisheries of the world, with catches over the last ten years (1973 to 1983) averaging approximately 9.8 million kg annually.

The continuing success of the fishery can be attributed mainly to effective management, which involves a complex system of regulations, the majority of which were introduced in 1963 and which are constantly being revised to accommodate changes in the fishery. One important piece of legislation, effective from 17 December 1965, was the introduction of a two inch (51 mm) escape gap in all rock lobster pots. The purpose of the escape gap was to allow the majority of undersize western rock lobsters 1 (less than 76 mm carapace length) to escape before the pot was brought to the surface. The escape gap was increased to 54 mm on 15 November 1972. In exchange for using a larger escape gap the regulation prohibiting fishing within one mile of the shore after 1 January each season was abolished.

However, despite the presence of the escape gaps, large numbers of undersize are caught still, especially from the 0-10 fm depth

range. It has been estimated that some 16 to 20 million undersize have been brought aboard the 765 professional rock lobster boats each season, and of those retained, 24% remained on board for ten minutes or more, with some being kept out of water in excess of two hours (Brown and Caputi 1983).

Even though the undersize are returned to the sea as required by the regulations, it has been shown that not all of them survive (Brown and Caputi 1983, Brown et al. in press). The reason is that damage suffered by many of them from conflict in the pot and from handling on board the boat (exposure, damage and displacement) may prove fatal. The effects of capture and handling also render them vulnerable to predation during the fall back to the sea floor, owing to disorientation caused by the experience.

Number of Pages

44

Keywords

Western Rock Lobster, Panulirus cygnus, Western Australia, Lobster fishery

Disciplines

Aquaculture and Fisheries | Marine Biology | Natural Resources and Conservation | Natural Resources Management and Policy | Sustainability

Recommended Citation

Brown, R S, and Dibden, C J. (1987), Fisheries Report No 78 - A Re-examination of the methods used for handling undersize Western Rock Lobsters. Fisheries Department, Western Australia, Perth. Report Fisheries Report 78.
https://library.dpird.wa.gov.au/fr_rr/308