Assessment report of the Western Rock Lobster Fishery 2002

Environmental assessment under the EPBC Act
Department of the Environment and Heritage, August 2002
ISBN 0 642 54877 3

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Executive summary

The fishery targets western rock lobster (Panulirus cygnus), about 75% of which is marketed live. The species is endemic to the west coast of Australia and has greatest abundance between Geraldton and Perth, while the fishery extends from 34°24'S to 21°44'S. Kailoa et al (1993) indicate that the planktonic larvae are carried into the Indian Ocean up to 1500km from the coast, with the return of pueruli to the continental shelf dependent on shifts in ocean currents and number of puerulus settling influenced by the strength of the Leeuwin Current. Despite the wide larval dispersal taking place over 9-11 months, the species does not appear to be harvested outside Western Australia. Approximately 10,000 tonnes of western rock lobsters are harvested in the fishery annually, at a landed value of over A$350 million. The gear used is a lobster pot placed on the seafloor and connected to a float on the sea surface.

Kailoa et al indicate that the target species reaches a maximum age of more than 20 years; attains a maximum carapace length of 200mm and a maximum weight of at least 4.5kg, (Anon, 2001 suggest animals may reach up to 5.5kg) although growth rates vary considerably along the coast. Juveniles migrate from shallow water to deeper as they mature; the greatest recorded migration of juveniles into deeper water is in the order of 170 nautical miles (Kailoa et al). Western rock lobsters are omnivorous feeders whose diet changes according to moult stage, season and habitat. Primary predators are finfish (on juveniles and adults), sharks and octopus (mainly on adults).

Byproduct taken in the fishery includes a variety of crabs including deep sea crab (target of a commercial fishery), some finfish and sharks (most of which is taken on lines and will be assessed through the wetline fishery assessment), and octopus. The most significant components of the bycatch are moray eels (captured in pots) and manta rays (entangled in pot lines). Protected species interactions include capture of juvenile Australian sea lions, and entanglement may occur with Australian sea lions, leatherback turtles and cetaceans; the incidence of this is low.

The area of the fishery also includes part of the distribution of the southern rock lobster (Jasus edwardsii), which can be found as far up the Western Australian coast as Dongara (Kailoa et al). No reference is made to the harvest of J. edwardsii in the submission, but as this species is harvested by similar pots and can be taken in depths of up to 200m it is likely that it comprises part of the bycatch or by-product of the fishery; any such harvest should be factored into the stock assessments and management regime for J. edwardsii. Western Australian Department of Fisheries (WADF) advise that J. edwardsii are not harvested in the western rock lobster fishery.

WADF also advise that sectors of the south coast fishery targeting J. edwardsii harvest some P. cygnus, but in inconsequential amounts.

The fishery is managed under an arrangement under the Offshore Constitutional Settlement that cedes management responsibility to the State to the outer edge of the Australian fishing zone. Although most catch is taken at depths up to 160m, some may be taken at depths up to 200m. The fishery is divided into three zones (Big Bank, Abrolhos Islands, and southern or Zone C), with the Abrolhos Islands zone further divided into Zone A (the Islands themselves) and Zone B (the continental coastal strip). WADF advise that the fishery zones are a result of historical fishing patterns, and that effort is spread evenly across all zones. The C (southern) zone is an amalgamation of two previous zones (C and D zones). The shorter season in the Abrolhos means that fishers may start the season in Zone B and then half (those with appropriate authorisations) go into the Abrolhos Islands when that zone is opened. Commercial operators can only operate in zones for which they have licences.

The management regime implements licence limitation, minimum size limits, gear restrictions, closures, total pot number limit, zonation and a comprehensive monitoring regime.

The fishery has been rebuilding stock since 1993/94, at which stage it was estimated the legal sized biomass was 15% of virgin legal sized levels. The management target is that legal sized biomass should be above 20% of virgin legal size biomass; currently the fishery is above this level.

Process followed in the assessment

A submission entitled Application to Department of the Environment and Heritage on the Western Rock Lobster Fishery Against the Guidelines for the Ecologically Sustainable Management of Fisheries for Continued Listing on Section 303DB of the Environmental Protection and Biodiversity Conservation Act 1999 was received in November 2001 after a period of discussion between the WA Department of Fisheries (WADF, formerly Fisheries Western Australia) and Department of the Environment and Heritage (EA) during which preliminary drafts were refined. The submission was released for a thirty-day public comment period that expired on 6 December 2001.

Notification that the submission was available on the Internet were sent to all persons on the Fisheries Public Comment Register, a register of interested persons maintained by Department of the Environment and Heritage, and published in The Australian and Western Australian newspapers. A total of three public comments were received and WADF provided a response on the issues raised in them. Comments also were sought from the Scientific Committee on Wildlife Use (SCWU), a body of scientists established by the Minister for the Environment and Heritage to provide independent advice.

Following the public comment period the assessment report was drafted by EA. In addition to the submission and associated documents, public comments and WADF's response informed the assessment.

A draft of the assessment report recommendations was provided to WADF for consideration in May 2002, and the assessment finalised when their views had been received.