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Research and Education: Ecological Risks for the Victorian Rock Lobster Fishery Assessed | FN0596 |
Greg Jenkins, PIRVic, Queenscliff
February 2007
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An ecological risk assessment of Victoria’s rock lobster fishery concluded that fishing practises pose a low risk to by-catch populations, populations of protected and endangered species, reef habitats and reef ecosystems.
Victoria’s rock lobster fishery is the second most valuable commercial fishery in the state. Rock Lobster catch is currently limited to 510 tonnes with landed value of $15.4 million in 2005/06. A live export trade into Asian markets and post-harvest processing of the rock lobster catches greatly increase the value of the rock lobster fishery and generate significant employment opportunities for Victorians.
Victoria’s Rock Lobster Fishery Management Plan (RLFMP) places a strong emphasis on the ecological sustainability of the fishery, which considers the effect fishing has on:
- target species,
- by-product and discards,
- protected and endangered species,
- habitats, and
- communities and ecosystems.
This approach also considers the impacts that other threats may have on the habitats and ecosystems on which rock lobsters depend, and the consequences these processes may have for the fishery.
A panel of experts undertook an ecological risk assessment of the Victorian rock lobster fishery to identify and rank the major ecological threats for this fishery. Expertise was drawn from Fisheries Victoria, Primary Industries Research Victoria (PIRVic), the Commercial Rock Lobster and Giant Crab Fishery Committee of the Fisheries Co-management Council, and from the Tasmanian Aquaculture and Fisheries Institute.
The expert panel identified 60 ecological threats, which are grouped into the following categories:
- impacts of rock lobster fishing by-catch on the environment,
- impacts of rock lobster fishing on protected and endangered species,
- ecological risks to reef habitats, and
- ecological risks to the reef ecosystem
The panel determined how likely each threat was to occur and the scale of impact it would have, to establish the level of risk the threat posed to the fishery. Six risk categories were recognised:
- negligible,
- low,
- moderate,
- high, and
- extreme
Of the 60 threats identified, 41 arose from rock lobster fishing gear and fishing techniques.
Fifteen of these threats were to by-catch species. All were determined to have a “Negligible” or “Low” risk ranking, indicating they would have no impacts on by-catch population size or dynamics.
The expert panel identified seven threats to endangered and threatening species. These threats primarily related to dolphins, seals, birds, turtles and whales becoming entangled in rock lobster fishing gear. The panel, while recognising that these interactions could have strong consequences for individual animals, considered that at the population level consequences would be very low and rated these risks as “Negligible” or “Low”.
Two ecological threats to reef habitat from the impacts of rock lobster gear and fishing methods were identified. These related to the disturbance caused by fishing gear to shallow and deep-water reef communities. The risk to shallow reef habitat was determined to be “Negligible”, whereas that for deep-water reefs was assessed to be “Low”.
This difference in the risk ranking arose from the experts’ concern that very little is known about deep-water reef habitats. The expert panel considered that while the area of deep reef impacted by rock lobster pots was relatively small; long-lived coral and gorgonian species are very susceptible to damage and have very slow regeneration rates.
The expert panel considered 17 threats arising from the activities of the rock lobster fishery to reef ecosystems. The majority (15) of these threats were determined to pose a “Negligible” or “Low” risk.
The expert panel determined that two threats arising from rock lobster fishing activities did pose a “Moderate” risk to reef ecosystems.
Rock lobsters are considered to be a keystone species in that their feeding activities can have a significant effect on the structure of reef ecosystems. Any significant reduction in the number of rock lobsters may have severe consequences for reef ecosystems. For example, a decrease in rock lobster abundance may lead to an increase in sea urchins and a reduction in algal cover. This scenario was considered to be very unlikely to occur in the foreseeable future because the current management regime is aimed at rebuilding lobster stocks.
The expert panel also considered the translocation of marine pests in the fishery also posed a “Moderate” risk. An industry code of practice has been developed and it was considered that adherence to this code will be essential to containing this risk.
The remaining 19 ecological threats identified by the Expert Panel arise from activities that an unrelated to the rock lobster fishery.
Fourteen threats to reef habitats were identified arising predominantly from coastal activities and 11 were determined to pose a “Negligible” or “Low” risk. Three threats however were determined to pose a “Moderate” risk to reef habitats:
- disposal of offshore dredge sediments,
- increased turbidity and sedimentation associated with coastal development, and
- changes to rock lobster habitat through the introduction of marine pests.
The expert panel determined that climate change poses an “Extreme” risk to reef habitat and the rock lobster fishery. The panel concluded that climate change could increase water temperature directly affecting the survival and distribution of rock lobster and the other plants and animals that live on the reefs. Indirectly climate change could alter ocean current patterns that deliver larvae to the juvenile habitat and increase extreme weather events that could cause damage to shallow reef habitat in particular.
A further five processes were identified, which threaten reef ecosystems. The panel determined that oil and mineral exploration and extraction poses a “Negligible” risk, whereas freshwater run-off carrying harmful chemicals (heavy metals and pesticides) onto reef ecosystems and the effects of seismic testing both posed a “Low” risk.
Oil spills were considered to be a rare event, but with the potential to have a severe effect on the reef ecosystem, and were determined to pose a “Moderate” overall risk, as were the effects of other fisheries’ practices on reef ecosystems. Effects from other fisheries could include damage to rock lobster habitat or ecosystems and effects of removing other fishery species from the ecosystem.
Fisheries Victoria will use this risk assessment as a guide for the development of management strategies for the Victorian rock lobster fishery.
Fisheries Victoria funded this work.
Further Information
For more information about this project, please contact Dr Greg Jenkins at, PIRVic Queenscliff on (03) 5258 0111.
Fisheries Research and Education Notes are available on the DPI website.
The advice provided in this publication is intended as a source of information only. Always read the label before using any of the products mentioned. The State of Victoria and its employees do not guarantee that the publication is without flaw of any kind or is wholly appropriate for your particular purposes and therefore disclaims all liability for any error, loss or other consequence which may arise from you relying on any information in this publication.
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