The recent change to quota management for the Western Rock Lobster fishery has resulted in significant changes in fishing behaviour which has affected the ability to use the long standing empirical catch rate indices that have been a major component of the assessment of lobster stocks (e.g. catch rates of legal, undersize and breeding lobsters). A recent FRDC funded study (2009/019) examined the possibility of using alternative data sources unbiased by effort to monitor biomass levels and exploitation rates using change-in-ratio techniques. The project concluded that:
1. The current data sources available to the fishery had too many unknowns including size and sex specific timing of growth and movement to enable the assessment of exploitation rates using these techniques.
2. A robust tag-recapture study using multiple release periods across different fishing seasons could generate independent assessments of legal biomass and exploitation rates providing an additional baseline level to improve the interpretation of post quota catch rate indices.
A comprehensive tag-recapture study would also provide increased resolution of the movement dynamics of lobsters, especially the rate of migration between management zones. Such information is considered vital by industry in their discussions of the potential benefits of voluntarily reducing quotas to generate increased localised catch rates.

The WRL Industry is currently moving from a decision-rule framework, based solely on breeding stock levels, to a more robust two-dimensional approach incorporating both breeding stock and harvest rate. This approach represents best practice fisheries management and is consistent with Commonwealth Fisheries Harvest Strategy Policy and was recently vetted during a review on stock assessment methodologies used in the WRL fishery. The review panel supported this new direction but highlighted the importance of having robust estimates of the indices on which this framework will be based, especially the sensitivity of the (empirical and model-derived) breeding stock indices and harvest rates to fishing efficiency. Due to speculation surrounding current estimates of efficiency creep, they further recommended exploring whether these indices could be determined using different techniques. Further development of these indices has now been incorporated in the current “Action Plan” to meet the requirements of the Marine Stewardship Council. Recent concern surrounding the current low levels of puerulus settlement, and their possible links to breeding stock levels, has heightened further the need for reliable estimates of harvest rate and efficiency creep.
Change-in-ratio and index removal techniques have been shown to produce robust estimates of these indices in other fisheries including the Southern Rock Lobster Fishery (Frusher et al., 1997). Although well developed for the SRL fishery, the success of these methods depend on the specific data sources available and may not be directly transferable to other fisheries. Consequently, the value of these techniques using data available in the WRL fishery needs to be thoroughly examined to determine if they could generate robust estimates that can be used in the management of this fishery. If they are considered robust they will provide valuable alternatives to the methods currently being used to monitor changes in fleet efficiency.

Continuation of the Marine Stewardship Council’s (MSC) accreditation of the Western Rock Lobster
Fishery (WRLF) depends on the fishery addressing issues outlined within the 2006 re-certification action plan. This plan states “no substantive evidence has been presented for assessment about the impacts of the fishery on ecosystem structure, function, diversity, productivity or habitats caused by the removal of target stocks.” The re-certification plan also identified the need to understand the impacts of the fishery on trophic linkages between lobsters and their predators and prey, at each of the main stages of lobster life history.

The need for these types of ecological data was highlighted by the most recent risk assessment, where the effects of removing lobster biomass in deep water was given a “moderate” risk. Re-assessment of the level of risk will require the gaps in the knowledge of deep water ecosystems to be addressed.

Research undertaken during FRDC 2004/049 increased the understanding of the relationship between lobster and their deepwater habitats, however the approach was ineffective in addressing MSC requirements. Therefore the EcoSRG have concluded that there is a need for future research in deep water to use research closures.

Based on the outcomes of FRDC 2004/049, the risk levels and the EcoSRG workshop, this proposal will use closed areas to examine the potential impacts of the rock lobster fishery in deep water, providing baseline information essential for the assessment of the impacts of the fishery on the ecosystem in the future.

This proposal will be conducted in two phases. Phase one will establish fished and unfished areas within deep water in collaboration with industry. Phase two will establish baseline information on lobster stocks, habitat and community structure. If at the end of phase one there is no agreement to establish closed areas, the second phase will not proceed.

The Scientific Reference Group (SRG), including Drs Alistar Robertson, Simon Thrush, Andrew Heyward, John Keesing, Colin Buxton, Chris Simpson and Jim Penn, was formed as an independent body to provide advice on research directions, to examine the effects of western rock lobster fishing on the ecosystem. The SRG identified that there is a major gap in the understanding of the interactions between the rock lobster fishery and the ecosystem in deep water. Although significant data is available on the shallow (40 m) water ecology of lobsters and the fishing impact there is gap in the knowledge of the deep-water ecology of lobster. They recognised that the major change in abundance and size structure of the western rock lobster population would have occurred in deep water (40-100 m), and concluded this was a priority area of research. There is a need to collect basic ecological information to determine if changes in lobster density and size structure,due to fishing has caused significant changes in habitat structure and benthic community composition in deep water. This will provide information on the level of ecosystem impact of removing lobsters from deep-water habitats to improve the assessment of risk to the ecosystem to ensure that the western rock lobster fishery maintains MSC certification and complies with DEH requirements for export permits. However, the SRG recognised that research needs to occur in a structured manner and have highlighted the need for research proposals which sit within the strategic framework which they have devised. The SRG recognises that the provision of a strategic framework and related scientific research will ultimately allow management of deep-water stocks in a more sophisticated ecosystem-based manner.