Assessment report of the Queensland Spanner Crab Fishery

Environmental assessment under the EPBC Act
Department of the Environment and Heritage, December 2001
ISBN 0 642 54860 9

Principle 1: A fishery must be conducted in a manner that does not lead to over-fishing, or for those stocks that are over-fished, the fishery must be conducted such that there is a high degree of probability the stock(s) will recover:

Objective 1: The fishery shall be conducted at catch levels that maintain ecologically viable stock levels at an agreed point or range, with acceptable levels of probability.

Information requirements

The information collection system in place for this fishery is appropriate to the scale of the fishery and incorporates a mix of fishery dependent and fishery independent research and monitoring.

The primary means of collecting fishery dependent data is through the compulsory daily logbook. Monitoring of fishing activity in MAA relies entirely on the information in the Prior Landing Report submitted through the logbook, which provides information on fishing location, catch, where and when the catch will be landed and to whom it will be unloaded. This information is also crosschecked against the processor dockets and provides sound validation of catch data. This process validates data collected in logbooks for MAA, however, whilst validation of MAB catch is cross-checked against the processor dockets, there appears to be no validation of effort logbook data for fishers operating in MAB. QFS should be prepared to provide information on how effort data for MAB is validated.

The submission expresses a general lack of confidence in the validation of effort data. This is a significant concern given that the stock assessment model and therefore the annual TACC setting process, relies on CPUE data. An analysis of the current mechanism for validating CPUE data is suggested.

The submission indicates that surveillance across the fishery is high but it is unclear exactly what level of coverage of the fishery this statement refers to. There are comprehensive logbook reporting requirements for MAA and MAB, and real time surveillance of fishing in MAA (ie prior landing reports). The submission also indicates that compliance with regulations and reporting requirements is high, however there is concern over the validation of logbook reported catch and effort data. A periodic review of the compliance and enforcement strategy, with particular attention given to the validation of CPUE data, is suggested to ensure emerging compliance risks are identified and addressed.

An annual fishery-independent survey is conducted as part of the QDPI Long Term Monitoring Program, however the first survey was conducted in April 2000 so there is little data for comparative analysis at this stage. Whilst the submission does not discuss the reliability or confidence in the data collected through the independent survey it is acknowledged that the value of the surveys may not become apparent for some years and notes its current limitations. EA accepts this point and notes that further development of the fishery independent survey is needed to obtain meaningful fishery independent data to complement existing fishery dependent information.

Beyond reporting total estimated weight of discards, which may include bycatch, there is no reporting required for bycatch or interaction with protected species. To improve the data collection regime for the fishery it is recommended that reporting of bycatch and protected species interaction be a requirement of the daily catch and effort logbook. This issue is discussed in greater detail under Principle 2 of the Guidelines.


The spanner crab stock is assessed annually as part of the annual TACC setting process and stock assessment review. The current stock assessment model is a simple catch-rate regression model based on CPUE data obtained from MAA. The submission indicates that the model was developed in the absence of biological data to develop a robust biologically meaningful model. Past attempts to develop such biologically based models have failed and QFS indicate they are continuing to work on the collection of data to aid further development.

There appears to be consensus that an assessment model for this fishery based upon CPUE data is not as robust as one based upon biological data with the ability to estimate stock biomass and recruitment relationships. The potential for manipulation or misrepresentation of catch and effort in the daily lift data recorded by fishers in logbooks, and its implications for setting an annual TACC, is an inherent concern with all CPUE based models. If catch and effort data is manipulated the assessment model may yield inaccurate results, resulting in an inappropriate annual TACC. A more robust assessment model that is independent of CPUE data would eliminate this risk. EA strongly encourages the continuation of work to develop a model based on sound biological data.

Whilst the reliance of the TACC setting process on CPUE data is not ideal, the submission indicates that the decision rules currently used with the model are sufficiently precautionary to provide resource sustainability. The decision rules were subject to sensitivity testing to determine the TACC setting approach's sensitivity to recruitment variability, catch rate, spatial definition of stock and CPUE/stock biomass relationship, including risks of hyperstability. The submission concluded from the simulation that the approach and decision rules were very conservative, precautionary and risk averse, and likely to perform well in a declining fishery.

Upon analysis of the decision rules and their application in the annual TACC setting process EA believes the decision rules are on the whole precautionary but there is some concern over the ability of the rules to adequately deal with effort creep. While the assessment method and its testing are sound, the level of precaution inherent in the approach is nevertheless strongly influenced by the form of relationship between CPUE and trends in mean CPUE within an assessment area. A systematic increase in efficiency over time could, in a fishery in which there is a declining stock, underestimate the rate of decline, which could result in a less conservative response than assumed in the TACC and decision rules. Relatively small annual changes in efficiency may become significant if they result in a progressive and directional change in the relationship between CPUE and stock abundance.

QFS have indicated that a review of the decision rules has commenced and, subject to funding on a research proposal, will evaluate the current Queensland and NSW monitoring and assessment procedures. EA suggests that an assessment of the impact of effort creep on the TACC process and triggers also be undertaken.

The management arrangements take into account the known spatial distribution and structure of the spanner crab stock. The fishery is currently managed in two sub-areas, MAA and MAB on the basis that there was uncertainty about the exploitable levels of the species in the MAB region. To encourage exploratory fishing MAB was established with less stringent management controls than MAA. MAA is managed primarily through a TACC/ITQ system and MAB has a daily catch limit.

EA understands that the original boundary between the two areas was based on historical catch data, with MAA including those areas where the stock resource was known, and MAB covering the remainder of the fishery where exploitable levels of the stock were largely unknown. It is now a number of years since the original fishery division and the current catch and effort in the fishery has changed considerably. The maps contained in the submission indicate that effort has shifted northwards (as expected with the creation of MAB) and that catch has also increased in the north. Historic fishing effort was concentrated away from the boundary area but current catch and effort shows a concentration across the boundary. Given the lack of confidence in the effort data collected through the logbooks, it may be pertinent to review the location of the boundary and recreate a buffer between the two areas in terms of catch and effort. It appears that the historic boundary is no longer appropriate and EA recommends a review of its location. A shift of the boundary further north would more accurately reflect the differences in stock abundance.

Estimates of all removals from the fished stock are obtained for this fishery. Estimates of commercial catches rely primarily on the logbook data whilst accurate estimates of recreational and indigenous take are less certain. At present there is no process for estimating the recreational catch of spanner crabs annually. Biennial recreational fisheries surveys are conducted and show historically low catches of spanner crabs. The harvest level by indigenous fishers is estimated to be extremely small (approx 2% of the total recreational spanner crab take).

Catches from MAB, recreational and indigenous fishers are not factored into the stock assessment process. The submission indicates that these catches are low and should they increase the current situation would be reviewed.

Removals of stock taken by the commercial fishing are factored into management responses. Specifically, catch (and effort) taken from within MAA is used to determine the annual TACC for that area. The reliance of the stock assessment process on fishery dependent data (ie logbooks) adds uncertainty into the accuracy of the model. Whilst conservative decision rules are built into the current model, there is a risk that input data may not be accurate. The validation of CPUE data has implications for the reliability of the annual TACC. In recognition of this uncertainty, an examination of the adequacy of current CPUE data validation is suggested and consideration should be given to the development of more robust validation mechanisms, for example, the use of Vessel Monitoring Systems across the fishery.

Management response

The current Plan provides for the adjustment of the TACC in response to changing CPUE and the stock assessment decision rules contain a point beyond which the stock must not be taken.

Consistent declines in CPUE in several sub-regions of the fishery since 1997 resulted in the recent significant reduction of 21.14% in the 2000/01 TACC and there is an expected further significant decline in the coming year's TACC. The continual decline in stock and the synchronised reduction in the annual TACC raised concerns about the long-term sustainability of the stock. Following analysis of the decision rules and historical catch data it appears that the original TACC set for the fishery was set too high and the recent declines in the TACC are evidence of an effective assessment process. The decision rules are a crucial part of this process and are currently performing well. EA believes that the current decision rules are effective and essential to its determination of the reliability and credibility of the assessment process.

In addition to the annual TACC set for MAA, there is a range of input and output controls employed in the fishery. The controls are well documented in the management plan, are capable of controlling the level of take from the fishery and are subject to periodic review.

The input controls include permitted gear restrictions, such as dilly size and mesh restrictions, limits on the number of apparatus per fisher and a spawning season closure. These measures combined with daily quota, size restrictions and the prohibition of taking egg-bearing females provide an adequate and effective means of controlling the level harvest from the fishery. There are no management arrangements governing the take of byproduct species as the selective nature of the spanner crab dilly ensures bycatch and the take of byproduct is minimal.

Conflict between the provisions contained in the Management Plan and Queensland State legislative requirements was brought to our attention during the public comment period. The management plan requires the Chief Executive to declare a reduction in the TACC if the review rules are triggered. However, we understand that under Queensland State legislation, QFS must prepare a Regulatory Impact Statement and seek public comment before the reduction of the TACC may occur. EA is concerned that the explicit trigger points and subsequent management actions required under the management plan may be prevented, or significantly impeded, under other state legislation. It is expected that the science underpinning the decision rules and subsequent TACC decisions would not be weakened by other state legislative activities. QFS should be prepared to provide assurance that decisions under the management plan would be upheld, and that should this not be the case, action will be taken to rectify the situation.


EA is satisfied that the information collection system, stock assessment process and management arrangements are sufficient to maintain ecologically viable stock levels with acceptable levels of probability and are consistent with Objective 1 of the Guidelines.

The management responses in place to control the level of take from the fishery are effective and include viable, precautionary reference points that trigger sound management actions. The decision rules are the primary instrument to ensure that stock levels do not fall below a critical point and, in the absence of a stock assessment based on fisheries independent data, such as biological modelling, provide a conservative and risk averse process. The strength of the decision rules strongly influenced EA's determination that the management of the target species stock is sufficient.

Overall, the information collection system in place for the Queensland Spanner Crab Fishery is adequate. The only area of concern is the validation of effort data and the absence of bycatch and protected species reporting requirements.

Other minor concerns were raised that may be easily addressed without major changes to the management arrangements. EA has made a number of recommendations, which are presented below. Whilst not essential for the fishery to achieve ecological sustainability the suggested improvements would further enhance the fishery's ability to maintain ecologically sustainable stock levels and monitor its impacts on the broader marine ecosystem.

Objective 2: Where the fished stock(s) are below a defined reference point, the fishery will be managed to promote recovery to ecologically viable stock levels within nominated timeframes.

The submission indicates that the stocks are not considered to be below the defined reference point specified in the decision rules under the TACC setting process. The decision rules used in the TACC setting process includes reference points to trigger reductions in the annual TACC across the fishery, including a bottom line, beyond which the TACC for the following year must be set at zero. EA is satisfied that this objective is not currently relevant to this fishery.