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Coastline map of Australian abalone-producing states, with inset depicting management zone boundaries of the Victorian fishery.
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Context 1
... Victoria, the abalone fishery is subdivided into three rela- tively large management zones, each spanning several hundred kilometers of coastline (Fig. 1). However, catch and effort data are reported for area codes of tens of kilometers and reef codes that generally represent headlands or reef complexes. Average catch rates for each zone have mostly increased during the past 20 y for which detailed records are available. Before we can interpret this as increased abundance, we need to ...
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... it incorporates a framework for dealing with variability in the distribution of growth within populations, and in its current form, it does not use effort. Like the NSW model, ours fits the model to several time series of abundances of different length classes obtained from fishery-independent dive surveys of commercially important populations (Fig. 1). Outputs from the Victorian model are essentially the same as those of the NSW model; however, in the absence of a management plan, there are no agreed reference points against which model outputs can be as- ...
Context 3
... reference point could be related to daily catch expectation with a trigger that is activated if average daily catches fall below a specified margin of an historical average. expressed as proportion (0.1, 0.2, 0.3, 0.4, 0.5 and 0.6), constant harvest strategy is expressed as a percentage of the current TAC (80, 90, 100, 110, and 120%), risk is expressed as a percentage probability (10, 20, and 30%) that the true value is below the estimated values for B t / B 0, and the projected time period is t years beyond 1998 (t = 0, 5, 15, and 25 years). U is the unaccounted catch as percentage of current TAC and, M is the rate of natural mortality]. ...
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... This group includes participants from all major stakeholder entities. A keystone of the regional assessment process is the prescribed use of a quantitative fisheries model of each zone to estimate the risk of reducing abalone biomass below zone-specific reference values corresponding to alternate levels of harvest (Gorfine et al., 2001). The Abalone Fisheries Committee, a subcommittee of the Fisheries Co-management Council, is charged with using these results from formal Abalone Fishery Assessment Group workshops to formulate independent advice about future zonal total allowable commercial catches (TACCs) that is communicated through the comanagement council to the Minister for Primary Industries (Fisheries Victoria, 2002). ...
Small-scale spatially complex fisheries resources present a particular challenge to centralized governmental top-down models of assessment and management. Such processes have an implicit scale and cost that cannot be simply resized to address the complexity, small scale, low unit value, and overwhelming number of these resources. International experience with alternative management systems has produced convergence on a solution to this issue, which involves redesigning the centralized top-down models of data collection, assessment, and management. Central to the solution are governance systems that confer secure exclusive access rights on fishers, so that they have strong incentives to engage in processes of data collection, assessment, and management. I suggest that the next layer of the solution is to recognize the generic nature of the issue and to develop a simpler generic approach that can be locally adapted to each small-scale resource. The generic approach proposed involves (1) the use of barefoot ecologists or change agents trained to work with both the social and biological dimensions of each resource with the aim of creating social capital and empowering local fishers to collect their own data and (2) the design and implementation of simple harvest policies intended to conserve local levels of spawning biomass.
... participants from all major stakeholder entities. A keystone of the regional assessment process is the prescribed use of a quantitative fisheries model of each zone to estimate the risk of reducing abalone biomass below zone-specific reference values corresponding to alternate levels of harvest (Gorfine et al., 2001). The Abalone Fisheries Committee (AFC), a sub-committee of the Fisheries Co-management Council (FCC), is charged with using these results from formal AbaloneFAG workshops to formulate independent advice about future zonal TACCs that is communicated via FCC to the Minister for Primary Industries (Fisheries Victoria, 2002). ...
To date, the development of fisheries harvest policies has typically focused on the use of indices estimated from quantitative stock assessment models. Where does this leave the small-scale and spatially complex resources for which costs and logistics prevent adequate data collection for the construction of quantitative assessment models at scales appropriate for the component populations being fished? This paper presents a novel harvest policy framework developed in Australia by the Victorian Western Zone Abalone Diver’s Association (WADA) to assess and manage their resource at the scale of component abalone reefs (100s–1000s m). This novel harvest policy framework uses a rapid visual evaluation of population fecundity based on shell shape and appearance. Codified and applied using a decision tree, it is being used in Australia by an increasing number of zonal abalone industry associations. Abalone populations on reef complexes are being assessed and managed with voluntary catch caps and voluntary minimum lengths larger than legal minimum lengths. It will probably be decades before a satisfactory quantitative analysis on the efficacy of the approach will be possible, but positive anecdotal accounts and the relatively rapid spread of the approach suggest industry members believe they are seeing benefits.
... Performance indicators and target/limit reference points for the biological and economic objectives are given in Table 2. Similar indicators and reference points have been used in other invertebrate fisheries (Gorfine et al. 2001). N/A *Note: These are suggestions only, and should be analysed and adjusted as the fishery proceeds. ...
A new policy incorporating an operational protocol was developed for the establishment of new fisheries in South Africa. The common octopus, Octopus vulgaris was used as a candidate species for the project. The operational protocol consisted of a three-phased development framework, namely information gathering (Phase 0), an experimental fishery (Phase 1) and the final implementation of a commercial fishery (Phase 2). The present study focussed on phase 0 of this theoretical framework and protocol and was implemented by using a proposed octopus pot fishery in South Africa as a case study. Phase 0 included a desktop study, information gathering in the field, an economic feasibility study and the formulation of a Fishery Management Plan and experimental design for the fishery. Information gaps identified during the desktop study were addressed during field investigations into the population structure and biology of O. vulgaris along the southeast coast. Immature females were found to use the intertidal area to feed and grow before migrating to the subtidal area to mature and spawn. Mean size differed substantially between intertidal and subtidal areas, with larger octopus found subtidally. Age and growth trials using tetracycline as a marker showed that O. vulgaris deposit daily growth lines in their beaks. A genetic study showed that there is most likely only one panmitic population along the coast. The economic feasibility study indicated that a longline pot fishery could be feasible provided a 30% catch in 6600 pots/month is attained. Only existing, debt-free vessels should be used in this fishery. The Fishery Management Plan proposed in this study includes management measures such as effort limitation of licences and gear, size restrictions, vessel monitoring systems, and observer programmes. Based on the population dynamics and biology of O. vulgaris it is suggested that a precautionary approach to developing fisheries for this species in both the inter- and subtidal areas along the South African coast.
Assessing the status or exploited marine fish populations often relies on fishery dependent catch and effort data reported by licensed commercial fishers in compliance with regulations and by recreational anglers voluntarily. This invariably leads to bias towards the fraction of a fish population or community that can be legally fished i.e., the stock as defined by legal minimum lengths and spatial boundaries. Data are restricted to populations which continue to be exploited at the expense of obtaining data on previously exploited and unexploited populations [1,2], so if a fishery is contracting spatially over time, then successively less of the overall fish community is monitored with bias towards where biomass is highest or most accessible [3]. A viable alternative is to conduct population monitoring surveys independently of a fishery to obtain information that is more broadly representative of the abundance, composition and size structure of fish communities and their supporting habitats [4-6]. Whereas catch and effort data often must be de-identified and aggregated to protect the confidentiality of fishers' commercial and personal interests, this constraint does not exist for independently acquired monitoring data, collected at public expense and hence publicly available at high levels of spatial and temporal resolution. Time series underpins the utility of fishery independent survey (FIS) datasets in terms of the life histories of exploited fish species and the time frames of their responses to various combinations of fishing mortality and environmental fluctuations and trends [7]. One-off surveys can establish a baseline and spatial distribution pattern, but regular surveys conducted consistently over time are necessary to detect trends from which population status can be inferred. We present several unique datasets focused on the commercially valuable blacklip abalone (Haliotis rubra), spanning three decades of annually collected data from up to 204 locations on subtidal rocky reefs along a coastline of almost 2500 km, the State of Victoria, Australia. It is rare for data to be collected consistently at this intensity over such a long period of monitoring [2], especially with surveys conducted by small teams of highly skilled research divers, some of whom up until recently had participated in every year. The data comprises ∼28,000 records from ∼4500 site surveys conducted during 1992 to 2021 [2]. Although the fixed site design remained unchanged, the number of sites surveyed varied over time, mostly increasing in number periodically, and the survey method was refined on several occasions. We defined three different variants in the survey method due to technological advancement for both enumerating abalone abundance and measuring shell size structure [7]. The relative abundance counts were standardized using a Bayesian generalized linear mixed model (GLMM) to test for interannual trends whilst allowing for inherent differences among sites, research divers, and their interactions [8].
Whether used for conservation or fisheries planning, matrix population models can help clarify how to allocate conservation effort across a species life history. In this research we develop and analyse a matrix population model for the New Zealand blackfoot pāua (abalone) Haliotis iris. Preliminary calculations for one population of H. iris yielded a population growth rate (PGR) of 16%. However due to uncertain parameter values we trialled larval settlement rates that resulted in population growth rates (PGRs) from 0 to 17%. The results showed that specific knowledge about settlement rate and juvenile survival was unimportant for the relative influence of these life-history parameters on this deterministic matrix model. Survival of the larger adults consistently had the highest sensitivity and elasticity, however in a rapidly growing population survival of the smaller animals gained importance. Also, the somewhat arbitrary placement of the shell length division between the two classes of adults created changes, with larger classes having higher elasticities. In addition elasticity, (indicating effect on the population growth rate) was concentrated in the older adults. However sensitivity, (with its greater emphasis on evolutionary change) placed more emphasis on slightly younger adults. These findings suggest that survival of larger adult paua, which is the stage typically targeted for harvest, is a key factor in fishery productivity, restoration, and conservation of the species.
Future management of disease-affected abalone must adapt to the changing circumstances, and adopting a precautionary approach will allow maximum potential for stock recovery. This approach is mandated by the observation that no documented examples are known of abalone populations recovering from catastrophic impacts such as have occurred in the abalone fisheries of Victoria's Western and Central zones. Indeed the balance of international evidence points towards the contrary, so these fisheries are in dangerous territory. This need not mean that recovery cannot occur.
However, the modelling results from this project confirm the above precautionary view and
suggest that unless it is known with certainty that disease-induced mortalities have been
moderate (less than 40%), then any resumption of fishing in the near term risks the future of the fishery. Acquisition of accurate mortality data is the only basis upon which fishing can recommence in the short term (within 5 years) and in many instances, such as for some among those reefs considered in our study, the opportunity has passed. The simulation results provide guidance, but their validity is conditional on myriad assumptions as well as on the accuracy of data employed. We already know that catches early in the fishery’s history were higher than reported officially, but how much higher is conjecture. Growth is highly variable over small
spatial scales and feedback effects from reduced abundance together with changed size structure and persistence of habitat will play roles in determining the rate, if any, of recovery. The extent of the contemporary illegal catch is uncertain, particularly given the unprecedented closure of the fisheries. The results show that even small illegal catches can significantly degrade recovery where the viral impact is high, with clear implications for the enforcement aspects of managing these fisheries.
Design of future data collection strategies within Victoria and its neighbouring states of South Australia, New South Wales and Tasmania should be focused on acquisition of base line data and a preparedness to sample disease affected populations as the disease is occurring and subsequently at a frequency that identifies its persistence. For instance, counting and measuring dying and dead abalone and evacuated shells may prove invaluable. Surveys such as these are expensive and industry should consider how it might contribute to the provision of comprehensive geographically detailed data such as size structure and abundance that will be responsive to mortality. Commercial abalone divers, driven by an imperative to earn a living, are already making assertions that the resource has recovered sufficiently to resume harvesting. Our study shows that they may be "telling it like it appears", but that appearances in this instance are deceptive.
Victoria now has a basis for assessing post-disease management complemented by a
comprehensive bank of tissue samples ready for testing previous exposure to disease once a properly validated test becomes available and aggregation data for the Western Zone that can be used to discriminate between future changes in true abundance and changes in distribution patterns on reefs due to movements. More work is required to investigate suitable indices that can be calculated from the aggregation data collected to measure changes in patterns over time. Once a reliable genetic test to determine previous disease exposure has been applied, the results should form part of an epidemiological study to ascertain the likelihood of disease recurrence and whether or not future outbreaks are likely to become less lethal.
The sustained production of abalone from the five state-managed (Tasmania, Victoria, South Australia, New South Wales, and Western Australia) Australian abalone fisheries has contrasted with many of those elsewhere that exhibited rapid and sustained declines in production. Australian abalone fisheries are significant at local, regional, state, national, and international scales. Key attributes are (1) harvesting, processing, and reinvestment of profits occur away from major metropolitan centers; (2) they are among the most valuable wild-catch species in all states; (3) the combined Australian abalone harvest in 2011 (>4,500 t) had a landed value of ∼AU$200M and represented 15% of the Australian total wild-catch production; and (4) this level of production made these fisheries the dominant contributor (60%) to global wild-catch abalone production. Unlike many other abalone fisheries, total catches were controlled by limited entry, quotas, size limits, and geographic boundaries, overseen by stringent compliance regimes, early in their history. Subsequently, state-based research programs, explicitly tasked with providing scientific advice to support management decisions, undertook assessments to match harvests with stock productivity. This information upon which to base management decisions contributed to long-term (>20 years) stable harvests and enabled relationships among stakeholders to develop around consideration of the information and advice for management. In general, rights-holders developed stewardship for the resource, and this has led to numerous important outcomes, including evolving resource co-management and a nationally representative industry entity, the Abalone Council of Australia. The Abalone Council of Australia, state-based industry entities, and ongoing relationships among rights-holders, fishery managers, and researchers play vital roles in addressing and overcoming current and impending challenges for these fisheries. These difficulties include (1) urban encroachment into coastal regions (the so-called “sea change” phenomenon); (2) a growing interest in access to the abalone resource, reflecting the increasing, culturally diverse Australian population; (3) the ever-present threat of illegal fishing; (4) recent total allowable commercial catch reductions, particularly in Victoria and New South Wales, to facilitate stock rebuilding; (5) changing market conditions; (6) declining profitability from increasing operational costs and appreciation of the Australian dollar; and (7) environmental changes, such as prolonged drought and warmer seas associated with shifts in climate. Overall, this review demonstrates that abalone can be harvested sustainably over extended periods, despite aspects of their demography that suggest higher vulnerability to overexploitation, providing the management systems that control harvesting activities and external impacts that encompass several key underpinning elements. This review also identifies likely challenges to sustained production and shows that the future of these stocks and fisheries will require proactive strategies to mitigate current threats to sustainability and to maintain economically viable productivity.
Industry participation in co-management has become a cornerstone of assessing the blacklip abalone, Halitois rubra, fisheries of South-Eastern Australia. Engaging industry in developing and implementing management strategies is aimed at stemming recent trends of stock depletion and reduced harvest. An alternative to the current strategy for determining harvests is under consideration. A central question is: which management strategy is most likely to maintain sufficient biomass to produce consistent harvest rates into the future? This question is addressed using a Systems Dynamics modeling approach. We evaluated the two strategies of harvest management planning under (i) unchanging environmental conditions and (ii) following a high-mortality event. To assess the performance of each strategy, an existing abalone model was used to estimate yield and mature biomass over three decades (>5 generations). A strategy using mean length of commercial catch as a novel performance measure generally provided a better path to recovery from the high-mortality event than the current harvest threshold strategy.
The management section of California's recently adopted Abalone Recovery and Management Plan (ARMP) uses results of fishery independent transect surveys at eight index sites to regulate total allowable catch (TAC) for the recreational red abalone, Haliotis rufescens (Swainson), fishery. The ARMP uses abalone densities over all depths, densities in deep water (8.4–19.7 m), and successful recruitment (>4,500 abalone/hectare in the 100–177 mm size class) to decide whether changes need to be made in the TAC (see Table 1 later). The catch is estimated from telephone surveys and returned abalone permit report cards. Recent surveys in 2003 and 2005 at four of the eight index sites show red abalone densities in the range of the baseline densities established by surveys in 1999 and 2000. Applying the results of the 2003 and 2005 surveys to the ARMP criteria indicates no change is needed in the current TAC. Two-way ANOVA showed there were no significant differences in density between sites (Van Damme and Salt Point; df = 1, F = 0.06, P > 0.8) and time periods (df = 1, F = 1.33, P > 0.25) for all depths combined. Likewise there were no significant differences at deep depths between the two sites (df = 1, F = 0.23, P > 0.63) and the two time periods (df = 1, F = 0.10, P > 0.75).
