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Blacklip Abalone

Haliotis rubra rubra

  • Craig Mundy (Institute for Marine and Antarctic Studies, University of Tasmania)
  • Ben Stobart (South Australian Research and Development Institute)
  • Corey Green (Department of Economic Development, Jobs, Transport and Resources, Victoria)
  • Greg Ferguson (South Australian Research and Development Institute)
  • Owen Burnell (South Australian Research and Development Institute)
  • Rowan Chick (Department of Primary Industries, New South Wales)
  • Stephen Mayfield (South Australian Research and Development Institute)

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Stock Status Overview

Stock status determination
Jurisdiction Stock Fisheries Stock status Indicators
New South Wales New South Wales NSWAF Sustainable Catch, CPUE, mean weight
NSWAF
New South Wales Abalone Fishery (NSW)
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Stock Structure

Empirical field studies1 and molecular techniques2,3 strongly suggest Blacklip Abalone (Haliotis rubra rubra) fisheries comprise a large number of small, ecologically independent populations. Each biological stock may extend over only a few hundred metres, with each Blacklip Abalone fishery likely consisting of an indeterminate number of small biological stocks (populations), which may number in the thousands for a single fishery management unit. Given the large number of biological stocks, it is not practical to assess each stock separately.

Here, assessment of stock status is presented at the jurisdictional level—Western Australia; and at the management unit level (for each spatial quota management area)—New South Wales Abalone Fishery, Victorian Central Zone Fishery, Victorian Eastern Zone Fishery, Victorian Western Zone Fishery, Tasmanian Bass Strait Zone Fishery, Tasmanian Central Western Zone Fishery, Tasmanian Eastern Zone Fishery, Tasmanian Northern Zone Fishery, Tasmanian Western Zone Fishery, South Australian Central Zone Fishery, South Australian Southern Zone Fishery and South Australian Western Zone Fishery.

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Stock Status

All states rely on empirical performance measures, specifically catch, catch per unit effort (CPUE; as kg of abalone harvested per hour), and commercial catch size structure. The annual catch in Blacklip Abalone fisheries is generally equivalent to the total allowable commercial catch (TACC) with negligible over-catch or under-catch of the TACC. In some jurisdictions, additional fishery-independent data (density, size structure) are available from underwater research surveys.

 

As the spatial extent of individual fishing events (dives4) or fishery-independent survey sites is approximately the same size as a functionally independent abalone population, and that habitat structure often changes on a similar spatial scale, the combination of these features make assessment of abalone stock status more complicated than most fisheries. Common values for catchability, recruitment, growth and natural mortality cannot be assumed for a management unit, and status of the many populations in a management unit should not be assumed to be trending in the same direction. Thus attempts to model a management unit as a single stock, or to use other methods to arrive at ‘global’ estimates of biomass should be approached cautiously. Catch rates are an index of local abundance only, that is, localised to each fishing event or to each survey site and local catch and catch rates do not inform status of more distant fishing grounds within the same management unit. Fishing effort in abalone fisheries is also subject to a range of influences (wave height and power, wind, currents, water clarity) creating short-term biases or variability in CPUE that are not related to resource abundance.

 

The New South Wales Abalone Fishery is managed as a single management unit with a single TACC, set by an independent Total Allowable Catch Committee. Annual assessments have relied heavily on fishery-dependent data from logbooks, including catch, catch rate (kg per hour) and mean weight, summarised at a range of spatial scales. Most recent assessments have also utilised estimates of legal size biomass density at fine spatial scales, derived from GPS data-loggers and data from logbooks.

The Victorian abalone fisheries are assessed using a weight-of-evidence approach, incorporating fishery-dependent commercial catch, effort, CPUE and length frequency data (from 1992 onwards), and fishery-independent fixed site surveys of abalone abundance and size structure. Trends in abalone abundance in two size classes are considered, using the legal minimum length (LML) established in 1992 (110 mm/120 mm Central Zone; 120 mm Eastern Zone, Western Zone)–density of abalone recruits (greater than the LML) and density of pre-recruits in a size band 40 mm below the LML. While fishery-independent survey data are available from 1992 onwards, data are only considered here from 2003–15, due to an increase in number of survey sites and other methodology changes introduced at this time, thus making it difficult to compare with data prior to 2003. The value of this fishery-independent survey is disputed by some sectors, although a recent review showed it to be broadly useful for determining relative stock status5. Commercial CPUE data and diver observations are evaluated at the scale of the management zones and at finer scales within each zone. Commercial CPUE data are used in both raw and standardised form6. Importantly, interpretation of these data is conducted within the context of historical changes in the management, fishing methods and other non-fishing impacts on the populations with each zone.

 

The Tasmanian abalone fishery has been quota managed with an annual TACC since 1985, and up to 1999 there was a single Tasmanian TACC that did not differentiate between species or area. In response to increased regional fishing pressure through the late-1990s, separate TACCs for Greenlip Abalone and Blacklip Abalone were implemented in 2000, and the Blacklip Abalone fishery was divided into two zones (Eastern Blacklip, Western Blacklip). Also in 2000, finer-scale reporting of fishing within sub-blocks was introduced. Further spatial partitioning of the Tasmanian Blacklip Abalone fishery occurred in 2001, with the northern areas of the Eastern and Western Zone moving into a Northern Blacklip Zone. In 2003, the Northern Zone was split into two zones with different size limits (Northern Blacklip and Bass Strait Blacklip). In 2009, the Western Blacklip Zone was split into Western Blacklip and Central West Blacklip zones, and the boundary between the Western and Central West Blacklip zones was moved northwards in 2013.

Around 65 per cent of the total Tasmanian wild abalone harvest is exported live to Asia, with the remaining fraction processed in canned or frozen form. The fishery lands abalone live, and all catch rates are in whole live weight.

An empirical harvest strategy (HS) was developed for the Tasmanian abalone fisheries in 2014–157,8 and tested by Management Strategy Evaluation (MSE)9,10. The HS was trialled in the Tasmanian abalone fishery assessment for the first time in 2015, jointly with the previous ad hoc approach4. The HS assesses the fishery performance against target reference points for three performance measures (PM) derived from standardised CPUE (SCPUE) data: current CPUE relative to an agreed target (55th percentile of the annual standardised mean CPUE within the reference period); the 4 year gradient of CPUE (target gradient is zero); and the per cent change in SCPUE in the past year (target change is zero). The reference period for the 2015 assessment spans fishery data between 1992 and 2015. A scoring function is applied to the three PMs resulting in a score between zero and 10, where five is the target PM value and zero and 10 are the zone-wide lowest and highest values for that PM within the reference period. Weightings are applied to the three PMs 05:0.25:02.5 to provide a combined final score used in the control rule. The HS is applied individually to each statistical reporting block, and a zone score is obtained from the mean block score weighted by block catch.

The zone target CPUE PM score is used as a proxy for biomass and the zone gradient CPUE PM score is used as a proxy for fishing mortality. A target CPUE score of one is the limit reference point (LRP) defining the boundary between recruitment overfished and transitional–depleting for all Tasmanian management units. This LRP is typically five per cent above the lowest SCPUE observed within the zone during the reference period. A negative zone gradient score gives evidence that fishing mortality is increasing and the magnitude of the gradient provides some information on the magnitude of fishing mortality. In order to emulate a normal phase plot, five is subtracted from the 4 year gradient PM score to provide a range of negative five–positive five, where the target reference point is zero, and defines the boundary between sustainable and transitional–depleting classifications, but also between transitional–recovering and recruitment overfished. The combination of a negative CPUE gradient and near-record low CPUE score represents a cautious proxy for the true recruitment overfished reference point. No reporting blocks have collapsed within the reference period, providing a degree of certainty that the LRP will prevent stock collapse, which is supported by MSE testing of the HS.

The Tasmanian Abalone Fishery Management Plan policy document requires size limits be established that allow two breeding seasons post-reproductive maturity. Research programs11 to obtain empirical data representing the geographic variability in growth rates and size at reproductive maturity have been underway since 1985, resulting in a range of LML regulations within the Tasmanian Blacklip Abalone fisheries ranging from 110–145 mm.

 

In South Australia, the harvest strategy in the Management Plan for the commercial abalone fishery12 produces a catch weighted determination of stock status for the fishing zone. However, the harvest strategy does not identify performance indicators or reference points for classifying the fishery under the Status of Australian Fish Stocks framework. The reference points described in the harvest strategy were developed as a scoring mechanism for the performance indicators, not as a stock classification tool. While there is some variability among management units, the harvest strategy was developed at a time when the fishery was considered to be stable and was partly designed to maintain that stability. Reference points are used to score performance indicators, with negative scores for low current values and positive scores for high current values, when assessed against a fixed 20-year reference period (1990–2009). The intent was to prevent the fishery declining to abundance levels in the 1990s, that preceded the large increase in abundance (presumably through strong recruitment) in the 2000s13,14, whilst simultaneously allowing increased abundance to translate to elevated TACCs. The harvest strategy appears to result in more optimistic assessments of stock status than those from weight-of-evidence methods applied elsewhere13,14. Concerns with the harvest strategy have resulted in a review that is currently underway. Consequently, in this assessment, nominal commercial catch rates (CPUE based on: meat weight in the Central and Western Zone management units; and shell [whole] weight in the Southern Zone management unit) are used as the primary index of relative Blacklip Abalone abundance. CPUE can provide a more optimistic index of relative abundance than measures from fishery-independent surveys, because catch rates in dive fisheries have been shown to be hyperstable13–18. Decreases in CPUE in abalone fisheries are considered to be a reliable indicator of declines in abalone abundance, but nominal CPUE can underestimate the actual magnitude of the reduction in harvestable biomass13–18.

New South Wales

Blacklip Abalone stocks in New South Wales have substantially recovered, or are recovering, from what are now understood to be historically persistent levels of overfishing and over-depletion19,20. Recent changes in the status of the stock, together with substantial contrast in historical and recent fishery-dependent measures (notably, catch and catch rate) provide a basis to infer historical status and reference levels of catch rate, assuming they are comparable and provide a relative measure of stock abundance through time.

The historical status of stocks, inferred largely from changes in the level of catch rate though time and the overfished status of the stock in the mid-2000s, strongly indicates that stocks were subject to recruitment overfishing and were overfished in the mid-1980s (catch rate less than 20 kg per hour) and that overfishing continued throughout the 1990s to the mid-2000s (catch rate less than 20 kg per hour, with intermittent peaks to less than 25 kg per hour). This period of declining and historically low catch rate occurred during a period of relatively stable catches through the 1990s and a reduction in TACCs during the early-2000s from 305–130 tonnes (t)

Following further reductions in TACCs, to 75 t in 2010, there has been a strong and steady recovery in catch rate and mean weight of abalone, particularly from southern areas of New South Wales, which provide most of the catch, to levels not previously recorded in the fishery. In 2010, the catch rate exceeded 30 kg per hour for the first time since the early-1980s and has increased annually, to about 50 kg per hour in 2015. In addition, recent measures of legal size biomass density (kg per hectare) derived from GPS-logger and logbook data, indicate that there has been a two-fold increase in biomass since 200919. These GPS-logger estimates have a greater precision than catch rates from logbook data alone, which may overestimate increases in abundance. In response to these indicators of increasing biomass19, the TACC has been cautiously increased since 2011, and in 2015 was 130 t. Additional protection for the fishery has also been achieved through several increases in the LML from 100 mm, established in 1972, through four increases to 117 mm in 2008. In the southern areas of the state, the LML for the commercial fishery was increased further to 120 mm in 2010 and then 123 mm in 2013. On this basis, a catch rate of 30 kg per hour seems appropriate as a limit reference point below which the stock would be classified as recruitment overfished.

Stock recovery has not been uniform throughout the state, with evidence indicating the greatest levels of rebuilding in the south. Northern stocks were subject to high exploitation rates through the mid- to late-1980s and early-1990s and were further depleted by mortality associated with infection by the parasite Perkinsus sp.19,20 during the 1990s and into the early-2000s. Stock within this northern area has not demonstrated similarly strong, consistent improvements in fishery-dependent data, compared to those observed in the south. Relatively low, sporadic catches, together with modest and variable increases in CPUE and mean weight, suggest that recovery is occurring, but the status of these northern stocks is less certain.

The evidence presented above indicates that the stock within the New South Wales management unit was overfished through the mid-1980s and into the early-2000s. Since the early-2000s, management measures have supported ongoing recovery, as indicated by changes in catch rate and mean weight of abalone in the commercial catch since the mid-2000s. Recent performance measures indicate that stocks are continuing to recover, although at a slower rate19 and current management measures provide greater protection to the fishable biomass, with LMLs being more precautionary than at any other time in the history of the fishery. A fishery harvest strategy is under development to provide greater certainty in the response of management to future changes in the performance of the fishery.

The above evidence indicates that stocks in the New South Wales Abalone Fishery are unlikely to be recruitment overfished and that the current level of fishing mortality is unlikely to cause these stocks to become recruitment overfished.

On the basis of the evidence provided above, the New South Wales Abalone Fishery management unit is classified as a sustainable stock.

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Biology

Blacklip Abalone biology

Biology
Species Longevity / Maximum Size Maturity (50 per cent)
Blacklip Abalone 20–50 years; 150–220 mm SL  ~ 5 years; 80–130 mm SL 
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Distributions

Distribution of reported commercial catch of Blacklip Abalone

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Tables

Fishing methods
New South Wales
Commercial
Diving
Indigenous
Diving
Recreational
Diving
Management methods
Method New South Wales
Commercial
Limited entry
Size limit
Spatial closures
Total allowable catch
Indigenous
Bag limits
Section 31 (1)(c1), Aboriginal cultural fishing authority
Size limit
Spatial closures
Recreational
Bag limits
Size limit
Spatial closures
Active vessels
New South Wales
29 in NSWAF
NSWAF
New South Wales Abalone Fishery (NSW)
Catch
New South Wales
Commercial 129.34t in NSWAF
Indigenous Unknown
Recreational Unknown
NSWAF
New South Wales Abalone Fishery (NSW)

a Victoria – Indigenous (management methods) In Victoria, managing fishing activities by Indigenous people is grouped with the recreational fishing sector. Recognised Traditional Owners (groups that hold native title or have agreements under the Traditional Owner Settlement Act 2010 [Vic]) can apply for permits under the Fisheries Act 1995 (Vic) that authorise customary fishing (for example, different catch and size limits or equipment). The Indigenous category in Table 3 has been interpreted to mean customary fishing being undertaken by Recognised Traditional Owners.
b New South Wales – Indigenous (management methods) Aboriginal Cultural Fishing Interim Access Arrangement - allows an Indigenous fisher in New South Wales to take in excess of a recreational bag limit in certain circumstances, for example, if they are doing so to provide fish to other community members who cannot harvest themselves.
c New South Wales – Indigenous Aboriginal cultural fishing authority - the authority that Indigenous persons can apply to take catches outside the recreational limits under the Fisheries Management Act 1994 (NSW), Section 37 (1)(c1), Aboriginal cultural fishing authority.

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Catch Chart

Commercial catch of Blacklip Abalone

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Effects of fishing on the marine environment

  • Blacklip Abalone are hand-selected by divers operating from vessels that seldom anchor, hence the fishery has negligible direct physical impact on the environment. There is also substantial evidence that the ecosystem effects of removing abalone are minimal34–36.
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Environmental effects on Blacklip Abalone

  • AVG established in the wild fishery following initial infection in two land-based abalone aquaculture farms and two offshore experimental farms adjacent to the wild fishery in 200524. AVG is highly pathogenic, resulting in estimated mortalities of between 60 and 95 per cent in infected wild populations.
  • South and westward strengthening of the relatively oligotrophic East Australian Current37 into the inshore waters in eastern Victoria and Tasmania is thought to have triggered changes in nearshore community structure over the past two decades38. This is primarily through range expansion of species such as the Long Spined Sea Urchin (Centrostephanus rodgersii) from New South Wales to Tasmania and Victoria, and the significant reduction in Giant Kelp (Macrocystis porifera) biomass39. This has resulted in localised depletions of abalone populations and a reduction in the habitat available for abalone40.
  • Above average warm water events were inferred to have resulted in minor mortalities of abalone in Tasmania in February 2010 (pers. comm., Tasmanian Abalone Divers), although the spatial extent and magnitude of the mortality was not quantified. These events are expected to increase under most climate change scenarios.
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References

  1. 1 Prince JD, Sellers TL, Ford WB, Talbot SR. 1987, Experimental-Evidence for Limited Dispersal of Haliotid Larvae (Genus Haliotis, Mollusca, Gastropoda). Journal of Experimental Marine Biology and Ecology 1987; 106: 243–263. .
  2. 2 Miller KJ, Maynard BT, Mundy CN. 2009, Genetic diversity and gene flow in collapsed and healthy abalone fisheries. Molecular Ecology 2009; 18: 200–211. .
  3. 3 Temby N, Miller K, Mundy C. 2007, Evidence of genetic subdivision among populations of blacklip abalone (Haliotis rubra Leach) in Tasmania. Marine and Freshwater Research 2007; 58: 733–742. .
  4. 4 Mundy C, Jones HJ. 2016, Tasmanian Abalone Fishery Assessment 2015. Institute for Marine and Antarctic Studies Report. University of Tasmania, Hobart.
  5. 5 Hart. 2016, Review of fixed site surveys used by the Victorian abalone science program. Western Australian Department of Fisheries.
  6. 6 Gorfine H, Taylor B, Smith DC. 2002, Abalone – 2001, Fisheries Victoria Assessment Report No 43. Marine and Freshwater Resources Institute, Queenscliff.
  7. 7 Buxton CD, Cartright I, Dichmont C, Mayfield S, Plaganyi EE. 2015, Review of the Harvest Strategy and MCDA process for the Tasmanian Abalone Fishery. Institute for Marine and Antarctic Studies.
  8. 8 Mundy C, Jones HJ. 2016, Multi-Criteria Decision Analysis based harvest strategy for the Tasmanian abalone fishery. Institute for Marine and Antarctic Studies, Hobart.
  9. 9 Haddon M, Mundy C. 2016, Testing abalone empirical harvest strategies, for setting TACs and associated LMLs, that include the use of novel spatially explicit performance measures. CSIRO Oceans and Atmosphere, Hobart.
  10. 10 Haddon M, Mayfield S, Helidoniotis F, Chick R, Mundy C. 2014, Identification and Evaluation of Performance Indicators for Abalone Fisheries. FRDC Final Report 2007/020. Commonwealth Scientific and Industrial Research Organisation (CSIRO), Hobart
  11. 11 Jones HJ, Pyke S, Mundy C. 2016, Review of Size at Maturity and Legal Minimum Length in Tasmanian Blacklip Abalone Fisheries. Institute for Marine and Antarctic Studies Report. University of Tasmania, Hobart.
  12. 12 PIRSA. 2012, Management Plan for the South Australian commercial abalone fishery. 2012. .
  13. 13 Burnell O, Mayfield S, Ferguson G, Carroll J. 2016, Central Zone Abalone (Haliotis laevigata & H. rubra) Fishery. Fishery Assessment Report for PIRSA Fisheries and Aquaculture. 2016.
  14. 14 Stobart B, Mayfield S. 2016, Status of the Western Zone Blacklip Abalone (Haliotis rubra) fishery in 2015. Report for PIRSA Fisheries and Aquaculture. 2016. .
  15. 15 Dowling NA, Hall SJ, McGarvey R. 2004, Assessing population sustainability and response to fishing in terms of aggregation structure for greenlip abalone (Haliotis laevigata) fishery management. Canadian Journal of Fisheries and Aquatic Science 2004; 61: 247–259.
  16. 16 Stobart B, Mayfield S. 2016, Assessment of the Western Zone greenlip abalone (Haliotis laevigata) Fishery in 2015. Fishery Stock Assessment Report to PIRSA Fisheries and Aquaculture. 2016. .
  17. 17 Tarbath D, Mundy C, Gardner C. 2014, Tasmanian Abalone Fishery Assessment 2013. Institute for Marine and Antarctic Studies .
  18. 18 Shephard S, Rodda KR. 2001, Sustainability demands vigilance: Evidence for serial decline of the greenlip abalone fishery and a review of management. 2001; 20: 829–841. .
  19. 19 Anon. 2015, Total Allowable Catch Committee Report and Determination for 2016 – Abalone Fishery 2015. New South Wales Government.
  20. 20 Liggins G, Upston J. 2010, Investigating and managing the Perkinsus-related mortality of Blacklip Abalone in NSW. 2010. .
  21. 21 DEDJTR. 2016, Victorian Abalone Stock Assessment – Central Zone. Fisheries Victoria.
  22. 22 Gorfine H, Bell J, Mills K, Lewis Z. 2012, Removing sea urchins (Centrostephanus rodgersii) to recover abalone (Haliotis rubra) habitat. Department of Primary Industries, Queenscliff, Victoria, Australia.
  23. 23 DEDJTR. 2016, Victorian Abalone Stock Assessment – Eastern Zone. Fisheries Victoria.
  24. 24 Mayfield S, McGarvey R, Gorfine HK, Peeters H, Burch P, Sharma S. 2011, Survey estimates of fishable biomass following a mass mortality in an Australian molluscan fishery. Journal of Fish Diseases 2011; 34: 287–302. .
  25. 25 Helidoniotis F, Haddon M. 2014, Modelling the potential for recovery of Western Victorian abalone stocks: The Crags. Interim Report to 2012/225. CSIRO, Hobart.
  26. 26 Gorfine H, Day R, Bardos D, Taylor B, Prince J, Sainsbury K et al. 2008, Rapid response to abalone virus depletion in western Victoria: information acquisition and reefcode assessment, final report to the Fisheries Research and Development Corporation, project 2007-066. The University of Melbourne .
  27. 27 WADA. 2016, Assessment of abalone stocks in Western Zone, Victoria: Submission to the TAC setting process for 2017 November 2016. WADA.
  28. 28 Tarbath D, Mundy C. 2015, Tasmanian Abalone Fishery Assessment 2014. Institute for Marine and Antarctic Science, University of Tasmania .
  29. 29 Tarbath D, Mundy C. 2004, Tasmanian Abalone Fishery 2003. Tasmanian Aquaculture and Fisherieis Institute .
  30. 30 Tarbath D, Gardner C. 2011, Tasmanian Abalone Fishery Assessment 2010. Tasmanian Aquaculture and Fisheries Institute .
  31. 31 Jones C H. J. Tarbath D. Gardner. 2014, Could harvest from abalone stocks be increased through better management of the size limit/quota interaction? Australian Seafood Cooperative Research Centre, Institute for Marine and Antarctic Studies, University of Tasmania .
  32. 32 Ferguson G, Mayfield S. 2016, Status of the Southern Zone blacklip (Haliotis rubra) and greenlip (H. laevigata) abalone fisheries in 2014/15. Report for PIRSA Fisheries and Aquaculture. 2016.
  33. 33 Lyle JM, Tracey SR. 2016, Tasmanian Recreational Rock Lobster and Abalone Fisheries: 2014-2015 Fishing Season. 2016. .
  34. 34 Jenkins GP. 2004, The ecosystem effects of abalone fishing: a review. Marine and Freshwater Research 2004; 55: 545–552.
  35. 35 Valentine JP, Tarbath DB, Frusher SD, Mundy CN, Buxton CD. 2010, Limited evidence for ecosystem-level change on reefs exposed to Haliotis rubra (“blacklip abalone”) exploitation. Austral Ecology 2010; 35: 806–817. .
  36. 36 Hamer PA, Jenkins G, Womersley BA, Mills KA. 2010, Understanding the ecological role of abalone in the reef ecosystem of Victoria. Final report to Fisheries Research and Development Corporation. Project No. 2006/040. 2010. .
  37. 37 Ridgway KR. 2007, Long-term trend and decadal variability of the southward penetration of the East Australian Current. Geophysical Research Letters 2007; 34. .
  38. 38 Johnson CR, Banks SC, Barrett NS, Cazassus F, Dunstan PK, Edgar GJ et al. 2011, Climate change cascades: Shifts in oceanography, species’ ranges and subtidal marine community dynamics in eastern Tasmania. Journal of Experimental Marine Biology and Ecology 2011; 400: 17–32. .
  39. 39 Ling SD, C.R. J, K. R, Hobday A, Haddon M. 2009, Climate-driven range extension of a sea urchin: inferring future trends by analysis of recent population dynamics. Global Change Biology 2009; 15: 719–731. .
  40. 40 Strain EMA, Johnson CR. 2009, Competition between an invasive urchin and commercially fished abalone: effect on body condition, reproduction and survivorship. Mar Ecol Prog Ser 2009; 377: 169–182.

Archived reports

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