Greenlip Abalone Haliotis laevigata

Stephen Mayfielda, Craig Mundyb, Anthony Hartc and Harry Gorfined
Greenlip Abalone

Table 1: Stock status determination for Greenlip Abalone

Jurisdiction

South Australia

Tasmania

Stock

SAWZF

SACZF

SASZF

TGAF

Stock status

 

Negligiblea

Sustainable

Transitional–depleting

Undefined

Indicators

CPUE, fishery-independent surveys

CPUE, fishery-independent surveys

Catch


CPUE = catch per unit effort; SACZF = South Australian Central Zone Fishery; SASZF = South Australian Southern Zone Fishery; SAWZF = South Australian Western Zone Fishery; TGAF = Tasmanian Greenlip Abalone Fishery

a 'Negligible' means historically low catch; no stock status. Catch from the Southern Zone Fishery biological stock in 2013 was 5.24 tonnes. In the past 10 years, the average catch from this biological stock was 5.5 tonnes.

 

Table 1 continued

Jurisdiction

Victoria

Western Australia

Stock

VWZF

VCZF

WAA2F

WAA3F

Stock status

Overfished

Overfished

Sustainable

Sustainable

Indicators

Catch

Catch

Catch, CPUE, catch length-frequency data, fishery-independent surveys

Catch, CPUE, catch length-frequency data, fishery-independent surveys


CPUE = catch per unit effort; VCZF = Victorian Central Zone Fishery; VWZF = Victorian Western Zone Fishery; WAA2F = Western Australia Area 2 Fishery; WAA3F = Western Australia Area 3 Fishery


Stock Structure

Greenlip Abalone is distributed across southern mainland Australia and northern Tasmania. The biological stock structure of Greenlip Abalone has recently been examined1,2. Genetic evidence has confirmed that Greenlip Abalone comprise numerous independent biological stocks, but at a spatially broader extent than the biological stock structure evident for Blacklip Abalone3. There are many biological stocks across Tasmania, Victoria, South Australia and Western Australia. Given the large number of biological stocks, it is not practical to assess each separately. Instead, status for Greenlip Abalone is reported at the management unit level: the South Australian Western Zone Fishery management unit, the South Australian Central Zone Fishery management unit, the South Australian Southern Zone Fishery management unit, the Tasmanian Greenlip Abalone Fishery management unit, the Victorian Central Zone Fishery management unit, the Victorian Western Zone Fishery management unit, the Western Australia Area 2 Fishery management unit and the Western Australia Area 3 Fishery management unit. Greenlip Abalone catches from the South Australian Southern Zone Fishery management unit are negligible and, consequently, stock status is not assessed.


Stock Status

Undertaking assessments of abalone stock status is complicated by several factors, including:

  • the high number of biological stocks, each at a different level of depletion
  • changes to management unit boundaries and size limits
  • absence of a performance indicator and reference points above or below which the fishery would be defined as sustainable or recruitment overfished, respectively
  • changes in fishing power, which impede comparisons of current and historical catch per unit effort (CPUE)
  • the multitude of factors that affect the effort component of CPUE
  • the degree to which CPUE reflects abalone abundance.

Assessment of stock status also varies among jurisdictions and management units.

The harvest strategy in the Management plan for the South Australian Commercial Abalone Fishery4 includes a catch-weighted determination of stock status for the fishing zone. However, the harvest strategy does not identify a performance indicator or a reference point below which the fishery would be defined as recruitment overfished. In addition, several weaknesses in the harvest strategy result in more optimistic assessments of stock status than those from more traditional weight-of-evidence methods5,6. Consequently, in this assessment, commercial catch rates (CPUE; kilograms of meat per hour) are used as indices of relative Greenlip Abalone abundance. This measure can, however, provide a more optimistic index of relative abundance than measures from fishery-independent surveys, because catch rates in dive fisheries can be hyperstable5–9. Decreases in CPUE in abalone fisheries are considered to be a reliable indicator of declines in abalone abundance, but can underestimate the magnitude of the reduction 5,6,9.

The Victorian abalone fishery management plan10 also does not identify a performance indicator or a reference point below which the fishery would be defined as recruitment overfished. In the absence of this key performance indicator, catch history and historical surveys are used to make inferences about stock status.

Catches in the Western Australia Area 2 and Area 3 abalone fisheries are controlled by a total allowable commercial catch (TACC), set by a harvest control rule that uses standardised CPUE as the key performance indicator11 against specified limit, threshold and target reference points. The fishery is defined as recruitment overfished if the standardised CPUE is below the limit reference point.

In Tasmania, commercial catch history and diver observations are used to inform stock status.

 

South Australian Western Zone Fishery management unit

The CPUE for Greenlip Abalone in the South Australian Western Zone fishery management unit was relatively stable between 1983 and 1996. It then increased rapidly, reaching a peak in 2003. Since 2003, CPUE has decreased each year. In 2013, it was 22 per cent below the 2003 peak and at the lowest level since 1998. Despite these decreases, CPUE across the zone and in many fishing grounds remains above that observed through the 1990s, which preceded a substantial increase in abundance occurring in at least the Western and Central zones of South Australia, from 2000. In addition, fishery-independent survey densities at long-term sites are similar to those in the 1990s, the legal minimum length of 14.5 cm allows several years of spawning to occur before recruitment to the fishery, and large Greenlip Abalone continue to dominate the catch5. The stock is unlikely to be recruitment overfished and, based on the current CPUE, the level of fishing pressure is unlikely to cause the stock to become recruitment overfished. However, the recent decreases in CPUE and redistribution of catch from traditional Greenlip Abalone to traditional Blacklip Abalone fishing grounds will be carefully monitored to ensure timely responses to any change in stock status.

On the basis of the evidence provided above, the management unit is classified as a sustainable stock.

 

South Australian Central Zone Fishery management unit

The CPUE for Greenlip Abalone in the South Australian Central Zone Fishery management unit was stable from 1979 to 1998. CPUE increased substantially from 1999 to 2001, when it reached its peak. Since 2002, CPUE has declined steadily, with the overall decline being 21 per cent over a 12-year period. The latest fishery-independent survey densities at Tiparra Reef, historically the key fishing ground, were also low relative to previous years6. As the TACC has remained unchanged, there has also been a large redistribution of catch from Tiparra Reef to other fishing grounds. For several of these grounds, catches and/or catch rates have not been sustained. The stock is not yet considered to be in a recruitment overfished state because CPUE remains above that in the mid-1990s, prior to a large increase in abundance, and the legal minimum length of 13.5 cm allows several years of spawning to occur before recruitment to the fishery. However, the current level of fishing pressure is likely to cause the stock to become recruitment overfished.

On the basis of the evidence provided above, the management unit is classified as a transitional–depleting stock.

 

Tasmanian Greenlip Abalone Fishery management unit

The reporting of effort against a combined harvest of Greenlip Abalone and Blacklip Abalone in the Tasmanian Greenlip Abalone Fishery management unit makes interpretation of CPUE as a proxy for Greenlip Abalone abundance problematic. Use of CPUE is also confounded by changes in fishery selectivity due to changes in the market, and variable approaches to Greenlip Abalone harvest by divers, which vary spatially. For example, fishers in some areas specifically target Greenlip Abalone, whereas in other areas Greenlip Abalone is taken as bycatch while targeting Blacklip Abalone. A high reliance on diver observations and commercial catch history is necessary for setting of annual TACCs, but there is insufficient information to confidently classify status 9.

On the basis of the evidence provided above, the management unit is classified as an undefined stock.

 

Victorian Western Zone Fishery management unit

Population abundance and size structure estimates from data collected during the late 1980s and 1990s indicated that the stock was small and mostly concentrated in Portland Bay12. Surveys conducted almost a decade later showed potential for a limited fishery on Julia Bank13, as well as Minerva and Hospital Reefs14. Prior to 2006–07, reported catches were limited and Greenlip and Blacklip Abalone were allocated as a combined TACC with an average annual catch of 100 kg during 2001–05. A separate Greenlip Abalone TACC of 4.2 tonnes (t) was set for the 2006–07 quota-year (1st Apr–31st Mar) and maintained for the next two years. Following a reduction in Blacklip Abalone catches due to the occurrence of Abalone viral ganglioneuritis during 2006–07 and in response to an analysis of Greenlip Abalone sampling from Minerva and Hospital reefs14, the TACC was increased to 16 t for 2009–10 resulting in an annual catch of 18.9 t in the 2010 calendar year and an average catch of 14.8 t during 2009–2011 . These catches were not sustained, with the TACC falling by 50 per cent between 2011 and 2012. The TACC was subsequently set at zero in 201315, reflecting the highly depleted status of Greenlip Abalone stocks in the Western Zone. The above evidence indicates that the stock is likely to be recruitment overfished. While current fishing pressure is constrained by management to a level that may allow the stock to recover from its recruitment overfished state, measurable improvements are yet to be detected.

On the basis of the evidence provided above, the management unit is classified as an overfished stock.

 

Victorian Central Zone Fishery management unit

Greenlip Abalone continues to comprise a small component of the commercial abalone catch in the Victorian central zone fishery management unit. A study in 1996 concluded that the resource had failed to recover from overfishing during the 1960s and 1970s, despite modest catches during ensuing decades 12. The TACC has remained unchanged at 3.4 t since 200915, and annual catches have been below this amount. The above evidence indicates that the stock is likely to be recruitment overfished and that levels of current fishing pressure are expected to prevent the stock recovering from a recruitment overfished state.

On the basis of the evidence provided above, the management unit is classified as an overfished stock.

 

Western Australia Area 2 Fishery management unit

Standardised CPUE has been relatively stable in the Western Australia Area 2 Fishery since 2004 and, in 2013, was above the threshold reference point. Additional data, including length-frequency distributions from catch sampling and fishery-independent surveys, validate the standardised CPUE trend. The fishery has a legal minimum length of 14 cm, which allows 2–5 years of spawning to occur before recruitment to the fishery. Overall, the evidence indicates that Greenlip Abalone stocks in Area 2 are unlikely to be recruitment overfished and that the current level of fishing mortality is unlikely to cause these biological stocks to become recruitment overfished11.

On the basis of the evidence provided above, the management unit is classified as a sustainable stock.

 

Western Australia Area 3 Fishery management unit

 

Standardised CPUE was relatively stable in the Western Australia Area 3 Fishery between 2004 and 2011, but declined to below the threshold reference point (10.98 kg/hour) between 2011 and 2013 (10.5 kg/hour). Additional data, including length-frequency distributions from catch sampling and fishery-independent surveys, validate the standardised CPUE trend. These triggered a 10 per cent TACC reduction for 2014, as required by the harvest control rule 11,16. If stocks continue on this trajectory, a larger TACC cut, of at least 30 per cent, will be initiated within 2 years. In addition, the fishery has a legal minimum length of 14 cm, which allows 2–5 years of spawning to occur before recruitment to the fishery. Overall, the evidence indicates that Greenlip Abalone stocks in Area 3 are unlikely to be recruitment overfished and that the reductions under the harvest control rule mean that it is unlikely that the stock will become recruitment overfished.

On the basis of the evidence provided above, the management unit is classified as a sustainable stock.


Table 2: Greenlip Abalone biology5,6

Longevity and maximum size

20 years; 200 mm SL

Maturity (50%)

4–5 years; 75–120 mm SL

SL = shell length


Greenlip Abalone distribution map

Figure 1: Distribution of reported commercial catch of Greenlip Abalone in Australian waters, 2013 (calendar year)




Table 3: Main features and statistics for Greenlip Abalone fisheries in Australia, 2013 (calendar year)

Jurisdiction

South Australia

Tasmania

Victoria

Western Australia

Fishing methods

Commercial

Diving

Recreational

Diving

Indigenous

Diving

Management methods

Commercial

Limited entry

Size limits

Total allowable catch

Recreational

Bag limits

Size limits

Indigenousa,b

Bag limits

Size limits

Active vessels

 

6 in SACZF

23 in SAWZF

121 in TGF

16 in VCZF

0 in VWZF

6 in WAA2F

7 in WAA3F

Catch

Commercial

143 t in SACZF

217 t in SAWZF

140 t in TGF

1 t in VCZF

0 t in VWZF

75 t in WAA2F

91 t in WAA3F

Recreational

Unknown

Unknown

Unknown

8 t

Indigenousa,b

Unknown

Unknown

0 t

Unknown

Markets

Domestic

Export


SACZF = South Australian Central Zone Fishery; SAWZF = South Australian Western Zone Fishery; TGF = Tasmanian Greenlip Abalone Fishery; VCZF = Victorian Central Zone Fishery; VWZF = Victorian Western Zone Fishery; WAA2F = Western Australia Area 2 Fishery; WAA3F = Western Australia Area 3 Fishery

a In Victoria, regulations for managing recreational fishing are also applied to fishing activities by Indigenous people. Recognised Traditional Owners (groups that hold native title or have agreements under the Victorian Traditional Owner Settlement Act 2010) are exempt (subject to conditions) from the requirement to hold a recreational fishing licence, and can apply for permits under the Fisheries Act 1995 that authorise customary fishing (e.g. different catch and size limits, or equipment). The Indigenous category in Table 3 refers to customary fishing undertaken by recognised Traditional Owners. In 2012–13, there were no applications for customary fishing permits to access Greenlip Abalone.

b Subject to the defence that applies under section 211 of the Native Title Act 1993, and the exemption from a requirement to hold a recreational fishing licence, the non-commercial take by indigenous fishers is covered by the same arrangements as that for recreational fishing.


Commercial catch of Greenlip Abalone in Australian waters, 1970–2010 (calendar year)

Figure 2: Commercial catch of Greenlip Abalone in Australian waters, 1980 to 2013 (calendar years)




Effects of fishing on the marine environment
  • Because Greenlip Abalone is hand selected by commercial divers operating from vessels that seldom anchor, the fishery has limited direct physical impact on the environment. There is also substantial evidence that the ecosystem effects of removing abalone are minimal17–19. All fisheries have export certification under the Environment Protection and Biodiversity Conservation Act 1999.


Environmental effects on Greenlip Abalone
  • Southward and westward strengthening of the warm East Australian Current into the relatively cold inshore waters in Tasmania has changed near-shore community structure and productivity, primarily through expansion of the range of the urchin Centrostephanus rodgersii from New South Wales to Tasmania20–22. This has resulted in localised depletions of abalone populations and a reduction in the habitat available for abalone23,24.



a South Australian Research and Development Institute
b Institute for Marine and Antarctic Studies, Tasmania
c Department of Fisheries, Western Australia 
d Department of Environment and Primary Industries, Victoria