Table 1: Stock status determination for Eastern Rocklobster
Jurisdiction |
New South Wales |
Stock |
NSWRLF |
Stock status |
|
Sustainable |
Indicators |
Biomass, CPUE, catch |
CPUE = catch per unit effort; NSWRLF = New South Wales Rock Lobster Fishery
Eastern Rocklobster (Sagmariasus verreauxi; formerly Jasus verreauxi) occurs on rocky reef and sand/mud substrates in depths of less than a metre to about 200 m, from southern Queensland to Port MacDonnell in South Australia, including around Tasmania. The greatest abundances and the only significant catches occur along the New South Wales coast, where Eastern Rocklobsters are taken by commercial and recreational fishers1–2. The species also occurs off New Zealand, predominantly around the North Island3. Genetic studies have shown that the stocks off Australia and New Zealand are discrete biological populations4–5.
Since stock delineation is known for this species, status is reported at the level of individual biological stock.
New South Wales Rock Lobster Fishery biological stock
The sustainability of the Eastern Rocklobster resource was of concern in the early 1990s. In response, management initiatives were introduced, including a maximum legal length, individually numbered management tags, share management and a total allowable commercial catch (TACC)6–7. Stock abundance has responded positively to these initiatives. The annual TACC and associated commercial catch has effectively been taken (>95 per cent caught) each year since 2004–05 and both have been increasing during this period. In the 2010–11 fishing season, 129 tonnes (t) of catch was recorded, marginally below the 2010–11 TACC of 131 t. Based on a prospective risk analysis of the consequences of alternative future catches, TACCs are set annually to maintain the spawning biomass above the biological reference point of 25 per cent of unfished biomass. The current level of fishing mortality is unlikely to cause the biological stock to become recruitment overfished.
Catch per unit effort (CPUE) has been increasing since a low point in the early 1990s, and abundance of spawning stock has been increasing since the late 1990s1. The base-case scenario of the most recent assessment1 estimates that spawning biomass at the beginning of the 2010–11 season was 26 per cent (90% confidence interval 20–37 per cent) of the unfished (1884–85) level, having more than doubled since 1994–95. The biological stock is not considered recruitment overfished.
On the basis of the evidence provided above, the biological stock is classified as a sustainable stock.
Table 2: Eastern Rocklobster biology2,8–9
Longevity and maximum size |
30+ years; 26 cm CL |
Maturity (50%) |
Females: 16.7 cm CL |
CL = carapace length
Figure 1: Distribution of reported commercial catch of Eastern Rocklobster in Australian waters, 2010
- Commercial catch of Eastern Rocklobster is predominantly taken using traps (approximately 99 per cent of catch). The remainder of catch is taken while free diving.
- A range of input and output controls are in place across the New South Wales Rock Lobster Fishery:
- Input controls include spatial closures throughout sanctuary zones in marine parks and aquatic reserves, restrictions on the size and design of traps, and restriction of recreational fishers to a single trap.
- Output controls include TACCs, individual transferable quotas, minimum (10.4 cm carapace length [CL]) and maximum (18 cm CL) legal lengths, bans on the take of berried females and a possession limit of two lobsters for recreational fishers.
- In 2010, there were 9727 shares in the fishery, and the commercial catch of Eastern Rocklobster was reported from 107 shareholders (representing approximately 107 vessels).
- The total reported commercial catch of Eastern Rocklobster in Australia in 2010–11 was 129 t. Recent modelling has assumed that the unreported catch by commercial fishers is 8.5–17 per cent of the TACC, and that recreational catch is 10–19 per cent of the TACC.
a)
b)
Figure 2: (a) Commercial catch of Eastern Rocklobster in New South Wales, 1950–51 to 2010–11 (financial year);
(b) percentage of unfished biomass, 1950–51 to 2010–11 (financial year) (median estimates from base-case of length-structured model, 2011 assessment)
Reported commercial catches have declined since a historical high in 1950–51. Commercial catches have been constrained by a TACC only since 1994–95 (Figure 2a). Decreases in the reported commercial catch before the mid-1990s were accompanied by decreasing CPUE, and decreasing model-based estimates of exploitable biomass and spawning biomass (Figure 2b), which indicated decreasing abundance of rocklobsters during this period. Since major management interventions in the early and mid-1990s, including the introduction of a system of TACCs and individual transferrable quotas, maximum legal lengths and management tags, commercial catch has remained steady, with slight increases in recent years.
- Bycatch from the commercial fishery is minimal, and fishing with traps results in limited physical disturbance of benthic habitats.
- Loss of traps in the deepwater component of the fishery, due to cut-off by other vessels, results in some mortality of rocklobsters from ghost fishing. This mortality is the subject of current research (funded by the Fisheries Research and Development Corporation) and is being mitigated using sacrificial panels in traps and acoustic release technology to provide ‘at call’ access to submerged headgear.
- Physical impacts of fish and prawn trawling on benthic areas inhabited by rocklobsters (in particular, low-relief reefs on the mid-continental shelf ) may have negative effects on the rocklobster population and subsequent catches at affected locations.
- Changes in water temperature and the spatial and temporal behaviour of the East Australian Current, as a result of climate change, could potentially affect the distribution of spawning stock, larval dispersal, and the strength and distribution of recruitment of peuruli. This will influence the distribution and abundance of juvenile rocklobsters recruiting to the fishable stock, and subsequently spatial and temporal patterns of catch in the fishery.
a Department of Primary Industries, New South Wales