Table 1: Stock status determination for Banded Morwong
Jurisdiction |
Tasmania |
Victoria |
Stock |
TBMF |
VBMF |
Stock status |
↓ |
|
Transitional–depleting |
Undefined |
Indicators |
Catch, effort, CPUE trends, size/age composition |
Catch, CPUE |
CPUE = catch per unit effort; TBMF = Tasmanian Banded Morwong Fishery; VBMF = Victorian Banded Morwong Fishery
Banded Morwong is large temperate reef fish species that is targeted by gillnets for the domestic live fish trade. The species is distributed around south-eastern Australia, including southern New South Wales, and eastern Victoria and Tasmania, as well as occurring off north-eastern New Zealand. It is relatively common in depths of less than 50 m. There is currently no information available regarding the biological stock structure. However, once settled after a relatively long oceanic larval phase, they show a high degree of site fidelity1–3, suggesting that the exploited Victorian and Tasmanian populations are likely to represent distinct populations. Banded Morwong has therefore been assessed at the management unit level.
Tasmanian Banded Morwong Fishery management unit
The most recent assessment4 estimates that biomass in 2012–13 was 31 per cent (east coast region) to 44 per cent (south-east coast region) of the unfished (1990) level. Mature biomass has declined steadily since the early 2000s, although the stock is not considered to be recruitment overfished. If fishing pressure was to be kept at historic levels it is likely that this would cause the stock to become recruitment overfished. As a result reductions in catch quotas have been progressively applied4 to halt the biomass decline, but these reductions have not yet been successful. The above evidence indicates that 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.
Victorian Banded Morwong Fishery management unit
The most recent assessment (undertaken in 2012) has not been published because of the limited number of operators and concerns about confidentiality. This work examined catch data from 2002 to 2012 and concluded that there was a clear downward trend in biomass since the mid-2000s. The standardised catch per unit effort may have fallen by up to 48 per cent from the peak. However, data from only two operators contributes to high levels of uncertainty. The total catch is currently less than 2 tonnes per year (catches are now limited to 625 fish per operator); some fish are also landed as byproduct from the Victorian Ocean Fishery. Insufficient information is available to confidently classify the status of this stock.
On the basis of the evidence provided above, the management unit is classified as an undefined stock.
Table 2: Banded Morwong biology5,6
Longevity and maximum size |
96 years; 578 mm FLa |
Maturity (50%) |
2.5 years; 320 mm FL |
FL = fork length
a Maximum length is the maximum recorded from >2300 fish measured during on-board observation and research fishing 7.
Figure 1: Distribution of reported commercial catch of Banded Morwong in Australian waters, 2013 (calendar year)
Table 3: Main features and statistics for Banded Morwong fisheries in Australia, 2013 (calendar year)
Jurisdiction |
Tasmania |
Victoria |
Fishing methods |
Commercial |
Gillnet |
✓ |
✓ |
Recreational |
Gillnet |
✓ |
|
Diving (spearfishing) |
✓ |
✓ |
Indigenousa |
|
None |
|
Management methods |
Commercial |
Limited entry |
✓ |
✓ |
Size limits |
✓
(lower and upper) |
✓ |
Gear restrictions |
✓ |
✓ |
Total allowable catch |
✓ |
✓ |
Effort limits |
✓ |
✓ |
Spatial closures |
|
✓ |
Seasonal closures |
✓ |
✓ |
Recreational |
Bag limits |
✓ |
✓ |
Size limits |
✓
(lower and upper) |
✓ |
Seasonal closures |
✓ |
✓ |
Indigenousa |
Customary fishing permits |
|
✓ |
Active vessels |
|
27 in TBMF |
2 in VBMF |
Catch |
Commercial |
40.1 t in TBMF |
Confidentialb |
Recreational |
1.6 t (2010) |
Unknown |
Indigenous |
Nil |
Nil |
Markets |
Domestic |
✓ |
✓ |
Export |
|
|
TSF = Tasmanian Banded Morwong Fishery; VBMF = Victorian Banded Morwong 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 Banded Morwong.
bData cannot be reported due to confidentiality clauses when fewer than five fishers are operating within a given fishery.
Figure 2: Commercial catch of Banded Morwong in Tasmanian waters, 1995 to 2013 (calendar years)
Note: Victorian catch could not be provided because of confidentiality clauses when fewer than five fishers are operating within a given fishery.
Banded Morwong are solely targeted by fishers using large mesh gillnets. Nearly 100 species are taken as bycatch or byproduct, including threatened, endangered and protected species that include seabirds, marine mammals and sygnathids (seahorses and pipefishes), albeit in very low quantities7.
The fish bycatch is dominated by four species: Draughtboard Shark (Cephaloscyllium laticeps), Marblefish (Aplodactylus arctidens), Bluethroat Wrasse (Notolabrus tetricus) and Longsnout Boarfish (Pentaceropsis recurvirostris). All but one of these (Bluethroat Wrasse) display high post-release survival7.
When targeting Banded Morwong, gillnets occasionally interact with sessile invertebrates, typically sea tulips (Pyura spp.) and macro-algae, although such interactions very rarely result in entire organisms being dislodged7.
The impact of environmental factors on Banded Morwong stocks is unknown. However, there is evidence that ocean warming is affecting growth at the northern extreme of the distribution8. Banded Morwong have a 6–9‑month oceanic larval phase, and there is potential for changing oceanographic patterns to lead to increased variability in recruitment success. Since the Tasmanian fishery is now heavily reliant on newly recruited fish4, and hence recruitment success, this will need to be monitored closely. Further, the formation of reef barrens due to algal grazing by the Long-spined Sea Urchin (Centrostephanus rodgersii) in both Victorian and Tasmanian waters, a phenomenon that is linked to climate change9, represents a potential threat for Banded Morwong populations through the reduction of suitable reef habitat.
a Institute for Marine and Antarctic Studies, University of Tasmania
b Department of Environment and Primary Industries, Victoria