Table 1: Stock status determination for Crimson Snapper
Jurisdiction |
Northern Territory, Queensland |
Queensland |
Western Australia |
Stock |
Northern Australian
(DF, FTF, GOCDFFTF, GOCLF, TRF) |
East coast Queensland
(CRFFF, DWFFF) |
North West Shelf
(NDSF, PDSF) |
Stock status |
|
|
|
Undefined |
Undefined |
Sustainable |
Indicators |
Catch, trigger reference points, length frequencies, performance indicators |
Catch, performance indicators |
Catch, CPUE |
CPUE = catch per unit effort; CRFFF = Coral Reef Fin Fish Fishery (Queensland); DF = Demersal Fishery (Northern Territory); DWFFF = Deep Water Fin Fish Fishery (Queensland); FTF = Finfish Trawl Fishery (Northern Territory); GOCDFFTF = Gulf of Carpentaria Developmental Fin Fish Trawl Fishery (Queensland); GOCLF = Gulf of Carpentaria Line Fishery (Queensland); NDSF = Northern Demersal Scalefish Fishery (Western Australia); PDSF = Pilbara Demersal Scalefish Fisheries (Western Australia); TRF = Timor Reef Fishery (Northern Territory)
Crimson Snapper is a widespread Indo–Pacific species found throughout tropical Australian waters. Research on the biological stock structure of this species has only occurred in northern Australian waters, including the Timor Sea, the Arafura Sea and the Gulf of Carpentaria1. A single genetic stock was found across this region. It is believed that the species has a similar biological stock structure to Saddletail Snapper (Lutjanus malibaricus)—that is, a North West Shelf biological stock and a biological stock off the east coast of Queensland, in addition to the northern Australian biological stock.
Northern Australian biological stock
This cross-jurisdictional biological stock has components in the Northern Territory and Queensland. Each jurisdiction assesses that part of the biological stock that occurs in its waters. Status presented here for the entire biological stock has been established using evidence from both jurisdictions.
The Northern Territory manages the commercial harvest of Crimson Snapper and Saddletail Snapper together, as red snapper. For the Northern Territory part of the biological stock, the most recent assessment2 estimated that the biomass of the red snapper group in 1990 was 24 000 tonnes (t). This estimate took into account high fishing pressure from foreign fleets, which peaked at 4200 t in 1989. Stock reduction analysis in 1996 indicated that, for the biological stock to be
reduced to 24 000 t in 1990, the unfished biomass would have been approximately 50 000 t. Hence, biomass in 1990 was estimated to be 45–50 per cent of the unfished level.
Licensed activity by foreign fleets in northern Australian waters ceased in 1991, and total commercial catch in the Northern Territory decreased substantially between 1991 and 1995 (to less than 100 t annually). Over the past 15 years (1995–2010), the commercial Northern Territory Crimson Snapper catch has not exceeded 350 t annually and has averaged around 22 per cent of the commercial red snapper catch. In 2010, the total commercial catch of Crimson Snapper was 275 t. The most recent estimate of annual sustainable yield for Crimson Snapper is 850 t2–3.
It is assumed that further reductions in biomass since this time are unlikely because of the reduced effort since 1990. Hence, the Northern Territory part of the biological stock is not considered to be recruitment overfished, and fishing mortality is unlikely to cause this part of the biological stock to become recruitment overfished.
For the Queensland part of the biological stock, commercial catch in 2010 was 279 t. Since no information is available on biomass, insufficient information is available to confidently classify the status of this part of the biological stock.
As a result of the uncertainty in the Queensland part of the biological stock, and the fact that the total catch in Queensland was higher than in the Northern Territory, the entire biological stock is classified as an undefined stock.
East coast Queensland biological stock
Since the quota management system was introduced in 2004, commercial harvest has increased from less than 1 t in 2005 to around 20 t per year since 2008. Current biological information is unavailable, and no stock assessment has been completed. Insufficient information is available to confidently classify the status of this biological stock; as a result, the biological stock is classified as an undefined stock.
North West Shelf biological stock
Crimson Snapper is exploited primarily on the north-west coast of Western Australia as a component of the Pilbara Demersal Scalefish Fisheries (Western Australia) and Northern Demersal Scalefish Fishery (Western Australia)4. Crimson Snapper is assessed on the basis of the status
of several indicator species (e.g. Red Emperor, Lutjanus sebae) that represent the entire inshore demersal suite of species (occurring at depths of 30–250 m). The major performance measures for these indicator species relate to spawning stock levels. The target level of spawning biomass is 40 per cent of the unfished level, and the limit level is 30 per cent of the unfished level. Data analysis using an integrated age-structured model determined that the spawning biomass levels of the indicator species were greater than 40 per cent of the unfished level in the Pilbara Demersal Scalefish Fisheries (Western Australia) and the Northern Demersal Scalefish Fishery (Western Australia) in 20075. The Crimson Snapper biological stock is not considered to be recruitment overfished.
Fishing mortality (F)–based assessments5 indicated that the fishing levels on the indicator
species were either lower than the target level, or between the target and threshold levels. These assessments use reference levels that are based on ratios of natural mortality (M) for each species, such that Ftarget = 2/3M, Fthreshold = M and Flimit = 3/2M. This level of fishing mortality is unlikely to cause the biological stock to become recruitment overfished.
On the basis of the evidence provided above, the biological stock is classified as a sustainable stock.
Table 2: Crimson Snapper biology6–7
Longevity and maximum size |
42 years; 47 cm SL |
Maturity (50%) |
Males: 27–28 cm SL Females: 35–37 cm SL |
SL = standard length
Figure 1: Distribution of reported commercial catch of Crimson Snapper in Australian waters, 2010
- Crimson Snapper is fished commercially using baited traps, handlines, droplines, trot lines and semipelagic otter trawls for fish. In the recreational and charter sectors, Crimson Snapper is primarily taken on rod and reel using bait or artificial lures.
- Management measures for Crimson Snapper fisheries in Australia include a range of input and output controls:
- Input controls include limited entry, gear restrictions, temporal and spatial closures, and effort restrictions.
- Output controls include total allowable catches (commercial); individual transferable quotas;
and size, bag and possession limits (recreational).
- The numbers of commercial vessels reporting catch of Crimson Snapper in 2010 were 15 in the Northern Territory, 95 on the Queensland east coast (Coral Reef Fin Fish Fishery and Deep Water Fin Fish Fishery), 3 in the Queensland Gulf of Carpentaria and 20 in Western Australia.
- The total commercial catch of Crimson Snapper in Australia in 2010 was 770 t, comprising 275 t in the Northern Territory, 20 t on the Queensland east coast, 279 t in the Queensland Gulf of Carpentaria and 196 t in Western Australia.
- The total amount of Crimson Snapper caught in the charter sector was 8.2 t, comprising 0.5 t in the Northern Territory, 2 t on the Queensland east coast and 5.7 t in Western Australia. The charter catch was negligible (<100 kg) in the Gulf of Carpentaria Line Fishery (Queensland).
- No data are available for the 2010 recreational catch for the three biological stocks. The most recent recreational survey estimated Queensland recreational catch to be approximately 124 000 individual nannygaia,9. No breakdown was available between the Saddletail and Crimson Snapper (large and small mouth nannygai). Indigenous catch across all biological stocks was considered to be negligible.
- The impact of illegal, unreported and unregulated (IUU) fishing in northern Australian waters, primarily by foreign fishers, remains uncertain. However, since 2007, increased surveillance across the north of Australia has resulted in a substantial reduction in the number of foreign fishing vessels accessing Australian waters. The scale and magnitude of IUU fishing, and thus its contribution to exploitation status or recovery of fish populations and ecosystems, are not known; this is an area of uncertainty in stock assessments.
Figure 2: Commercial catch of Crimson Snapper in Australian waters, 2000–10 (calendar year)
Note: Queensland catch is for the financial year, with data for 2009–10 plotted against 2010.
The commercial catch of Crimson Snapper in the northern Australian biological stock steadily increased from around 200 t in 2000 to a peak of 664 t in 2008. The majority of this increase was
a result of the Queensland-managed sector of the Gulf of Carpentaria, where harvests grew from around 3 per cent of the total northern Australian catch in 2000 to 50 per cent in 2010. In 2009, a record 342 t of Crimson Snapper was reported in the Gulf of Carpentaria Developmental Fin Fish Trawl Fishery (Queensland). There was a significant decrease in catch in the Gulf of Carpentaria Line Fishery (Queensland), from 11.5 t in 2007 to 1.4 t in 2009.
The catch of the east coast Queensland biological stock peaked at around 30 t in 2001–02, and then decreased steadily to 1 t in 2005. It remained low until 2007, when it began to increase again. This may have been the result of changes to reporting requirements. In 2007, a new logbook was introduced to the Coral Reef Fin Fish Fishery (Queensland), and reporting of 'nannygai-unspecified'
dropped from 18 t in 2006–07 to less than 100 kg in 2009–10. By 2010, reported catches of Crimson Snapper had increased to 20 t.
The catch of Crimson Snapper in the North West Shelf biological stock has been stable, in the range of 180–205 t, over the past three years (2008–10), despite variation in effort allocation levels across multiple fisheries.
- Beyond the removal of fish, there is little evidence to suggest that the fisheries targeting Crimson
Snapper impact significantly on benthic or pelagic ecological communities in the area as a whole.
- Climate change and variability have the potential to impact fish stocks in a range of ways, including geographic distribution (e.g. latitudinal shifts in distribution). However, it is unclear how climate change may affect risks to sustainability.
- Changes in ocean chemistry have the potential to affect the replenishment rates of fish populations9, as well as individual growth rates and spawning output10.
a Department of Primary Industry and Fisheries, Northern Territory
b Department of Agriculture, Fisheries and Forestry, Queensland
c Department of Fisheries, Western Australia
a+ In Queensland, Saddletail Snapper and Crimson Snapper are often referred to as nannygai.