Table 1: Stock status determination for Redthroat Emperor
Jurisdiction |
Queensland |
Western Australia |
Stock |
East coast Queensland
(CRFFF) |
West Australian (GDSMF, WCDSIMF) |
Stock status |
|
|
Sustainable |
Undefined |
Indicators |
Catch, CPUE, stock assessment |
Catch |
CPUE = catch per unit effort; CRFFF = Coral Reef Fin Fish Fishery (Queensland); GDSMF = Gascoyne Demersal Scalefish Managed Fishery (Western Australia); WCDSIMF = West Coast Demersal Scalefish (Interim) Managed Fishery (Western Australia)
Genetic analysis indicates that there are two separate biological stocks of Redthroat Emperor in western and eastern Australian waters1. Reporting of stock status is at the biological stock level.
East coast Queensland biological stock
The most recent assessment (2006) of the east coast Queensland biological stock2 of Redthroat Emperor analysed fishery data using an age-structured model that incorporated all available information on catch, catch per unit effort and age structure. The model estimated that biomass in 2004 was approximately 70 per cent of the unfished (1946) level. The maximum sustainable yield was estimated to be in the range of 760–964 tonnes (t) per year. Since 2004–05, annual commercial catches have averaged approximately 250 t. The latest recreational estimate (for 2010) was 90 t, with the combined catch being well below the estimated maximum sustainable yield3. The biomass of the stock is therefore not recruitment overfished.
Fishing mortality over the past decade has been low compared with the maximum sustainable yield estimate, and both catches and commercial standardised catch rates have been historically stable. Although recreational fishing effort is not capped, the current level of fishing pressure is highly unlikely to cause the stock to become recruitment overfished.
On the basis of the evidence provided above, the biological stock is classified as a sustainable stock.
Western Australian biological stock
A stock assessment of Western Australian Redthroat Emperor has not yet been conducted. Commercial catches have been stable over the past 5 years, but insufficient information is available to confidently classify the status of this biological stock.
On the basis of the evidence provided above, the stock is classified as an undefined stock.
Table 2: Redthroat Emperor biology1,4,5
Longevity and maximum size |
20 years; 650 mm TL |
Maturity (50%) |
Females: 1.2 years; 280 mm FL, 310mm TL |
TL = total length
Figure 1: Distribution of reported commercial catch of Redthroat Emperor in Australian waters, 2013 (calendar year)
Note: Data for the Western Australian catch align with the 2013 calendar year, whereas data for Queensland align with the 2012–13 financial year.
Table 3: Main features and statistics for Redthroat Emperor fisheries in Australia, 2013 (calendar year)
Jurisdiction |
Queenslanda |
Western Australiab |
Fishing methods |
Commercial |
Hand line |
✓ |
✓ |
Rod and line |
✓ |
|
Fish trawl |
|
✓ |
Fish trap |
|
✓ |
Recreational |
Hand line |
✓ |
✓ |
Rod and line |
✓ |
✓ |
Spearfishing |
✓ |
✓ |
Indigenousc,d |
Hand line |
✓ |
✓ |
Rod and line |
✓ |
✓ |
Spearfishing |
✓ |
✓ |
Management methods |
Commercial |
Limited entry |
✓ |
✓ |
Gear restrictions |
✓ |
✓ |
Size limits |
✓ |
✓ |
Vessel restrictions |
✓ |
✓ |
Catch restrictions |
✓ |
✓ |
Spatial zoning |
|
✓ |
Spatial closures |
✓ |
✓ |
Temporal closures |
✓ |
|
Effort limits |
|
✓ |
Total allowable effort |
|
✓ |
Recreational |
Licensing (fishing from a boat) |
|
✓ |
Gear restrictions |
✓ |
✓ |
Size limits |
✓ |
✓ |
Catch limits |
✓ |
✓ |
Spatial closures |
✓ |
✓ |
Temporal closures |
✓ |
✓ |
Charter |
Limited entry |
✓ |
✓ |
Spatial zoning |
|
✓ |
Gear restrictions |
✓ |
✓ |
Passenger restrictions |
✓ |
✓ |
Size limits |
✓ |
✓ |
Catch limits |
✓ |
✓ |
Spatial closures |
✓ |
✓ |
Temporal closures |
✓ |
✓ |
Indigenousc,d |
Laws of general application |
|
✓ |
Active vessels |
|
163 in CRFFF |
12 in GDSMF
35 in WCDSIMF |
Catch |
Commercial |
218 t in CRFFF |
4 t in GDSMF6
44 t in WCDSIMF |
Recreational |
65 000 fish (2010)3; ~90 t |
9100 fish (2011–12); ~11 t7 |
Charter |
72 t |
2600 fish; ~3 t |
Indigenous |
Unknown |
Unknown |
Markets |
Domestic |
✓ |
✓ |
Export |
|
|
CRFFF = Coral Reef Fin Fish Fishery (Queensland); GDSMF = Gascoyne Demersal Scalefish Managed Fishery (Western Australia); WCDSIMF = West Coast Demersal Scalefish (Interim) Managed Fishery (Western Australia)
a Data for Queensland align with the 2012–13 financial year.
b Data for Western Australia align with the 2013 calendar year.
c In Queensland, under the Fisheries Act 1994 (Qld), Indigenous fishers in Queensland are able to use prescribed traditional and noncommercial fishing apparatus in waters open to fishing. Size and possession limits, and seasonal closures do not apply to Indigenous fishers. Further exemptions to fishery regulations may be applied for through permits.
d Subject to the defence that applies under section 211. of the Native Title Act 1993 (Cth), 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.
Figure 2: Commercial catch of Redthroat Emperor in Australian waters, 2000 to 2013 (calendar year)
Note: Data for Western Australian catch align with calendar years, whereas data for Queensland align with financial years.
- Beyond the removal of target fish and smaller quantities of coral reef finfish species, there is little evidence to suggest that the fisheries targeting Redthroat Emperor impact significantly on the marine environment or ecosystems.
Coral bleaching events8, indicating changes in ocean chemistry due to ocean acidification, have the potential to impact on the replenishment rates of coral reef finfish populations by affecting larval survival9, as well as individual growth rates and spawning output10.
There is evidence that tropical cyclones have resulted in both positive and negative changes in the catch rates of Redthroat Emperor, well beyond the duration of the cyclone itself11. The reasons for this are not yet understood but possibly relate to water temperature and food availability11. A related species (Red Snout Emperor—Lethrinus reticulatus) has been shown to have relatively low tolerance to increased water temperature12.
a Department of Agriculture, Fisheries and Forestry, Queensland
b Department of Fisheries, Western Australia