Sand Whiting Sillago ciliata

Charles Graya and Anthony Roelofsb


Sand Whiting

Table 1: Stock status determination for Sand Whiting

Jurisdiction

New South Wales, Queensland

Stock

Eastern Australian
(ECIFF, EGF, OHF)

Stock status

 

Sustainable

Indicators

Catch, CPUE, length and age frequencies

CPUE = catch per unit effort; ECIFF = East Coast Inshore Fin Fish Fishery (Queensland); EGF = Estuary General Fishery (New South Wales); OHF = Ocean Hauling Fishery (New South Wales)


Stock Structure

Sand Whiting occurs from northern Queensland to eastern Victoria; however, little is known about the biological stock structure of the population. Tagging studies have shown movement of fish between estuaries. Hence, a single biological stock is assumed throughout the range of the species in eastern Australia, and reporting of status is undertaken at the biological stock level.


Stock Status

Eastern Australian biological stock

Sand Whiting is a key commercial and recreational species that is fished throughout its distribution along the east coast of Australia. It has a long history of relatively stable commercial landings in both Queensland and New South Wales.

In the Queensland part of the biological stock, commercial catch per unit effort (CPUE) decreased slightly in 2010, but was within historical levels (Figure 2b). CPUE has been relatively stable since the early 2000s (Figure 2b). Length-frequency data from commercial and recreational catch have been consistent since these data were first collected in 2008, indicating a stable biological stock with good recruitment. This evidence indicates that the Queensland part of the biological stock is unlikely to be recruitment overfished. Catch also decreased slightly in 2010, but is within historical levels; it has remained relatively stable since the early 2000s. Fishery-dependent monitoring of commercial and recreational catches in the main fishery area indicates that total mortality in 2010 was below the threshold level, which is set at twice the natural mortality1. The minimum size limit (23 cm fork length) is based on knowledge of size-at-first-maturity, which ensures that a large proportion of the population can spawn before capture1. The combination of a stable commercial catch history, acceptable total mortality estimates and a precautionary minimum legal size indicates that the current level of fishing mortality is unlikely to cause this part of the biological stock to become recruitment overfished1.

In the New South Wales part of the biological stock, Sand Whiting has a history of relatively stable landings (113–160 tonnes [t] between 2001 and 2010; Figure 2a)2. CPUE for estuarine commercial seining in New South Wales has been relatively stable since 1998–99 (Figure 2b), as has the length composition of landings since the 1960s. Sand Whiting grow fast, and retained commercial landings predominantly comprise fish between 2 and 5 years of age3. There is no evidence that recruitment is limited2. This part of the biological stock is not considered to be recruitment overfished. The minimum legal length in New South Wales (27 cm total length) provides opportunity for Sand Whiting to spawn before recruiting to the fishery2. This evidence indicates that the current level of fishing mortality is unlikely to cause this part of the biological stock to become recruitment overfished.

On the basis of the evidence provided above, the entire biological stock is classified as a sustainable stock.


Table 2: Sand Whiting biology4

Longevity and maximum size

12 years; 50 cm FL

Maturity (50%)

Males: 17 cm FL Females: 19 cm FL


Figure 1: Distribution of reported commercial catch of Sand Whiting in Australian waters, 2010
Figure 1: Distribution of reported commercial catch of Sand Whiting in Australian waters, 2010

Main features and statistics for Sand Whiting stocks/fisheries in Australia in 2010
  • Commercial fishers primarily catch Sand Whiting between spring and autumn in seine (haul) nets in estuaries, although significant catches are also taken in tunnel nets and gillnets5–7. Seine nets are used to catch Sand Whiting on ocean beaches. Recreational fishers use hook and line.
  • A range of input and output management measures are applied across the Sand Whiting biological stock:
    • Input controls include limited entry and gear restrictions.
    • Output controls include minimum size limits and recreational bag limits.
  • In 2010, a total of 346 vessels reported catching Sand Whiting in New South Wales. In Queensland, 207 vessels (198 net and 9 line) reported catching Sand Whiting.
  • The total amount of Sand Whiting caught commercially in Australia in 2010 was 418 t, comprising 277 t in Queensland and 141 t in New South Wales. In Queensland, the most recent estimate of recreational catch indicates that approximately 5 427 000 fish were caught in 20058. Indigenous catch in Queensland was estimated at 19 879 fish in 20019. In New South Wales, the recreational catch of Sand Whiting is thought to be between 230 and 460 t2, and the Indigenous catch is unknown.

a)
Figure 2a) Commercial catch of Sand Whiting in Australian waters, 2000–10 (calendar year)
b)
Figure 2b) commercial catch rates of Sand Whiting in Queensland 2000–10 (all methods combined) and New South Wales 2000–09
Figure 2: a) Commercial catch of Sand Whiting in Australian waters, 2000–10 (calendar year);
b) commercial catch rates of Sand Whiting in Queensland 2000–10 (all methods combined) and New South Wales 2000–09 (estuarine seine nets)

Catch Explanation

In Queensland, commercial catches of Sand Whiting have been stable, varying between 269 and 394 t per year. The catch in 2010 decreased slightly from the preceding year to approximately 277 t. Catches in Moreton Bay are likely to have been affected by marine park closures to fishing as a result of rezoning and buy-back of fishing licences, which may explain some of the reported decrease. Commercial fishing catch rates of Sand Whiting increased in 2009, but fell again in 2010, although they were within recent limits since 2001 (Figure 2b). Catch-related performance measures were not triggered.

In New South Wales, commercial catches of Sand Whiting have ranged between 113 and 160 t per year. The 2009 catch of 140 t was slightly higher than in the preceding two years, but within levels since 2001. Catch rates decreased in 2009, but were still within recent levels since 2001.


Effects of fishing on the marine environment
  • Tunnel netting may interact with marine turtles, but interactions with turtles are considered to be very low risk because of attendance rules, the requirement for the tunnel to be set at least 30 m beyond the low water mark and in water more than 30 cm deep, and fishers' codes of conduct; as a result, the tunnel is never dry. Marine turtles are released with minimal difficulty.
  • Seining in estuaries can incur large bycatches of undersized organisms and unwanted species, but use of appropriately sized mesh can reduce unwanted mortalities6,10–12.
  • Gillnets used in estuaries can incur substantial bycatches, including the capture of undersized individuals of key species5,7,13.

Environmental effects on Sand Whiting
  • No significant environmental effects on Sand Whiting have been identified.


Department of Primary Industries, New South Wales
b Department of Agriculture, Fisheries and Forestry, Queensland