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Trygonoptera mucosa

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Taxonomy [top]

Kingdom Phylum Class Order Family
ANIMALIA CHORDATA CHONDRICHTHYES RAJIFORMES UROLOPHIDAE

Scientific Name: Trygonoptera mucosa
Species Authority: (Whitley, 1939)
Common Name(s):
English Bebil, Kejetuck, Western Shovelnose Stingaree, Western Stingaree
Taxonomic Notes: Trygonoptera mucosa needs to be compared carefully with the undescribed Trygonoptera spp. (A and B [in Last and Stevens 1994]) to determine the relationships between these forms (Last and Stevens 1994).

Assessment Information [top]

Red List Category & Criteria: Least Concern ver 3.1
Year Published: 2006
Date Assessed: 2006-01-31
Assessor(s): White, W.T.
Reviewer(s): Kyne, P.M., Fowler, S.L. & Compagno, L.J.V. (Shark Red List Authority)
Justification:
A small (to 37 cm disc width), Eastern Indian endemic stingaree from southwestern Australia (the states of South Australia and Western Australia). Common in shallow water over sandy substrates and near seagrass at 1 to 35 m depth. Although Trygonoptera mucosa forms a considerable component of the biomass of bycatch in the scallop and prawn trawl fisheries that operate off Perth and Mandurah (northwestern most part of its range), this species is of no commercial value and those caught by trawlers are typically returned alive. Only a small number of trawlers operate in this fishery. The South Australian Prawn Fisheries operate at the eastern extremity of the species' range, but overall fishing pressure is low across the range of the species with large areas generally unfished. Given the low fecundity of the species (1 to 2 young per year), the high abortion rates among pregnant females landed by trawlers is the only real threat to this species and the catches of this species as bycatch should be monitored into the future.

Geographic Range [top]

Range Description: Endemic to the Eastern Indian across southwestern Australia: from Glenelg, South Australia (138°30'E) west to at least Dongara, Western Australia (29°15'S) (Last and Stevens 1994).
Countries:
Native:
Australia (South Australia, Western Australia)
FAO Marine Fishing Areas:
Native:
Indian Ocean – eastern
Range Map: Click here to open the map viewer and explore range.

Population [top]

Population: Common in shallow water over sandy substrates or near seagrass.
Population Trend: Stable

Habitat and Ecology [top]

Habitat and Ecology: Trygonoptera mucosa is a common species found over sand and seagrass habitats in depths of 1 to 35 m (Last and Stevens 1994, Hyndes et al. 1999).

Aplacental viviparous species with ovulation and conception occurring in June and parturition occurring 12 months later, i.e., June (White et al. 2002). Litter size ranges from one to two and females reproduce each year. Females and males are mature at 25 and 22 cm DW, respectively, and attain maximum sizes of 36.9 and 28.3 cm DW, respectively (White et al. 2002).

Females and males are mature by the end of their fifth and second years of life, respectively, and reach maximum ages of 17 and 13 years, respectively (White et al., 2002). Von Bertalanffy growth parameters for both sexes were: DWinf = 30.8 cm (F) and 26.1 cm (M), t0 = -2.52 (F) and -1.36 (M) years, k = 0.24 (F) and 0.49 (M).

Diet consists primarily of polychaete worms (errant and sedentary) (Platell et al. 1998).

Life history parameters (from White et al. 2002)
Age at maturity: 5 years (female); 2 years (male).
Size at maturity (disc width): 25 cm DW (female); 22 cm DW (male).
Longevity: 17 years (females); 12 years (males).
Maximum size (disc width): 37 cm DW (females); 28 cm DW (males).
Size at birth: 11.3 cm DW.
Average reproductive age (years): Unknown.
Gestation time: 12 months.
Reproductive periodicity: 1 litter per annum.
Average annual fecundity or litter size: 1 to 2 young per annum.
Annual rate of population increase: Unknown.
Natural mortality: Unknown.
Systems: Marine

Threats [top]

Major Threat(s): This species forms a considerable component of the biomass of bycatch in the scallop and prawn trawl fisheries that operate off Perth and Mandurah (northernmost part of their range). A trawl survey of demersal fishes on the coastal shelf regions of southwestern Australia in the early 1990s reported that T. mucosa constituted 4.9% of the total biomass of fish caught (Laurenson et al. 1994, Hyndes et al. 1999). The South Australian Prawn Fisheries operate at the eastern extremity of the species' range and possibly take this species as bycatch, although it was not reported in a preliminary survey of bycatch in the Spencer Gulf component of the fishery by Carrick (1997).

Overall, only a small number of trawlers operate within the range of this species and large parts of its distribution are unfished or have extremely low fishing pressure, particularly inshore areas of the Great Australian Bight.

This species is of no commercial value and all those caught by trawlers are returned alive. The only real concern for this species and other urolophids is that a large percentage of pregnant females landed abort their young before they are returned (White et al. 2001). Since the fecundity of this species is so low (one to two) and gestation is relatively long (12 months), any additional fishing pressure could have a significant effect on populations of this species.

This species is generally not caught by recreational fisherman. There are no real threats from pollution within the range of this species.

Conservation Actions [top]

Conservation Actions: None in place. Monitoring of this species and other elasmobranchs caught as bycatch in southwestern Australia should be conducted to establish whether the population sizes are stable or declining. A follow-up trawl survey, identical to that conducted in the early 1990s, on the lower west coast of Australia should be conducted to determine any trends in population sizes of such species.

The effective implementation of the Australian National Plan of Action for the Conservation and Management of Sharks (Shark Advisory Group and Lack 2004) (under the FAO International Plan of Action for the Conservation and Management of Sharks: IPOA-Sharks) will help to facilitate the conservation and sustainable management of all chondrichthyan species in Australia.

Citation: White, W.T. 2006. Trygonoptera mucosa. The IUCN Red List of Threatened Species. Version 2014.1. <www.iucnredlist.org>. Downloaded on 23 July 2014.
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