|Scientific Name:||Rhizoprionodon taylori (Ogilby, 1915)|
|Red List Category & Criteria:||Least Concern ver 3.1|
|Assessor(s):||Simpfendorfer, C.A. (SSG Australia & Oceania Regional Workshop, March 2003)|
|Reviewer(s):||Fowler, S. & Cavanagh, R.D. (Shark Red List Authority)|
Rhizoprionodon taylori is a small abundant inshore shark restricted to southern Papua New Guinea and northern Australia where it is caught as bycatch in inshore gillnet and trawl fisheries. Catches at times are large, but sporadic. It is not a targeted species and is one of the most productive species of shark known, growing very rapidly, maturing after one year with females producing up to 10 pups every year. This life history makes them able to sustain considerable fishing pressure, especially when the immature animals are not exploited.
|Range Description:||This is an abundant inshore species that occurs across in northern Australia and in southern Papua New Guinea (Last and Stevens 1994).|
Native:Australia (Northern Territory, Queensland, Western Australia); Papua New Guinea
|FAO Marine Fishing Areas:|
Indian Ocean – eastern; Pacific – western central
|Range Map:||Click here to open the map viewer and explore range.|
|Population:||There are no data available on the population size, but the demographics of the population has been investigated by Simpfendorfer (1999).|
|Current Population Trend:||Unknown|
|Habitat and Ecology:||This species is abundant in inshore waters, especially over soft-bottomed habitats. The diet includes mostly teleost fishes, but also crustaceans and cephalopods (Simpfendorfer 1998). The young are born at 25 cm, males and females mature at approximately 55 cm, and they reach a maximum size of 67 cm (Last and Stevens 1994). This species has one of the most r-selected life histories of any shark species. Simpfendorfer (1992) reported that mature females produce litters of 1 to 10 young every year after a gestation period of 11.5 months. Interestingly, this is the only species of shark in which a period of embryonic diapause occurs (7.5 months) during which embryonic development is arrested. R. taylori is a rapidly growing species, reaching maturity after only one year, and living to a maximum of seven years (Simpfendorfer 1993). Estimates of natural mortality rates using catch curve analysis are 0.56 per year for females and 0.70 per year for males (Simpfendorfer 1999). Estimates of the intrinsic rate of population increase are 0.27 which give a population doubling time of 2.55 years. This rate of population increase is amongst the highest for any species of elasmobranch, and means that they are able to sustain relatively high levels of fishing pressure. If all age classes are fished equally the population can withstand an instantaneous fishing mortality rate of 0.18, and if the immature animals are not fished then this increases to 0.67.|
This species of taken as bycatch in inshore gillnet fisheries for mackerel and barramundi along the Queensland coast. At times large catches are made, but these events are sporadic and the overall catch is relatively small. In the waters off the Northern Territory this species makes up about 0.5% of the catch in gillnet and longline fisheries (Stevens 1999), but its size is considered to be too small for retention (Last and Stevens 1994). Many of the animals discarded in these fisheries are already dead.
Despite the level of fishing on this species its life history makes it relatively resilient to the moderate levels of fishing pressure to which it is subjected.
|Conservation Actions:||The fisheries in which R. taylori is caught in northern Australia are regulated by either the relevant state government, or the federal government. However, there are no specific regulations that apply to this species.|
|Citation:||Simpfendorfer, C.A. (SSG Australia & Oceania Regional Workshop, March 2003). 2003. Rhizoprionodon taylori. The IUCN Red List of Threatened Species 2003: e.T41852A10580308.Downloaded on 20 October 2017.|
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