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Prototroctes oxyrhynchus

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Taxonomy [top]

Kingdom Phylum Class Order Family
ANIMALIA CHORDATA ACTINOPTERYGII OSMERIFORMES RETROPINNIDAE

Scientific Name: Prototroctes oxyrhynchus
Species Authority: Günther, 1870
Common Name(s):
English New Zealand Grayling

Assessment Information [top]

Red List Category & Criteria: Extinct ver 3.1
Year Published: 2014
Date Assessed: 2014-07-10
Assessor(s): West, D, David, B. & Ling, N.
Reviewer(s): Gibson, C. & Hitchmough, R.
Justification:
The New Zealand Grayling (Prototroctes oxyrhynchus) is assessed as Extinct. It was endemic to New Zealand, where it was widely distributed in lowland rivers and streams throughout the North and South Islands. It was abundant at the time of European settlement in the 1860s, but population decline was noted by the late 1870s. The species' disappearance continued rapidly and, by the 1920s the species was known to exist only in some streams in the east Cape, Wairarapa and Otaki districts in the North Island, and on the West Coast of the South Island. Even in these areas, it had undergone significant rapid decline and specimens were rarely encountered. In the early 1930s a specimen, possibly the last, was brought to the British Museum, however, the origin and date of collection were not noted. The New Zealand Grayling was an amphidromous species, which migrated up rivers in large shoals in late summer, spent the autumn and early winter up-stream (perhaps spawning), then disappeared again in early spring, presumably returning to the sea. It was an important fishery species to New Zealand's indigenous Maori and vast numbers were caught using a variety of techniques including net, weir traps and drive fishing. The roe of this species was also consumed. The demise of the New Zealand Grayling was possibly due to a combination of factors including over-exploitation by early settlers, the deterioration of the freshwater habitat through the clearance of forest cover resulting in increased light penetration and raised water temperature and the impact of invasive salmonids. Although it is unlikely that any targeted surveys to look for this species have occurred in the last couple of decades, drift diving (a widely conducted method to survey for trout) in clear lowland rivers (prime Grayling habitat) would be an ideal way to record this species, but there have been no sightings.
History:
1996 Extinct
1994 Extinct (Groombridge 1994)
1990 Extinct (IUCN 1990)
1988 Extinct (IUCN Conservation Monitoring Centre 1988)
1986 Extinct (IUCN Conservation Monitoring Centre 1986)

Geographic Range [top]

Range Description: The New Zealand Grayling (Prototroctes oxyrhynchus) was endemic to New Zealand, where it was widely distributed in lowland rivers and streams throughout the North and South Islands (Baillie and Groombridge 1996, McDowall 2010).
Countries:
Regionally extinct:
New Zealand
FAO Marine Fishing Areas:
Regionally extinct:
Pacific – southwest
Range Map: Click here to open the map viewer and explore range.

Population [top]

Population: This species was abundant at the time of European settlement in the 1860s, but population decline was noted by the late 1870s. Hector (1871) reported of immense and conspicuous shoals ascending the Hutt River (southern North Island) in January. Apparently, however, signs of decreasing numbers were evident soon afterwards. The disappearance of the fish from the Waikato River (North Island) was noted to have occurred in 1874. In 1878, Rutland (who studied the species in the Nelson and Marlborough district, South Island), noted that in the Maitai River (n the north of the South Island) it had 'become very scarce during the past three years'. This disappearance continued rapidly and, by the 1920s the species was known to exist only in some streams in the east Cape, Wairarapa and Otaki districts in the North Island, and on the West Coast of the South Island. Even in these areas, it had undergone significant rapid decline and specimens were rarely encountered. There are reports of this species being caught in the 1920s and in the early 1930s a specimen (possibly the last), was brought to the British Museum, however, the origin and date of collection were not noted (Baillie and Groombridge 1996, McDowall 2010, Best 1929, Radway-Allen 1949).
Population Trend: Unknown

Habitat and Ecology [top]

Habitat and Ecology: The New Zealand Grayling was an amphidromous species, inhabiting freshwater, brackish and marine environments, including rivers, streams, at the mouths of tributary streams and in quiet backwaters. Formerly, they migrated up rivers in large shoals in late summer, spent the autumn and early winter up-stream (perhaps spawning), then disappeared again in early spring, presumably returning to the sea. Spawning apparently occurred in freshwater streams and hatched larvae made their way downstream to the sea where they remained until maturity and returned to freshwater spawning areas (Baillie and Groombridge 1996, Radway-Allen 1949).
Systems: Freshwater; Marine

Use and Trade [top]

Use and Trade: This was an important fishery species to New Zealand's indigenous Maori prior to European settlement and vast numbers were caught using a variety of techniques including net, weir traps and drive fishing. The roe of the grayling was also consumed (Best 1929).

Threats [top]

Major Threat(s): The extinction of this species was possibly due to a combination of factors including over-exploitation by early settlers, the deterioration of the freshwater habitat through the clearance of forest cover resulting in increased light penetration and raised water temperature and the impact of invasive salmonids (Baillie and Groombridge 1996, McDowall 2010).

Bibliography [top]

Best E. 1929. Fishing Methods and Devices of the Maori. In: E.C. Keating (ed.), The Published Works of Eldon Best, Victoria University of Wellington, Wellington.

Groombridge, B. (ed.). 1994. 1994 IUCN Red List of Threatened Animals. IUCN, Gland, Switzerland and Cambridge, UK.

IUCN. 1990. IUCN Red List of Threatened Animals. IUCN, Gland, Switzerland and Cambridge, UK.

IUCN. 2014. The IUCN Red List of Threatened Species. Version 2014.3. Available at: www.iucnredlist.org. (Accessed: 13 November 2014).

IUCN Conservation Monitoring Centre. 1986. 1986 IUCN Red List of Threatened Animals. IUCN, Gland, Switzerland and Cambridge, UK.

IUCN Conservation Monitoring Centre. 1988. 1988 IUCN Red List of Threatened Animals. IUCN, Gland, Switzerland and Cambridge, UK.

McDowall, R.M. 1978. Family Proctotroctidae. In: New Zealand Freshwater Fishes: a guide and natural history. Heinemann Educational Books Ltd, Auckland, New Zealand.

McDowall, R.M. 1990. Freshwater fishes and fisheries of New Zealand -The angler's Eldorado. Aquatic Science 2(2): 281-341.

McDowall R.M. 2010. New Zealand Freshwater Fishes: an Historical and Ecological Biogeography. Fish and Fisheries Series. 32.

Radway Allen, K. 1949. The New Zealand Grayling - A Vanishing Species. Tuatara 2(1): 22-27.

WCMC. 1996. Prototroctes oxyrhynchus. Available at: www.iucnredlist.org. (Accessed: 29th October).


Citation: West, D, David, B. & Ling, N. 2014. Prototroctes oxyrhynchus. The IUCN Red List of Threatened Species. Version 2014.3. <www.iucnredlist.org>. Downloaded on 24 November 2014.
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