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Mustelus whitneyi

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Taxonomy [top]

Kingdom Phylum Class Order Family
ANIMALIA CHORDATA CHONDRICHTHYES CARCHARHINIFORMES TRIAKIDAE

Scientific Name: Mustelus whitneyi
Species Authority: Chirichigno F., 1973
Common Name(s):
English Humpback Smoothhound
Spanish Musola Prieta, Tollo Común

Assessment Information [top]

Red List Category & Criteria: Vulnerable A2d ver 3.1
Year Published: 2007
Date Assessed: 2007-03-01
Assessor(s): Romero, M.
Reviewer(s): Kyne, P.M., Cavanagh, R.D., Francis, M. & Acuna, E. (Shark Red List Authority)
Justification:
Mustelus whitneyi is a temperate demersal triakid shark recorded from the Southeast Pacific from Peru to southern Chile. The Peru tollo fishery probably consists mainly of M. whitneyi. The abundance of M. whitneyi decreases towards the south, and consequently the Chilean tollo fishery probably catches mainly M. mento, which has a more southern distribution. Thus the Peruvian fishery constitutes the main threat to M. whitneyi.

In Peru, the tollo fishery has shown remarkable productivity over a period of more than 30 years, but is probably now somewhat depleted. Landings of tollo were high for a 24-year period between 1966 and 1989, averaging 11,276 t per year and reaching a peak of 25,000 t in 1984. From 1990 to 2004, there was a substantial drop in landings to an average of 4,806 t. The sharp decline in 1990 between two periods of relative stability is not a typical response to overfishing, indicating that landings may not be a good index of abundance. However, it is thought that the population did decline by an unknown extent during the 1990s, leading to a shift of fishing effort away from tollo. Furthermore, the implementation of a new minimum size regulation in 2001 may have also reduced catches. The effects of the new regulations are not yet known.

Mustelus whitneyi is assessed globally as Vulnerable based on a suspected population decline of more than 30% as a result of a long period of high catches in Peru, the main part of the distribution range of this species. The fishery is still operating, though at a lower level than formerly. The minimum size limit currently in place protects only small juveniles and may be providing little conservation benefit.

Geographic Range [top]

Range Description: Mustelus whitneyi is found in the Southeast Pacific from Peru to southern Chile (39°52' S). Chirichigno and Cornejo (2001) also report the species from Costa Rica, but this is probably erroneous.
Countries:
Native:
Chile; Peru
FAO Marine Fishing Areas:
Native:
Pacific – southeast
Range Map: Click here to open the map viewer and explore range.

Population [top]

Population: Unknown.
Population Trend: Decreasing

Habitat and Ecology [top]

Habitat and Ecology: An offshore bottom-dwelling shark found on the continental shelf. Recorded in depths of 16 to 211 m, but is more common at 70 to 100 m. Prefers rocky bottom around islands. Feeds on crabs, mantis shrimp, and small bony fishes. Viviparous, with 5 to 10 young per litter and a size at birth of 25 cm total length (TL) (Compagno in prep). Size at maturity is 74 to 87 cm TL for females and the smallest adult male recorded measured 68 cm TL (Compagno in prep). M. whitneyi reaches at least 87 cm TL (Compagno in prep.), with a recorded maximum size of 95 cm TL (Chirichigno and Cornejo 2001).
Systems: Marine

Threats [top]

Major Threat(s): In Peru this species is probably grouped with M. mento and maybe Triakis maculata under the local name "tollo". The Peruvian tollo fishery probably consists mainly of M. whitneyi. The abundance of M. whitneyi decreases towards the south, and consequently the Chilean tollo fishery probably catches mainly M. mento, which has a more southern distribution. Thus the Peruvian fishery constitutes the main threat to M. whitneyi.

In Peru, landings of tollo were high for a 24-year period between 1966 and 1989, averaging 11,276 t per year and reaching a peak of 25,000 t in 1984 (FAO 2006). From 1990 to 2004, there was a substantial drop in landings to an average of 4,806 t. The sharp decline in 1990 between two periods of relative stability is not a typical response to overfishing, indicating that landings may not be a good index of abundance. However, it is thought that the population did decline by an unknown extent during the 1990s, leading to a shift of fishing effort away from tollo. Furthermore, the implementation of a new minimum size regulation in 2001 may have also reduced catches. The effects of the new regulations are not yet known.

The Peruvian tollo fishery has shown remarkable productivity over a period of more than 30 years, but is probably now somewhat depleted.

Conservation Actions [top]

Conservation Actions: In order to guarantee chondrichthyan resources in the long term, a Peruvian legal regulation was put into force in 2001, establishing minimum catch sizes of 60 cm TL for Mustelus whitneyi, Mustelus mento and Triakis maculata. These species are the main commercial sharks caught off Peru. Improved awareness and education regarding these regulations is lacking and this is now a priority, as is adequate enforcement.

The lack of accurate species-specific information on this species not only in Peru, but elsewhere in its range reinforces the need for further research with a focus on Mustelus whitneyi and other tollo species.

Citation: Romero, M. 2007. Mustelus whitneyi. The IUCN Red List of Threatened Species. Version 2014.2. <www.iucnredlist.org>. Downloaded on 26 October 2014.
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