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Zapteryx brevirostris

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Taxonomy [top]

Kingdom Phylum Class Order Family
ANIMALIA CHORDATA CHONDRICHTHYES RAJIFORMES RHINOBATIDAE

Scientific Name: Zapteryx brevirostris
Species Authority: (Müller & Henle, 1841)
Common Name(s):
English Shortnose Guitarfish

Assessment Information [top]

Red List Category & Criteria: Vulnerable A2ab+3b+4ab ver 3.1
Year Published: 2006
Date Assessed: 2006-01-31
Assessor(s): Vooren, C.M., Lamónaca, A.F., Massa, A. & Hozbor, N.
Reviewer(s): Kyne, P.M., Valenti, S. & Heenan, A. (Shark Red List Authority)
Justification:
An inshore guitarfish (10 to 40 m off Rio Grande do Sul, Brazil), endemic to the Southwest Atlantic, with a relatively restricted distribution off Southern Brazil, Uruguay and Northern Argentina. This species is viviparous with litters of 4 to 8 (average six) neonates per breeding cycle which is synchronized in the population and which probably has a duration of two years. Rio Grande do Sul, Brazil, where there have been records of commercial catches since 1988, appears to be the stronghold of the species in terms of population density and abundance. Species-specific catch statistics are not available from Brazil. In Argentina, on the fishing grounds off Buenos Aires province, biomass of the species decreased by 86% from the year 1994 to 1999. Although the species has no commercial value and is discarded in Argentina, fishing mortality is reducing the abundance of the species. The species is rarely captured in Uruguay. Given documented declines in Argentina, heavy fishing pressure in the centre of its abundance in Brazil and low fecundity the species is assessed as Vulnerable. However, it may prove to be more threatened in the near future as heavy fishing pressure continues or even increases.

Geographic Range [top]

Range Description: Z. brevirostris has been reliably recorded from the coasts of the Southwest Atlantic in southern Brazil, Uruguay and northern Argentina, between Rio de Janeiro at lat. 22°S (Müller and Henle 1841, Batista 1987) and Mar del Plata at lat. 38°S (Müller and Henle 1841, Castello 1971, Sadowsky 1973, Batista 1987, Vooren 1997). As the species appears to be an inhabitant of temperate to subtropical waters, an older record from Bahia (lat. 14°S) from the year 1907, cited by Bigelow and Schroeder (1953) requires confirmation.
Countries:
Native:
Argentina; Brazil (Rio de Janeiro); Uruguay
FAO Marine Fishing Areas:
Native:
Atlantic – southwest
Range Map: Click here to open the map viewer and explore range.

Population [top]

Population: Z. brevirostris has been reliably recorded from the coasts of the Southwest Atlantic between Rio de Janeiro at lat. 22°S (Müller and Henle 1841, Batista 1987) and Mar del Plata at lat. 38°S (Müller and Henle 1841, Castello 1971, Sadowsky 1973, Batista 1987, Vooren 1997). On the continental shelf off Rio Grande do Sul, Brazil (lat. 29°S to 34°S) the species is common all year round at depths of 10 to 40 m (Vooren 1997). Since the year 1988 there are records of commercial trawl catches of the species from this area, with landings of 1 to 3 ton per fishing trip (Vooren and Lamónaca 2003, unpublished data). This relatively small area, which extends along 700 km of coastline and measures about 50 km in width, appears to be the stronghold of the species in terms of population density and abundance. Nowhere else is Z. brevirostris an important fishery resource. This species is rarely captured in Uruguay (A. Domingo, pers. comm).
Population Trend: Decreasing

Habitat and Ecology [top]

Habitat and Ecology: Off Rio Grande do Sul (Brazil) the species occurs on the inner shelf at depths of 10-50m, where it feeds on polychaetes and bottom-dwelling crustaceans. Maximum size of females is 55 cm TL off Rio de Janeiro, 53 cm TL (total weight of 970 g) off São Paulo and 64 cm TL (total weight 1,500 g) off Rio Grande do Sul. Maximum size of males is 52 cm TL off Rio de Janeiro and 63 cm TL off Rio Grande do Sul. The size of 10 specimens (three females and seven males) from Mar del Plata, Argentina measured 42 to 66cm TL. Off Rio de Janeiro and São Paulo, size at first breeding is 42 to 48 cm TL (female) and 43 to 45 cm TL (male). Off Rio Grande do Sul, females less than 47 cm TL are sexually immature. Size of full-term embryos is 13 cm TL off São Paulo and 16 cm TL off Rio Grande do Sul. Body size varies with latitude, being smaller near the northern limit of the area of distribution. Birth occurs in autumn, from April to June. The species is aplacental viviparous with uterine fecundities of 4 to 8 (average six) neonates per breeding cycle which is synchronized in the population and which probably has a duration of two years (Nani 1964, Castello 1971, Batista 1987, Louro 1995, Vooren 1997, Gonzalez and Reis 2002, Vooren and Lamónaca 2003, Vooren unpublished data).
Systems: Marine

Threats [top]

Major Threat(s): On the continental shelf of Rio Grande do Sul, Brazil (lat. 29°S to 34°S) there are records of commercial trawl catches of Z. brevirostris since 1988, with landings of 1-3 ton per fishing trip (Vooren and Lamónaca 2003, unpublished data). In south Brazil the species is not listed separately in the fisheries statistics but included in the categories "unidentified rays and skates" and/or "guitarfish" which refers mostly to Rhinobatos horkelii. Therefore there are no data on CPUE of Z. brevirostris. In view of the low reproductive potential of the species (on average three neonates per year per adult female), recruitment overfishing will easily occur, and directed fishing will drive the population soon to extinction on the continental shelf of south Brazil which is the centre of the distribution of the species.

In Argentina on the fishing grounds off Buenos Aires province, biomass of the species decreased by 86% from the year 1994 to 1999. Although the species has no commercial value and is discarded in Argentina, fishing mortality is reducing the abundance of the species. The species is rarely captured in Uruguay (A. Domingo, pers. comm.).

Conservation Actions [top]

Conservation Actions: There are no legal restrictions of the fishery for Z. brevirostris. The species survives capture by trawl and can be discarded alive (Vooren and Lamónaca 2003, unpublished data). A ban on landings would protect the species.

Citation: Vooren, C.M., Lamónaca, A.F., Massa, A. & Hozbor, N. 2006. Zapteryx brevirostris. The IUCN Red List of Threatened Species. Version 2014.3. <www.iucnredlist.org>. Downloaded on 27 November 2014.
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