|Scientific Name:||Mustelus schmitti Springer, 1939|
|Red List Category & Criteria:||Endangered A2bd+3bd+4bd ver 3.1|
|Assessor(s):||Massa, A., Hozbor, N., Chiaramonte, G.E., Balestra, A.D. & Vooren, C.M.|
|Reviewer(s):||Walker, T.I., Kyne, P.M., Cavanagh, R.D. & Musick, J.A. (Shark Red List Authority)|
Mustelus schmitti is subject to intensive fishing in its entire area of distribution, including heavy pressure on its nursery grounds. Known to migrate seasonally in large numbers between wintering grounds in south Brazil and summer grounds off Uruguay and/or Argentina (Vooren 1997). In winter, the species is fished in south Brazil as a component of a mixed-species fishery and also by directed fishing. Bottom trawl fishery CPUE data in south Brazil are evidence that due to intensive fishing from 1985 onwards, the abundance of the winter migrant population of the species had decreased by 85% in 1997, and the fishery continues without restraint (Miranda and Vooren 2003). In addition, a smaller, local population, known to breed in south Brazil during the spring seems to have disappeared and this is attributed to fishing in inshore pupping and nursery areas (Vooren and Lamónaca unpublished data). In Argentina, the species has been an important fishery resource since 1988 and market demand is increasing (Chiaramonte 1998). In the main fishing area off Buenos Aires Province (Argentina) and Uruguay, biomass has decreased by 22%, while national landings in Argentina decreased by 30% between 1998 and 2002 (Massa and Hozbor unpublished data). The most recent data (2003) indicate a continuing decline in the stock. Size at first breeding and mean total length have also decreased in Argentina (Diaz de Astarloa et al. 1997). As the winter migrants continue to be fished in Brazil, biomass will likely continue to decrease off Uruguay and Argentina where the species is also heavily exploited, declines of the order 22 to -30% are apparent and there are clear signs the resource may not be able to withstand current exploitation levels. Although the Maximum Permitted Catch (MPC) established by the Argentine fisheries authorities has been reduced annually for the last four years, landings of M. schmitti have continued to decline. Mustelus schmitti is assessed as Critically Endangered in Brazil given the observed declines of 85% of the winter migrating population, probable extirpation of a local breeding population and continuing intense fishing. In Argentina and Uruguay the species is considered Vulnerable based on recent declines (despite MPC regulations). An overall global assessment of Endangered summarises the situation throughout the species' range and is of great cause for concern given that market demand is increasing and fisheries are continuing. The protection of breeding females and nursery areas is vital, as is improved management of the species throughout its range.
|Range Description:||Endemic to the Southwest Atlantic, from southwest Brazil to the coast of central Argentina, between latitudes 22°S (Rio de Janeiro) and 48°S (Patagonia) according to Figueiredo (1977) and Chiaramonte and Pettovello (1998).|
Native:Argentina; Brazil; Uruguay
|FAO Marine Fishing Areas:|
Atlantic – southwest
|Range Map:||Click here to open the map viewer and explore range.|
|Population:||Pupping occurs inshore in spring throughout the range from south Brazil to Patagonia, and body size of the adults increases with latitude in Argentina (Cousseau 1982, 1986, Chiaramonte and Pettovello 1998, Vooren and Lamónaca unpublished data, Domingo unpublished data). This is evidence of the existence of several populations of the species. One large population migrates to south Brazil in autumn and leaves that area in spring, presumably in a southward migration with unknown route. A locally breeding smaller population existed in south Brazil but may have been extirpated by the fishery. Important nursery areas exist in Argentina off Buenos Aires Province in Cabo San Antonioand El Rincón (Cousseau 1986). Another two nursery areas probably of lesser importance occur in north (Bahía Engaño, 43°20´S) and south (Puerto Deseado, 48°S) Patagonia (Van der Molen et al. 1998, Chiaramonte and Pettovello 2000).|
|Current Population Trend:||Decreasing|
|Habitat and Ecology:||In south Brazil, the species occurs mostly at depths of 10 to 140 m, at bottom temperatures of 12 to 20°C on the wintering grounds from April to November (Vooren 1997, Haimovici et al. 1996). Winter migrants include juveniles, adult males and gravid adult females. Winter migrants arrive in large numbers in April and stay until November, then presumably migrate southward to Uruguay and/or Argentina. A small population was known to give birth in south Brazil in November and remain during January and February, but this population appears to have been extirpated (Vooren unpublished data). The species feeds mostly on crabs (Capitoli et al. 1995). In Argentina, the species occurs from coastal waters to 120 m, at temperatures of 5.5 to 11.0°C (Menni 1985). |
Population parameters of the Brazilian winter migrants (Souto 1986, Batista 1988) and from Argentinean waters (Menni et al. 1986, Menni 1985, Diaz de Astarloa et al. 1997, Chiaramonte and Pettovello 2000) are as follows:
Maximum Total Length: Argentina: 90 cm (males), 108.5 cm (females); Brazil: 78.0 cm (males), 96.0 cm (females).
Modal Total Length: Brazil: 60.0 cm (males), 72.0 cm (females).
Maximum age: Brazil: 9 years (males), 16 years (females).
Total Length at first breeding: Brazil (50% maturity): 57.0 cm (females), 55.0 cm (males). North Argentina: 54.9 to 60.0 cm (males), 60.5 to 62.6 cm (females). Patagonia: 70.8 to 75.9 cm (males), 79.1 to 79.5 cm (females).
Age at first breeding: Brazil: 4 years (females), 3 years (males) (from growth curve with observed TL); Argentina (age of first maturity, preliminary): 6.5 years (females), 5.7 years (males) (Massa and Hozbor, unpublished data).
Total Length at birth: Brazil: 24 to 28 cm, modal size 24 cm.
Gestation period: 11 months.
Duration of female breeding cycle: 12 months.
Litter size: 2 to 14, modal value 8.
Individual annual fecundity: Average 8.
Annual rate of population increase: Brazil: 1.058 in the years 1980 to 1994.
The species is subject to intensive fishing in its entire area of distribution, including its nursery grounds.
From the observed decline in abundance under intensive fishing, it is concluded that in Brazil the fishery causes recruitment overfishing. In winter, the species is fished in south Brazil as a component of a mixed-species fishery and also by directed fishing. Bottom trawl fishery CPUE in south Brazil are evidence that since intensive fishing has occurred from 1985 onwards, the abundance of the winter migrant population of the species had decreased by 85% by 1997, and the fishery continues without restraint (Miranda and Vooren 2003). In south Brazil a small local population reproduced in spring, and remained during the summer. Neonates used to be commonly caught by beach seine and bottom trawl in the 1980s. In a recent summer shore fishery survey (2003) the species was not recorded. This population seems to have disappeared and this is attributed to fishing in its inshore pupping and nursery areas (Vooren and Lamónaca unpublished data).
In Argentina, this species has been an important fishery resource since 1988 (Chiaramonte 1998) and market demands have increased over the last eight years. Intensive fishing in coastal nursery areas threatens recruitment while fishing for adults is increasing. In the main fishing area off Buenos Aires Province (Argentina) and Uruguay (the Bonaerensean region), biomass has decreased by 22%, while national landings in Argentina decreased by 30% between 1998 and 2002 (Massa and Hozbor unpublished data). Fisheries statistics may underestimate the actual volume landed, however reductions in landings are an indication that the resource cannot withstand the current level of exploitation. The most recent data (2003) indicate a continuing decline in the stock. This area appears to have the greatest abundance of the species.
In industrial and artisanal fisheries in Uruguay this species is not targeted but taken as bycatch. Together with M. fasciatus, estimated capture for the period 2000-2002 was 900t per year (M. schmitti was the main species taken).
|Conservation Actions:||There are no conservation measures at present for the species, except the Maximum Permitted Catch (MPC) established by the Argentine fisheries authorities. Although the MPC was reduced annually for the last four years, landings of M. schmitti have continued to decline. Understanding the migrations of the populations of the species is necessary for conservation. The migratory populations should be conserved through international management of the fishery involving Argentina, Uruguay and Brazil. The local population in south Brazil (if it still remains) should be conserved through marine protected areas in the shallow coastal zone. Marine protected areas in nursery areas throughout its range are necessary to protect breeding females and juveniles.|
Batista, V.S. 1988. Determinação de idade e análise do crescimento do cação Mustelus schmitti Springer 1939 (Elasmobranchii, Triakidae) da plataforma continental do Rio Grande do Sul. Rio Grande, Universidade do Rio Grande 99p. (unpublished M.Sc. thesis).
Capitoli, R.R., Ruffino, M.L. and Vooren, C.M. 1995. Alimentação do tubarão Mustelus schmitti Springer na plataforma costeira do Estado de Rio Grande do Sul, Brasil. Atlântica 17: 109–122.
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Chiaramonte, G.E. and Petovello, A.D. 2000. The biology of Mustelus schmitti in southern Patagonia, Argentina. Journal of Fish Biology. 57: 930–942.
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Haimovici, M., Martins, A.S. and Vieira, P.C. 1996. Distribuição e abundância de peixes teleósteos sobre a plataforma continental do Sul do Brasil. Revista Brasileira de Biologi 56: 27-50.
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Menni, R.C. 1985. Distribución y biología de Squalus acanthias, Mustelus schmitti y Galeorhinus vitaminicus en el mar argentino en agosto-septiembre de 1978 (Chondrichthyes). Revista del Museo de la Plata (nueva serie). Sección Zoología. Tomo XIII Nº 138: 151–182.
Menni, R.C., Cousseau, M.B. and Gosztonyi, A.R. 1986. Sobre la biología de los tiburones costeros de la provincia de Buenos Aires. An. Soc. Cient. Arg. Tomo CCXIII: 3–26.
Miranda L.V. and Vooren C.M. 2003. Captura e esforço da pesca de elasmobrânquios demersais no sul do Brasil nos anos de 1975 a 1997. Frente Marítimo 19B: 217–231.
Souto C.F.M. 1986. Estudo comparativo da reprodução dos cações Mustelus schmitti Sprionger 1939 e Mustelus canis Mitchill 1815 na platafortma continental do Rio Grande do Sul. Rio Grande, Universidade do Rio Grande (Unpublished M.Sc. Thesis).
Van der Molen, S., Caille, S.G. and Gonzales, R. 1998. Incidental capture of shark in Patagonian coastal trawl fisheries. Marine and Freshwater Research 49: 553–572.
Vooren C.M. 1997. Demersal elasmobranchs. In: U. Seeliger, C. Odebrecht and J.P. Castello (eds). Subtropical Convergence Environments: The Coast and Sea in the Southwestern Atlantic. pp: 141-145. Berlin, Springer Verlag.
|Citation:||Massa, A., Hozbor, N., Chiaramonte, G.E., Balestra, A.D. & Vooren, C.M. 2006. Mustelus schmitti. The IUCN Red List of Threatened Species 2006: e.T60203A12318268.Downloaded on 22 March 2018.|
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