|Scientific Name:||Mustelus fasciatus (Garman, 1913)|
|Red List Category & Criteria:||Critically Endangered A2abd+3bd+4abd ver 3.1|
|Assessor(s):||Hozbor, N., Vooren, C.M. & Lamónaca, A.F.|
|Reviewer(s):||Musick, J.A., Kyne, P.M., Cavanagh, R.D. & Fowler, S.L. (Shark Red List Authority)|
This species is endemic to a restricted area of the inner continental shelf (South Brazil to Argentina) in the Southwest Atlantic ocean. In southern Brazil fishing is intense in the habitat of this demersal shark. CPUE is not available because the species is landed with others as "unidentified shark". Gravid females migrate to shallow inshore waters to give birth in October-December. The small juveniles remain in this area, known to be the nursery grounds for this species. The fishery in this area catches the gravid females and small juveniles. During the 1980s, neonates were caught in large numbers in gillnets set off the beach during summer (10-100 per set), but by 2003 are caught only sporadically. This is clear evidence that the species is nearing extinction in Brazilian waters. In the coastal region of the Bonaerensean District of northern Argentina and Uruguay, the biomass of the species, as measured by trawl surveys, decreased by 96% between 1994 and 1999. Fishing for more abundant species is still intense across this species' limited distribution, and observed declines are significant to warrant a Critically Endangered assessment. There is serious concern regarding further declines in the absence of conservation and enforced management measures.
|Range Description:||This endemic Southwest Atlantic species occurs at low densities over a restricted area (1,500 km of coastline). In Brazil the species occurs only in the extreme south, between latitudes of approximately 29°S and 34°S. The range extends southward to around 35°30'S in Argentina. Nursery area and birth of young occur only on the coast of Rio Grande do Sul State, Brazil, at latitudes from approximately 29 to 34°S and into northern Uruguay (Soto 2001), which is a considerable portion of the species' distribution.|
Native:Argentina (Buenos Aires); Brazil (Rio Grande do Sul); Uruguay
|FAO Marine Fishing Areas:|
Atlantic – southwest
|Range Map:||Click here to open the map viewer and explore range.|
|Current Population Trend:||Decreasing|
|Habitat and Ecology:||In southern Brazil, the species occurs all year round over smooth bottom of the inner continental shelf at depths down to 250 m, being classified as a non-migratory permanent resident of the area, but the adult females carry out a seasonal inshore-offshore migration. The gravid females stay at depths greater than 20 m during most of the year but migrate to shallow inshore waters in spring. Neonates and small juveniles stay in these waters, which constitute the nursery area of the species (Vooren 1997, Vasconcellos and Vooren 1991, Soto 2001). Pupping occurs in October-December. The presence of large-yolked eggs in the ovary of females with near term pups indicates a yearly reproductive cycle with a gestation period of 11 to 12 months (Soto 2001). |
Population parameters are as follows:
Size at maturity: 111.5 cm total length (TL) (females); 120 cm TL (males) (Soto 2001)
Maximum size: Males 147 cm TL (males); 158 cm TL (females)
Size at birth: 39 to 43 cm TL (Vasconcellos and Vooren 1991); 35 cm TL (Soto 2001)
The species feeds mostly on shrimps and crabs (Vooren 1997, Soto 2001).
Intensive demersal fisheries exist over the entire area of distribution of this species, already naturally low in density (as evidenced from catches typically of the order of one to ten specimens per one-hour trawl haul in 1980 when the species was still relatively unexploited (Vooren, unpubl. data)).
In southern Brazil fishing is intense in the habitat of this demersal shark (Miranda and Vooren 1999). The major threat to the species is intensive fishing by pair trawl, shrimp trawl, gillnet and beach seine in the coastal nursery area of the species at depths less than 10 m. The species is caught as bycatch in the shrimp fishery and in the multi-species fishery aimed mostly at an assembly of sciaenid fishes, flounders, mullets, angel sharks and guitarfish (Haimovici and Mendonça 1996, Vooren and Lamónaca, unpubl. data). The fishery in the nursery area catches gravid females during their inshore migration in spring and the small juveniles all year round. In gillnets set off the beach during summer, neonates used to be caught in large numbers (10-100 per set) in the 1980s but were caught only sporadically and in much smaller numbers in 2003 (Vooren and Lamónaca, unpubl. data). The coastal fishery is driving the species towards extinction through recruitment overfishing.
In Uruguay, where it is not targeted but taken as bycatch in industrial and artisanal fisheries, species-specific catch data are not available. Together with M. schmitti, which is the main species taken, estimated capture for the period 2000-2002 was 900 tonnes per year (Domingo, pers. comm.).
In the coastal region of the Bonaerensean District of northern Argentina and Uruguay the biomass of the species, as measured by trawl surveys, decreased by 96% between 1994 and 1999 (Massa and Hozbor, unpubl. data).
|Conservation Actions:||In Brazil, trawl fishing at distances less than three nautical miles from shore (which means at depths of less than about 10 m) is forbidden by law but enforcement of this law meets with practical difficulties, and trawling in the nursery area proceeds almost without restriction. Gillnetting in the nursery area proceeds without legal restrictions. Due to the multi-species nature of the fisheries, regulation measures aimed at a particular species are a difficult proposition. The best solution would be to establish two or three large coastal protected areas in which fishing would be banned, as recommended by Musick et al. (2000) for long-lived marine species threatened by capture as bycatch in fisheries targeting other species. Several other species of elasmobranchs have their nursery and pupping ground in the same shallow coastal waters and would also benefit from this. Public awareness of the problem is increasing. By Decree of the State Government of Rio Grande do Sul, Mustelus fasciatus was, in the year 2002, classified as a species threatened with extinction (Marques 2002).|
|Citation:||Hozbor, N., Vooren, C.M. & Lamónaca, A.F. 2004. Mustelus fasciatus. The IUCN Red List of Threatened Species 2004: e.T44581A10908329.Downloaded on 25 February 2018.|