Narrow-nosed smooth shark
| Narrow-nosed smooth shark | ||||||||||||
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| Mustelus schmitti | ||||||||||||
| ( Springer , 1939) |
The narrow-nosed smooth shark ( Mustelus schmitti ), also known as the Argentine smooth shark, is a species of shark from the genus Mustelus within the family of the smooth sharks . It lives close to the coast in the southwestern Atlantic and is classified as critically endangered by the IUCN . This means that this species has a very high risk of becoming extinct in nature in the immediate future.
Occurrence
Basically the narrow-nosed smooth shark lives in the southwest Atlantic between the south of Brazil and the north of Argentina. However, different populations of this species exist. A large population can be found in southern Brazil in summer and in more northerly waters in winter, from April to November.
Another large population migrates to southern Brazil in autumn and leaves this area again in summer. Other populations live south of Buenos Aires and on the coast of North and South Patagonia . The body size of the animals and the depth of the sea in which they reside varies slightly between the Brazilian and Argentine populations.
features
Mustelus schmitti is a rather slender shark that reaches a maximum body length of just over one meter.
Male specimens of the Argentine population grow to a maximum of 90 centimeters, female 105 centimeters. Male specimens of the Brazilian population grow to a maximum of 80 centimeters and females about 100 centimeters. On average, however, Argentine right sharks are around 50 to 60 centimeters long. This makes it one of the smallest shark species. Its torso is 17 to 21 percent of its length and its head is quite short. The larger than average pectoral fins are characteristic of this species. The shark's dorsal fin lies in the middle between the pectoral and pelvic fins. It also has quite large and long eyes and many blunt teeth that are arranged asymmetrically. It is a gray shark that becomes light towards the belly, it often has light spots. Males are around 9 years old, females around 16 years old. The Brazilian population reaches sexual maturity in males with an age of approx. 3 years and a height of approx. 55 centimeters. Females around 4 years old and around 57 centimeters tall. The Argentine populations do not reach sexual maturity until about 5 years and 55 to 75 centimeters in male sharks. In female sharks at approx. 6 years and a length of approx. 60 to 80 centimeters.
behavior
The Argentine smooth shark is found close to the ground on the continental shelf off the east coast of South America. Mostly between 60 and 190 centimeters deep. Due to its small size, it can also be found in extremely shallow waters, so it happens that it even penetrates into rivers and canals. It can also track its prey to ports. Its prey consists of small schooling fish, bottom-dwelling invertebrates such as crabs, and organic waste near urban areas.
Danger
The shark has been subject to heavy fishing throughout its habitat since the 1980s , regardless of whether it is caught alone or as bycatch. In the winter of 1997, the population in southern Brazil shrank by 85 percent, but the stock continued to be fished. The population that lives in southern Brazil in summer even seems to have disappeared. In Argentina , the catch of the narrow-nose smooth shark has played a role since 1960; For the first 7 years of record, the stock fished was always below 4,500 tonnes, but then it rose and peaked in 1988 at 13,597 tonnes. After that, the catch fell back to 10,000 tons per year.
Catching near breeding grounds and shark schools is particularly detrimental to the population. Due to the decreasing population, the captured mass of sharks is also shrinking. According to the FAO, 8,157 tons of this species were fished in 2000 and only 4,538 tons in 2014. Although the populations could recover fairly quickly, the conservation of this species is very difficult as it continues to be heavily fished.
There is currently a maximum allowable catch (MPC) set by the Argentine Fisheries Organization. MPC stands for Maximum Permitted Catch . Although the MPC has been reduced annually for the past four years, the Mustelus schmitti population continues to decline. The IUCN proposes an international management of Argentina, Uruguay and Brazil for the protection of the species. A sanctuary for this species should be established, especially near breeding grounds and shark schools.
Given these circumstances, it is believed that populations will continue to decline and therefore this species is classified as Critically Endangered by the IUCN .
literature
- Antal Vida: 365 fish . Tandem Verlag 2006, ISBN 3-8331-2070-3 , p. 31.
supporting documents
- ↑ a b c d e f Antal Vida: 365 fish . Tandem Verlag 2006, ISBN 3-8331-2070-3 , p. 31.
- ↑ a b c d e f g h Mustelus schmitti in the Red List of Threatened Species of the IUCN 2017-1. Posted by: Massa, A., Hozbor, N., Chiaramonte, GE, Balestra, AD & Vooren, CM, 2006-01-31.
- ↑ a b c Mustelus schmitti on Fishbase.org (English)
- ↑ a b c d Leonard JV Compagno : FAO SPECIES CATALOG. Vol.4. Sharks of the world. Part 2. Carcharhiniformes, 1984, ISBN 92-5-101383-7 , pp. 424–425 ( PDF; 27 MB ( page no longer available , search in web archives ) Info: The link was automatically marked as defective. Please check the link according to the instructions and then remove this notice. ).
- ^ A b Food and Agriculture Organization of the United Nations: Mustelus schmitti (Springer, 1940). FAO Departments and Offices, accessed July 31, 2017 .
Web links
- Engnasen-Glatthai on Fishbase.org (English)
- Mustelus schmitti inthe IUCN 2017-1 Red List of Endangered Species . Posted by: Massa, A., Hozbor, N., Chiaramonte, GE, Balestra, AD & Vooren, CM, 2006-01-31.