An extremely rare and poorly understood houndshark, the sharpfin houndshark (Triakis acutipinna) is named for the sharp tips of its fins, from which the scientific name of ‘acutipinna’ is defined. Although very few descriptions of living sharpfin houndsharks have been made, the colour of a preserved specimen in alcohol indicates that it is uniformly brownish-grey on upperparts, fading to a brownish-yellow underneath. The fins are slightly darker than the body with a patch of white at the tips, and the lateral line has tiny white spots (3).
A rare and elusive shark, the sharpfin houndshark has a broad head and a rounded mouth, with tiny spiracles located behind the eyes. The gill slits are slightly arched, and this shark has conspicuous pores on its long snout. Its nostrils are separated from the mouth, and the teeth have large cusps, or projections (3).
The sharpfin houndshark, as with all houndsharks, has two moderately sized spineless dorsal fins, an anal fin, and membranes over its oval eyes (4). It also has long, narrow pectoral fins, which are curved in adults (2).
- Also known as
- Tollo del Ecuador.
- Maximum adult male length: 90 cm (2)
- Maximum adult female length: 102 cm (2)
Sharpfin houndshark biology
There is very little known about the biology and life history of the sharpfin houndshark (1). Other species in the genus Triakis are either ovoviviparous or viviparous, so it is likely that this species uses one of these reproductive strategies (3).
Species in the family Trakidae often feed primarily on invertebrates and bony fishes (4).
Sharpfin houndshark range
The sharpfin houndshark is endemic to Ecuador, in the Province of Manabí in the south-eastern Pacific Ocean. Its exact distribution is unknown; however, it is estimated to inhabit an area no larger than 5,000 square kilometres (1).
Sharpfin houndshark habitat
The sharpfin houndshark is found in tropical continental waters (1).
Sharpfin houndshark status
The sharpfin houndshark is classified as Endangered (EN) on the IUCN Red List (1).
Sharpfin houndshark threats
Small scale fisheries are common throughout Ecuador and sharks, including hound sharks, are often victims of bycatch. Sharks used to be specifically targeted by Ecuadorian fishing communities; however, this was banned in 2004. Nevertheless, catch statistics are poorly documented and there is inadequate monitoring of fishing activities (1).
Shark fins continued to be exported illegally from Ecuador, and so export of shark fins and meat from bycatch is now permitted as a means of monitoring shark catches. Small scale fisheries in the port of Daniel López are said to rarely catch the sharpfin houndshark; however, it is unknown how frequently it is caught at other fisheries (1).
Sharpfin houndshark conservation
There is little management of fisheries in Ecuador; however, a recently introduced national action plan for the protection of sharks, which aims to reduce the numbers of sharks caught as bycatch, as well as increasing the number of Marine Protected Areas (MPAs) off Ecuador from 13 to 15, should hopefully aid shark population recovery in this area (1) (5).
As so little is known about the sharpfin houndshark, field surveys are required to learn about its distribution and habitat, and to find out which fisheries are catching it. The rarity of this species, and its presence in exploited waters, means immediate conservation actions, such as full legal protection, may be needed to ensure this shark’s future survival (1).
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- Anal fin
- In fish, an unpaired fin on the under surface of the fish, behind the anus.
- In the fishing industry, the part of the catch made up of non-target species.
- Dorsal fin
- The unpaired fin found on the back of the body of fish, or the raised structure on the back of most cetaceans (whales, dolphins and porpoises).
- A species or taxonomic group that is only found in one particular country or geographic area.
- A category used in taxonomy, which is below ‘family’ and above ‘species’. A genus tends to contain species that have characteristics in common. The genus forms the first part of a ‘binomial’ Latin species name; the second part is the specific name.
Invertebrates: animals with no backbone, such as insects, crustaceans, worms, molluscs, spiders, cnidarians (jellyfish, corals, sea anemones) and echinoderms.
- Animals with no backbone, such as insects, crustaceans, worms, molluscs, spiders, cnidarians (jellyfish, corals, sea anemones) and echinoderms.
- Lateral line
- A row of receptors that can detect movement via vibrations in water. The receptors are typically embedded in the skin, and in fish they form a line along the sides of the body.
- Producing young that develop inside eggs, but the eggs hatch inside the female’s body and the young are born live.
- Pectoral fins
- In fish, the pair of fins that are found on either side of the body just behind the gills. They are generally used for balancing and braking.
- In sharks and some other fish, small holes behind the eye through which the fish can take in water while lying on the seabed. Water enters the spiracles and is passed out over the gill openings, bypassing the mouth.
- Giving birth to live offspring that develop inside the mother’s body.