: Marine researchers have identified three rare species of sharks caught by fishers in Thiruvananthapuram over the last week, highlighting the need for systematic documentation of marine biodiversity in the region.
The three species were identified as part of a marine biodiversity survey undertaken by Friends of Marine Life, a city-based non-governmental organisation. According to the fishers, two species, the Common Thresher and Shortfin Mako shark, were caught from the deep sea region, about 300 km off the Thiruvananthapuram coast at a depth of 200 metres, while the third, a Tiger Shark, was netted about 100 km from the coast.
Distinguished by a long tail, the Common thresher ( Alopias vulpinus ) has a streamlined body and short pointed snout. It is blue in colour, with a white band running along its belly. The IUCN Red List of species has classified A. vulpinus as vulnerable because of its declining population due to a combination of slow life history characteristics, inability to recover from moderate levels of exploitation and high level of mortality in target and bycatch fisheries.
Listed as vulnerable, the Shortfin Mako shark or Bonito shark ( Isurus oxyrinchus ) is cylindrical in shape with a vertically elongated tail, pointed nose and hook-like teeth. It is distinguished by its combination of brilliant metallic blue and white.Significant decline
The IUCN has estimated that the species may have undergone significant decline in abundance over various parts of its habitat. The species is threatened by high fishing pressure and its vulnerable life history characteristics.
A near threatened species, the Tiger shark ( Galeocerdo cuvier ) is a large predator with nocturnal hunting habits and sometimes referred to as a man eater shark. Characterised by the dark stripes on its body resembling a tiger skin, the shark is hunted across the world for its meat and fins. G. cuvier is caught regularly in target and bycatch fisheries leading to the decline of several populations.
According to Robert Panipilla, chief coordinator, FML, the identification of the three species underlined the need to document the rich traditional knowledge of the fishermen community.