Giant tiger shark captured in offshore waters near Indus Swatch
Karachi,Agigantic tiger shark was captured by fishermen about 186 km south of Karachi in the Indus Swatch area, off Keti Bunder on 9 October 2016.The specimen measured 3.8 metre in length and weighted 550 kg. The tiger shark is are quiem shark known for its ferocious nature and is widely distributed in tropical and subtropical waters of the Indian, Pacific and Atlantic Oceans. Although a large number of tiger sharks were caught in Pakistani waters previously, their stocks are now dwindling andits capture has become rare. A few specimens are caught every month but are usually small (about 50 to 150 kg). However, catching a large specimen of more than 200 kg is very rare in Pakistan.
Locally known as nar mani in Balochi and aiyan more or aiyan in Sindhi, tiger sharks are caught mainly by bottom set gillnet and long lines. In addition, they are also caught by handline using live bait and pelagic gillnets. Although tiger sharks are caught along the Pakistan coast the Indus Swatch area is one of three hotspots while the other two are off Ormara and Jiwani. The Indus Swatch is a deep canyon at the mouth of the Indus River and has a maximum depth of more than 1,000 m. Shark concentrations have been reported from both sides of the canyon up to a depth of 300 m. Tiger sharksare also reported in shallow coastal waters and in estuary and lagoon areas along the Pakistani coast.
Noor Muhammad, a WWF-Pakistan trained fisherman who captured the shark said that the species was already dead when it was retrieved from the water. It was too large to be handled and preserved and thusthe fisherman used a mechanical lifting device. The male tiger shark was landed at Karachi Fish Harbour where it was weighed and auctioned at PK 55,000 and converted into finger fish for sale in the market. ‘Its liver weighed about 150 kg and around 120 litres of oil was extracted, which will be used to smear the hull of fishing boats to keep them smooth and free from fouling organisms,’ he added.
According to Muhammad Moazzam Khan, Technical Advisor (Marine Fisheries), WWF-Pakistan ,tiger sharks were once common along the coast of Pakistan. However, due to excessive overfishing, especially during 1987 and 2002, aimed shark fisheries almost collapsed. Larger specimens of sharks have already diminished and it is very rare that they are caught. The tiger shark is a prolific breeder and a female produces about 10 to 80 pups in a litter but due to excessive fishing stock have seriously declined. The species is considered near threatened according to the International Union for the Conservation of Nature(IUCN) Red List because of excessive pressure from fishing, including finning, and demand for its meat.
Considering the over-exploitation of sharks, the Government of Sindh and Balochistan recently enacted a ban on catching a number of shark species including rare silky, oceanic white tip, thresher, whales and hammerhead sharks as well as guitarfish and mobulids which are relatives of sharks.
The tiger shark is a voracious predator and fishermen are very careful when dealing with its entanglement in line gears as it is known for unprovoked attack. It is killed using spears and harpoon before being hauled on to a fishing boat. The tiger shark is known to consume a variety of prey including shrimp, crab, lobster, fish, marine mammals, birds, squid, turtle sand sea snakes and dolphins and even other sharks. The tiger shark has been known to eat inedible, floating objects including tires, wood, cans and even stones, therefore, it is also known as a ‘garbage eater’ shark.
Rab Nawaz, Senior Director Programmes, WWF-Pakistan pointed out that sharks such as tiger sharks are apex predators of the ecosystem of coastal and offshore waters and their decline has disturbed the tropic balance resulting in the appearance of some species which were not found in abundance in the past. The Indian mackerel is one such species which was not caught commercially before 2000 but removal of the apex predator has likely resulted in its increase (annual landings reached around 50,000 m. tons by 2005). The Indian mackerel is now a major target species of large fishing fleets in the coastal area and its landings, although reduced to about 20,000 m. tons annually, still supportsthe large processing industry in Pakistan.
Rab Nawaz also said that WWF-Pakistan initiated studies on shark resources in 2012, which revealed that major shark stocks in offshore waters are depleting whereas sharks harvested by fleets in coastal waters are also under serious threat. He stressed the need for the implementation of legislations to ensure protection of shark resources which were recently promulgated. ‘There is also an urgent need for endorsement of National Plan of Action (NPOA)by the provincial governments for protection of the sharks,’ he added.
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