Commercial and recreational fishing practices, the effect of non-shark fisheries on the prey base of the sharks and their habitat, the alterations of shark habitat by humans, marine pollution, and coastal development are some of the reasons that are threatening the survival of the shark species of the world. The demand for shark products has risen over the years, fuelling the hunting of sharks. Such activities are little regulated or monitored. It has been reported that some species of sharks have suffered a nearly 90% population decline, as nearly 100 million sharks are killed by fishing activities each year. The killing of sharks for shark fin soup is also highly prevalent. Given all the above reasons, there is little doubt why the conservation status of many species of sharks is today labeled as critically endangered, endangered, or vulnerable on the IUCN Red List. Here, we discuss some of the most threatened species of shark and the factors which have been responsible for their critically endangered status:
10. Natal shyshark
The Natal shyshark (Haploblepharus kistnasamyi) is a catshark species of the family Scyliorhinidae. The shark is endemic to a small area off the coast of South Africa. It prefers to stay near the coast and has benthic habits (meaning close to the seabed). The shark is threatened by commercial fishing activities and habitat degradation and is therefore classified as "critically endangered" by the IUCN.
9. Pondicherry shark
The Pondicherry shark (Carcharhinus hemiodon) is a species of requiem shark who belongs to the Carcharhinidae family. The shark is relatively small in size and does not usually grow longer than 3.3 feet. The sharks have a stocky body with a long, pointed snout. The teeth structure of the species is unique, with upper teeth being smooth-edged at the tip and strongly serrated at the base. The shark has prominent black tips on the pectoral, caudal, and second dorsal fin. The Pondicherry shark was once widespread throughout the coastal waters of the Indo-Pacific region stretching from New Guinea to the Gulf of Oman. However, currently, the sightings of this species have only been reported in the rivers in Sri Lanka. Most aspects of the biology of this species are unknown since only about 20 specimens of this species have been studied. The shark is known to feed on bony fishes, crustaceans, and cephalopods. The escalating fishing pressure within the range of this species is regarded to be the biggest threat to their survival.
8. Angel shark
Squatina squatina is an angelshark species, also known as monkfish that belongs to the family Squatinidae. The shark was once widespread in the coastal waters of the northeastern Atlantic Ocean. Today, however, extensive fishing in the range of this shark species has greatly reduced the numbers of this shark. Coupled with the low reproductive rate of this species, the sharks have become highly endangered necessitating the need for them to be classified as critically endangered by the IUCN. The monkfish are well adapted to camouflage themselves on the ocean floor. They have a flattened form and large pectoral and pelvic fins. They possess a stout, broad body, thornless back, conical barbels, and grayish or brownish color on the dorsal surface. The shark is an ambush predator who hunts at night. They feed on prey like benthic bony fishes, invertebrates, and skates. These sharks usually do not pose any threat to humans but may attack if disturbed.
7. Smoothback angel shark
The smoothback angelshark (Squatina oculata) is a shark species that belongs to the Squatinidae family of sharks. It is found in the eastern Atlantic Ocean between the latitudes 47°N and 28°S. The sharks grow up to 1.6 meters in length and are ovoviviparous in nature, meaning they reproduce by hatching eggs. Due to overfishing off the coast of Africa and death as bycatch, the smoothback angelshark has been classified as critically endangered by the IUCN.
6. Sawback angelshark
The sawback angelshark (Squatina aculeata) is an angelshark species belonging to the Squatinidae family. The sharks are dull gray to light brown in color with scarcely distributed small irregular white spots and regular dark brownish spots. The sawback angelsharks occur in the eastern Atlantic Ocean where they range from the western Mediterranean coast to the western Atlantic coast of Africa. Little is known about the behavior and biology of this shark species, except that they are known to feed on bony fishes, crustaceans, cuttlefish, and other small sharks. The sharks have a long minimum population doubling time of 4.5 to 14 years making them highly vulnerable to threats within their habitat.
5. Striped smooth-hound
The striped smooth-hound (Mustelus fasciatus) is a shark belonging to the Triakidae family. The sharks are found on the subtropical southwest Atlantic Ocean’s continental shelves. The range of this species stretches from northern Argentina to southern Brazil. The sharks can attain a length of 1.5 meters. The sharks are classified as "critically endangered" by the IUCN.
4. Daggernose shark
The daggernose shark (Isogomphodon oxyrhynchus), the only extant member of the Isogomphodon genus, lives in the shallow tropical waters off the coast of northeastern South America. The shark favors muddy habitats such as estuaries, mangroves, and river mouths within its range. The shark is quite small with a length of about 4.9 feet. It has tiny eyes, a pointed and flattened snout, and big paddle-shaped pectoral fins. The daggernose shark is highly threatened with IUCN classifying the species as critically endangered. It is possible the species might be going through a phase of reproductive collapse that might lead to its extinction in the near future. The fish is caught by humans for food and also as bycatch. The slow reproductive rate and restricted range of the daggernose shark further threaten the survival of the species.
3. Irrawaddy river shark
The Irrawaddy river shark (Glyphis siamensis) is an extremely rare shark species about whom very little is known. Only one specimen of this species that was caught at the Irrawaddy River’s mouth in Myanmar and housed in a museum, has been extensively studied. The shark is plain gray in color, has a thick body, tiny eyes, broad first dorsal fin, and a short rounded snout. The Irrawaddy river shark is believed to be a fish eater and viviparous in nature. Although little is known about this rare shark species, it is believed that the species is subjected to several threats such as overfishing, water pollution, and habitat degradation.
2. New Guinea river shark
The New Guinea river shark (Glyphis garricki), also known as the northern river shark, has a scattered distribution in the tidal rivers and coastal waters of Papua New Guinea and northern Australia. The sharks prefer a habitat with soft bottoms, large tides, and poor visibility. The sharks have a stocky gray color, high back, broad fins, and tiny eyes. They are about 8.2 feet long. The New Guinea river sharks are piscivorous and viviparous with females giving birth to litters of about 9 offsprings every alternate year. The sharks are classified as critically endangered by the IUCN and suffer from habitat degradation or die as bycatch of fishing.
1. Ganges shark
The Ganges shark (Glyphis gangeticus) lives in the waters of the Ganges River and the Brahmaputra River, and some of their tributaries and distributaries in India and Bangladesh. The critically endangered species is often confused with the bull shark (Carcharhinus leucas) which is a more common shark species sharing the Ganges River habitat with the Ganges shark. The Ganges sharks are true river sharks which do not need to migrate to the salt water to reproduce. Very little is known about the Ganges shark due to its rarity. The species grows to a length of about 5.8 feet at maturity and has a stocky appearance. The sharks can be identified by the presence of a second dorsal fin that is about half the height of the first dorsal fin. The Ganges shark is vulnerable to habitat changes since the species has a highly restricted range. Overfishing, pollution, developmental activities, dam construction, and habitat degradation are major threats to this species.