The dusky shark (Carcharhinus obscurus) also known as the bay shark, black whaler, brown common gray shark, brown dusky shark, brown shark, common whaler, dusky ground shark, dusky whaler, river whaler, shovelnose, and slender whaler shark, is a species of requiem shark, in the family Carcharhinidae, occurring in tropical and warm-temperate continental seas worldwide. There have been some accounts in Madeira, Portugal, Spain, and Morocco.In the western Atlantic Ocean, it is found from Massachusetts and the Georges Bank to southern Brazil, including Cuba and the Bahamas.In the Indian Ocean, the Dusky shark can be found off South Africa, Mozambique, and Madagascar, with some records in the Arabian Sea, the Bay of Bengal, and even the Red Sea.In the Pacific Ocean, the Dusky shark can be found off the coast of Japan, mainland China and Taiwan, Vietnam, Australia, and New Caledonia in the west, and from southern California to the Gulf of California, around Revillagigedo, and even possibly off northern Chile.The Dusky shark is nomadic and strongly migratory, with recorded distances of up to 2,400 miles. This is a list of recorded fatal shark attacks in South African territorial waters in reverse chronological order. Mitochondrial DNA and microsatellite evidence suggest that Indonesian and Australian sharks represent distinct populations.In the eastern Atlantic Ocean, it has been reported from the western and central Mediterranean Sea, the Canary Islands, Cape Verde, Sierra Leone, and Senegal. Dusky sharks in the western Atlantic seem to produce slightly smaller litters than those from the southeastern Atlantic. Prey – Small sharks feed on bottom dwelling animals. The white shark reference I linked to in the article included reports of bite scarring on living juvenile North Atlantic right whales, suggesting the sharks attacked whales that were healthy enough (or had a parent nearby) to survive the attack.
This would be advantageous given the sharks’ itinerant natures and low natural abundance, which would make encounters with suitable mates infrequent and unpredictable. It is one of the slowest growing shark species. It is interesting that in some locations, despite this fact, some areas and locations seem to have much higher concentrations of Dusky sharks.Dusky sharks can sometimes be found following ships far from land. Dusky sharks are a part of the annual Sardine Run off the eastern coast of South Africa every winter. (Jr.) (1993). Newborn and juvenile sharks subsist mainly on small pelagic prey such as sardines and squid; older sharks over 6.6 feet long will start to eat larger bony and cartilaginous fishes. The annual estimated growth rate is 3.1–4.3 inches over the first five years of its life.The maximum lifespan of a Dusky shark is believed to be 40–50 years or more.The Dusky shark is positioned as an apex predator at the top trophic web. Large specimens feed on a variety of reef and pelagic fish including sardines, tunas, eels, lizardfishes and flatfishes, smaller sharks, rays, skates, squid, octopus, cuttlefish, crabs, lobsters, starfish, barnacles, bryzoans and even whale meat and garbage.Reproduction – Viviparous, with a yolk-sac placenta.
Dusky shark is a carnivore (meat-eater). Size at birth is 27 to 39 inches [69 to 100 cm]. However, pregnant females, or post-partum females do not participate. In South African and Australian waters, bony fishes are again the most important prey type. Dusky shark Carcharhinus obscurus . (Pratt, H.L.