FAMILY: Carcharhinidae
SCIENTIFIC NAME: Carcharhinus melanopterus
COMMON NAMES: Blacktip Reef shark, Black Fin Reef Shark, Black Finned Shark, Blackfin Reef Shark, Blacktip Shark
TYPE: Fish
IUCN Red List Status: Vulnerable (assessed 2020)
Blacktip reef sharks are named for the characteristic black tips or margins on their fins. Additionally, Their coloring provides camouflage from above or below; a dark back helps them blend in with the dim seafloor and a white belly blends in with the brighter ocean surface.
SIZE:
Blacktips can grow to 6ft with most adults reaching less than 5.25 ft (1.6 m) in total length. Males mature around 3-3.25 ft and females mature between 3- 3.7 ft.
AVERAGE LIFE SPAN:
Blacktip reef sharks can live 15-25 years based off of field samples as well as captive animal data.
This species is viviparous with both annual and biennial reproductive cycles reported across its range. Mating generally occurs during the summer or early autumn months with gestation varying by location from 8-9 months, 10-11 months, or 16 months.
Shark pups are born from late winter to early summer with most blacktip reef shark litters containing 2-4 pups (usually 4). Pups are 13-20 inches (33-52 cm) at birth and utilize mangrove systems during their early life if available.
DID YOU KNOW:
Blacktip reef sharks swim in shallow waters just a few meters deep near reefs, drop-off zones and have also been sighted in brackish water.
DISTRIBUTION:
The Blacktip Reef Shark occurs in tropical and subtropical waters. They prefer shallow, clear waters (up to at least 75m). This species can be found on coral reefs, reef and sand flats, over reef drop offs, in atolls as well as mangrove environments they use as nurseries. These sharks have small home ranges, exhibiting strong site fidelity and restricted movements that appear to be closely tied to the distribution of coral reef habitat
Blacktip reef sharks are one of the most common species at islands in the Pacific Ocean, as far east as the Hawaiian Islands.
They can be found along the coastlines of Pacific regions like Thailand, Japan, Philippines, New Caledonia and northern Australia as well as in the Indian Ocean from South Africa to the Red Sea.
DIET:
Often found in small groups or aggregations, blacktip reef sharks primarily feed on reef fish (wrasses, surgeonfish, groupers, jacks, etc.) but are also known to eat crustaceans, cephalopods and mollusks (cuttlefish, squid, octopus, shrimp).
Interestingly, these sharks have also been reported to have consumed terrestrial and sea snakes!
CONSERVATION:
The reliance on coral reefs makes this species particularly susceptible to climate change which has already resulted in large-scale and more frequent coral bleaching events worldwide. According to the IPCC report (2019), almost all warm-water coral reefs are projected to suffer significant losses of area and local extinctions, even if global warming is limited to 1.5 ºC.
Coral reef ecosystems and the marine species that live on and around them- including sharks, face other threats like destructive fishing practices, declining water quality due to human-caused pollution and ever more frequent environmental disasters like oil spills.
In addition to habitat destruction, blacktip reef sharks are targeted for their fins, meat and liver oil. They are caught throughout their range in industrial and small scale longline, gillnet, trawl and handline fisheries- most taken as bycatch. Blacktips are a commonly utilized species for display in public and private aquaria worlwide and are exported live from countries like Australia and Indonesia for that industry.
For all the threats sharks face, there is hope through governments realizing the importance of establishing marine protected areas and the economy boost that eco-tourism through diving can bring in. Indeed, divers report blacktip reef sharks are a inquisitive species that are usually easy to drive off if they come too close.
However, around speared fish, sharks can become more aggressive which may be exacerbated by the presence of other competing sharks. In these scenarios, Blacktip reef sharks rush in to take wounded fish or baits that have led to injuries but overall, this species does not pose a serious threat to humans.
Specifically, this shark species is responsible for non-fatal incidents involving spearfishermen, surfers, swimmers and waders. The International Shark Attack File (ISAF) has recorded just 11 unprovoked blacktip reef shark bites on humans since 1959.
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