Although there are no active reef shark fisheries in the US Pacific, the reef sharks' disappearance could be caused by recreational fishing or illegal shark finning, which, combined, kill 26 million to 73 million sharks each year. Another possible explanation is that the reef sharks are starving. Their food sources, including coral reef fishes, are decreasing in number because of habitat destruction and human exploitation, and could be taking the sharks with them.

Cyanobacteria do not have skeletons and individuals are microscopic. Cyanobacteria can encourage the precipitation or accumulation of calcium carbonate to produce distinct sediment bodies in composition that have relief on the seafloor. Cyanobacterial mounds were most abundant before the evolution of shelly macroscopic organisms, but they still exist today (stromatolites are microbial mounds with a laminated internal structure). Bryozoans and crinoids, common contributors to marine sediments during the Mississippian (for example), produced a very different kind of mound. Bryozoans are small and the skeletons of crinoids disintegrate. However, bryozoan and crinoid meadows can persist over time and produce compositionally distinct bodies of sediment with depositional relief.
Based on morphological similarities, Jack Garrick in 1982 grouped this species with the bignose shark (C. altimus) and the sandbar shark (C. plumbeus), while Leonard Compagno in 1988 placed it as the sister species of the grey reef shark (C. amblyrhynchos). A phylogenetic analysis based on allozyme data, published by Gavin Naylor in 1992, indicated that the Caribbean reef shark is the sister taxon to a clade formed by the Galapagos shark (C. galapagensis), dusky shark (C. obscurus), oceanic whitetip shark (C. longimanus), and the blue shark (Prionace glauca). However, more work is required to fully resolve the interrelationships within Carcharhinus.[3]
In California, Reef Check helps ensure the long-term sustainability and health of the nearshore rocky reefs and kelp forests. Reef Check California volunteers are divers, fishermen, kayakers, surfers, boaters, and a wide range of Californians who take a proactive role in making sure that our nearshore ecosystems are healthy and well managed. We monitor rocky reefs inside and outside of California's marine protected areas (MPAs). We work with marine managers, researchers and the public to provide the scientific data needed to make informed, science-based decisions for the sustainable management and conservation of California's ocean environment. We would love your support, volunteer today!
A heavy-bodied shark with a "typical" streamlined shape, the Caribbean reef shark is difficult to distinguish from other large requiem shark species. It usually measures 2–2.5 m (6.6–8.2 ft) long; the maximum recorded length is 3 m (9.8 ft) and the maximum reported weight is 70 kg (150 lb).[5][6] The coloration is dark gray or gray-brown above and white or white-yellow below, with an inconspicuous white band on the flanks. The fins are not prominently marked, and the undersides of the paired fins, the anal fin, and the lower lobe of the caudal fin are dusky.[2][4]

Typically a solitary animal, juvenile blacktip reef sharks will commonly conjugate in shallow regions during high tide. Vulnerable to larger predators, they will reside in shallower areas until larger in size. Blacktip reef sharks tend to be more active during dawn and dusk, but like most sharks they are opportunistic feeders. Their diet consists of crustaceans, squid, octopus, and bony fish.
The Caribbean reef shark was originally described from off the coast of Cuba as Platypodon perezi by Poey in 1876. Bigelow and Schroeder later described the same species as Carcharhinus springeri in 1944 and the reef shark appears in much literature under this scientific name. The genus name Carcharhinus is derived from the Greek “karcharos” = sharpen and “rhinos” = nose. The currently accepted valid name is C. perezi (Poey 1876).
The International Union for Conservation of Nature (IUCN) has assessed the Caribbean reef shark as Near Threatened; its population has declined off Belize and Cuba from overfishing and exploitation continues in other regions. They are also threatened by the degradation and destruction of their coral reef habitat.[1] Commercial fishing for this species is prohibited in United States waters.[4] They are protected in the Bahamas due to their significance to ecotourism, as well as in a number of Marine Protected Areas (MPAs) off Brazil and elsewhere. However, enforcement against illegal fishing is lacking in some of these reserves, and many areas in which this species is abundant are not protected.[1]
Generally a coastal, shallow-water species, grey reef sharks are mostly found in depths of less than 60 m (200 ft).[11] However, they have been known to dive to 1,000 m (3,300 ft).[2] They are found over continental and insular shelves, preferring the leeward (away from the direction of the current) sides of coral reefs with clear water and rugged topography. They are frequently found near the drop-offs at the outer edges of the reef, particularly near reef channels with strong currents,[12] and less commonly within lagoons. On occasion, this shark may venture several kilometers out into the open ocean.[4][11]
Grey reef sharks are often curious about divers when they first enter the water and may approach quite closely, though they lose interest on repeat dives.[4] They can become dangerous in the presence of food, and tend to be more aggressive if encountered in open water rather than on the reef.[13] There have been several known attacks on spearfishers, possibly by mistake, when the shark struck at the speared fish close to the diver. This species will also attack if pursued or cornered, and divers should immediately retreat (slowly and always facing the shark) if it begins to perform a threat display.[4] Photographing the display should not be attempted, as the flash from a camera is known to have incited at least one attack.[3] Although of modest size, they are capable of inflicting significant damage: during one study of the threat display, a grey reef shark attacked the researchers' submersible multiple times, leaving tooth marks in the plastic windows and biting off one of the propellers. The shark consistently launched its attacks from a distance of 6 m (20 ft), which it was able to cover in a third of a second.[14] As of 2008, the International Shark Attack File listed seven unprovoked and six provoked attacks (none of them fatal) attributable to this species.[29]
Although they only grow to about 1.6 to 3 meters (5 to 10 feet) in length, these sharks are the apex predators on the very delicate coral reefs. That means, around coral reefs, they are the top of the food chain. The significants of this goes largely unnoticed, but theWorld Wildlife Fund has classified the Reef Shark as one of the most important species on the entire planet!
Off Enewetak, grey reef sharks exhibit different social behaviors on different parts of the reef. Sharks tend to be solitary on shallower reefs and pinnacles. Near reef drop-offs, loose aggregations of five to 20 sharks form in the morning and grow in number throughout the day before dispersing at night. In level areas, sharks form polarized schools (all swimming in the same direction) of around 30 individuals near the sea bottom, arranging themselves parallel to each other or slowly swimming in circles. Most individuals within polarized schools are females, and the formation of these schools has been theorized to relate to mating or pupping.[25][26]
A heavy-bodied shark with a "typical" streamlined shape, the Caribbean reef shark is difficult to distinguish from other large requiem shark species. It usually measures 2–2.5 m (6.6–8.2 ft) long; the maximum recorded length is 3 m (9.8 ft) and the maximum reported weight is 70 kg (150 lb).[5][6] The coloration is dark gray or gray-brown above and white or white-yellow below, with an inconspicuous white band on the flanks. The fins are not prominently marked, and the undersides of the paired fins, the anal fin, and the lower lobe of the caudal fin are dusky.[2][4]
Reef Ambassadors are forever just passing through, crossing borders, taking in cultures, and exploring foreign shores. And now you can follow our ambassadors more closely, as we roll out a new monthly film series for 2016, showcasing their adventures in the best waves around the globe. This 10 Episode series will bring you along with our team to far off, exotic locales to iconic surf destinations.
×