Sharks are not all grey, but can have color. Not only the impressive bold colors of some wobbegong sharks, but there is the red of the ginger carpet shark, the dark blue of the Blue shark, the pink of the Goblin and Sofa sharks and the lime green of the lemon shark. And there is the beautiful bronze of some (others are grey) brown sharks (Carcharhinus plumbeus). Due to their preferred habitat they are also called sandbar sharks.

Carcharhinus plumbeus front.jpg
Von Srinayan Puppalashark, CC BY-SA 2.0

Like with nearly all colors, the choice to wear brown is a result of the chosen habitat of the shark – camouflage is key. This species can be found over muddy or sandy bottoms in river mouths or bays (especially newborn or juveniles) in tropical to temperate shallow coastal waters worldwide, even in the Mediterranean Sea. It is known for seasonal migration (influenced mainly by temperature) and sex-segregated schools. It is an opportunistic bottom-feeder and preys on relatively small fishes, mollusks and crustaceans. In comparison to other requiem sharks, sandbar sharks thus receive a more regular supply of food (inferred from stomach contents).

As apex predators sandbar sharks mature slowly (at 13 years old) and females give birth to only 8 living young (ovoviviparous) biennially or triennially after a year long gestation period. It is remarkable that both sexes are almost always represented in a 1:1 ratio in a litter. Sandbar sharks can live up to 35–41 years.

Despite being one of the biggest coastal sharks in the world (up to 8.2 ft – 2.5 m – long, in average 6 ft – 1.8 m), the sandbar shark is no danger to humans (there have been reported only 5 biting incidents with sandbar sharks in the last 400 years), since it is essentially a bottom-dwelling species that is seldom seen at the water’s surface and feeds on only small prey. It is considered one of the safest sharks to swim with.

Worldwide the sandbar shark is valuable to recreational fishermen as a game fish and targeted commercially for its meat, skin, liver oil and especially fins. Often pregnant females are particularly targeted when they move inshore to give birth, intensifying the problem. It resulted in a Near Threatened status. But measures to protect sharks by regulations requiring carcasses to be landed along with shark fins, as taken by U.S. and European governments, had unexpected consequences. Due to their high fin-to-body weight ratio (because of its taller than average first dorsal fin) in recent decades sandbar sharks became the primary targeted species in the commercial shark fishery along the eastern United States (they are not native at the west coast). Now, it is globally assessed as Vulnerable, even Endangered in the Mediterranean Sea and other European waters (but Least Concern in Hawaii since it is not fished there). In 2008, the U.S. fishery agency NMFS banned all commercial landings of sandbar sharks, a measure that European governments have yet to take (except Turkey).

Sources: herehere and here

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