Galapagos Shark, Carcharhinus galapagensis
Galapagos Shark, Carcharhinus galapagensis. Fish caught from coastal waters off Lord Howe Island, Australia, October 2016. Length: 1.47 m (4 feet 10 inches). Catch, photograph and identification courtesy of Eli (obsessiveangling.wordpress.com).
The Galapagos Shark, Carcharhinus galapagensis, is a member of the Requiem Shark or Carcharhinidae Family, that is known in Mexico as tiburón de Galápagos. Globally, there are thirty-five species in the genus Carcharhinus, of which seventeen are found in Mexican waters, seven in the Atlantic, four in the Pacific, and six in both the Atlantic and Pacific Oceans.
The Galapagos Shark is a large shark has a slender, streamlined fusiform shark-like body. They are brownish gray dorsally transitioning to white ventrally with faint white stripe on the sides. Their fins are a uniform darker color. Their caudal fin is strongly asymmetrical with a well-developed lower lobe with a notch under the tip of the upper lobe; the first dorsal fin is large with a straight front edge and a short rear tip that originates over the rear of the pectoral fins and is tall and sickle shaped; the second dorsal fin originates over the anal fin; their pectoral fins are large, semiflacate and narrowly rounded to pointed tips with a straight rear edge; and, their pelvic fins are well behind the first dorsal fin. Their is a low inter-dorsal ridge between the first and second dorsal fins. Their head has a moderately long broadly rounded snout with indistinct anterior nasal flaps, round large eyes and a mouth that has 14 rows of teeth on both sides of the jaw, plus one tooth at the symphysis. The upper teeth are serrated, triangular and stout; the lower teeth are narrower with serrated edges.
The Galapagos Shark form large aggregations in shallow island waters with a preference for clear waters with strong currents over coral, reef and rocky substrate around oceanic islands from the surface to depths of 286 m (940 feet). They are one of the largest coastal sharks reaching a maximum of 3.3 m (13 feet 0 inches) in length and 85.5 kg (188 lbs) in weight with females being larger than males. As of March 31, 2023, the International Game Fish Association world record for weight stood at 140 kg (309 lbs) with the fish caught in coastal waters off Ascension Island in July 2004. They are active predators often found in large groups that consume a wide variety of bottom fishes, octopus, seals, sea lions and squid with their diets changing to rays and smaller sharks as they mature. They are known to practice cannibalism on their juveniles. Reproduction is aplacental viviparous and occurs once every two or three years. The embryos are nourished by a yolk-sac placenta, require one full year to develop inside their mother and are born live. Liter sizes are four to sixteen 57 cm (22 inch) to 80 cm (2 feet 7 inch) pups that are born in shallow nursery areas that appear as miniature adults. The juveniles remain in shallow water at depths less than 25 m (82 feet) for a couple of years to avoid predation. They have life spans of 24 years.
The Galapagos Shark is a resident of all Mexican waters of the Pacific Ocean with the exception that they are absent from Guerrero Negro northward along the central and northwest coasts of Baja. They have a preference for waters surrounding oceanic islands including the Clipperton and Revillagigedo Islands. They are known to be able to travel long distances crossing the open ocean between islands. Distribution limits are not well defined due to confusion with similar species of requiem sharks.
The Galapagos Shark is difficult to distinguish from other large requiem sharks and are most likely confused with the Copper Shark, Carcharhinus brachyurus (deeper body with a non-erect first dorsal fin), the Dusky, Shark, Carcharhinus obscurus (shorter dorsal fins and smaller teeth) and the Gray Reef Shark, Carcharhinus amblyrhynchos (robust body, pointed first dorsal fin tip).
From a conservation perspective the Galapagos Shark is currently classified to be of Least Concern with stable, widely distributed populations. Although widely distributed they are long-lived, they are late maturing with long reproductive rates with low fecundity and prone to heavy fishing pressure and human-induced habitat destruction of their inshore habitats. They are caught as a bycatch by commercial fishermen in longline, purse seine and gill net fisheries across many parts of their range. Their meat is considered to be excellent. The United States has banned all commercial landings. They remain, however, unregulated throughout the majority of their range. They are known for being aggressive, inquisitive and persistent and considered to be very dangerous to humans with three documented attacks of which two were fatal.