November Elasmobranch of the Month: Galapagos Shark
Author Linda Weiss
The Galapagos shark, also known as a grey reef whaler, has a slender body with a broad, round snout. It is gray to brownish on top and white underneath. The first dorsal fin is tall, relatively straight with a slightly rounded tip, while the second dorsal fin is small. There is a low inter-dorsal ridge between the two. Their pectoral fins are large and pointed. The broadly triangularly shaped teeth in the upper jaw are relatively long and serrated. The teeth in the lower jaw are more pointed with very fine serrations. Both jaws contain 29 teeth each. The Galapagos’ average length is 3 m (9.8 ft) with the maximum known length for this species being 3.7 m (12 ft). This shark’s average weight is 45 kg (100 lbs) and its maximum is 86 kg (190 lbs).
Habitat and Distribution
The Galapagos shark resides over continental and insular shelves, preferring reef habitats near tropical islands. In the Atlantic Ocean it lives near Saint Helena, Ascension Island, Cape Verde, Madeira, the Virgin Islands and Bermuda. In the Pacific Ocean its range includes the Marshall Islands, Marianas Islands, Lord Howe Island, Hawaiian Islands, Revillagigedo Islands, Galapagos Islands, Kermadec Islands, Cocos Islands, the Tuamotu Archipelago and Tupai. South of Madagascar at the Walter’s Shoal in the Indian Ocean this species also resides. They occupy depths ranging from the surface to 180 m (591ft).
The Galapagos shark’s diet consists mainly of bottom dwelling animals including bony fishes such as triggerfish, flounder, sea bass and grouper, as well as eels, octopi, crustaceans and squid. In the Galapagos Islands, off Ecuador’s coast, they may prey on marine iguanas and sea lions.
Galapagos shark reproduction is viviparous, where embryos develop inside the female nourished by a yolk sac placenta. After an estimated 12-month gestation period, approximately 4 -16 live pups are born per litter. Each pup measures approximately 75-89 cm (30-35 inches) long. Mating occurs every 2 – 3 years.
The IUCN Red List of Threatened Species currently lists the Galapagos shark as Least Concern, with an unknown population trend.
The Galapagos shark’s natural predators include its own species and other larger shark species.
A parasitic flatworm (Dermophthirius carcharhinid), is known to attach itself to the shark’s skin and can be fatal. They are targeted by the commercial fishing industry for their meat and fins, and like many other shark species, they are also caught as bycatch.
Florida Museum of Natural History
Galapagos Conservation Trust
Monterey Bay Aquarium
Planet Shark Divers
Shark Research Institute
The IUCN Red List of Threatened Species
Kyne, P.M., Barreto, R., Carlson, J., Fernando, D., Fordham, S., Francis, M.P., Herman, K., Jabado, R.W., Liu, K.M., Pacoureau, N., Romanov, E. & Sherley, R.B. 2019. Carcharhinus galapagensis. The IUCN Red List of Threatened Species 2019: e.T41736A2954286. https://dx.doi.org/10.2305/IUCN.UK.2019-3.RLTS.T41736A2954286.en. Downloaded on 09 November 2021.