September Elasmobranch of the Month: Finetooth Shark
Author: Linda Weiss
The Finetooth shark is named for its small, narrow, clear, fine, smooth teeth. Both the upper and lower jaws contain similarly sized and shaped teeth. The teeth in the upper jaw may have miniscule serrations. This species is medium sized with a streamlined body shape. Adult females average 1.8-2.3 m (5.9-7.5 ft) in length and males average 1.5-2.3 m (5-7.4 ft). They are dark bluish-grey or bronze on their dorsal side, fading to gray on the sides and white underneath. Their snout is long and pointed while their mouth is rounded broadly. They have fairly large eyes for their size and long gill slits. The first dorsal fin is small, originating over or just slightly behind the pectoral fin insertions. The second dorsal fin is located directly above the anal fin. There is no interdorsal ridge present. The pectoral fins are small and pointed. The caudal fin is forked, with the straight upper lobe significantly longer than the lower lobe.
Habitat and Distribution
The Finetooth shark resides in the western Atlantic Ocean, including the Gulf of Mexico. It ranges from North Carolina in the Unites States to Cuba and Brazil. This coastal species is often found close to shore in shallow water to depths of 10 m (32.8 ft). They are not known to swim deeper than 152 m (498 ft). They can be found in lagoons, river mouths, estuaries and bays. Finetooth sharks that call the United States’ Carolina coasts home, migrate to the Florida coast during the winter months.
The Finetooth’s diet consists largely of bony fish including mackerel, mullet, and menhaden. They also prey on invertebrates such as crustaceans and squid.
Finetooth shark reproduction is viviparous, where embryos develop inside the female nourished by a placental yolk sac. Gestation is approximately 12 months long and results in the live birth of 1 -13 pups per litter, typically 2-6. Each pup measures approximately 51-64 cm (20-25 inches) long. Pups are typically born between May and June.
The IUCN Red List of Threatened Species currently lists the Finetooth shark as Near Threatened, with a stable population trend.
Finetooth sharks are targeted by the commercial fishing industry primarily for their meat. Like many other shark species, they are also caught as bycatch in gillnets and on longlines. Habitat destruction due to coastal development also negatively impacts this species. A natural threat is predation by larger sharks.
Florida Fish and Wildlife Conservation Commission
Florida Museum of Natural History
The IUCN Red List of Threatened Species
Carlson, J., Charvet, P., Avalos, C., Briones Bell-lloch, A., Blanco-Parra, MP, Cardenosa, D., Crysler, Z., Derrick, D., Espinoza, E., Herman, K., Kyne, P.M., Morales-Saldaña, J.M., Naranjo-Elizondo, B., Pacoureau, N., Pérez Jiménez, J.C., Schneider, E.V.C., Simpson, N.J., Talwar, B.S. & Dulvy, N.K. 2021. Carcharhinus isodon. The IUCN Red List of Threatened Species 2021: e.T161524A890428. https://dx.doi.org/10.2305/IUCN.UK.2021-1.RLTS.T161524A890428.en. Downloaded on 12 September 2021.