Facts About Porbeagle Sharks
Porbeagle sharks are generally a cold water species. These cartilaginous fish are also known as mackerel sharks, blue dogs and bottle-nosed sharks. It is uncertain where the name porbeagle originated. One reference states that the name is possibly from the Cornish words porth for "harbor" or "cove" and bugel for "shepherd." It may also originate from the Cornish words for "porpoise" and "beagle," in reference to the shark's shape and skill in hunting.
Porbeagle sharks are part of the group of sharks known as the mackerel sharks (Lamnidae, or lamnoids). These sharks have five pairs of gill slits, two spineless dorsal fins, and an anal fin. They have large eyes, an extremely hydrodynamic body and crescent-shaped tail fins. This group also includes white, mako and salmon sharks.
Porbeagle sharks (Lamna nasus) can grow to about 12 feet in length and over 500 pounds in weight. They have a bluish-gray to brownish coloration on their back with a white underside. They also have a white patch on the trailing (back) edge of the dorsal fin. Populations in the southern hemisphere have a duskier coloration with dark blotches. They have a cone-shaped snout, large eyes and a lunate tail (caudal) fin.
- Kingdom: Animalia
- Phylum: Chordata
- Class: Elasmobranchii
- Order: Lamniformes
- Family: Lamnidae
- Genus: Lamna
- Species: nasus
Porbeagle sharks live in coastal and pelagic areas in temperate waters worldwide, including in the North Atlantic, South Atlantic, southern Indian, southern Pacific and Antarctic Oceans.
Click here for a range map. This fish seems to prefer waters in the temperature range of 35-65 degrees Fahrenheit. They are found individually or in small groups and seem to associate with sharks of similar size or sex.
Porbeagle sharks eat fish (sharks and other fish) and squid. They have smooth, sharp teeth. On either side of the main "tooth" are mini-teeth called lateral cusplets.
These sharks reproduce sexually, with internal fertilization. During mating, males bite and hold on to females. Thus, teeth marks on females can indicate that they have recently mated. Young are nourished in the uterus by oophagy - embryos eat eggs produced by the ovary. The gestation period for porbeagle sharks has been estimated at 8-24 months. Young are 23-31 inches long at birth. Females give birth to 1-5 young at a time.Porbeagle sharks are thought to be capable of living more than 40 years.
Due to low reproduction rates (females produce a small number of young at a time) and relatively slow growth, porbeagles can be vulnerable to overharvesting. They are listed as vulnerable on the IUCN Red List.
Porbeagles are considered of little threat to humans. There are only 2 non-fatal unprovoked attacks of porbeagle sharks on humans listed in the International Shark Attack File.
References and Further Reading:
- Bailly, N. 2014. Lamna nasus (Bonnaterre, 1788). In: Froese, R. and D. Pauly. Editors. (2014) FishBase. Accessed through: World Register of Marine Species, July 31, 2014.
- Campagno, L., Dando, M. and S. Fowler. 2005. Sharks of the World. Princeton Field Guides. 368 pp.
- NOAA Fisheries: Office of Protected Resources. 2013. Porbeagle Shark (Lamna nasus). Accessed July 31, 2014.
- Ritter, E. K. 2009. Fact Sheet: Mackerel Sharks. SharkInfo. Accessed JUly 31, 2014.
- Roman, B. Porbeagle. Florida Museum of Natural History Department of Icthyology. Accessed JUly 31, 2014.
- Shark Trust. 2009. Porbeagle Shark Fact Sheet. Accessed August 27, 2015..
- Stevens, J., Fowler, S.L., Soldo, A., McCord, M., Baum, J., Acuña, E., Domingo, A. & Francis, M. 2006. Lamna nasus. The IUCN Red List of Threatened Species. Version 2014.2. Accessed July 31, 2014.