A commonly mistaken shark
The Sandbar shark (Carcharhinus plumbeus) is a species of requiem shark, and part of the family Carcharhinidae. It can be found in the Indo-Pacific and the Atlantic Oceans. The Sandbar shark can oftentimes be seen with Silkies and Dusky sharks. We oftentimes see Sandbar sharks here in Jupiter, Fl.
Family: Carcharhinidae – Requiem sharks
Common Name– Ground Sharks
Common Name– Requiem Sharks
Status: IUCN Red List VULNERABLE
Average Size and Length: Sandbar sharks average anywhere from 6.5 feed to 8.2 feet in length.
Average Weight: The average weight of a Sandbar shark is anywhere from 99 to 198 pounds, with a maximum recorded weight of 260 pounds.
Teeth and Jaw: The upper teeth of the Sandbar shark are broadly triangular, serrated with high cusp. The lower teeth are narrower and more finely serrated. The front teeth are erect and symmetrical but become smaller and increasingly oblique as they move toward the corners of the jaws.
Head: The snout is blunt and round, and shorter than the width of the mouth.
Denticles: The Sandbar shark has widely spaced dermal denticles that have no definite teeth and don’t overlap.
Demographic, Distribution, Habitat, Environment and Range: The Sandbar shark is found over muddy or sandy bottoms in shallow coastal waters such as bays, estuaries, harbors, or the mouths of rivers. It is believed that the Sandbar shark favors a smooth substrate and will avoid coral reefs and other rough-bottom areas.
It spends most of its time between 60 and 200 feet, but is known to move into deeper waters of 656 feet or more and also into the intertidal zone.
Sandbar sharks are coastal-pelagic and found in tropical to temperate waters worldwide; in the western Atlantic they range from Massachusetts to Brazil. Juveniles are common to abundant in the lower Chesapeake Bay, and nursery grounds are found from Delaware Bay to South Carolina. Other nursery grounds include Boncuk Bay in Marmaris, Muğla/Turkey and the Florida Keys. They are found in the eastern Atlantic, including the Mediterranean. In the Indo-Pacific, The Sandbar shark ranges from the Persian Gulf, Red Sea and South and East Africa to the Hawaiian Islands. It also inhabits the Revillagigedo and Galapagos islands in the Eastern Pacific.
The sandbar shark undergoes seasonal migrations influenced mainly by temperature. It is believed that ocean currents also play a significant role in their migration habits. Male sandbar sharks demonstrate congregated migrations and often travel in large schools while females exhibit solitary migrations. The only anomaly is the population off of the Hawaiian Islands. That population is thought to be annual residents.
Diet: The Sandbar shark is primarily a bottom-feeder that preys on small fishes, mollusks and crustaceans. Some include various bony fishes, eels, skates, rays, dogfish, octopus, squid, bivalves, shrimp and crabs.
The Sandbar shark feeds throughout the day but becomes more active at night.
Because of the high percentage of sharks found with partially full stomachs and their relatively large liver (which contains high percentage of oil and vitamins) it is believed that Sandbar sharks have a very successful feeding strategy and receive a regular supply of food.
Natural predators of the Sandbar shark include the Tiger shark, and even Great White sharks.
Aesthetic Identification: Sandbar sharks have heavy set bodies. They are bluish to brownish gray above, and counter-shaded a lighter shade of the same color to white under. Although the tips and outer margins of the fins are sometimes a darker tone, the Sandbar shark has no obvious markings.
The Sandbar shark has a taller than average first dorsal fin, which originates above or slightly anterior to the pectoral axis. An interdorsal ridge is present between dorsal fins. The pectoral fins are large and broad. Its second dorsal fin and anal fin are close to the same height.
Biology and Reproduction: The parasite found on the Sandbar shark is the copepod Alebion lobatus.
The Sandbar shark is viviparous. There is some aggression in mating habits like with other sharks.
In the northern hemisphere, mating occurs in the spring or early summer (May-June). Sharks in the southern hemisphere, in correlation with the warmer summer season, mate in late October to January.
The gestation period of a Sandbar shark can range from 8-12 months depending upon geographical location. Female Sandbar sharks of the western Atlantic generally carry their young for 9 months whereas in southeastern Africa, the gestation period can last as long as 12 months. Most Sandbar sharks have pups every other year. However, females have been found to exhibit both biennial and triennial reproductive cycles.
In the western Atlantic, pups are born from June through August while off southeastern Africa, pups are born from December to February.
Shallow water bays and estuaries are perfect nursery areas for Sandbar shark pups. Regardless of location, litter size is dependent upon region, the size of the mother, with larger sharks producing larger litters. Juvenile sandbar sharks remain in the nursery areas until late fall at which time they form schools and move southward and further offshore only to return for the summer months. This movement between shallow coastal waters and warmer, deeper waters may continue for a period of up to five years but should not be confused with adult migrations that involve much greater distances.
Both sexes are almost always represented in a 1:1 ratio. Young Sandbar sharks resembles their adult parents.
Females reach sexual maturity around the age of 13 with an average fork-length of 154.9 cm, while males tend to reach maturity around age 12 with an average fork-length of 151.6 cm. Females can grow to 6.6–8.2 feet, males up to 5.9 feet.
The sandbar shark typically lives 35–41 years.
Behavioral Traits, Sensing and Intelligence: Sandbar sharks swim alone or gather in sex-segregated schools that vary in size.
Sandbar Shark Future and Conservation: Sandbar sharks have been disproportionately targeted by the U.S. commercial shark fisheries in recent decades due to their high fin-to-body weight ratio, and U.S. fishing regulation requiring carcasses to be landed along with shark fins. In 2008, the National Marine Fisheries Service banned all commercial landings of sandbar sharks based on a 2006 stock assessment by SEDAR, and Sandbar sharks were listed as vulnerable, due to overfishing. Currently, a small number of specially permitted vessels fish for sandbars sharks for the purpose of scientific research. All vessels in the research fishery are required to carry an independent researcher while targeting Sandbar sharks. (Baremore, Ivy E.; Loraine F. Hale (1 June 2012). “Reproduction of the Sandbar Shark in the Western North Atlantic Ocean and Gulf of Mexico”. Marine and Coastal Fisheries: Dynamics, Management, and Ecosystem Science. American Fisheries Society. 4: 560–572).
The Sandbar shark is a primary targeted species. It had been harvested in the eastern North Atlantic as well as the South China Sea for its fins, flesh, skin and liver. In addition to the significant impact the Sandbar shark has on the commercial fishery, it is valuable to recreational fishermen as a game fish.
Sandbar Shark Recorded Attacks on Humans: Very few attacks are credited to Sandbar sharks, so they are considered not to be dangerous to people. As a result, they are considered one of the safest sharks to swim with and are popular sharks for aquaria.