Spot A Shark USA is a citizen-science program that engages anyone who spends time on the water in sand tiger shark research along the Atlantic coast. Divers, snorkelers, and others are asked to photograph encounters with sand tiger sharks and post their images to the Spot A Shark USA website. Scientists then use unique spot patterns visible along the sides of the photographed sharks to identify individual animals.
Identifying individual sand tiger sharks helps track shark movement and behavior over time. It also determines which coastal habitats sand tiger sharks use during their lives. This information is used by Spot A Shark USA researchers, as well as international partners, to facilitate
management decisions aimed towards conserving sand tiger sharks, which are critically endangered in several parts of the world.
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About the Species
Sand tiger sharks(Carcharias taurus) are highly-migratory, large coastal sharks found in many parts of the world. These sharks, which primarily eat fish, rays, and small sharks, have several prominent, identifying features, such as brown spots on their sides that help distinguish individuals and an iconic ‘ragged-tooth’ smile, making them ideal subjects for underwater photographers. Along the east coast of the US, sand tiger sharks often occur in large
aggregations of 20-80 individuals. They are about 3 ft long at
birth and can grow to 10 ft as
adults. Sand tiger sharks often appear to hover motionless because they control their buoyancy
using not only their large, oily liver, but also air that they gulp from the surface.
While sand tiger sharks are known to occur in a variety of shallow coastal habitats, little is
known about which habitats sand tiger sharks in the northwestern Atlantic use during their
different life phases.
It is not known where sand tiger sharks give birth to their
pups. Our team is
conducting research to locate sand tiger shark pupping grounds.
Juvenile sand tiger sharks of ~1-2 years old use northern
estuaries, such as
Long Island Sound, as nursery grounds. Generally, juvenile sand
tiger sharks spend
summertime in these northern nurseries, and when the season shifts, they migrate south to
Adults are presumed to migrate seasonally between northern
southern wintertime habitats, although some sharks may
use habitats off North Carolina,
USA as year-round habitat.
Sand tiger sharks often occur in aggregations of 20 to 80 individual sand tigers, and likely
contain complex social networks. Important unanswered questions
remain regarding how sand
tiger sharks use coastal habitats. Images uploaded to Spot A Shark USA will help fill these knowledge
gaps about what habitats sand tiger sharks use over time.
Sand tiger sharks have one of the lowest reproductive rates
among sharks because they exhibit
delayed sexual maturity (6-7 years for males, 9-10 years for females), have a long gestation time (9-12 months), and produce 1-2 pups every several years. Unlike other
sharks, female sand tigers
have two uteri. Within each uterus, intrauterine cannibalism,
where larger pups consume weaker
siblings in the womb, occurs. The slow and unique reproductive strategy of sand tiger sharks,
which may live up to 17 years in the wild and over 25 years in
human care, makes sustaining
populations of these sharks challenging. Data gathered with
Spot A Shark USA will provide important
clues as to where and when these sharks are mating, breeding,
and giving birth.
Juvenile and adult sand tiger sharks can be distinguished by their size. Juveniles are
smaller than adults, with
4 feet length, whereas adults are larger with > 4 feet fork
length. The fork length is the distance from the snout to the base of the caudal fin.
While male sharks are usually smaller than female sharks,
the best way to tell a male from a
female is by looking at the underside of the shark. Male
sharks have appendages called claspers
on their underside. Claspers are modified pelvic fins that
are used to insert sperm into female
sharks during mating. In contrast, female sand tiger sharks
do not have claspers.
Sharks are marvels of natural selection with remarkable
adaptations that evolved over 400
million years to play a critical role in marine food webs and ocean health. Our understanding of
sharks is ever evolving. Active research projects, such as Spot A Shark USA, assist scientists in gaining
valuable information to support effective, science-based conservation for shark species, such as
sand tiger sharks.
Due to overfishing, numbers of sand tiger sharks have declined globally. In some locations, sand
tiger sharks are listed as
In the northwest Atlantic Ocean, for example,
the species is listed as
By supporting this project, you are helping researchers and
the NC Aquariums gather valuable data, which may help provide
long-term protection for
sand tiger sharks and their habitats.