Largest of the Carcharinid Sharks. Head large with a blunt, square snout. Long labial furrows around mouth. Small but noticeable spiracles behind eyes. Subtle dermal keels on caudal peduncle. Dorsal coloration variable; shades of charcoal-grey, greenish-grey, or brownish grey, with a pattern of dark irregular blotches or vertical stripes forming subtle bars. In juveniles the patterns appear much more spot-like and bold. Over time, the spots become bars but also fade. Extremely large individuals may have barely discernible markings.
Maximum length 549cm, possibly shorter. There are a few records of larger tiger sharks but most are unverifiable. For example, in 1961 a renowned researcher named Fourmanoir mentions a photograph he received from M. Teisseyre of a female tiger shark from Indochina that was 7.4m long. However, the shark was not actually measured by any scientists. Considering the enormous size difference between this report and verified records of the largest accurately measured tiger sharks, it is very unlikely to be a credible account. Even the size listed above of 549cm is questionable. The report was sent in 1948 to Bigelow and Schroeder from Luis Howell-Rivero in Cuba. This shark may have been accurately measured but Mr Rivero also reported the largest white shark in the world; a record which has since been dismissed. With this in mind, the largest accurate record may be a 472cm tiger shark taken off Maroubra, NSW, Australia in 1936.
Tropical/warm-temperate seas. Found from inshore estuarine environments to the edge of the continental shelf and around oceanic islands. Turbid or clear water. Often seen near coral reefs.
Generally in shallow water but recorded at 1,136m.
I have deployed baited deep camera systems that was visited by tiger sharks at 600m and 800m off of South Bimini Island.
The tiger shark is extremely cosmopolitan along most tropical and warm-temperate coastlines and offshore islands.
This species has relatively fast growth rates and large litters (on average 26-33 pups) but the likely triennial reproductive cycle reduces its ability to recover from fishing pressure. The Tiger Shark is caught by commercial, recreational, and artisanal fisheries as a target species or bycatch. However, records of Tiger Shark catches by many fisheries globally are still largely unknown. The species is one of the major components in catches from shark control programs that target large shark species in Australia, South Africa, and Reunion Island. Information on stock assessment, population structure and overall population trends are lacking for much of the species’ distribution and available trends in catch rates are based on analyses of the long term shark control programs and on observer surveys from the Western North Atlantic. In Australia, the Queensland Shark Control Program showed declines in catch rates since the 1980s and in New South Wales, evidence of a decline was also seen in the last 20 years. Additionally, a significant reduction of the proportion of mature sharks in catches over 60 years suggests shifts in population structure and raises concerns over possible effects from this program on the Tiger Shark population off New South Wales. The decline off eastern Australia is likely to continue while the shark control programs off Queensland and New South Wales remain active. In the U.S. fisheries of the Western North Atlantic, observer surveys variously recorded increases in Tiger Shark relative abundance and no change in abundance. In South Africa, the beach protection program showed a 3% increase per year in Tiger Shark catch rates. The increasing rates in the Western North Atlantic and South Africa seem consistent with the pattern observed in the first 20 years in Queensland and the interpretation of such upward trends should be made with caution. In the Arabian Seas region, the Tiger Shark has been assessed as Vulnerable based on a suspected decline of at least 30% over the past three generations based on levels of exploitation, with the continued demand from the shark fin market suspected to result in further population reduction in the future. Globally, The Tiger Shark is suspected to have declined by close to 30% over the past three generations (53-68 years) due to exploitation from commercial, recreational, and unregulated fisheries, as well as shark control programs. A further population reduction is suspected over the future three generation lengths (2018-2086) based on current levels of exploitation that are likely to continue into the future. As such this species is assessed as Near Threatened (close to meeting Vulnerable A2bd+3d).
Citations and References
Ferreira, L.C. & Simpfendorfer, C. 2019. Galeocerdo cuvier. The IUCN Red List of Threatened Species 2019: e.T39378A2913541. https://dx.doi.org/10.2305/IUCN.UK.2019-1.RLTS.T39378A2913541.en. Downloaded on 01 October 2020.
The tiger shark is the only aplacental viviparous carcharinid. It has a yolk sac but does not develop a placental connection to the uterus. Embryos develop inside shells filled with a yellowish liquid. Jose Castro noted that embryos he examined all had partially everted stomachs. He speculated that they may be absorbing extra nutrients from this fluid, which would explain their large size at birth; larger than the nutrients from their yolk sac could realistically supply.
Tiger sharks have an extremely varied diet. They are known to eat bony fishes, sea turtles, sharks and rays, molluscs, and crustaceans. They are largely opportunistic hunters and scavengers, eating whatever is readily available at any given time.
Some tiger sharks migrate over great distances, while others stay in one spot for most of the year. The availability of food is probably an important factor. There are records of tagged tigers traveling from the northeastern USA to Brazil.
Reaction to divers
Given their size, tiger sharks are often surprisingly wary around divers, even when food is introduced. In areas where they are habituated to divers such as at Tiger Beach, they are extremely nonchalant towards divers that are not carrying food.
CAUTION: Tiger Sharks have been implicated in numerous attacks in some areas, e.g. attacks on surfers and swimmers in Hawaii.
There are now quite a few baited encounters with tiger sharks but none that compare to the reputation and reality of Tiger Beach in The Bahamas. TB is a phenomenon in its own right. Not a beach at all, Tiger Beach is a shallow sandy area (with no land in sight) on Little Bahama Bank. At one particular dive site with the Tiger Beach area named Fish Tales, it is not uncommon to see 4-12 tigers on a dive; sometimes even more.
The diving at TB is very shallow (7-15m) so the dives often last 90-120 minutes if you’re good on air. The visibility is generally pretty good too, so the photographic opportunities are exceptional.
Any time is good for tigers except for the middle of summer when the water is too warm and the big sharks leave the area. Winter probably gathers slightly more sharks than other times but winter storms can be a huge problem, with many trips being cut short or cancelled. We (Big Fish Expeditions) run our trips in April when there are still plenty of tigers in the area and the weather is generally excellent.
At Fuvahmulah Atoll in the Maldives, there is a relatively new tiger shark feed that seems to be reliable and gaining in popularity. I have not been there yet but the reviews sound very promising.
In Fiji, the bull shark feed at Beqa Lagoon sometimes attracts tiger sharks but not reliably and not in great numbers.
At Aliwal Shoal near Durban in South Africa, there is a tiger shark feed that is a bit hit and miss for tigers but worth doing if only for the excellent oceanic blacktip encounters.
Un-baited Tiger Sharks are randomly seen at numerous popular locations. In the eastern Pacific, they frequently make an appearance at San Benedicto Island in the Revillagigedo Archipelago, Mexico. And at Cocos Island in Costa Rica. Theoretically, these encounters are the results of curiosity but at Socorro (and maybe Cocos too) I have known of divemasters bringing a little bait, even though those activities are not permitted in those parks.
Due to the tiger shark’s unusual markings, often enormous size, and blunt, square snout, it is unlikely to be misidentified in the field.