The University of Miami (UM) Rosenstiel School of Marine and Atmospheric Science has revealed the changes to tiger shark movements including timings and locations in the western North Atlantic Ocean. This is due to an increase of ocean temperatures. The sharks have become more vulnerable through moving outside of protected areas.
By Annette J Beveridge
Found in tropical and temperate regions, the tiger shark is one of the largest sharks in the world growing over 5 m in length. They weigh between 800-1500 pounds, and live up to 50 years. Tiger sharks are the only surviving member of the genus Galeocerdo. The name tiger shark originates from the dark stripes running down its body but these fade as the shark matures. Skin varies in colour from a blue or green hue and there is a light yellow underbelly. Females grow bigger than the males.
Tiger sharks are nomadic
Tiger sharks are guided by warmer currents. They remain in deep water moving along reefs but will move closer to the shore when following prey. These are aggressive predators, often circling prey, nudging it before establishing a full attack.
Tiger sharks will eat anything they are able to capture and this includes a variety of fish species and invertebrates. They prey on sea turtles, seabirds, smaller sharks, sea snakes and marine mammals and with a sharp eyesight, and a keen sense of smell, they also use electroreception which is a biological ability to detect natural electrical stimuli.
A recent study has revealed that tiger sharks have expanded poleward on their annual migrations paralleling rising sea temperatures. The study indicates that over the last 10 years as ocean temperatures increased – becoming the warmest on record, tiger shark migrations have moved further poleward by approximately 250 miles for every 1 degree Celsius increase above average temperatures. Tiger sharks also migrated approximately earlier by 14 days to the waters off the US north-eastern coast.
There are concerns that these changes may impact ecosystems because tiger sharks are apex predators which may affect predator/prey interactions. Ecological imbalances are possible but a change of movement and location could also increase interactions between people and tiger sharks.
Tiger sharks are on the list as near-threatened with extinction. Review the scientific research here.
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