Sharks dive deeper when the moon is full

The full moon cycle and the warmth of the sea will cause some sharks to dive deeper, according to new research.

Researchers from Australia observed nearly 39 gray sharks (Carcharhinus amblyrhynchos) living near coral reefs in Palau, Micronesia, east of the Philippines for nearly three years.

The results show that changes in water temperature can influence shark activity. In winter, sharks are near the surface of the water about 35m to maintain the necessary warmth. Meanwhile, this species dives deeper about 60m if the temperature starts to rise in the spring.

Sharks Carcharhinus amblyrhynchos. (Photo: P. Ayotte)

Sharks also convert living habits corresponding to the moon's cycle. They dive deeper in the full moon, but will rise to the start of a new cycle.

Other predators such as swordfish and large-eyed tuna also dive deeper when the lunar cycle takes place. This proves that the moon light has an impact on the activities of many large fish species. The sun also has the same effect. Sharks dive deepest in the middle of the day when sunlight is strongest and begin to return to the surface in the afternoon.

Live Science quoted Gabriel Vianna of Western Australia University as saying: "As far as we know, this is the first time such living habits have been carefully observed in gray sharks."

Researchers believe that the above-mentioned trend of sharks can help them conserve energy, find food and avoid other larger sharks. Conservationists warn that the number of sharks is declining worldwide. A statistic this year shows that 100 million sharks are killed every year and many species are at risk when overfished.