Every winter after December, hundreds of great white sharks gather in the middle of the pacific ocean in a supposedly “sterile” and deserted area. But why? A team of researchers have come to discover the reason but another question remains unsolved.
During the second half of the year, great white sharks from the north-east Pacific ocean feed on marine mammals along the Californian coast generally between the months of August and December. These predators then head for the middle of the ocean between Baja and Hawaii where they spend winter and spring before returning to California. For the moment, available data suggests this area is a deserted part of the ocean, devoid of prey. If this is the case, why would these sharks waste so much energy to spend time in such an area?
Barbara Block and her team from Hopkins marine station from Stanford University, United States have recently followed the sharks in the hope of understanding these mysterious gatherings. However they have discovered this area i home to an enormous amount of fish. Choosing to stay in deeper water during the day, thousands of little fish venture into shallower water as night falls. By following the journey of 30 sharks, researchers have now learnt that these great whites follow a similar path diving to depths of 450 m during the day before reaching 200 m below the surface at night.
Sharks don’t generally dive at these depths as it is too cold and the pressure means that they can’t digest their prey. However it seems that the sharks and their prey are following a hot water current which researchers were unaware of before.
What initially was thought of as a deserted area in fact comes to life at night, attracting sharks to the appropriate currents. Researchers have also remarked that the males dive more often during the month of April (diving up to 140 times per day) in comparison females. For the time being, researchers are unable to explain these different behaviours. More research will need to be carried out in order to understand this mystery.