Great white sharks are capable of high speeds but prefer to mosey

Remote sensor tags helped scientists track the swim speeds and diving patterns of great whites off the tip of South Australia. Photo by Andrew Fox

Feb. 19 (UPI) — New research showed great white sharks choose to swim at a more leisurely pace despite an ability to hit impressive speeds.
Unlike most other fish, great whites are endothermic, which means they keep their body temperature warmer than the surrounding water. In theory, the trait should allow them to swim at considerably faster speeds.

To measure how the great white shark’s warmer body impacts its swimming speeds and behavioral patterns, researchers tagged several specimens off the coast of South Australia. The tags measured movements, swim speeds and depth.

Though the tagging process proved difficult, scientists were able to tag 10 sharks.

“They needed to swim nice and slow, close to the boat with their dorsal fins breaking the surface, but we rarely had such ideal situations,” Yuuki Watanabe, a scientist with the National Institute of Polar Research in Tokyo, said in a news release.

To observe each shark’s size, age and sex, scientists had to watch from cages.

“When seen from the boat, they look very aggressive, but I was surprised how elegantly they swim when seen underwater,” said Charlie Huveneers, a researcher at Flinders University in Australia.

When tags automatically detached after several days, researchers collected them and analyzed the data. They were surprised to find only one shark that touched top speeds during the testing period. Scientists think the shark maxed out on a trip in between two feeding grounds. Sharks swimming near the congregation of seals in the area averaged speeds of between 0.8 and 1.35 meters per second.

Swimming slowly is actually inefficient and requires more energy. Researchers think great white sharks prefer a slower pace because it increases their odds of encountering an ideal feeding scenario — of coming across a vulnerable seal.

“This strategy is as close to a ‘sit-and-wait’ strategy as is possible for perpetual swimmers, such as white sharks,” Watanabe said.

The study data — published this week in the Journal of Experimental Biology — also showed sharks prefer to glide as they dive, and do so quite often. The math showed diving is more energy efficient than battling surface level waves, but like the shark’s slow but elegant swimming patterns, a gliding descent likely offers sharks a better chance of finding food.

In future studies, scientists hope to measure exactly how often great whites successfully catch a fatty seal snack.