Scientists are gaining new insights into how whales dive and search for food after attaching multi-sensor tags to them. These sensors measure the acceleration of the animal as well as its swimming depth. This information can be used by computer software to visualise the whale’s movement in three dimensions, as well as recording the timing of each dive the whale makes for food.
Baleen whales, the type followed in this study by the the Cascadia Research Collective in Olympia, Washington, feed by filtering large volumes of water through special plates instead of teeth. They eat small fish and microscopic animals.
The data gathered from these sensors has provided several new insights into the foraging behaviour of these filter-feeding whales. Rorqual whales, a group which includes blue whales, were found to have a very different feeding strategy to other types of whales studied. These whales made quick, high-energy dives at patches of prey, pausing to filter the water they trap afterwards. This is very different to the slow-swimming, low-energy dives that are characteristic of right and bowhead whales, the other types of whale studied. In addition it was found that Rorqual whales have to return to the surface to breathe more often than other types of whales, likely to be as a result of the higher-energy dives.
This new technology will give scientists a better understanding of how efficiently different whales are diving and finding food. They can then relate this efficiency to how available different types of prey are. Whales are thought to be key predators in oceanic food webs, so these findings may have important implications for ocean ecosystems.
