Diet quality key to survival of whales, dolphins: study

The survival of whales and dolphins depends on the quality of their diet and this plays an important role in conservation, according to a new study.

The study, published in the online journal PLOS ONE, was conducted by researchers from the University of British Columbia (UBC) in Canada and University of La Rochelle (ULR) in France.

"The conventional wisdom is that marine mammals can eat anything," said co-author Andrew Trites, a marine mammal expert at UBC. "However, we found that some species of whales and dolphins require calorie rich diet to survive while others are built to live off low quality prey."

The researchers compared the diet of 11 species of whales, dolphins and porpoises in the Northeast Atlantic Ocean, and found differences in the qualities of prey consumed that could not be explained by the different body sizes of the predators.

The key to understanding the differences in their diet was to look at their muscle performance, as high energy prey tend to be more mobile, and require their predators to spend more energy to catch them, according to the researchers.

The researchers believe the findings will help better assess the impact of resource changes to marine mammals.

"Species with high energy needs are more sensitive to depletion of their primary prey," said Jerome Spitz, first author of the study and a post-doctoral fellow at ULR in France.

"It is no longer a question of how much food do whales and dolphins need, but whether they are able to get the right kinds of food to survive." Spitz added.