VANCOUVER, British Columbia -- In the marine
world, high-energy prey make for high-energy predators. And to survive,
such marine predators need to sustain the right kind of high-energy
diet. Not just any prey will do, suggests a new study by researchers
from the University of British Columbia and University of La Rochelle,
in France.
Published today in the online journal PLOS ONE,
the study is the first to show that the survival of whales and dolphins
depends on the quality of their diets and this plays an important role
in conservation.
"The conventional wisdom is that marine mammals
can eat anything," says co-author Andrew Trites, a marine mammal expert
at UBC. "However, we found that some species of whales and dolphins
require calorie rich diets to survive while others are built to live off
low quality prey—and it has nothing to do with how big they are."
The team compared the diets 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 diets was to look at their muscle
performance.
"High energy prey tend to be more mobile, and
require their predators to spend more energy to catch them," says
Trites. "The two have co-evolved."
Jérôme Spitz, the study's first author, says the
research 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," says Spitz, a
post-doctoral fellow at ULR in France, who completed the research while a
visiting scholar at UBC. "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."
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