Whales are underweight 

BOSTON — North Atlantic right whales are thin and unhealthy compared with individual whales from the three populations of Southern right whales, according to a study led by Fredrik Christiansen from Aarhus University in Denmark recently published in the journal Marine Ecology Progress Series. 

According to a press release from the New England Aquarium, the whales face a change in the abundance and distribution of the rice-sized plankton that they eat, in addition to risks from vessel strikes and entanglement with fishing gear. 

To quantify “thin and unhealthy,” Christiansen and his colleagues investigated the body condition of individual North Atlantic right whales and compared their condition with individuals from three increasing populations of Southern right whales off Argentina, Australia and New Zealand. 

“Good body condition and abundant fat reserves are crucial for the reproduction of large whales, including right whales, as the animals rely on these energy stores during the breeding season when they are mostly fasting,” said Christiansen. Stored fat reserves are particularly important for mothers, who need the extra energy to support the growth of their newly born calf while they are nursing. 

The study is the result of a collaborative effort by scientists from 12 institutions in five countries. 

The international research team used drones and a method called aerial photogrammetry to measure the body length and width of individual right whales in these four regions around the world. From aerial photographs, the researchers estimated the body volume of individual whales, which they then used to derive an index of body condition or relative fatness. 

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