Sea otter mothers spend so much energy taking care of their pups that, by the time the pup is weaned, even minor infections can kill them. Sea otter researchers call this phenomenon “end-lactation syndrome” and believe it contributes to high female sea otter mortality rates in some areas. In a new study, researchers from UC Santa Cruz examined the cause of end-lactation syndrome.
Sea otters eat nearly a quarter of their body weight in seafood every day, even when they don’t have a pup to nurse, due to their high energy requirements. They live in cold waters and have thick fur, but they lack a layer of blubber to protect them, which means they need to maintain a high metabolic rate to stay warm.
It takes six months for a female sea otter to raise a pup until it’s fully weaned and can feed itself. During that time, the mother’s energy demands skyrocket. In the first few weeks, they jump by 17 percent and eventually grow to be 96 percent higher than before she had a pup. That means she has to eat nearly twice what she normally would in order to keep herself and her pup fed.
These findings explain why so many female sea otters are found in poor weak and underweight at the end of the lactation period.
UC Santa Cruz biologist Nicole Thometz explained in a news release: “These fundamentally high energy demands are likely the underlying reason why we see so much mortality among prime age females in the middle of their range, where the density of the sea otter population is highest and resources are limited.”
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