Meet the biologists deciphering marine-mammal histories from baleen, whiskers and tusks

A new laboratory setup includes equipment for processing whale baleen into powder and running biochemical assays. Baleen plates, made of keratin, can be up to 2.5 metres long and grow continuously, preserving growth lines that can reflect roughly a decade of life history. These records can capture reproduction, stress levels, and environmental conditions. Blood sampling is nearly impossible for whales, so researchers rely on baleen to measure endocrine signals. Work in wildlife endocrinology uses baleen to study how hormones, diet, and pollutants relate to fecundity and welfare, expanding beyond earlier hormone sampling methods.

"As she removed a 2-metre-long plate of keratin that looks like horsehair trapped in fingernails, she lamented her clumsy first attempts, back in 2013, to sample it for hormones. Five-centimetre-long punctures where her drill bit pierced the material are visible every few centimetres, along striations that seemed to represent growth lines. "We took enormous amounts of powder because, at the time, we thought we needed it," she explains."

"The plate is baleen, or whalebone, which North Atlantic right whales (Eubalaena glacialis) and a dozen or so other species use to filter plankton, krill and other food. Each plate can range from 0.5 to 2.5 metres in length, and whales can have several hundred of them hanging from each side of the upper jaw. The sheets grow continuously as the oldest material at the bottom is filed away, and can represent up to about ten years of life history in North Atlantic right whales: a time-stamped record of their reproduction, stress levels and environment."

"For many species, these signatures can easily be measured using blood samples. But whales are among the most elusive creatures on Earth and samples of their blood are all but impossible to collect. Studies of baleen by Hunt and other researchers have opened a window into the inner lives of these animals and buoyed the field of wildlife endocrinology, which looks for clues as to how hormones, diet and environmental pollutants affect their fecundity and overall welfare."

Read at Nature