BALEEN GIVES CLUES TO WHALE HEALTH

You can tell a lot from a person’s fingernails. Fingernails are made of keratin, a tough protein manufactured by the body. If you are suffering from anemia, it’s likely that your fingernails will be white at their bases. If your nails are yellow, you could have a problem with your respiratory system. Other changes to fingernails may indicate diabetes, auto-immune ailments or other systemic illnesses.

But human beings aren’t the only creatures to produce keratin. We make fingernails; whales make baleen. So what could baleen tell researchers about the health and well-being of whales? As it turns out, a good deal

Whales such as the humpback, bowhead and right whale grow baleen plates which they use to filter seawater for their food. That food is typically microscopic phytoplankton and zooplankton, which the whales eat by the ton. A humpback whale might have 600 flexible baleen plates in its upper jaw which can grow 15 centimeters or more each year. Each plate is rimmed with a ring of stiff hair-like fringe which overlap each other. A humpback will swallow huge amounts of seawater, then push it out through the baleen plates with its tongue, trapping food behind. A right whale, by contrast, moves slowly through the water with its mouth open; water flows in the front of the mouth and out in between the baleen plates.

Most whales are strictly protected by national and international law; gaining access to any part of their bodies, such as blood, to determine their health is extremely difficult. Kathleen Hunt, a research scientist at the New England Aquarium in Boston, uses various proxies, such as feces, whale breath and now baleen, to study whale physiology.

Hunt came up with the idea to study the blow of whales. Whales must surface to breath and when they do, they exhale the held breath forcefully out a blow hole. Hunt suspected that all the constituents found in a whale’s blood, such as hormones, also would be found in its exhaled breath. Beginning in 2009, she created a breath sampler composed of a plastic bottle wrapped with a nylon veil attached to a long pole. To make it work, Hunt had to be near, but not too near, a whale when it surfaced in order to sweep the contraption through the exhaled breath. 

The process was successful. Hunt and her colleagues published a scientific paper showing that they could detect the sex hormones progesterone and testosterone, as well as the stress hormone cortisol, in the breath of humpback and North Atlantic right whales. The presence and amount of progesterone and testosterone indicate the animals’ sex and reproductive state.

Now Hunt is examining whale baleen to gather similar data. Because baleen is constantly renewed during the course of a whale’s life, it provides a record of the animal’s health. She has collaborated with native Alaskan people to examine baleen from 16 whales killed during the legal annual whale hunt. Bowheads are closely related to North Atlantic right whales. They may live for 25 years or longer; baleen plates record their health during those years. Hunt found detectable levels of cortisol and progesterone in the baleen, indicating levels of stress and the sex of the animals. She also found spikes in progesterone levels that might indicate past pregnancies.

To corroborate the findings, Hunt and her team then examined baleen taken from two right whales killed in 1999. The whales had been tracked over the years so scientists knew the times at which each had been pregnant and given birth. Hunt found that the levels of progesterone in the baleen corresponded to times of known pregnancy, then dropped off after each birth.

The fact that baleen can provide this sort of data is significant to whale researchers. The duration of time between pregnancies gives clues about the health status of the mother whale. If the period of time is longer than usual, that indicates something isn’t right with the female. If cortisol levels are high, that suggests that the animal is under either man-made or natural stress. Studying right whale “fingernails” may give researchers a treasure trove of new data about these endangered residents of the sea.