Chuck Bednar for redOrbit.com – Your Universe Online
By measuring hormone in tissues comprised from keratin, researchers from the New England Aquarium in Boston and North Slope Borough in Alaska are hoping to find a way to study the physiological condition and reproductive activity of bowhead whales.
Doing so has proven difficult over the years, the researchers explain. Typically, if a scientist wants to analyze a creature and study the fluctuating hormone amounts in its body over a growth period, they conduct a one-time capture and sample removal. This technique can provide experts with a veritable treasure trove of information about a creature, they added.
However, as Dr. Kathleen Hunt, a scientist with the New England Aquarium, points out in a statement, there is no such capture method for live whales. As a result, when she first started working with the facility, she found that there was little information available about bowhead whales, including how often they give birth, when they mate, or even how long they live.
She and her colleagues are looking to change this by studying tissues made of keratin, the same substance that makes up hair and fingernails. Learning about animals by extracting steroid hormones out of keratinized tissues has become common for difficult to capture creatures, they explained, and the technique is now being applied to the massive marine mammals.
By using this method, Dr. Hunt’s team hopes to learn more about the current physiological condition of the bowhead whales, as well as a record of their reproductive activity over the past 15 to 20 years. This information will allow them to closely monitor the overall condition of the population, which can currently be legally hunted.
In right whales, a species that is a close relative of the bowheads, the interval between pregnancies can indicate whether or not the population is in trouble. For instance, if the period between calves becomes longer, it could serve as a warning sign that something is amiss. However, the normal birthing rate of bowheads is currently unknown. Without that information, it is impossible for scientists to tell when reproduction is altered, for better or worse.
Dr. Hunt, who presented her research at the 2015 annual conference of the Society for Integrative and Comparative Biology in West Palm Beach, Florida, used baleen from the mouths of bowhead whales to obtain the keratin used in the study. Baleen plates help the whales filter water and collect food, and continually grow from the gum line at a rate of up to 20 cm per year.
While baleen cannot be extracted from live whales, the researchers were able to collect samples from those that have been hunted and harvested. Dr. Hunt and her colleagues collected baleen samples from several male and both pregnant and non-pregnant females and studied them to see if there were any hormones in the material, and if so, what the hormone profile could reveal.
Once the samples were collected, the investigators ground bits of them down and measured progesterone levels, a steroid hormone found in high amounts during pregnancy. They predicted that baleen closer to the gum line (which had grown most recently) would have higher levels of progesterone in currently pregnant females, lower levels in non-pregnant females, and the lowest levels in male whales.
As they expected, Dr. Hunt and her associates found that the steroids were present in the baleen, and followed the expected pattern, with levels highest in pregnant females and lowest in males. The findings confirmed that steroid hormones are deposited in whale baleen, and could provide scientists with a way to monitor the whale’s recent physiology, the study authors said.