We can learn a huge amount about the whales we study from minute samples of skin and superficial blubber. We use a specially designed remote biopsy dart system to obtain a tiny sample from each whale we identify in the field.
We collect the samples using a small surgical biopsy tip that we deliver using a crossbow. The tip has a foam collar that ensures that we take only superficial tissue and also helps the darts to float after they bounce off the whale. Each sample measures about 25 mm in length and 5 mm in diameter and weighs only a few grams. In contrast, the whales are about 15 meters long and weigh 40 to 50 tons. The best analogy we can think of is that it’s like a mosquito bite to you or me.
We work hard to ensure that we identify each whale before attempting a sample and compare pictures of its flukes with our catalog, which is stored on an iPad that we bring onboard. If the whale is new to us (as most have been this year), we move our Zodiac alongside the whale and fire the biopsy dart at its flank when it arches to dive, usually from a distance of 10 or 15 meters. Needless to say we are extremely careful throughout the entire sampling process. Zach is a very good shot and rarely misses. And yes, I know, he is shooting at an enormous whale, which helps.
The tiny samples provide an enormous amount of information about each whale we sample, including its sex, recent dietary history, reproductive status, and health. We also use genetic markers to infer which breeding population the whale comes from. Logan Pallin, who graduated from Duke last spring, and will be attending graduate school at Oregon State University next year, will be conducting progesterone assays from our blubber samples to determine if female whales are pregnant. We are looking forward to having Logan tell us which whales we can expect to see with new calves next year!