Science at the Kodiak History Museum

What is the scientist, Dana, doing?

Dana is collecting a samples of baleen from multiple places along the baleen plate using a drill.

What is a baleen plate?

Baleen plates grow from the upper gum of baleen whales. They are made out of keratin – the same thing as our hair and fingernails! Baleen whales use baleen plates to help filter their food. The baleen traps small animals, like zooplankton or fish, in the mouth, while allowing water to pass through.

Why is Dana collecting baleen tissue?

Baleen plates record a time-series of information about the animal in the form of elements and molecules. Just like a tree ring, baleen is deposited every year.

Dana is sampling along the baleen to reconstruct a time-series of where the whales swam and what they ate.

Why is that important?

Scientists currently do not know where N. Pacific right whales swim to in winter! They in-effect disappear for half the year!

Scientists and managers really want to know where they swim and what they eat in winter to properly protect them. Without protection, the whales are at risk of getting tangled in fishing gear or getting struck by ships depending on where they're going.

Map showing vessel traffic density for the year 2018 by season. Figure from Silber et al. (2021).

How do scientists know where whales swim using baleen?

The scientist acts like a detective with clues. For Dana, the clue is a stable isotope value, which is a ratio of stable isotopes of an element.

Samples of baleen can be put in a machine, called an isotope ratio mass spectrometer, that separates elements based on their atomic mass (# of protons + neutrons) and provides a stable isotope ratio. Stable isotopes of different elements give scientists an idea of where the animal was swimming and what it was eating, because stable isotope vary naturally in different ecosystems based on natural processes including rainfall, water currents, and sunlight.

What is a stable isotope?

‘Stable isotopes’ are variants of an element with different numbers of neutrons. For example, nitrogen on the periodic table has seven protons and seven neutrons. This gives Nitrogen-14 an atomic mass of 14 (7 protons +7 neutrons). Nitrogen-15 also exists and has 8 neutrons and 7 protons. Because Nitrogen-15 is heavier by 1 neutron, it will cycle through food webs and ecosystems differently than Nitrogen-14. These elements are named stable, because they don’t decay with time like radioactive isotopes; instead they have been cycling throughout our world from the time our planet was formed – from me, to you, to whales, to birds, to bugs, to plants!