I believe whales primarily eat krill, which eat phytoplankton. Phytoplankton eat whale poop. In the Netflix documentary Our Planet, the episode The High Seas di

I believe whales primarily eat krill, which eat phytoplankton. Phytoplankton eat whale poop. In the Netflix documentary Our Planet, the episode The High Seas discusses how the whaling ban in the 80s has led to a resurgence of the humpback whale population and how they help provide nutrients to promote phytoplankton growth.