Good morning, everyone. Today we'll continue our discussion on marine biology, focusing on the migration patterns of the humpback whale. As you know, these whales travel thousands of kilometers between their feeding grounds in cold polar waters and their breeding grounds in tropical seas. Interestingly, recent studies have shown that the timing of their migration is not solely determined by water temperature. Instead, it appears to be closely linked to the availability of their primary food source, krill. When krill populations peak in the polar regions, the whales begin their journey southward. This finding challenges the earlier assumption that daylight length was the main trigger.
❓ According to the lecture, what is the main factor influencing the timing of humpback whale migration?