Sei Whale
Humans are constantly disrupting the food chain. through this we are destroying many marine habitats including the open waters where the whales live. This can lead to them beach and die.
Hausserman, Vreni. "Sei Whales Beached at the Gulf of Penas, Chile." ABC News, 4 May, 2016. Date Accessed: 6 May, 2020. https://www.abc.net.au/news/2015-12-02/sei-whales-beached-at-the-gulf-of-penas,-chile/6994034?nw=0.
One role of whales is the stabilization of the aquatic food chain. Sei whales are near the top of the food chain (it's only natural predator being the orca whale), and they feed on fish, squid, krill (small, shrimp-like creatures), copepods, and zooplankton. Their diet helps regulate the flow of food throughout the food chain and ensure that specified populations do not grow out of control. When sei whales are killed, the distribution of food/prey in the ocean becomes irregular, affecting the food web, which impacts other marine life as well (Whale Facts).
The cetacean species, which includes dolphins, porpoises, and whales, have been used to help advancements and discoveries with echolocation, marine biology/life in general, and the intelligence of marine mammals. Even whale excrement plays a crucial role in the ecosystem: It helps reduce carbon in the atmosphere, which leads to an increase in health for the atmosphere and for the aquatic ecosystems.