Wired published a piece on the disappearing Beluga whales of Alaska and their importance on passing “cultural knowledge across generations”:
Some cultural practices, like which language whales speak, may not have much impact on survival. But others, like techniques for finding food, can be critical. When killer whales go through lean times, scientists can see long-term knowledge at play: Killer whales move in pods, and when food gets scarce, the oldest females move to the front. They’re likely using knowledge from times when conditions were similar—possibly decades earlier—to show younger whales where to find prey. “It’s called the grandmother hypothesis,” said Sam Ellis, a behavioral ecologist at the University of Exeter. He and his colleagues have shown that killer whales with living grandmothers are more likely to survive than those without.
Cultural adaptations have also helped species like belugas and killer whales survive, said [Greg] O’Corry-Crowe, and behaviors can develop much faster than genes can be revamped. To cope with warming waters, belugas could learn to move to regions that are still cold enough for their bodies (as long as such regions still exist). Otherwise, they may need to evolve to dissipate heat more efficiently—a process that would take at least a few generations and likely much longer. When resources are patchy, “it’s important to remember where they are, and to pass that knowledge on,” he said. But old practices can pose a problem if they don’t allow the group to adapt to new circumstances. When the world changes quickly, “suddenly, you’re let down,” Ellis said.
The main causes appear to be low birth and survival rates which are linked to wider issues such as climate change, whaling, increased ship traffic, and pollution. Aren’t humans great?
More on the subject: a USGS report on the declining Beluga population in Alaska and a linked cause being low birth and survival rates