Climate Change's Role in the Strandings of Gray Whales

Reporting on behalf of CNN, Daniel Wolfe talks to NOAA scientists, marine mammal forensic scientists, and volunteer gray whale spotters along the Pacific coast to understand how and why this sentinel species has been winding up across shorelines dead and emaciated.

An adaptive mammal, these whales are opportunistic feeders able to eat small prey they find on the seafloor. Historically, a main source of food includes sea bugs (benthic arthropods), which are found in the whales' summer feeding grounds in the Arctic Circle. As seasonal temperatures cause the sea ice to retreat, this food source becomes more available to the whales. With climate change, the arctic sea ice recovers less and less each season, broadening the whales’ feeding grounds. So why would these whales be found starving along California beaches?

One potential clue marine biologists are investigating is to what extent sea bugs have been more severely impacted by warming climates than previously thought. Without protection from a regenerative ice shelf, the population of sea bugs may not be recovering over successive seasons. The level of whale malnutrition observed suggests that sea bug populations may be on their way to a collapse, which may cause even more whales in the coming years to migrate thousands of miles on an empty stomach.