Beaches in California, Oregon, Alaska, Washington, and Canada aren’t just strewn with umbrellas and seaweed anymore. Since January, over 70 dead gray whales have washed up on coasts across the seaboard, and that’s not the worst part. Scientists don’t know what is killing these whales or why so many are washing ashore.

What do we know about these whales?

While it is not uncommon to see lots of gray whales off the west coast this time of year, the number of dead washed-up whales so far is unprecedented. Gray whales make the trek from southern California to the seas north of Alaska between March and June every year and then turn around and head back to the warm waters around November. And although whales turn up unexpectedly on shore from time to time, there have already been 73 whale bodies found this year, more than any other year since 2000.

Researchers don’t yet know what is killing these whales, but they have started gathering some clues. First, many of the whales’ bodies are malnourished and skinny, which could mean that they died of starvation. This particular theory breeds further concern because when whales starve to death, their bodies usually sink to the bottom of the ocean floor. If this is correct, the number of dying whales could be over 700 instead of over 70 as scientists predict that the deaths we’re seeing are only 10% of whale starvation deaths overall.

In addition to the large number of dead whales, tourists and marine biologists alike have been seeing more whales close to the shore this migration season than in previous years. Scientists predict that the number of whales in bays, marinas, and harbors is related to the malnourished whales washing up on beaches: these whales are potentially moving out of their comfort zone in search of additional food.

Has this ever happened before?

Gray whales aren’t currently on the endangered list, but they used to be. This species was once greatly threatened by whalers, so much so that by 1946 there were fewer than 2,000 gray whales left in existence.  Thanks to an international agreement and whaling prohibitions, gray whale numbers grew so much that they were removed from the endangered list in 1994 with an approximate population of 20,000.

However, in 1999, an unspecified and unknown event caused the gray whale population to plummet from around 20,000 down to 16,000. By 2016, though, scientists estimated a gray whale population of about 26,000. This historical information gives scientists hope that whatever is causing gray whales to die off in large numbers now might not mean the end of the species as it seems that they are able to rebound even after major unexplained events, known as Unusual Mortality Events (UME) by the National Oceanic and Atmospheric Administration (NOAA).

What are scientists doing about these whale deaths?

With the NOAA designation of UME comes requisite further investigation. This discovery of an unprecedented number of dead whales has already spurred scientists to do further research on water conditions and possible causes, but most of all, they’re trying to get as much information as they can from the found whale bodies. That they are malnourished is a good first step, but there is still a ways to go before the problem can be definitively found and solved. Currently, scientists are tying this uptick in whale deaths to climate change and declining populations of fish, but only time and more research will tell. For now, all we can do is hope that once again, these whales are able to bounce back.