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The U.S. Geological Survey has seen a record number of sick, injured and dead sea otters along the California in the past year.

Despite conservation efforts to protect sea otters, the species is still in danger. Last year, 335 dead or injured sea otters were found off the California coast, a record number.

By some estimates, hundreds of thousands of sea otters lived in the Pacific Ocean for centuries — until hunters took their toll.

In the early 20th century, only a few thousand sea otters remained. Between an international hunting ban and a growing environmental movement, the otters began to slowly come back. The last official count put the number at about 3,000.

But in just the past year, the U.S. Geological Survey has seen a record number of sick, injured and dead sea otters along the California coast.

The main culprit? Shark attacks, which account for about a third of the otter deaths.

The other causes are disease, accidents with boats and gunshot wounds.

"The southern sea otter, once hunted to the brink of extinction, is staging a comeback but still faces multiple challenges on its road to recovery," explained Marcia McNutt, director of the U.S. Geological Survey, in a press release. "Careful work can help us understand which threats are in our power to mitigate and which are inevitable risks of living in the wild for this beautiful animal, often considered a bellweather for ocean health."

Scientists say if those factors aren’t addressed, there’s no way the otter population can ever be fully restored.

Guest:

Tim Tinker, biologist with the U.S. Geological Survey and professor at UC Santa Cruz.