These carcasses were embedded in the the beach which is made of shells next to the water. Sand is further up the beach. I've read that the Salton Sea is getting more and more salty as the water evaporates. It's now so salty that only Tilapia can do well there.
Because of the years long drought and the efforts of farmers to limit water use, the Sea is not being replenished as fast as it is evaporating. It's thought that no fish will survive in its waters soon.
There were thousands of these fish carcasses on the beach. These Tilapia were suffocated by low-oxygen water stirred up by winds from the depths. See this article for more. The Sea isn't all that deep at about 52 feet (15.8 meters) at its maximum. This phenomenon occurs every year and yields balls of rotting fish flesh that wash ashore. The odors can apparently be overwhelming. Luckily, I was spared this part of the event.
The Salton Sea
Southern California, USA
Part of The Great American West series.