Declining Sea Otter Summary

The professor talks about the real reason behind the declining of the sea otter,which is predation. He mentions three points that are the lack of dead sea otter in the beach, some animal chasing their diet , and location of sea otter makes them easy to hunt. The information he discusses is opposite the points in the reading.
First, the lecturer mentions that there is no dead sea otter body on the beach, that means the sea otter gets killed and eaten by a predator, not because of pollution , ON the other hand, the reading points out that the main reason is pollution, also, some experts test the water and find a high levels of chemicals that affect the sea otter.
Second, the professor explains that due to the lack of whales, some of the animals