Summarize the point made in the lecture and explain how the speaker cast doubt on specific points made in the reading passage.

The reading and the lecture both discuss the possible reason for the population decrease of sea otters. While the author believes that pollution is most likely causing this issue, the lecturer in the listening passage disagrees. He claims that predation is the root cause of this issue and challenges each of the writer's points in the text. In the reading, the writer begins by stating that pollution sources releasing harmful substances that negatively affect the otter's health were found in areas where the otter's population was diminishing. The speaker disagrees with this viewpoint. He says that the lack of dead bodies of sea otters washing up on the shore contradicts the point given. The most likely explanation for missing dead bodies is that the otters were eaten by predators. The article also mentions that the death of other sea animals in the same regions indicated that the cause was something that affected the entire ecosystem rather than a single species. It goes on to reason that predators like orcas couldn't be the cause as they usually prefer larger prey. The professor believes there are flaws in the writer's argument. He claims that orcas might have started hunting smaller animals like otters and seals due to the lack of its usual larger prey like whales. Finally, the author suggests that the uneven concentrations of polluting chemicals in the waters due to water currents along the coast explain the fact that more otters were dying in certain areas than others. On the other hand, the lecturer believes that otters in areas easily accessible by predators would be declining faster compared to other areas. Moreover, the otter population in shallow areas being stable suggests that his view might be correct.