Otters declining Explanations

The reading and the lecture both try to explain why the otter population has declined along the western coast of North America. While the former states that this depletion has been provoked by pollution, the latter posits that a predator theory is more likely to cause this phenomenon. First and foremost, it is mentioned in the passage that pollutants have caused the death of many otters. Evidence of this is oil rings and other sources of industrial chemical pollution. On the other hand, the lecturer questions this fact due to the reason that no one has seen dead otters in the coasts. The professor implies that predators don't leave the body of their prey - in this case, the otters - on the coast, and this fact is proof of the predator theory. Second, the passage indicates that not only otters have been affected by pollution, but also other mammals have declined, such as seals and sea lions. However, the professor refutes this statement saying that orcas, which usually hunt whales, are now hunting sea otters. This phenomenon is because hunters have provoked the depletion of the whale’s population, and consequently, orcas are adapting by eating other mammals. Additionally, she points out that other mammals - such as sea lions - have also decreased their population. Third, the reading attributes the uneven pattern of decline in otters population to the different concentrations of pollutants along the coast. On the other hand, the lecturer also associates this fact to the theory predation. She elaborates on the point that whales, which eat otters, cannot access the shallow or rocky places where otters live. As a result, there are more otters in the areas that are not accessible by whales. In summary, the lecture - with its theory of predation - refutes the passage by providing compelling evidence that refutes each one of the three main reasons to explain the depletion in sea otters population.