TPO-10 - Integrated Writing TaskThe sea otter is a small mammal that lives in waters along the western coast of North America from California to Alaska. When some sea otter populations off the Alaskan coast started rapidly declining a few years ago, it ca

The article states that more likely pollution is a reason for the declination of sea otter along the western coast of North America from California to Alaska and provides three reasons for support. However, the professor refutes each of an author's point and discusses why predation, mainly by orcas, is a better explanation of evidence presented in the reading passage.

First, the reading claims that increased level of pollution by oil rigs and factory chemicals, detected along the Alaskan coast could cause the deaths of sea otters by making them vulnerable to infections. The professor refutes this point by saying that no dead sea otters have been found washed up on the shore, this weakens the pollution theory but supports the predator theory, since the predators could eat the otters immediately as they caught them, leaving no remaining hence can’t washed up on shore.

Second, the article posits that the decline of other sea mammals like seals and sea lions indicates to a systemic cause such as environmental pollution. The orca, a predator that could conceivably hunt several sea mammal species, is not likely the cause as it prefers larger prey like whales. However, the professor says that whales have been disappeared from the coast because of human hunters, so orcas started hunting smaller prey such as sea lions, seals, and otters.

Third, the reading says that the decline of sea otter populations is greater in some locations than in other which seems consistent with the pollution theory since varying concentrations of pollutants may cause an uneven pattern. The professor opposes this point by explaining that the uneven pattern of sea otter decline can be understood by predation theory. According to this theory, some locations where sea otters live are available to orcas; there the number of sea otters has declined greatly and sea otters at shallow and rocky locations can’t be found by large orcas, hence here there populations have not been declined.