TPO 10 Integrated Writing Task The 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 c

The reading passage presents the views of scientists who believe environmental pollution is the primary cause of the rapid decline in sea otter populations off the Alaskan coast. The lecturer, however, asserts that recent investigations have shown that predation is more likely to be the main cause.

First, according to the article, it is water pollution caused by oil rigs and other industrial chemicals that has led to deathly infections in the otter. The speaker cites the fact that no dead sea otters have been found near the shore, suggesting their deaths couldn’t be blamed on the environment. On the contrary, the predation hypothesis goes more consistently with this observation.

Second, although the scientists in the reading hold a strong belief that pollution is the reason why the populations of sea otters and other sea mammals were negatively affected, the professor doesn't think the same. He points out that the orca's main prey - the whale - have disappeared from the location due to human activities. This explains why the orca have had to hunt other smaller mammals for survival, thus causing their populations to drop simultaneously.

Third, while the scientists use ocean currents and other environmental factors to explain the uneven concentrations of otter populations along the coast, the lecturer states this unusual pattern can be better unraveled by the predation hypothesis. To be specific, Alaskan locations where the otter populations decreased are also places where it is easy for the orca to get access to. In contrast, in shallow and rocky locations, it is challenging for the orca to approach, so the number of sea otters along the coast doesn’t seem to decrease.