What do the data tell you?
Estes and his colleagues estimated the impact of killer whales on sea otter populations by comparing trends in population size and survival rates of individually marked otters between two adjacent locations on Adak Island--Clam Lagoon and Kuluk Bay. Kuluk Bay is on an open coast, so sea otters there are exposed to killer whales. In Clam Lagoon, the entrance from the open sea is too narrow and shallow for killer whales to get in. Based on Figures 3 and 4 below, what can you conclude about the effects of killer whales on sea otter populations? Why do you think the scientists both counted all the sea otters and did the tagging and radio tracking?