Could predation by killer whales account for a 90 percent decrease in otter numbers?
If increased predation by killer whales was the primary cause of the sea otter decline in Alaska from 1990-1996, as Estes and his group suspected, killer whales would have to have eaten 40,000 sea otters in six years! How many killer whales would it take to eat this many sea otters? We know that killer whales travel in groups ranging from five to 25 individuals. Would it take one such group or 100? This is an important question to answer to determine whether killer whale predation could account for all of the missing sea otters. Using data provided in the table below, calculate how many whales feeding exclusively on sea otters it would take to eat 40,000 sea otters.