in California, gathered anecdotes for a paper published in the October 1998 Marine Mammal Science. However, it is true that the cost to clean and rehabilitate oiled sea otters was about $80,000 per animal. What effects do you expect sea otters to have on the rest of the kelp forest community. Not only did we see killer whales but we started seeing 'em eating otters. Killer whales had not been known to … In support of this theory, the first well-documented attack of a sea otter by a transient killer whale was observed in 1991, with 9 other attacks observed since then. Their population has dropped from about 53,000 animals in the early 1990s to only 6,000 today. How do you think the sea otters are affecting these two groups of species? Estes said he wasn't convinced killer whales were eating sea otters until he and Tim Tinker, also from Santa Cruz, did a study in which they compared two populations of sea otters at Adak Island. Estes said he wasn't convinced killer whales were eating sea otters until he and Tim Tinker, also from Santa Cruz, did a study in which they compared two populations of sea otters at Adak Island. This is an urban legend, as explained at Snopes.com. The Sea Otter (Enhydra lutris) is the smallest marine mammal in North America – males measure 1.2 metres in length and weigh an average of 45 kilograms (females are a bit smaller).At the same time, the Sea Otter is the largest member of its family, the mustelids, which includes River Otters, weasels, badgers, wolverines and martens. Killer whales are top-level predators in the ocean. Please report any problems or feedback concerning this website to uaf-rcs@alaska.edu. A male killer whale would need to eat 5 (4.66) male sea otters or 7 (6.9) females per day. Jim Estes, a wildlife research biologist who works for the U.S. Geological Survey at the University of California, has watched sea otters in Alaska since the 1970s. An otter is “no more than a mouthful” for a killer whale, Bowlby says. What do these data tell you about the role of sea otters in their community? Researchers doing wildlife surveys following the Exxon Valdez oil spill and biologists studying otters in the Aleutians witnessed killer whales attacking sea otters. With the kelp forest gone it throws off the whole ecosystem because there ae many other species that depends on the kelp. "All of the available data point to increased numbers of killer whales as the direct cause of the sea otter decline in southwest Alaska," says coauthor Jim Estes of the U.S.G.S. More attacks witnessed since then. It explains that the possible eradication of the kelp forests will pose a great threat to the ecological balance and the fishing industry of the region. What do you think has caused the killer whales to start eating sea otters? Let's get otter here! Killer whales are the largest predator of warm-blooded animals alive today.Globally, killer whales appear to have an extremely diverse diet. When sea otters are present, they eat a huge amount of sea urchins. At first, Estes didn't consider killer whales as a reason for the sea otter decline. Course Hero is not sponsored or endorsed by any college or university. As a result, populations of sea otters in the Aleutian Islands have declined from an estimated 60,000 animals in the mid-1980s to under 10,000 by 2000. With less energy, there is less reproduction and more mortality, which leads to decreases in population size.   Privacy First, although killer whales and sea otters have been observed in close proximity for decades, the first attack on a sea otter was seen in 1991. One killer whale would need to eat 1,825 otters a year to live. 3. Why do orcas eat sea otters? "We were seeing killer whales near the beach all the time," Estes said during a phone interview from his office in Santa Cruz, California. The killer whales have eaten more than 40,000 otters since the early 1990’s, leaving fewer otters to consume sea urchins from the ocean floor. The Orca diet also consists fish, squid, seals, sea lions, dolphins, porpoises, and large whales such as the Blue Whale. On his 1990s cruises to the Aleutians, he and other biologists noticed a 25 percent decline in sea otters each year. When the whales start to eat the otters the otter population starts to dwindle in numbers and then the sea urchins has the chance to multiply in number and then they start to devour the kelp forest. clude that the sea otter population declines were caused by increased mortality. No. Killer whales mostly eat sea lions, seals, and other marine mammals that spend most of their time far offshore, away from sea otters. Course Hero, Inc. They feed on sea otters in means of survival that is survival of the fittest. Since it was established by an Act of Congress in 1946, scientists at the Geophysical Institute have studied geophysical processes from the center of the Earth to the surface of the sun and beyond, turning data and observations into information useful for state, Arctic and national priorities. How do the otters keep warm? Why the killer whales changed their diet is still a matter of speculation, but people may be the culprits. This, of course, begs the very important question: Killer whales and sea otters had co-existed peacefully for decades prior to the 1990s, so why would the whales suddenly start eating otters? In Alaska, the rapid loss of sea otters turns out to have a shocking cause. Assignment #8 - Population and Community Ecology, Central Washington University • BIOLOGY 181, Georgia Institute Of Technology • BIOL 1502, Copyright © 2021. What caused the loss of sea otters along the coasts of Washington State and Oregon? Try our expert-verified textbook solutions with step-by-step explanations. What do you think has caused the killer whales to start eating sea otters I, 19 out of 19 people found this document helpful. The killer whale (also known as the orca) generally did not consume sea otters in the past, but now consumes thousands of otters. A mother otter clambers onto a motorboat in Tutka Bay, Alaska as the white underside of a killer whale chases after her. Humans also kill sea otters when they use fishing gear that traps the otter or hit the otter with boats. John Dornellas, 37, filmed sea otter frantically swim towards his boat for safety   Terms. Comparison of the weight and metabolic rate of sea otters and killer whales suggests that only 2-4 whales could eat 40000 sea otters in 6 six years, and due to the fact that the whales move in groups of 25-100, it is possible for them to cause 90% of the reduction. 4. Killer whales have not always preyed on sea otters. The changes came after the 2010 death of SeaWorld … Transient killer whale populations likely decreased as well, because the cost-benefit ratio of eating otters is less favourable, resulting in an overall worse energy trade-off for individual whales. What is kelp and why is it important? clude that the sea otter population declines were caused by increased mortality. Orcas were eating otters because the really big whales they used to eat were nearly wiped out by commercial whalers back in the 1950s. The GI is located on the West Ridge of the University of Alaska Fairbanks campus. October 19, 1998 Web posted at: 2:50 PM EDT. 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