Sea otter being chased by a killer whale leaps to safety on a boat with just seconds to spare. She wails after her baby is eaten by the huge predator. The changes came after the 2010 death of SeaWorld … Let's get otter here! One killer whale would need to eat 1,825 otters a year to live. One reason for his doubt was that in several decades of going to sea and observing otters, he had never actually seen a killer whale eat a sea otter. Let's get otter here! Some biologists think the missing otters of western Alaska have disappeared to an unlikely place--the bellies of killer whales. Alligators DON'T eat sea otters, Killer whales (orcas) do! One method the whales used was to breach near floating otters and land on top of them, presumably eating the stunned otters underwater because the animals never returned to the surface. Researchers doing wildlife surveys following the Exxon Valdez oil spill and biologists studying otters in the Aleutians witnessed killer whales attacking sea otters. Clam Lagoon is an area uniquely protected from killer whales by a narrow channel only three or four feet deep, while Kuluk Bay is open coastline that offers otters no protection from killer whales. A mother otter clambers onto a motorboat in Tutka Bay, Alaska as the white underside of a killer whale chases after her. I think killer whales are eating sea otters because their primary food source may be scarce and they may be going to the second most abundant food sources, which may be affecting the overall population of sea otters. Three lines of evidence point to increased predation by killer whales (Orcinus orca)asthe reason for this mortality. Find answers and explanations to over 1.2 million textbook exercises. But hungry killer whales aren’t finding enough of their preferred prey: seals and sea lions. However, these smaller urchins are a favourite food of sunflower stars. So Estes looked at the history of … 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. Alaska Science Forum article has no image, a placeholder has taken its place. Assignment #8 - Population and Community Ecology, Central Washington University • BIOLOGY 181, Georgia Institute Of Technology • BIOL 1502, Copyright © 2021. 5. 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. What do you think has caused the killer whales to start eating sea otters I, 19 out of 19 people found this document helpful. One not accessible to killer whales, and sea otter decline 5x greater in areas accessible to killer whales. This is important because the sea urchins eat the kelp. How do we know for sure that killer whales feed on sea otters (3 reasons)? This preview shows page 2 out of 2 pages. Although from the Estes and his group study, it is clear that the killer whales have been the cause of the decline in the population of sea otters in Alaska, this has been greatly contributed to the fight for the survival of the whales and also the ecological interaction of the animals and their … 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? It was SeaWorld’s first show that did not include trainers in the water with the killer whales. John Dornellas, 37, filmed sea otter frantically swim towards his boat for safety The whale sightings in shallow waters frequented by sea otters coincided with a nosedive in the population of harbor seals and Steller sea lions, but Estes said he was skeptical about the killer whale-sea otter connection. On his 1990s cruises to the Aleutians, he and other biologists noticed a 25 percent decline in sea otters each year. Sea otter being chased by a killer whale leaps to safety on a boat with just seconds to spare. Change then began to happen near shore when the killer whales began eating sea otters. Is it true that two oiled seals were rehabilitated at a cost of $80,000 each and upon being released into the wild were promptly eaten by a killer whale? Kuluk Bay had a rapidly decreasing sea otter number which Clam Lagoons fluctuates normally. Hatfield concluded that the lack of reports of killer whales eating sea otters may be due to the fact that killer whales have only recently shifted their diets to include sea otters, possibly because of the decline of Steller sea lions and harbor seals. No. 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. Some feed exclusively on fish, while others hunt marine mammals such as seals and other species of dolphin. (The sea otter is an endangered species). Killer whales had not been known to … More attacks witnessed since then. What might threaten sea otters? This suggests that four killer whales, feeding exclusively on sea otters, could have driven the population into decline. What do you think has caused the killer whales to start eating sea otters? Killer whales are top-level predators in the ocean. Killer whales mostly eat sea lions, seals, and other marine mammals that spend most of their time far offshore, away from sea otters. However, these two have experienced a significant decline in their population. Not only did we see killer whales but we started seeing 'em eating otters. ... Sea otters eat invertebrates such as sea urchis, clams, crabs, etc. One killer whale with a taste for sea otters could eat more than 1,800 sea otters a year, Estes said. In Clam Lagoon, the entrance from the open sea is too narrow and shallow for killer whales to get in. Explain why Killer whales are eating sea otters now There was most likely a decline in the populations of the killer whales usual prey. That decline in animals was happening mainly out in the ocean. Three lines of evidence point to increased predation by killer whales (Oiecliis or-ca) as the reason for this mortality. What is kelp and why is it important? Scientists say killer whales off Alaska have begun hunting sea otters because their usual prey, seals and sea lions, have gone into serious decline. Their calculations suggest that only four transient marine mammal eating killer whales would have needed to switch to an exclusive sea otter diet to account for the decline. Killer whales have a diverse diet, although individual populations often specialize in particular types of prey. 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. The number of sea otters in Clam Lagoon remained stable from 1993 to 1997, while sea otters in nearby Kuluk Bay disappeared at a rate five times greater. Yet, individual ecotypes or populations are often extremely specialized. affected. No one had published a scientific paper on killer whale predation on sea otters until Brian Hatfield, also of the U.S.G.S. 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. When the big whales got hard to … clude that the sea otter population declines were caused by increased mortality. 3. Humans also kill sea otters when they use fishing gear that traps the otter or hit the otter with boats. Their population has dropped from about 53,000 animals in the early 1990s to only 6,000 today. 7. 4. 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. How do you think the sea otters are affecting these two groups of species? 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. IN this picture, you can see a sea otter eating a sea urchin in a kelp bed. Killer whales have started eating them. Otters are eaten by large predators, such as great white sharks, killer whales, bears, sea lions, eagles and coyotes, depending on their geographical location. Icon Attribution: Newspaper by Alexandria Eddings from the Noun Project, Killer Whales Develop a Taste For Sea Otters, The northern shrike: songbird like no other. Killer whales have not always preyed on sea otters. 10. The otter is much smaller than the sea lions and seals so the killer whales must eat … With less energy, there is less reproduction and more mortality, which leads to decreases in population size. Given that, prior to 1991, there had been no confirmed attacks by killer whales on sea otters, the discovery was puzzling. Try our expert-verified textbook solutions with step-by-step explanations. "All of us commented on how peculiar that was.". Killer whales are the largest predator of warm-blooded animals alive today.Globally, killer whales appear to have an extremely diverse diet. "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. Course Hero is not sponsored or endorsed by any college or university. And they sometimes use rocks to break open their prey. A female killer whale would need to eat 3 (3.1) male sea otters or 5 (4.6) females per day. An otter is “no more than a mouthful” for a killer whale, Bowlby says. Sea otters are getting harder to find along the western part of the Aleutian chain. The GI is located on the West Ridge of the University of Alaska Fairbanks campus. clude that the sea otter population declines were caused by increased mortality. October 19, 1998 Web posted at: 2:50 PM EDT. Specifically, it discusses the effects of killer whales eating sea otters in the North Pacific. By Environmental News Network staff. 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. However, it is true that the cost to clean and rehabilitate oiled sea otters was about $80,000 per animal. Why the killer whales changed their diet is still a matter of speculation, but people may be the culprits. When sea otters are present, they eat a huge amount of sea urchins. What do you think has caused the killer whales to start eating sea otters? By Environmental News Network staff. Why do orcas eat sea otters? During reading: What is causing the rapid loss of sea otters in Alaska? Their favorite prey has always been sea lions and seals. The University of Alaska Fairbanks is an AA/EO employer and educational institution and prohibits illegal discrimination against any individual: Learn more about UA's notice of nondiscrimination. ©2020 Geophysical Institute, University of Alaska Fairbanks. "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. Sea otters do an excellent job of eating large sea urchins over eight centimetres in diameter, but they tend to leave behind smaller urchins. What caused the loss of sea otters along the coasts of Washington State and Oregon? 1) 1st killer whale attack on sea otter observed. 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. Deprived of their normal food, killer whales turned to the sea otter. As a result, the population of sea urchins has risen dramatically, and the sea urchins began eating kelp at an alarming rate. A male killer whale would need to eat 5 (4.66) male sea otters or 7 (6.9) females per day. 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. 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