This crash began in the early 1990s, in the same year as one of the first confirmed sightings of a killer whale attacking a sea otter. The data are presented in Table 1. The report “Killer whale predation on sea otters: Linking oceanic and nearshore systems” by James A. Estes et al. Members of all marine mammal families, except the river dolphins and manatees, have been recorded as prey of Killer Whales; attacks have been observed on 20 species of cetaceans, 14 species of pinnipeds, the Sea Otter… No one had published a scientific paper on killer whale predation on sea otters until Brian Hatfield, also of the U.S.G.S. re-evaluate the evidence for killer whale predation and to review evidence for alternative causes. Killer whales in seas off the coast of Alaska are reported to be eating the world's smallest sea mammal, the sea otter, which they previously … 5 Estes et al. Killer Whale Predation on Sea Otters Linking Oceanic and Nearshore Ecosystems In the Aleutian Islands, a decline in sea otter populations in the 1990s was controversially attributed by some scientists to killer whale predation, although with no direct evidence. One killer whale is more than a hundred times heavier than a sea otter. I don't know about you but lately I have been seeing lots of stories about Animals being more intelligent than we give them credit for. Images from Estes et al. After nearly a century of recovery from overhunting, sea otter populations are in abrupt decline over large areas of western Alaska. However, these two have experienced a significant decline in their population. The aim of this study was twofold: 1) to conduct a literature review of the evidence that killer whales caused the sea otter … But hungry killer whales aren’t finding enough of their preferred prey: seals and sea lions. Describe two experiments that would allow you to test the hypothesis that increased predation by killer whales was the cause of the sea otter decline. Given that, prior to 1991, there had been no confirmed attacks by killer whales on sea otters, the discovery was puzzling. It was speculated that these interactions reflected an increase in killer whale predation as a result of “transient” (mammal-eating) killer whales adjusting their diet to include sea otters, possibly in response to declines in other marine mammal prey, including harbor seals and Steller sea lions (Estes et al., 1998, … This was an unusual idea, since killer whales and sea otters had been observed together in Alaska for decades with no obvious interactions occurring between them. A. Estes,* M. T. Tinker, T. M. Williams, D. F. Doak After nearly a century of recovery from overhunting, sea otter populations are in abrupt decline over large areas of western Alaska. According to the article, an attack on a sea otter by a killer whale was first seen in 1991 and since then there … Elevated sea … Their favorite prey has always been sea lions and seals. Elevated sea urchin density and the consequent deforestation of kelp beds in the nearshore community demonstrate that the otter… Increased killer whale predation is … Killer whales have not always preyed on sea otters. The caloric value of sea otters compares killer whale foraging behavior created a linkage with a range of 0.78 to 3.55 kcal gm–1 of wet 1965 and 1992, sea otter counts decreased at all but between oceanic and coastal ecosystems and in one, for an average reduction of 58%. Elevated sea urchin density and the consequent … 5. Another threat to the Alaskan sea otter is the killer whale. By Nearshore Ecosystems, J. Killer whales live on, at the expense of otters Researchers say the ocean's top predators have been forced to change their diet as a direct result of human-induced ecological change. The first John Dornellas, 37, filmed sea otter frantically swim towards his boat for safety Hey guys, bill here. 1998). Sea otters are the primary natural predators of sea urchins. Increased killer whale predation is the likely cause of these … Increased killer whale predation is the likely cause of these declines. (16 Oct. p. [473][1]) poses an intriguing explanation for the recent precipitous decline of sea otters in the Aleutian Islands. (1998) hypothesized that killer whale predation is responsible. Killer Whale Predation on Sea Otters Linking Oceanic and Nearshore Ecosystems J. This hypothesis has not been challenged nor tested empirically. Sea otter being chased by a killer whale leaps to safety on a boat with just seconds to spare. 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. CiteSeerX - Document Details (Isaac Councill, Lee Giles, Pradeep Teregowda): After nearly a century of recovery from overhunting, sea otter populations are in abrupt decline over large areas of western Alaska. JA Estes, MT Tinker, TM Williams, and DF Doak, Killer whale predation on sea otters linking oceanic and nearshore ecosystems: … A. Estes,* M. T. Tinker, T. M. Williams, D. F. Doak After nearly a century of recovery from overhunting, sea otter populations are in abrupt decline over large areas of western Alaska. Sea otters in the Western Aleutian Islands have experienced a drastic population decline since the 1990s and Estes et al. Elevated sea urchin density and the consequent deforestation of kelp beds in the nearshore community demonstrate that the otter's … in California, gathered anecdotes for a paper … This decline caused trophic cascades throughout local coastal systems, as sea urchins were freed from predation pressure from otters and … 3. Killer Whale Predation on Sea Otters Linking Oceanic and Nearshore Ecosystems J. "Killer Whale Predation on Sea Otters Linking Oceanic and Nearshore Ecosystems" Estes, Tinker, Williams, Doak General Hypothesis *Reduced Fertility *Increased morality *Redistribution CORRECT? Increased killer whale predation is the likely cause of these declines. John Dornellas, 37, filmed sea otter frantically swim towards his boat for safety; Otter swims towards boat as it is chased by orca in Halibut Cove Lagoon, Alaska ; Mr Dornellas said the otter hopped back into water before … The decline of sea otters followed a decline in harbour seal and Steller sea lion populations, the killer whale's preferred prey, [a] [126] which in … Researchers have also demonstrated how killer whale predation on sea otters link oceanic and near shore ecosystems. A report by J. Estes et al. Killer whale predation on sea otters: how predation can cause major changes in an ecosystem ... Killer whale prey in the Aleutians. Rejected "reduced fertility" and "redistribution" after testing (radiotagging) Survival (Riedman and Estes 1990, Larson 2015) The Most widely accepted hypothesis is that increased predation by killer whales had caused the decline of the sea otters in the Aleutian archipelago. 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