(B) Global overview of PCB concentrations in killer whale blubber (ppm, parts per million).Light and dark green circles represent males and females, respectively. Populations of mammal-eating transient orcas, gray whales and humpback whales are increasing. An analysis of the DNA will determine if this is actually a completely new species or just an unusual subtype. This suggests that four killer whales, feeding exclusively on sea otters, could have driven the population into decline. It is estimated that there are around 50,000 killer whales globally. Different populations of killer whales make different vocalizations, and different pods within these populations may even have their own dialect. Sea otter numbers were stable from 1993 through 1997 in Clam Lagoon, whereas in Kuluk Bay they declined by 76%. . Lull for killer whales. It lives in parts of the ocean near Antarctica — and it could be the largest animal to have remained unidentified by biologists. The killer whale, also known as an orca (Orcinus orca), is a toothed whale belonging to the oceanic dolphin family, of which it is the largest member. Ecologists say killer whales are eating the otters. But sea otters living in the Bering Sea off Alaska probably think differently. The whales were smaller than other killer whales, and they had rounded heads and pointier fins. Killer whales, or Orcas (Orcinus orca) are toothed whales in the oceanic dolphin family. The Navy estimates the southern population of killer whales in the Puget Sound region could be subject to the non-lethal take two to 51 times a year during the seven years of Navy activity. "And you can imagine them thinking, 'Hey, where's our fish?' The team was able to snip off small tissue samples from the whales by firing a harmless dart, attached to a line, into their skin. Danita Delimont/Getty Images Reproduction and Offspring . The killer whale is easy to identify by its size and its striking coloration: jet black on top and pure white below with a white patch behind each eye, another extending up each flank, and a variable “saddle patch” just behind the dorsal fin. (A) Conceptual model of PCB bioaccumulation and magnification, leading to elevated PCB concentrations in killer whale populations. "This study was really a decade-long look at what do killer whales die from, from California to Alaska all the way out to Hawaii," he sasy. NIELSEN: Williams is part of a team that first observed these sneak attacks seven years ago when they were studying the otter die-off along the Aleutian Islands. Killer whales, just like their dolphin cousins, communicate through underwater sounds with one another. Some feed exclusively on fish, while others hunt marine mammals such as seals and other species of dolphin. A new theory suggests a massive decline in seals, sea lions and sea otters in the North Pacific may have been triggered by over-fishing of great whales. When the sea lion population crashed, they started fishing sea otters. Before reading: Describe a sea otter. Approximately 2,500 killer whales live in the eastern North Pacific Ocean—home to the most well-studied killer whale populations. When the big whales got hard to find, Williams says, the orcas switched to big, stellar sea lions and then to medium-sized seals. Then, when seals became rare, the killer whales turned to sea lions. Photos from New Zealand showed a bunch of whales stranded on a beach. Marine scientists suggest the Southern Resident orcas face problems centered on their diet. Scientists are finding the same trend around the world. Whale researchers spotted a baby orca swimming energetically with its mother west of San Juan Island on Friday. Copyright © 2005 NPR. Pitman adds: "It's like seeing a dinosaur or something. Killer Whale Predation on Sea Otters Linking Oceanic and Nearshore Ecosystems J. Since 1990, otter populations off the Aleutian Islands have fallen by as much as 80 percent. Courtesy of J.P. Sylvestre 2). If there were more fish, they say, marine mammals and orcas would have plenty to eat. NIELSEN: Williams says it's hard to overstate how much these findings upset people who all but worship killer whales. NPR transcripts are created on a rush deadline by Verb8tm, Inc., an NPR contractor, and produced using a proprietary transcription process developed with NPR. ", It was a slow start. Second, we evaluated the impact of killer whales on sea otter populations at Adak Island by contrasting otter population trends and sur-vival rates between Clam Lagoon, an area uniquely inaccessible to killer whales, and ad-jacent Kuluk Bay, an open coastal environment (Fig. Ecologists say killer whales are eating the otters, but as NPR's John Nielsen reports, not everyone buys that theory. Williams says the answer turned out to be a simple one. But not everyone is buying the theory. Some researchers can distinguish individual pods, and even matrilines (the line of relationship that can be traced from one mother to her offspring), just by their calls. It's one of those moments that biologists live for. "And I looked down, and there they were, the New Zealand killer whales," he recalls. Many people are trying to figure out why. This is due to the fact that killer whales are used to eating animals two to five times the size of otters, so they need to eat two to five times as many otters as seals or sea lions. A group of ecologists says it has solved the mystery of Alaska's missing sea otters. It's still waiting to be tested. All three pods uniting is referred to as a s uper pod. Killer whales have a diverse diet, although individual populations often specialize in particular types of prey. Populations of otters along the Alaskan and Canadian coast, which had recovered to a few hundred thousand, were driven back down to just a few thousand. Washington’s sea otter population isn’t growing as fast as it once was. Other researchers are studying why California’s sea otters seem to have become more vulnerable to disease and parasites. The domino effect reaches even farther. I should point out that killer whales around the world are doing fine, but this population is listed as endangered on both sides of the border of the U.S. and Canada. A rare photo of "type D" killer whales off South Georgia island, located between South America and Antarctica, shows the whales' blunt heads and tiny white eye patches. Then she multiplies that number by 365 days. First, Williams determines that the average orca needs to eat the equivalent of five to seven sea otters a day just to get by. Then in 2005, Pitman met a French biologist at a science conference who showed him a photo of an odd-looking killer whale swimming in the southern Indian Ocean. Orcas have mostly black skin with white patches. Last year, he assembled a team to go to Cape Horn, in Chile, to look for what's now technically called the "type D" killer whale. Orcas were eating otters because the really big whales they used to eat were nearly wiped out by commercial whalers back in the 1950s. "Visibly," she says, "this form is the most unusual and distinct form of killer whale on the planet.". That's the New Zealand killer whale!' For the moment this debate is largely academic; nobody is seriously talking about killing orcas to protect otters, seals and sea lions. Mr. DOUG DeMASTER (Director, Alaska Fisheries Science Center): This hypothesis is too simplistic, and it's not ready for the textbooks yet. One killer whale would need to eat 1,825 otters a year to live. NOAA biologist Lisa Ballance, who's married to Pitman, was part of the team. "But that was definitely the way to bring them to the boat.". NPR’s John Nielsen reported that this caused up to an 80% decline in the otter population. NIELSEN: But it's not just whale-huggers who hate the orca hypothesis. What kinds of other animals share the sea otters’ habitat? And I said, 'That's it! ", "There they were," Ballance recalls, for a moment at a loss for words. Question Sheet: Sea Otters, Kelp, and Killer Whales. Killer whale, (Orcinus orca), also called orca, largest member of the dolphin family (Delphinidae). But Jim Hasties, a federal biologist and a major proponent of the orca theory, says there is one solution that almost everyone can agree on: continuing efforts to rebuild the region's stocks of great whales. People raised on movies like "Free Willy" tend to think of killer whales as well-meaning, fence-jumping giants who want nothing more than to live in perfect harmony with all the other creatures in the ocean. (The sea otter is an endangered species). NIELSEN: In the current issue of the journal Ecology, Williams and her colleagues show just how big the killer-whale bite out of the otter population is. The killer whale (also known as the orca) generally did not consume sea otters in the past, but now consumes thousands of otters. SCIENCE. It's gone. Later, they realized why the whales swam up to them. PCBs first came under scrutiny in the 1970s, when birds, seals, and otter populations began rapidly decreasing. These giant pectoral fins come up on either side of the sea otter. John Nielsen, NPR News, Washington. All rights reserved. He also says the original idea that these orcas once ate the great whales can't be proven. And by the late 1990's, I'd see 'em three or four times a day. They can tell, even in the darkest parts of the sea, where items are by how quickly their noises bounce back. Since 1990, otter populations off the Aleutian islands have plummeted by as much as 80 percent. Scientists recently found that as many as half of the world’s killer whale populations may not survive the next 100 years because of PCB pollution. Visit our website terms of use and permissions pages at www.npr.org for further information. Share this: Facebook; Twitter; Reddit; Google Classroom; Email; Print; By Science News for Students. They use these sounds to help travel underwater. The authoritative record of NPR’s programming is the audio record. The photograph above was taken on July 7, 2010. "The idea is that, if we can figure that out, we might be able to find some ways that we can further help recover the endangered population, like Southern residents." To have remained unidentified by biologists 's John nielsen reported that this caused up to an 80 decline... 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