Secret Killers of Monterey Bay

Giant orcas (killer whales) are going missing along the California coast. Wild Chronicles sets out to find the culprit before it's too late.
1. There are two populations of orcas in Canada's Pacific Northwest, permanent residents and "transients," or migratory animals who are just passing through. What is the difference in diet between the two populations?
  
  Show Answer
  
  Permanent residents mostly eat fish, while transients prey on marine mammals such as seals.
2. Why doesn't Nancy, the biologist, recognize the pod of orcas in Monterey Bay?
  
  Show Answer
  
  The whales are not the regular transient pod that Nancy expects. The new pod is a group of permanent residents from Canada.
3. What behaviors distinguish the permanent resident pod from the transient pod?
  
  Show Answer
  
  The permanent residents are generally much more social, and display behaviors such as breaching and spyhopping.
4. How does Nancy evaluate the health of the orcas? What does she find?
  
  Show Answer
  
  Nancy tests samples of the orcas' blubber, taken with a dart gun. These blubber samples showed very high levels of PCBs, a toxic substance.
  
  Marine biologists think the toxic PCBs may be contributing to the shrinking population of orcas along the West Coast—that PCBs may be the real "secret killer."
Audio & Video
- National Geographic Wild: Canadian Killer Whales
- National Geographic Kids: Videos—Whale of a Leap
Websites
- National Geographic Kids: Animals—Orca

Term	Part of Speech	Definition	Encyclopedic Entry
breach	Verb	behavior exhibited by whales, when they jump above the surface of the water.
coast	Noun	edge of land along the sea or other large body of water.	Encyclopedic Entry: coast
culprit	Noun	person responsible for an offense or fault.
killer whale	Noun	carnivorous whale, actually the world's largest species of dolphin. Also called an orca.
PCB	Noun	(polychlorinated biphenal) chemical substance that can occur naturally or be manufactured that may cause cancer.
pod	Noun	group of whales or dolphins.
spyhopping	Noun	behavior where an aquatic animal pokes its head vertically out of the water.

Credits

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Writer

Caryl-Sue, National Geographic Society

Editor

Jeannie Evers, Emdash Editing

Producer

Caryl-Sue, National Geographic Society

Last Updated

Nov. 14, 2016

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