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Cyclic Behavior of Animals

Describes behaviors that occur on a daily or yearly cycle.

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Threats To Wild Salmon
Teacher Contributed

Threats To Wild Salmon

Pacific salmon are an important food source for many animals like these Alaskan brown bears (Ursus arctos gyas). This photo is from Brooks Falls in Katmai National Park and Preseve, Alaska, USA. Brown bears congregate annually in large numbers at these falls to take advantage of the salmon run.


Salmon Disease

Student Exploration

Are the runs of a lifetime in danger?

Salmon are an iconic species in the Pacific Ocean where they have been an important food source for people and animals longer than recorded history. Their importance as a food source shaped both the culture of people living around the Pacific Rim, as well as the life history of the animals who live there. Recently, reports of the appearance of a marine virus common in farmed Atlantic salmon off of British Columbia, Canada has caused great concern. Fortunately, researchers are ready to find out what's going on.


An ocean salmon farm in Norway. Salmon anemia virus was introduced to Chile through eggs from a Norwegian hatchery.

Extension Investigation

Use the resources below to answer the following questions:

  1. What is the connection between the salmon anemia virus and farmed fish? What about the process of farming fish creates favorable conditions for disease?
  2. What kind of facilities are available for studying disease at the USGS Seattle facility? Why is it advantageous to have this variety of facilities in one place?
  3. Why is it important that the presence of salmon anemia virus in the Eastern Pacific Ocean could not be confirmed by other researchers? What could the initial report have been a result of? Why are wildlife managers concerned about situations like this one?
  4. How does the life history of the Pacific salmon and the Atlantic salmon differ? How could this change the way disease is transmitted through the populations?

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