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Population Structure

Gender ratios and reproductive age heavily influence the growth of populations.

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Where's My Otter?
Teacher Contributed

Where's My Otter?

What Is Happening To The California Sea Otter?

The sea otter (Enhydra lutris) population in California is currently around 2800 animals (for comparison 9356 animals were taken in California in a single year during the fur trade). Unfortunately, the size of the population is shrinking, and the question is why? The challenges facing sea otter researchers in answering this question are many. A number of sources of mortality have been identified which is a good thing, but unfortunately these reasons are not entirely separate and interact with each other. For example, a sea otter exposed to pollution will have to expend energy to deal with the toxins. Such exposures not only increase the amount of energy the sea otters’ immune systems need but also occupies the immune system so it is less able to fight disease. This creates the situation where a dead sea otter may be found riddled with disease. The disease seems to have had a significant effect on the animal’s health, but the question that remains unanswered is whether the sea otter succumbed to the disease because its immune system was not strong enough naturally to fight off the disease or whether it succumbed to the disease because its immune system had been weakened from exposure to pollutants?

Here's a review of some of the current research going on

Here is Dr. Chris Kreuder Jonhson explaining some of the problems researchers face

Extension Investigation

If you need help scratching a mental itch, use the resources below:

  1. How do toxic algal blooms potentially affect sea otters?
  2. How do thorny headed worms cause mortality in sea otters?
  3. How do pollutants affect sea otters?
  4. How can the presence of Toxoplasma gondii help Great White Sharks (Carcharodon carcharia)?


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