Which Is The Invasive Species?

A Chinook, or King Salmon

 

Zebra mussels

This article tells us that there are issues with the viability of the economically significant king salmon fishery in the Great Lakes because of invasive species such as the zebra and quagga mussels and their effect on the salmon food supply, the alewife.

The story also points out that the king salmon themselves, a specie native to the Pacific, were introduced to the Great Lakes about 50 years ago. It seems that those aggressive fish are invasive themselves, although their arrival was the result of conscious human effort, rather than the accidental distribution of mussel larva through dumping of ship ballast.  In any event, both salmon and mussels have an effect on other organisms in the Great Lakes ecosystem, the alewives, themselves, for instance. The salmon are OK because they support a sport fishing industry, the mussels plug up water intakes. The ultimate value of an animal is directly related to its positive or negative relationship to humans. Mosquitoes are bad, pandas are good.