One thing a lot of people don't know is these species, which are all in the same family, have been implicated in EMS (Early Mortality Syndrome). This is due to an enzyme they produce that causes a thiamine deficiency in fish that eat them exclusively, especially lake trout and other salmonids.

http://afsjournals.org/doi/abs/10.1577/H08-019.1

If pigs could fly bacon would be harder to come by and there would be a lot of damaged trees.