> they do it because it makes business sense

That's far from being the point, and it doesn't answer anything at all.

I mean, I assume this "environmental nightmare" happened on a fish farming business located in Washington. After a brief googling, it appears that Aquaculture companies in Washington are required to apply for a commercial license.

http://wdfw.wa.gov/licensing/commercial/misc_additional_perm...

Why on earth would a commercial license be granted to a business that involves introducing invasive species on a protected ecosystem?

Primary industries have a lot more political clout than environmental protection. Primary industries generate tax dollars for the government; conservation consumes it.