Risks from Aquaculture
•Nutrient pollution
–Organic matter, nitrogen, phosphorus
–Algae and phytoplankton blooms
–Oxygen depletion
•Bacterial pollution
•Water conflicts (depletion of water supplies)
•Hatchery predators
•Chemical pollution  (herbicides, antibiotics)
Taking one step back from what impacts introductions have, what about the hatchery itself?  Hatchery effluents can have a big impacts on water quality. Depletion of water supplies would also impact the native fauna.  Many trout hatcheries use a tremendous amount of water for their flow through systems. Hatcheries tend to attract thousands of birds and mammals. In a recent 4 year period, over 50,000 birds alone were legally killed at aquaculture operations of which 20,000 were herons and egrets.  I can only imagine how many others came to an untimely end and were not reported. And there is chemical pollution with herbicides and antibiotics.