ShepherdsDog ShepherdsDog:
Lake Winnipeg is dying due to algal blooms. The water actually becomes too toxic to swim in.
Much bigger system, ie the ocean. Lake Winnipeg has likely been polluted for decades by phosphate runoff. Doubt this one dump will do much long term harm, doubt if it will do much good either. If it were to be repeated annually, that's another matter. I'm not sure if the natives have considered they'd have to do this annually if it does work, and offset those costs against any increase in salmon.
The question is why did the salmon disappear? If it really is because lack of phytoplankton, why did that disappear? I doubt of there's all of a sudden an iron oxide shortage that developed in the ocean. I would guess that the salmon disappeared because of overfishing and habitat destruction of their breeding grounds in BC. Alaska doesn't seem to have the same problem.
We cause enough problems fertilizing the land with pollution and micronutrient depletion. Maybe we should at least leave the ocean alone.