When there were many canneries, fishermen would catch fish and then at the end of the day the fishermen would take the fish to the canneries. Many times canneries had to refuse salmon brought by fishermen because of an excess amount of salmon already brought in. Many of these fish were dumped back into the streams where they would not only rot but cause pollution. This would also occur if the commercial fishermen had over caught salmon. In 1877, there was an outbreak of typhoid fever due to unsanitary conditions caused by wastes from salmon canneries along the Fraser.
Hatcheries have many limitations to what they can do for the salmon population.
A hydro power dam is one of the biggest problems facing the salmon population. When going down stream a salmon can be killed in the turbines. If salmon go over a dam they could be stunned. They are an easy prey for birds at this time. Nitrogen is produced when water splashes after it spills over the spillway.