Fish Kills

Fish kills occur when the oxygen dissolved in water depletes. Under most circumstances, fish kills are highly localized because fish and other organisms can leave an area when oxygen levels become low.

However, widespread fish kills may occur following large algal blooms. As blooms age and begin to die, the decay process uses oxygen. When blooms are extensive, oxygen can deplete quickly over a large area. Fish may be unable to find refuge to sustain themselves as a result.

At times, algal toxicity can be a factor in fish kills and other wildlife mortality events.