Fish kill dead zones in the gulf are mainly created by the nitrogen and phosphorus enrichment of the Lower Mississippi River. Some species of fish exhibit mass simultaneous mortality as part of their natural life cycle. Fish kill due to spawning fatalities can occur when fish are exhausted from spawning activities such as courtship, nest building, and the release of eggs or milt (sperm). Fish are generally weaker after spawning and are less resilient than usual to smaller changes in the environment. Examples include the Atlantic salmon and the Sockeye salmon where many of the females routinely die immediately after spawning. A
Fish species of Aravaipa Canyon itself. Various methods are used to survey the type and abundance of fish species present at each location. The most common of these is seining, a method that involves dragging a long net through the water and catching many fish at a time. This is best done by two individuals (one on either side of the net) who run downstream, scooping up the fish that are attempting to swim upstream against the current. Another form of seining involves the same two people on either side of the net, but this time they plant the edges of the net into the