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
Pain in fish birds, frogs, salamander, reptiles, fish, and crustaceans. A recent article by Howard Browman and colleagues provides an overview of what different perspectives regarding fish pain and welfare mean to in the context of aquaculture, commercial fisheries, recreational fisheries, and research. It has been argued that fish can not feel pain because they do not have a sufficient density of appropriate nerve fibres. A typical human cutaneous nerve contains 83% GroupC nerve fibres, however, the same nerves in humans with congenital insensitivity to pain have only 24–28% C-type fibres. Based on this, James Rose, from the University of Wyoming, has argued