What is a fish kill?

Like it or not sometimes fish kills occur. It is a harshly worded phrase used to define a massive localized die off of a fish population. When there is a fish kill it is a serious matter that environmental agencies use an indicator something may have run a muck in the local ecosystem. Although, fish kills can occur due to natural causes or artificial causes.

For instance, recently in New Jersey the Department of Environmental Protection (DEP) determined that a menhaden fish kill was attributed to a lack of oxygen (hypoxia). It seems as though over one million of the tiny bait fish were swam right into shallow water, perhaps being chased by a predator such as bluefish. All those fish in the shallow water used up the limited oxygen before the tide could take them back out to sea. The water was tested by the DEP and was said to have a very low oxygen level due to very warm air and water temperatures. Fish kills are very prevalent in the warmer months. Other natural causes of fish kills may include drought or underwater earthquakes.

Meanwhile, in Mississippi there was a similar fate for speckled trout that may have been caused by the tar balls and patties that locals have been seeing wash ashore.  Thermal pollution (heated water let off of a nuclear plant), oil, chemical or hazardous waste spills are some of the major causes of man-made fish kills.

What can you do to prevent a fish kill? Please do not over fertilize your lawn, overstock fish in your pond at home, feed ducks or sport fish, and always try to prevent garbage from entering your local watershed.

Photo (c) http://ian.umces.edu

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