The Effects of Pollution on Fisheries

Toxins cause health problems for marine and freshwater fish, and in turn for the people who eat those fish. Pollution is linked to fish diseases, reproductive problems and mutations. The toxins include industrial chemicals and pesticides that enter fisheries through ground and surface water and through the air. The fish become contaminated because they absorb the toxins in the water, and the toxins are passed on to other animals and people through the food chain.

  1. Effects of Toxins

    • Even medical waste can find its way into fisheries.

      Mercury is one of the worse contaminants found in fish and can cause illness in people eating them. Mercury poisoning manifests itself with symptoms similar to cerebral palsy. Other toxins found in fish, such as PCBs, dioxins, lead, residential waste and pharmaceutical waste, contribute to everything from mild headaches to cancer and even death. Long-lived large fish, including shark, swordfish and varieties of tuna can have a greater buildup of toxins simply because they have been around longer to absorb them. In addition, land animals that eat toxin-laced fish absorb the contaminants and pass those on to people who in turn eat the animals.

    Algal Blooms as Pollution

    • Algal blooms can be toxic and suffocate fish.

      Marine fisheries can be struck by "red tide" or algal blooms, which are caused by thick concentrations of algae. The blooms are pollutants, giving off natural poisons and biotoxins that can suffocate fish by clogging their gills. The effects of algal blooms are the loss of millions of dollars when fisheries are forced to close. Tourism and recreational fishing are also struck, devastating coastal economies.

    Impact on Fisheries

    • Pollution "ages" fisheries.

      Pollution depletes fisheries and reduces the number of commercially valuable fish. For example, trout and salmon numbers have been cut in lakes and estuaries hit by pollutants. In addition, pollution ages fisheries, changing the environment of the water and adding to the sediment, turning some areas into bogs decades before they naturally would have changed. Pollution can interfere with fish migration, changing the normal aquatic population of an area.