The Effects of Pollution on Fish Reproductive System & Life

Pollution has negative effects on fish reproduction and life. Pollution from sewage leads to increased sexual hormones in fish water habitat and lowers fish reproduction rates. Agricultural runoff accumulates in bodies of water, leading to a decrease in life-supporting oxygen. Other pollution may increase suspended solids in the water, effecting water temperature.

Lowered Reproduction

• Karen Kidd of the University of New Brunswick performed an experiment to confirm the effects of estrogen pollution on fish populations. She found that sensitive minnow populations dwindled significantly with the introduction of a small but constant amount of synthetic estrogen. The study attempted to duplicate pollution resulting from excretion of excess estrogen from birth control pill consumption. Similarly, U.S. Geological Survey scientists found high rates of testicular oocytes (immature female egg cells), a form of feminization, in fish of the Potomac River. Areas with high human population densities and farming prevalence exhibited the most fish feminization, indicating a possible waste pollution cause. According to Science Daily, scientists have also found intersexed fish in the St. Lawrence River, Great Lakes, Colorado, Mississippi, the U.K., Denmark, Germany, South Africa and Italy. Intersexing reduces fish reproduction rates by creating an imbalance in the number of fertile males versus females.

Difficult Respiration

• Pollution may cause hypoxia, meaning a deficiency of oxygen. Nitrates that run off from agricultural fertilizers and livestock manure into bodies of water result in the overgrowth of aquatic algae. When dead algae settles to the bottom, the process of decomposition absorbs oxygen from the water. Fish need oxygen to breathe, and they extract it from the dissolved oxygen atoms in water. In hypoxic environments, however, fish do not breathe properly and may perish. According to the State of Pennsylvania, suspended solids from pollutants or silt also interfere with fish respiration and may clog or damage fish gills.

Out-Migration

• Suspended solids darken water, which causes the water to absorb more sunlight and may raise the temperature. Fish only survive in a water temperature range fit for their species. Therefore, any unusual change in temperature resulting from pollution may result in fish death or out-migration--leaving their current habitat. When the sediment settles, it may cover and suffocate fish eggs or engulf fish habitat, leading to lowered reproduction rates and out-migration.