A strategy for assessing the effects of xenobiotics on fish reproduction

Environmental pollutants, such as industrial and agricultural chemicals, heavy metals, drugs and products with hormonal activity may disrupt reproduction of aquatic wildlife such as fish. Such xenobiotics may cause disruption of the reproductive endocrine system, or they may directly affect gamete development and viability as a result either of their cytotoxicity or by altering the hormonal environment during gamete development. The various possible sites of action are reviewed, and it is suggested that tests for toxicity should isolate the specific component of the reproductive system that is most sensitive to such disruption and that this may be at levels well below that which causes mortality or visible signs of stress. Fish are proposed as the most suitable aquatic organism for such tests.