Environmental control of fish reproduction: a different perspective

Nearly all studies on the environmental control of fish reproduction have, to date, focused on the roles played by various parameters of the natural environment, such as changes in water temperature and photoperiod. While these factors undoubtedly still play significant roles, other factors, which have arisen as a consequence of man's activities, also play major roles in at least some aquatic environments. One such factor is pollution; whereas attention is usually focused primarily on severe pollution and the fish mortality that can result, recently some emphasis has been given to the more subtle, but potentially serious, consequences of less severe pollution. Many freshwater habitats, particularly rivers in urban areas, now receive substantial volumes of effluent from various sources (both industrial and domestic). This effluent can contain chemicals capable of mimicking endogenous hormones, and hence has the potential to disrupt endocrine-mediated processes such as reproduction. This paper is concerned with the identity of these endocrine-disrupting chemicals, their mechanisms of action, and the effects they have on reproduction, both in wild fish and in fish maintained in the laboratory.