A section of the Upper Enoree River in South Carolina, USA, was contaminated with chemical waste in 1985, and high concentrations of zinc persist decades later. In this study, we examined the zinc concentrations in the water, the accumulation of zinc in a variety of fish tissues, the effects of the contaminated water on fish sperm motility in vitro, and the mortality rates of introduced fish. Zinc concentrations in the water samples collected from six sites decreased as distance from the spill site increased, ranging from 7.3 to 0.34 mg/L (p< 0.001). The zinc concentrations of tissues from native fish were highest in liver (mean across sites of 110 ppm/g tissue) and gills (77.4 ppm/g tissue), followed by gonads (30.7 ppm/g tissue) and muscle (6.9 ppm/g tissue) (p < 0.001). The duration of fast motility of Salmo trutta sperm was significantly diminished in sperm activated in samples from the contaminated stream compared with the control stream (p < 0.05). To further evaluate the ability of fish to survive at the sites with different zinc concentrations, groups of Gambusia holbrooki were placed in traps at a reference site (uncontaminated local tributary), and three sites along the contaminated stream. Rapid mortality was observed in the two sites closest to the spill, including one site in which native fish had been found. The introduced G. holbrooki expressed higher zinc concentration in gills than gonads or muscle (p < 0.001), and water zinc concentration significantly affected fish mortality (p < 0.001). The results from these experiments indicate that zinc contamination of streams can have sublethal effects on populations and physiology of fish that are able to survive in the contaminated water.

Nine mature spotted seatrout Cynoscion nebulosus (seven females and two males) were placed in a recirculating‐water culture system at the University of Miami Experimental Hatchery in July 1993. Photo‐period and water temperature were maintained at 14 h light: 10 h dark and 27.5°C. Spotted seatrout held in this controlled photo‐thermal culture system spawned on 172 occasions between August 1, 1993, and April 22, 1994, producing approximately 168 million eggs. On average, spawning occurred every 1.5 d. The 172 spawns during the 265‐d spawning period represent an average of 24.6 spawns/female or 1 spawn/female every 10.8 d. The mean volume of eggs collected per spawn was 306 mL (SD = 215). The estimated average number of spotted seatrout eggs per milliliter was 3,184 (SD = 499). The mean percentage of viable eggs per spawn was 47.5% (SD = 29). Spotted seatrout held in the constant photo‐thermal regime of 14 h light: 10 h dark and 27.5°C consistently produced eggs over a 9‐month period.