In experiments at the Bureau's Salmon-Cultural Laboratory, to determine the excretory products of significance in rearing ponds and the possible effect of these products on fingerling chinook salmon (Oncorhynchus tshawytscha), the results demonstrated that ammonia and urea are the principal products. The relative amounts of these products vary with the concentration of fish and with their metabolic activity. Ammonia assumes dominance in an unfavorable environment. Water temperature, pH, and pond type affect the toxicity of ammonia solutions. Continuous exposure to levels of ammonia normally encountered in rearing ponds produced extensive hyperplasia of the gill epithelium in controlled experiments.

Addressing the numerous gaps in current information, Target Organ Toxicology in Marine and Freshwater Teleosts is an essential resource for researchers and professionals in aquatic toxicology and environmental risk assessment. All the chapters are written by researchers who are internationally recognised for their work in mechanistic aspects of aquatic toxicology. Each chapter focuses on a specific target organ or physiological system and describes how various agents disrupt the normal physiological system and processes. This volume is devoted to specific organs with coverage of the gill, kidney, skin, liver and gut. The companion volume, Systems, provides coverage of toxic effects in the central nervous, immune, neurobehavioural and reproductive systems as well as describing general mechanisms of toxicity.