Water quality in Salmonid culture

Abstract

This article reviews the relationship between salmonid aquaculture, both in fresh and saltwater, and water quality, focusing on the effects of bad water quality at the lethal and sublethal level, water quality assessment using physicochemical parameters, and new developments for water quality estimations: from mathematical indices and models for the interpretation and/or prediction of analytical results, to the assessment of water quality by biological methodologies. The main problems of different rearing systems, for example, land‐based farms and caged and net‐pen salmonid cultures, are also considered, taking into account not only the water quality problems originated by the culture conditions but also those related to external causes of water pollution.

Particular attention is conceded to micropollutants, chemicals dumped into the environment by human activities, chemicals that can be toxic at very low concentrations, usually at the range of μg/1. Many of these chemicals are highly persistent in the environment and are a hazard even for culture areas located far from industrial pollution sources. Acid rain and the related risk associated to both pH and heavy metals are the major global hazard in freshwater systems, which are also threatened by industrial effluents and local accidental spills. Persistent pollutants, including heavy metals, organochlorine compounds, and petroleum hydrocarbons are of major concern in marine aquaculture. The toxicological risk related to these micropollutants focuses on sublethal problems, such as histopathological lesions, alterations in growth or reproduction, and increases in susceptibility to infectious diseases. Additionally, some of them, such as mercury, planar PCBs, or chlorinated dioxins, can also be a risk for human consumers. Biological methodologies, including the study of stress response and specific biomarkers, offer a cost‐effective system to monitor the risk of micropollutants and can be considered almost ready‐to‐use in culture conditions.

Key words:

• fish kills
• aquaculture
• water quality parameters
• micropollutants
• salmonid cultures