This classification method encompasses fish abundance, taxonomic composition and age structure. The tool relates the number of salmon and trout caught in a survey to the predicted abundance and prevalence of the species at the specific site.
Estuarine fish communities are good indicators of a range of man-made disturbances. They are mobile, relatively long lived, found near to the top of the food chain (so are affected by other parts of the chain and prone to bioaccumulation effects) and are easy to identify and return to the water: all of these characteristics make them ideal for the monitoring of estuaries. This method is based on the principle that the abundance of fish and the number of individual species found can change depending on the pressures on the estuary.