Hydroacoustics as a tool for studying the impact of habitat modification [degradation] upon fish: a review

Hydroacoustical methods due to their very high resolution in time and space can be used to register subtle changes in fish distribution and behaviour, thus enabling observation of the effect of habitat modification upon the fish. A number of examples have been presented which show dependence between fish parameters measured acoustically (such as depth, density, degree of aggregation, length frequency distribution), and different environmental parameters characterising the habitat quality (trophic levels, presence of chemicals, littoral coverage, predation pressure, temperature and oxygen gradients). This suggest that by performing hydroacoustical monitoring one can measure fish reactions to the habitat changes on a scale and with an accuracy not available with other methods.