Hydroacoustics is well established method for pelagic fish stock assessments. This technique makes possible to assess large marine areas and collect great amounts of georeferenced inventory data, which can be analysed directly or used for spatial modelling. Lately, rapid technical and computational development opened possibilities by using hydroacoustics (often in combination with other methods) to study other components of marine ecosystem. For example using multi-frequency acoustics methods we were able to demonstrate possibilities of quantitative assessment and spatial distributions modeling of other pelagic organisms such as: mesozooplankton (e.g. copepods), macrozooplankton (e.g. mysids), and jellyfish. Read more in the following reports (Swedish language); MMSS Stockholm, MMSS Södermanland.
Using stationery mounted echo-sounders is possible to address complex questions of fish (and other organism) behavior; for example study fish migration and behaviour in relation to possibly disturbing factors such as wind turbines, river dams, marine traffic etc.
Passive acoustic equipment can be used to detect cetaceans by their echo-localisation clicks. This is a very cost-efficient survey method and can even be used for estimations of absolute abundance. Read more about the SAMBAH project, which is estimating the abundance of the Baltic harbour porpoise population based data from acoustic harbour porpoise detectors.