Fish species in estuaries – from partial association to complete dependency

Estuarine dependency by certain fish species has been clearly demonstrated in a number of studies, but the term has also been used for those species and guilds that are not dependent on estuaries. The origins and development of the term are explored, and definitions for four types of estuarine fish association are provided which may be helpful in facilitating classification and comparisons between fish taxa using estuarine systems in different parts of the world. In addition, a diagrammatic representation of more recent estuary‐associated guild categories is presented to provide context and clarity on the estuarine dependency issue, and the fact that a continuum in terms of dependency is perhaps most appropriate for describing fish species relationships with estuaries. Ethical statement This brief communication is a philosophical discussion and did not involve the capture, use or care of any living or dead fish. Therefore, no permit or animal ethics clearance was required to undertake the literature review.