A global review of the spatial, taxonomic, and temporal scope of freshwater fisheries hydroacoustics research

Abstract

This review assessed the status and scope of freshwater hydroacoustic fisheries research in global aquatic ecosystems with emphasis on (i) geographical and spatial scope, (ii) taxonomic range at the species and family levels (restricted to bony fishes of the Actinopterygii and Sarcopterygii), and (iii) temporal scope. Hydroacoustic measures have been used by ecologists and managers of freshwater systems for several decades, with major progress in technology and methods in recent years. A literature review indicated 296 research contributions that employed hydroacoustics to study freshwater fisheries in 294 different aquatic ecosystems. Spatially, hydroacoustics research in freshwater systems have thus far been concentrated in developed countries, particularly in North America and Northern and Central Europe (83% of the studies reviewed here). Most studies were small in spatial scale and short-term, with 80% including only a single body of water and 63% conducted over a single year or season (75% spanning less than two years). In addition, effects of fish morphology and behavior on acoustic target strength (TS) and taxonomic identification are not well parameterized, with only 21 species receiving empirical study of TS. Despite progress, the present study reveals gaps in the knowledge needed for wider applications to management. These include larger biogeographical and temporal scales of study and further empirical research on TS and taxonomic identification. Recent advances in size rather than species-based methods and theory offer potential solutions to this issue but require further investigation. We conclude with recommendations for systematic hydroacoustic research to enable more effective monitoring, management, and conservation of fisheries and freshwater ecosystems.