How do fish react to passing boats in the Tagus Estuary?

MARE researchers André Matos, Clara Amorim and Manuel Vieira are co-authors of the article ‘Reaction of two sciaenid species to passing boats: Insights from passive acoustic localisation’ recently published in the scientific journal Estuarine, Coastal and Shelf Science. 

How do fish react to the passage of boats in the Tagus estuary? This is the question the article attempts to answer by studying the behaviour of two species of meagre, the white croaker (Argyrosomus regius) and the royal croaker (Cynoscion regalis). 

‘In this study, we monitored the vocalisations produced by these fish during the breeding season and estimated the position of the vocal individuals using passive acoustic localisation techniques with a hydrophone network,’ explains Clara Amorim. This approach made it possible to observe the reaction to boat noise, both in terms of changes in vocal activity and its localisation.

What the researchers observed was that ‘the shoals of white croaker and royal croaker moved with the passage of the boats, suggesting a reaction to this disturbance.’ In addition, these animals also ‘reduced their acoustic activity during the passage of each boat’, although ‘no changes were detected in the acoustic behaviour of the royal corvinata’.

The MARE researcher also emphasises that ‘this study was carried out when both species form aggregations associated with spawning, so in the future it will be important to investigate the implications of successive disturbances caused by passing boats on their reproduction’.

This study is especially important in contexts where fish are exposed to human-made noise, which is highly prevalent during the breeding season, such as estuaries and busy coastal areas.

To access the article click HERE

To listen to the sound produced by the fish click HERE