Phenology of fish movements between a mediterranean lagoon and the sea: Insights from acoustic camera and fishers’ local ecological knowledge

Studying fish movement is an essential and complex task that is necessary to improve our understanding of fish ecology. The present study simultaneously used Acoustic Camera Videos (ACV) and professional fishers’ Local Ecological Knowledge (LEK) to describe fish movements between a lagoon and the sea. Results showed consistency and complementarity between ACV and fishers’ LEK. Three size groups were identified in the fish community based on ACV data: < 15 cm, 15–35 cm, and > 35 cm. Fishers reported that fish < 15 cm could either be juveniles or adult individuals of small species, those 15–35 cm were mainly Gilthead seabreams ( Sparus aurata ) and those > 35 cm were mainly European seabass ( Dicentrarchus labrax ). The main periods during which fish entered into the lagoon (February-April) and exited to the sea (September-November) detected on ACV data matched fishers’ LEK for the Gilthead seabream and the European seabass. Daily movements of fish < 15 cm and > 35 cm showed asynchronous phenology, the former being more abundant during night-time hours, and the latter during the afternoon. This study highlights the additional benefits of combining ACV and fishers’ LEK to study fish movement phenology, and thus presents new research opportunities. • Acoustic camera videos and fishers knowledge were complementary approaches. • Three fish size groups (<15, 15–35, >35 cm) were identified in the lagoon. • Gilthead seabream and European seabass dominated the lagoon’s fish community. • Seasonal and daily movements phenology were identified for the dominant species.