Seasonal and diel effects on acoustic fish biomass estimates: application to a shallow reservoir with untargeted common carp (Cyprinus carpio) - Archive ouverte HAL Accéder directement au contenu
Article Dans Une Revue Marine and Freshwater Research Année : 2016

Seasonal and diel effects on acoustic fish biomass estimates: application to a shallow reservoir with untargeted common carp (Cyprinus carpio)

Résumé

The aim of the present study was to understand how seasonal fish distributions affect acoustically derived fish biomass estimates in a shallow reservoir in a semi-arid country (Tunisia). To that end, sampling events were performed during four seasons (spring (June), summer (September), autumn (December) and winter (March)) that included day and night surveys. A Simrad EK60 echosounder, equipped with two 120-kHz split-beam transducers for simultaneous horizontal and vertical beaming, was used to sample the entire water column. Surveys during spring and summer and daytime hours of winter were deemed unusable owing to high methane flux from the sediment, and during the day survey of autumn, fish were close to the reservoir bottom leading to low detectability. It follows that acoustic surveys should be conducted only at night during the cold season (December-March) for shallow reservoirs having carp Cyprinus carpio (L.) as the dominant species. Further, night-time biomass estimates during the cold season declined significantly (P < 0.001) from autumn to winter. Based on our autumn night-time survey, overall fish biomass in the Bir-Mcherga Reservoir was high (mean (+/- s.d.) 185 +/- 98 tonnes (Mg)), but annual fishery exploitation is low (19.3-24.1 Mg) because the fish biomass is likely dominated by invasive carp not targeted by fishers. The results suggest that controlling carp would help improve the fishery.
Fichier non déposé

Dates et versions

hal-01602364 , version 1 (02-10-2017)

Identifiants

Citer

Imed Djemali, Jean Guillard, Daniel L. Yule. Seasonal and diel effects on acoustic fish biomass estimates: application to a shallow reservoir with untargeted common carp (Cyprinus carpio). Marine and Freshwater Research, 2016, 68 (3), pp.528-537. ⟨10.1071/MF15249⟩. ⟨hal-01602364⟩
60 Consultations
0 Téléchargements

Altmetric

Partager

Gmail Facebook X LinkedIn More