From operculum and body tail movements to different coupling of physical activity and respiratory frequency in farmed gilthead sea bream and European sea bass. Insights on aquaculture biosensing

Abstract

The AEFishBIT tri-axial accelerometer was externally attached to the\noperculum to assess the divergent activity and respiratory patterns of two\nmarine farmed fish, the gilthead sea bream (Sparus aurata) and European sea\nbass (Dicentrarchus labrax). Analysis of raw data from exercised fish\nhighlighted the large amplitude of operculum aperture and body tail movements\nin European sea bass, which were overall more stable at low-medium exercise\nintensity levels. Cosinor analysis in free-swimming fish (on-board data\nprocessing) highlighted a pronounced daily rhythmicity of locomotor activity\nand respiratory frequency in both gilthead sea bream and European sea bass.\nAcrophases of activity and respiration were coupled in gilthead sea bream,\nacting feeding time (once daily at 11:00 h) as a main synchronizing factor. By\ncontrast, locomotor activity and respiratory frequency were out of phase in\nEuropean sea bass with activity acrophase on early morning and respiration\nacrophase on the afternoon. The daily range of activity and respiration\nvariation was also higher in European sea bass, probably as part of the\nadaptation of this fish species to act as a fast swimming predator. In any\ncase, lower locomotor activity and enhanced respiration were associated with\nlarger body weight in both fish species. This agrees with the notion that\nselection for fast growth in farming conditions is accompanied by a lower\nactivity profile, which may favor an efficient feed conversion for growth\npurposes. Therefore, the use of behavioral monitoring is becoming a reliable\nand large-scale promising tool for selecting more efficient farmed fish,\nallowing researchers and farmers to establish stricter criteria of welfare for\nmore sustainable and ethical fish production.\n