Behaviour of European sea bass,Dicentrarchus labraxL., in cages - impact of early life rearing conditions and management

Abstract

European sea bass, Dicentrarchus labrax L., groups reared under different conditions during larval stages (mesocosm and intensive rearing) were monitored during on-growing in sea cages until marketable size (350-400 g). Four caged groups were followed for a period of 17 months each at a pilot scale farm, where vertical distribution behaviour was monitored. This was performed while fish were under calm conditions, during feeding and when stress events occurred. Also during two specific periods: (i) spawning and (ii) high water temperature. Clear differences in the behavioural pattern of swimming depth, displacement and used space between the groups were observed. The individuals from the mesocosm rearing were more sensitive to human presence, showing stronger reactions (speed of displacement and vertical distribution). Most pronounced differences were observed during the 'extreme' warm period and the reproductive season. Within the seasons, European sea bass responded during feeding and stress showing a tendency to move deeper compared to calm conditions. The increased displacements were longer during feeding and stress.

Effects of sound exposure from a seismic airgun on heart rate, acceleration and depth use in free-swimming Atlantic cod and saithe

“…The sound exposure might have caused both diving to deeper depths and an increased heart rate. Other studies have shown that fish may move to deeper depths during stress (Papandroulakis et al , 2014; Neo et al , 2018). No significant diving behaviour after sound exposures was observed in the video data.…”

Scale matters: performance of European sea bass,Dicentrarchus labrax, L. (1758), reared in cages of different volumes

“…On the contrary, rapid capture by luring fish to the surface via feed pellets resulted in low basal cortisol concentrations. It should, however, be kept in mind that when feed is supplied, E. sea bass fish perform a ‘tornado‐like’ movement, which describes the creation of a vortex by the fast movement of the fish in a circle (Papandroulakis, Lika, Kristiansen, Oppedal, Divanach & Pavlidis ). It could, therefore, be possible that more competitive fish may overtake less competitive ones in the feeding area, as these high densities in the upper layer of the water surface suggest high competition between con‐specifics (Andrew, Noble, Kadri, Jewell & Huntingford ).…”

Spatial distribution and activity patterns as welfare indicators in response to water quality changes in European sea bass, Dicentrarchus labrax

“…Thus, group swimming behaviour appears to be a sensitive welfare indicator even if it is still lacking calibration efforts to be precisely translated into an operational welfare indicator; nevertheless some examples exist (Papandroulakis et al, 2014;Pettersen et al, 2014). Moreover, the appraisal of negative or positive stimuli and, hence, the psychological dimension of stress as defined for fish by Galhardo and Oliveira (2009) is seldom tackled in welfare research.…”