Express your personality or go along with the group: what determines the behaviour of shoaling perch?

Abstract

Behavioural syndromes, defined as correlated behaviours in different contexts, have been studied across species and taxa including humans as part of a personality concept. While most studies have focused on solitary individuals, less is known on how shoaling fish compromise between own personality and group behaviour. Risk-taking behaviour in 1-year-old perch (Perca fluviatilis) was observed to compare individual behaviour when in a group and when alone. An experimental design gave the fish the choice between foraging in an open area in the presence of a piscivore and hiding in the vegetation. We quantified the variation accountable by the effect of individuals being in a group, individuals alone and repeated measurements, using hierarchical mixed effects models. Within-group variances were low, but when individuals were later tested alone, individual differences explained most of the variation. Still, the individual best linear unbiased predictors (BLUPs) of time spent in the open area, extracted from the random effects of the mixed effects model, were positively correlated with the corresponding BLUPs when alone. The results indicate that individual behavioural traits are to some degree expressed also within groups. Most fish showed a shyer behaviour when alone, but bolder individuals changed less between treatments than did shyer ones, suggesting a more influential role of bold fish in the group.

Shoal size as a key determinant of vulnerability to capture under a simulated fishery scenario

“…Shoaling tendency in fish has been shown to be both heritable (Dochtermann, Schwab, & Sih, 2015; Wright, Rimmer, Pritchard, Krause, & Butlin, 2003) and repeatable (Magnhagen & Bunnefeld, 2009; Ward et al., 2004). Therefore, if more social fish tend to be found in larger groups in the wild, then it is possible that sociability as a trait could be under selection in trap fisheries.…”

The role of individuality in collective group movement

“…Other studies also report that the maintenance of these traits depends on both the level of the trait and state dependencies. In perch (Perca fluviatilis), for example, traits such as time spent in open habitat are consistently expressed between asocial and social contexts (groups of four fish); however, bolder individuals changed their behaviour less between contexts [46]. Similarly, three-spined sticklebacks (Gasterosteus aculeatus) maintain their behavioural traits in a pair, where the bolder individual of the pair will initiate more foraging trips, while a shyer individual will follow [11,47].…”

Personality traits and dispersal tendency in the invasive mosquitofish (Gambusia affinis)

“…Finally, it has recently Personality and the spread of invasion J. Cote et al 1577 been shown that the expression of personality might depend on group composition and even that the personality of others matters in the formation of a group (Harcourt et al 2009;Magnhagen & Bunnefeld 2009) and the behaviours of conspecifics also matter in dispersal decisions. More experiments are needed to test how individual social behaviour interacts with average social behaviour in the population.…”