Familiarity, prior residency, resource availability and body mass as predictors of the movement activity of the European catfish

When animals compete for resources, their competitive abilities and behavioural strategies can be expressed as changes in movement activity. Stress is an important predictor of activity, and the variability of this predictor reflects the impact of environmental and social factors, while the effects of stress are further influenced through individual behavioural syndromes. We examined the effects of social (familiar vs. unfamiliar and resident vs. intruder) and environmental (resource availability) factors and individual characteristics (body mass) on the movement activity of juvenile European catfish Silurus glanis (L.). Familiarity and prior residency decreased the movement activity of these catfish, whereas resource unavailability significantly increased the movement activity of intruders to a level 1.5 times greater than that of the residents. The occurrence of an interaction involving an individual whose body mass was higher than that of individuals from the opposite group predicted a low level of movement activity of this individual. These results suggest that familiarity, prior residency, and high body mass decrease stress from the limited availability of resources.