Social effects on AVT and CRF systems
Stress and aggression have negative effects on fish welfare and productivity in aquaculture. Thus, research to understand aggression and stress in farmed fish is required. The neuropeptides arginine-vasotocin (AVT) and corticotropin-releasing factor (CRF) are involved in the control of stress and aggression. Therefore, we investigated the effect of agonistic interactions on the gene expression of […]
Investigating fear in rainbow trout (Oncorhynchus mykiss) using the conditioned-suppression paradigm
Trout learned the operant task of pendulum-pressing for a food-reward in a mean of 4.3 sessions lasting 1 hr. In a separate phase, fish also learned–through classical conditioning–to associate a neutral light cue with an aversive stimulus. When again allowed to pendulum-press for food, after aversive classical conditioning, there was a drop in the rate […]
Effect of noxious stimulation upon antipredator responses and dominance status in rainbow trout
A potentially painful experience may modify normal behavioural responses. To gauge the importance of pain relative to predation or social status, we presented competing stimuli, a predator cue or an unfamiliar social group, to two groups of noxiously treated rainbow trout, Oncorhynchus mykiss. In the predator cue experiment, fish were classified as bold or shy. […]
A comparison of aggressive and foraging behaviour between juvenile cutthroat trout, rainbow trout and F1 hybrids
‘Successful’ introduced species are often thought to cause declines or extinctions of native species through competitive superiority. In western North America, introduced rainbow trout, Oncorhynchus mykiss, have completely replaced many native cutthroat trout, Oncorhynchus clarkii, populations; however, few studies have identified the mechanisms that may allow rainbow trout to outcompete cutthroat trout. We raised Yellowstone […]
Plasticity of Boldness in Rainbow Trout, Oncorhynchus mykiss: Do Hunger and Predation Influence Risk-Taking Behaviour?
Boldness, a measure of an individual’s propensity for taking risks, is an important determinant of fitness but is not necessarily a fixed trait. Dependent upon an individual’s state, and given certain contexts or challenges, individuals may be able to alter their inclination to be bold or shy in response. Furthermore, the degree to which individuals […]
Effect of food abundance on aggressiveness and territory size of juvenile rainbow trout, Oncorhynchus mykiss
How food abundance affects (1) whether or not individuals defend territories and (2) what size of territory is defended are crucial to understanding the role that territoriality plays in regulating the population size of stream-dwelling salmonids. The threshold model of feeding territoriality predicts that territorial defence will be most intense at intermediate levels of food […]
Environmental change alters personality in the rainbow trout, Oncorhynchus mykiss
Boldness is a personality trait that defines how individuals respond to risky situations and has clear fitness consequences. Since the adaptive value of boldness is context dependent, the benefit of a distinct personality is less clear when the environment is unpredictable. An ability to modulate behaviour can be beneficial, although as behavioural plasticity itself may […]
Welfare assessment of rainbow trout reared in a Recirculating Aquaculture System: Comparison with a Flow-Through System
A multi-parameter analysis was applied in order to acquire an integrated and objective assessment of the effects of recirculating aquaculture systems in rainbow trout farms on a range of welfare indicators. We compared growth, cortisol and behavior in trout previously held in a Recirculating System (RS) developed in the PEIMA (Brittany, France) with optimized water […]
Stress during slaughter increases lipid metabolites and decreases oxidative stability of farmed rainbow trout (Oncorhynchus mykiss) during frozen storage
The consequences of slaughter on the formation of lipid metabolites and oxidative stability of fish muscle during long term frozen storage (−10 °C) were evaluated using farmed rainbow trout killed by asphyxia in air or percussion. The level of major adenine nucleotides and their related compounds was determined in order to check the stress level […]
Effect of temperature and diet on wound healing in Atlantic salmon (Salmo salar L.)
Compromised skin integrity of farmed Atlantic salmon, commonly occurring under low temperature and stressful conditions, has major impacts on animal welfare and economic productivity. Even fish with minimal scale loss and minor wounds can suffer from secondary infections, causing downgrading and mortalities. Wound healing is a complex process, where water temperature and nutrition play key […]