**2. Swimming behaviour**

have to adapt. As a phenotype, behaviour is certainly the mean and the most useful to survive under the new conditions. So during the domestication process, behaviour allows the animal to adapt to its new environmental conditions. Through domestication, the artificial selection is a process of changing characteristics of animals by artificial means such as directional selection, familial selection [1] or genomic selection [2], and the domestication may impact the behaviour

Behavioural traits are among the first traits to be affected by domestication [5, 6]. Behaviour is more easily moulded than morphology or chemical composition and thus the costs of behavioural modification are more efficiently adjusted to environmental variations. In his book, Jensen [7] described the effects of domestication in vertebrates, mainly on birds and mammals but there was nothing on fishes. Before that, there were three major reviews [3, 4, 8] on the influence of aquaculture and domestication on fish behaviour. In these papers, the authors summarised most of the available information on the effects of domestication on different traits of fish behaviour. The major aim of these reviews was to consider the importance of behavioural modifications due to domestication on the economic interest of the culture of fishes and on the welfare of animals in fish farms. In this chapter, I focus on the behavioural traits that have been modified by domestication without consideration to either economic

There are many difficulties to analyse papers dealing with the effects on domestication. First, it is not easy to identify precisely neither the number of generations in captivity nor the link between captive and wild animals. It is easy when it concerns the first generation obtained in captivity, but it is more complex when we address to 'individuals reared in hatcheries' for several years. Most often, we do not know if there was time introduction of wild animal (e.g. males) during the domestication process. Second, in most studies comparing wild and domesticated strains, we have very few information on the characteristics of the wild animals and on those of their native sites. It is important because there is an important variability of the behavioural trait parameters between different populations. Third, in general, fish performances of behavioural traits are tested under laboratory conditions except for displacements for which some experiments were realised in natural water areas. So whatever the experimental sites, the foreigner population (wild or domesticated) needs a period of acclimation to its new rearing conditions. These could introduce a bias in the

Behaviour is the basis of all relationships between the animal and its environment and concerns with several behavioural traits: swimming, foraging, predator avoidance, relationships with conspecifics and reproduction. Moreover, it is now known that individuals exhibit behavioural or physiological characteristics, which, if they are consistent over time, define a coping style or personality [9]. As through domestication, human beings select some individuals among a population, this could modify the equilibrium between the different behavioural profiles (or coping styles) of the individuals of a population. Now, some researches integrate this individual component and highlight the effects of domestication on individual behaviour as it has recently been done considering the learning and other cognitive abilities

even after only one generation [3, 4].

92 Animal Domestication

objectives or animal welfare.

results.

of fish.

Swimming is a general behavioural trait, which is used in different situations: foraging activity, predator avoidance, stress responses or reproduction. For fish, one of the most determinant traits that are able to improve foraging is the swimming ability. In rearing conditions, swimming is no longer as important as in nature; in general, fish have less space at their disposal, but if domestication selects individuals on their morphological and physiological characteristics, this could influence directly their swimming performances.

This behaviour trait has been tested on fishes in response to a predator attack. It is the case for juveniles (between 55 and 125 days old) of the sea bass (*Dicentrarchus labrax*); wild individuals showed a greater angular velocity and a stop distance to a new object more important than reared fishes [10]. These responses decrease with habituation in both groups. It means that wild individuals have a greater reactivity and a longer escape distance from an unknown object in their environment.

In the context of swimming behaviour, one of the more common tested parameter is the C-start response: this is the ability of an individual to rest from a novel environmental situation; it is characterised by a rapid reaction of the body with a C posture and after an S followed by a rapid (less than 10 ms) displacement. It measures the physical ability of a fish to react to a stress situation by using its physical abilities to swim. It has been tested in different environmental situations: pollution [11], water temperature [12], hypoxia [13] or the influence of conspecific presence by comparing solitary and grouped individuals [14]. In all cases, wild fishes showed a greater velocity and more rapid swimming abilities, so it seems that domestication decreases the swimming performances of the fish. This decrease could be parallel to physiological events. Comparisons of swimming and metabolic physiology were done in aquaculture-reared California yellowtail (*Seriola dorsalis*) in comparison to wild individuals. Incremental swimming velocity trials showed that aquaculture-reared fish had a significantly slower mean maximum sustainable swimming speed (4.16 ± 0.62 Body Length s−1) in comparison to that of wild fish (4.80 ± 0.52 BL s−1). In addition, oxygen consumption was significantly higher in aquaculture-reared fish (7.31 ± 2.32 vs. 3.94 ± 1.60 mg O2 kg−1 min−1 at 18°C) in comparison to wild-caught yellowtail (15.80 ± 5.78 mg O2 kg−1 min−1) [15].

This could alter other behaviours, which depend directly on swimming (i.e. foraging, survival). One point that concerns with swimming performances is the ability for reared individuals to be released in wild sites. This is the case for the European grayling (*Thymallus thymallus*) that were tagged with radio-transmitters and tracked in the Blanice River, River Elbe catchment (Czech Republic) [16]. Wild and hatchery-reared fish increased their dial movements and home range with environmental variables (light intensity, flow, temperature and turbidity), but hatchery-reared fish displayed greater total migration distance than did wild fish, which was caused mainly by their higher dispersal. Patterns in space use and activity were compared for wild and hatchery-reared Mulloway (*Argyrosomus japonicus*) using acoustic telemetry. Adult individuals were followed during 288 h in a river. Hatchery-reared fish used significantly larger areas with higher rate of activity than wild fish, but their movement ranges were more variable [17] than those of wild fish. By comparing initial movement, habitat use, growth and mortality between stocked hatchery and wild fish of juveniles of Florida Bass (*Micropterus floridanus*) with a radio telemetry experiment, Thomson et al. [18] showed that tagged hatchery fish exhibited greater movement (75 and 124 m/d, respectively), greater proportion of locations offshore (8 and 23%, respectively), but slower growth (1.73 and 0.41% of their body weight gained per day, respectively), and higher predation (47 and 0%, respectively) than wild fish.

individuals in terms of survival and growth. If we compare the survival rate of aquaculturereared or wild Chinook salmon fry (*Oncorhynchus tshawytscha*) facing predation by rainbow trout (*Oncorhynchus mykiss*) or sculpin (*Cottus rhotheus*) under experimental conditions, wild fry had a survival advantage within the two next years of experiment [29]. So it is possible that the domestication can affect the vulnerability of juveniles of salmon after only one generation in a culture system. But it is not always the case. For example, the survival of Atlantic salmon (*Salmo salar)* in the Baltic Sea was examined in relation to the origin, and prey fish abundance (here herring *Clupea harengus* and sprat *Sprattus sprattus*). The study was based on recapture data for tagged hatchery-reared, and wild smolts demonstrated a combined influence of origin and environmental factors on survival; prey fish abundance had no influence on the survival of reared or wild smolt groups [30]. The results suggest that some larger smolt of the reared groups compared with the wild groups compensated for their lower ability to

Effects of Domestication on Fish Behaviour http://dx.doi.org/10.5772/intechopen.78752 95

The anti-predator behaviour is highly sensitive to artificial rearing and so to domestication [12, 31–36]. Anti-predator behaviour is thought to change during domestication, along with other traits. One prediction is that domestication should reduce behavioural responses to predation risk. This prediction was supported by a lot of studies most of the time on salmonids, on rainbow trout (*Oncorhynchus mykiss*) [31, 32], on brown trout (*Salmo trutta***)** [12] and on

In wild population, decreased activity, spatial avoidance of risky areas and the use of refuges reduce the rate of mortality caused by predators [38, 39]. This natural reaction of a fish faced to a high level of predation seems to disappear after two or three generations reared under artificial conditions; that is, after two generations, the common trout becomes non-sensitive to the predation risk; animals were active during the daylight and not during the night as their wild conspecifics [40]. As a consequence, domestication would decrease the level of defences against predators, as the reared animals would not experiment contacts with predators or some other life history traits should be affected by domestication and consequently affect the response of the animal to predator risk. For example, wild fishes react more rapidly to a predator than reared fishes [41, 42]. Wild animals may use natural refuges in their environment they know to escape from predation [43]. Moreover, wild individuals seem more careful to predators than reared fishes in the common carp (*Cyprinus carpio*); but these results are under suspicion because 'wild' animals are in fact reared individuals, which were returned back to natural conditions [44]. Domestication may also affect the reaction to a novel object in the environment; reared fishes approach more easily to a novel object and take more risks [36, 45]. This difference in behaviour is linked to physiological variations (heart activity, mobility, swimming abilities…) [35, 37]: but the results are not so clear and in a large number of cases, the responses of reared fishes to predators are variable [19, 46]. Some more recent results confirm the complexity of the relationships between this behavioural trait (anti-predator behaviour) and domestication. For example, the anti-predator behaviour of juvenile Atlantic salmon of conventional hatchery compared with that of wildcaught juveniles from the same population, tested in two unfamiliar environments, did not

live in the wild.

**4. Predator avoidance behaviour**

Atlantic salmon (*Salmo salar*) [35, 37].

These results showed that domestication can not only be influenced through selecting the physical characteristics of the individuals, but also through their swimming performances and consequently the foraging and space use by hatchery-reared individuals when released in wild conditions.
