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abs/10.1111/raq.12164

1801-1812

90 Animal Domestication

Additional information is available at the end of the chapter Alain PasquetAdditional information is available at the end of the chapter

http://dx.doi.org/10.5772/intechopen.78752

#### **Abstract**

Domestication is a process by which humans select some phenotypes of wild animal species (i.e., morphological traits or growth), but as all traits are linked, the selection of a particular one has consequences on others. In that context, behavioural traits may be affected by human selection. In this chapter, through classical behavioural traits, such as swimming capacities, foraging, social interactions, or reproduction, and also personality or cognitive abilities, what domestication modifies in fish behavioural traits is shown. The information is taken only from studies that make a clear comparison between domesticated and wild animals; the major difficulty was that the domesticated status was not clearly determined. Whatever the behavioural trait considered, domestication affects some of them even after only one generation. These data deserve to be taken into consideration when humans try, not only to domesticate new species but also to release domesticated species into their natural habitats. In this last case, alteration of behavioural traits could make the fish incapable to adapt to their new wild environment and alter their foraging or reproductive performances. Moreover, fish behaviour in farm is currently recognised as an essential component of the welfare and all behavioural modifications must be considered.

**Keywords:** behavioural traits, hatchery-reared fish, wild fish, performances, behavioural responses

#### **1. Introduction**

Behaviour is an animal phenotype and could be considered as a variable of adjustment for an animal to changes of environmental factors. Domestication gives new environmental conditions to animals; they have to adapt to these restricted surroundings. In general, captive conditions are less complex than those of a natural environment but even with less complexity, the environmental conditions of farms or other rearing structures could appear as new for animals. So they

© 2016 The Author(s). Licensee InTech. This chapter is distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/3.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited. © 2018 The Author(s). Licensee IntechOpen. This chapter is distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/3.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

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 even after only one generation [3, 4].

In this chapter, I will review some of these behavioural traits in hatchery-reared fishes that

Effects of Domestication on Fish Behaviour http://dx.doi.org/10.5772/intechopen.78752 93

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

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

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

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

kg−1 min−1 at 18°C) in comparison to wild-caught yellowtail

have often been altered in a characteristic manner by domestication.

characteristics, this could influence directly their swimming performances.

**2. Swimming behaviour**

object in their environment.

(7.31 ± 2.32 vs. 3.94 ± 1.60 mg O2

kg−1 min−1) [15].

(15.80 ± 5.78 mg O2

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 objectives or animal welfare.

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 results.

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 of fish.

In this chapter, I will review some of these behavioural traits in hatchery-reared fishes that have often been altered in a characteristic manner by domestication.
