| dc.description.abstract | Animal personalities are well defined as expression of individual behavioural syndromes that are stable over time and context. Personalities are interesting and equally important to study the individual differences that prevail in them. The study was done with an interest and eagerness to know what kind of personality brown trout (Salmo trutta) possesses. The study was done in Bø fish hatchery. The number of fish used in this study was 100 of total length 6cm and one summer old brown trout 0+ years. Boldness, explorative and risk taking behaviour were investigated in the studies. Based on these results, brown trout individuals were categorized into shy, intermediate and bold respectively. The study focuses on the behavioural responses of individuals exposed to the novel object. An experimental tank (418 L*424 W * 144 H mm) divided into acclimation area and a novel object in the experimental area by plywood door was used in the experiment. The novel object used in the experiment was glass jar (80 W* 130 H mm) with natural stones. The fish were kept in the acclimation area for 5 minutes before opening the door to explore, experimental area where the novel object was placed. The responses were observed as movements in fish. The time taken to explore and reach the novel object by fish was noted. To keep track of fish movement, the tank was covered with a translucent plexiglass (500 L*475 W mm) divided into a grid of 64 (5*5) cm squares. Those fish which managed to reach the novel object within a distance of 5 cm at specified time of 120 seconds were categorized as bold, those taking 300 seconds as intermediate and those taking more than 300 seconds or not approaching the novel object at all as shy. In the first experiment, 84 shy, 13 intermediate and three bold were found. The result found in the second experiment was more or less the same with 70 shy individuals, 12 intermediate and eight bold. The number of shy individuals was found high in both the experiments. Plasticity and propensity to take risk was found low in the studied individuals. Compared to previous studies where fish from hatchery were supposed to be bold, the results from my study showed high number of shy individuals. Also the exploring and risk taking behaviour was found less in my study as compared to other studies, where trout were found bold. | |
