RP2E INRA Université de Lorraine

Cannibalism and personality in larval pikeperch (Sander lucioperca)

39th Annual Larval Fish Conference,, 12-17 juillet, Vienne, Autriche

Faux, E., Colchen, T., Fontaine, P., Teletchea, F., Pasquet, A.


Cannibalism is frequently observed during the early life stages of many fish species under culture conditions and is largely due to size differences but depends also on specific traits. The heritability of cannibalism in fish has barely been studied such as for Poecilopsis spp and, the existence of cannibalistic ecomorphotypes is still highly controversial, even in species with strong individual dietary specialization. Cannibalism appears most often in piscivorous species and the risk can be tempered by prey size preferences, as cannibals rarely eat prey larger than themselves. Besides cannibalism is neither strongly affected by food availability nor by other environmental variables. It seems to be an individual characteristic. Many animal species exhibit personalities, suites of two or more behaviors that correlate across environmental contexts. Behavioral syndromes constrain the direction of evolution, affect an animal fitness, maintain individual differences in behavior, and may explain maladaptive behaviors. According to the aggression– boldness syndrome, animals that are more aggressive will also be bolder and more explorative in novel environments. Aggression– boldness has been described in many animals, including mammals, birds, and fish. This is also an individual characteristic. The question now is: is there a link between the cannibal status of an individual and its behavioral personality? In the framework of the European project Diversify (KBBE-2013-GA N° 603121), we studied this question with pikeperch (Sander lucioperca) larvae. Fish larvae were reared under laboratory conditions. Cannibalism appeared at 21 days post hatching (dph) and lasted at least until 70dph. The rate of cannibalism was high (3 observations/hour/day) and in general the cannibal was larger than that of the prey. Some couples (n=32) of cannibal and prey were removed from the tanks, measured and put in formalin (4%) for histological analysis.  On the other side, the personality of 42 larvae was described using three different tests: the labyrinth, a stress test and a test of sociability (two larvae were put in the same aquarium). These tests allowed us ranking larvae along a boldness-shyness scale using their performances in the different behavioral situations. After the behavioral tests, the larvae were put together in small groups (n=6) during 48 hours. After that, all the larvae were measured and put in formalin (4%). During the personality tests, we identified only three cannibals. So it was not possible to establish a direct link between the cannibal status and the behavioral performances, but we compared the morphological data of cannibals (and prey) to those of the larvae placed along the boldness-shyness scale. 

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