Effects of environmental conditions in the period of early ontogenesis on the formation of defensive behavior in juvenile roach Rutilus rutilus (Cyprinidae)

2010 ◽  
Vol 50 (1) ◽  
pp. 127-136 ◽  
Author(s):  
E. S. Smirnova ◽  
Yu. V. Gerasimov
Keyword(s):  
Environmental Conditions ◽  
Defensive Behavior ◽  
Rutilus Rutilus ◽  
Early Ontogenesis ◽  
Roach Rutilus Rutilus ◽  
Juvenile Roach

Front Individuals Lead in Shoals of Three-Spined Sticklebacks (Gasterosteus Aculeatus) and Juvenile Roach (Rutilus Rutilus)

Behaviour ◽  
1993 ◽  
Vol 125 (3-4) ◽  
pp. 189-198 ◽  
Author(s):  
Dirk Bumann ◽  
Jens Krause
Keyword(s):  
Gasterosteus Aculeatus ◽  
Rutilus Rutilus ◽  
Swimming Velocity ◽  
Front Part ◽  
Roach Rutilus Rutilus ◽  
Video Recordings ◽  
New Directions ◽  
Short Time ◽  
Juvenile Roach ◽  
Dominant Influence

AbstractFish shoals are usually seen as anonymous leaderless groups in which all individuals have the same influence on swimming velocity and direction. This hypothesis was tested by investigating swimming directions of shoals of roach (Rutilus rutilus) and three-spined stickleback (Gasterosteus aculeatus). In roach, the influence of front and rear fish on the shoal's swimming direction was compared by analysing video recordings. Front fish initiated new directions significantly more often and were followed by rear fish. In a second experiment two shoals of sticklebacks were released from two channels which were positioned at an angle relative to each other. The shoals usually appeared with a short time difference at the opening of the channels and then merged. Initially the two shoals faced in different directions based on the orientation of their respective channel and it was recorded which direction prevailed after the shoals had merged. The shoal that left the channel first, and therefore formed the front part of the merged shoal, clearly dominated the direction. Thus, both experiments gave evidence for front fish having a dominant influence on the direction of the shoal. In the context of sustained position preferences of individual fish, recently observed in roach, this suggests that fish shoals may have leaders over extended time periods.

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