NOTE Masuda and Tsukamoto: Association behavior of Pseudocaianx dentex in relation to floating objects 



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Figure 2 



Association ratios for each type of flotsam in each stage. Each plot represents an average 

 (±SE) of three tanks with the same type of flotsam. * shows significant difference between 

 tests and controls (P<0.05; Scheffe's test). Expected value of random distribution (=0.25) is 

 represented as a dotted line in each graph. Shaded bar corresponds with dark hours. 



cues to migratory orientation (Hunter and Mitchell. 1967; 

 Gooding and Magnuson, 1967; Kingsford, 1993). Flotsam 

 may provide the first cue to finding conspecifics and to 

 forming a school because association behavior may also be 

 related to school formation and maintenance (Masuda and 

 Tsukamoto, 1998b). 



In conclusion, the association behavior of striped jack 

 appeared at 12 mm and is probably dependent on a mech- 

 anosensory system, as well as vision. Association behavior 

 may also help the development of schools and may pro- 

 vide transportation for migration. Environmental modifi- 

 cations that reduce flotsam, such as the removal of drift 



