500 



Fishery Bulletin 93(3). 1995 



Limitations of the data 



Direct enumeration of giant bluefin tuna from aerial 

 survey involves potential sources of error that must 

 be addressed. These include species and size-class 

 identification, differences in surfacing behavior caused 

 by environmental or biological variables, and redun- 



dant counts as fish migrate through the study area. In 

 the 1993 feasibility study, we identified and resolved 

 only a few of these issues but nevertheless obtained 

 information vital for improving future aerial surveys. 

 We observed small differences (<1%) in medium- 

 size and large school totals when three different 

 individuals examined and counted bluefin tuna in 



