648 



Fishery Bulletin 91(4). 1993 



20 



10- 



a. o 



-10 



-20 



y = 0.58792 - 5.8069e-2x, R*2 = 0.029, 

 n = 48. p = 0.119 



READER 1 



10 20 30 40 50 



20 



10 



-10 



-20 



y = - 2. 7246 + 8.85 12e-2x. R"2= 0.074. 

 n = 48,p = 0.066 



a READER 2 



— i 1  1 1 1 1 1 1 — 



10 20 30 40 50 



20 



10 



£ o 



-10- 



-20 



y = 1.7801 - 1 5724e-2x. R*2 = 002 

 n = 48, p = 0.792 



10 20 30 40 



50 



Time (chronological sequence of photo counts) 

 Figure 4 



Percent deviation (PDl values regressed on "time." Time represented 

 the chronological sequence, unique for each reader, in which photo- 

 graphed schools were counted during the counting period. Zero on the 

 y axis represents the mean count while negative and positive values 

 represent the percent deviation of the count from the mean. 



Perrin, W. F. 



1975. Distribution and differentiation of popu- 

 lations of dolphins of the genus Stenella in 

 the eastern tropical Pacific. J. Fish. Res. 

 Board Can. 32:1059-1067. 

 Scott, M. D., W. L. Perryman, and W. G. Clark. 

 1985. The use of aerial photographs for esti- 

 mating school sizes of cetaceans. Inter-Am. 

 Trop. Tuna Comm. Bull. 18(51:383-404. (In 

 English and Spanish.! 

 Shapiro, S. S., and M. B. Wilk. 



1965. An analysis of variance test for normal- 

 ity (complete samples). Biometrika 52:591- 

 611. 

 Sokal, R. R., and F. J. Rohlf. 



1981. Biometry: the principles and practice of 

 statistics in biological research. Second 

 ed. W.H. Freeman and Co., New York, 859 p. 

 Wade, P. R., and T. Gerrodette. 



1992. Estimates of dolphin abundance in the 

 eastern tropical Pacific: preliminary analysis 

 of five years of data. Rep. Int. Whal. Comm. 

 42:533-546. 

 Winer, B. J. 



1971. Statistical principles in experimental de- 

 sign. Second ed. McGraw-Hill, New York. 



