FLANAGAN and HENDRICKSON: FISHERY AND REPRODUCTIVE BIOLOGY OF TOTOABA 



2,4 00-1 



2,0 00 



(A 



C 



o 



0) 



E 



r 

 o 



1,6 00- 



1,2 00- 



< 



(J 800 



4 00 



r-1 3 



12 



■10 



- 8 



CATCH 



19 30 



I T T I I I — [— r 



19 35 1940 



r I I 



1945 



1950 



1 I r 



1955 



1960 



T-T 



■^ 



I I I I 



I I I I 





O 



-6 (0 



5 ^-' 

 4 O 



u. 



I- 3 



1965 



1970 



19 75 



YEAR 



Figure 7.-Colorado River flow in thousands of acre-feet and totoaba fishery annual yield in metric tons for the 1930-75 period. Totoaba 

 annual yield data are those of Figure 1. Flow data were calculated from records published in Water Supply Papers 1313, 1733, and 1926 

 (U.S. Geological Survey, respectively, 1954, 1964, and 1970). Flow data for 1966-75 are not shown but we do not expect them to deviate 

 beyond the 1960-65 variation above. We have calculated the flow delivered to Mexico at the southerly international boundary (near San 

 Luis, Ariz.) as follows (data sources are cited only on first mention): 1930-36: Colorado River at Yuma (1954:710) + Yuma Main Canal 

 Wasteway (1954:717) + Calif. Drainage Canal (1954:723) - Alamo Canal (1954:724) + Eleven-mile Wasteway (1954:726) + Cooper 

 Wasteway (1954:726); 1937-50: Colorado River at Rockwood Gate, Calif. (1954:712) - Alamo Canal -i- Eleven-mile Wasteway -(- 

 Twenty-one Mile Wasteway (1954:727) + Cooper Wasteway; 1951-65: Colorado River at southerly boundary, near San Luis (1964:563; 

 1970:519-521). 



p 

 «.io 

 >.io 



<.001 



6 7 8 9 



FLOW (10* acre-feet) 



12 



Figure 8. -Plot of annual totoaba 

 yield and annual Colorado River flow 

 for the 1942-58 period. Data are those 

 displayed in Figure 7. The points 

 below the dashed line represent the 

 1951-58 flow years. Though the rela- 

 tionship between catch and flow for 

 the 1942-58 period are highly sig- 

 nificant, the disparity between the r^ 

 levels for the component periods 

 1942-50 and 1951-58 invites caution in 

 interpretation of these results. 



539 



