LO and SMITH: INCIDENTAL MORTALITY OF DOLPHINS 



Zr = 



V(T 59 ) 



Cov(T 59 , f 60 ) V(f 60 ) 



Cov(f 59 , f 72 ) Cov(f 60 , f 72 ) . . . V(f 72 ) 



V(X' 59 Q 59 ) 



Cov(Z' 59 Q 59 , X' 60 Q 60 ) V(X' 60 Q 60 ) 



Cov(X' 59 Q 59 , X' 12 Q 72 ) Cov(X' 60 Q 60 , X' 72 Q 72 ) . . . V(X' 72 Q 72 ) 



with VCfy = X' f lQ t X t 



as the diagonal elements of If 



(6) 



where 1q t = 



V(R. in f t )Cov{R. ul f t ,R. 2n f t ) 



V&.211 ft) o o 



^.21.) 



V(R. 22 .) 



(7) 



The diagonal elements of If can be computed by 

 noting that R, i2 . is uncorrelated with R. in , P t , or C, 

 and the covariance of P t and C is zero because one 

 C value is used for all years in 1959-72 and P t can 

 be different between years. 



The off-diagonal elements of If are 



Cov(t „ tj = CovPT'A, X' m Q m ) 



4 4 



= 11^ Cov(Q MJ , Q mj ) X„ 



i=i i=i 



(8) 



,mj) ■"■my 



Expressions for each of the terms in If are given 

 in the Appendix. 



RESULTS AND DISCUSSION 



The estimates of the total number of dolphins 

 killed incidentally in the tuna purse seine fishery 

 from 1959 to 1972 (Table 4, from Equation (4)) vary 

 from a low of 55,000 in 1959 to a high of 534,000 

 in 1961. Three distinct maxima of 534,000, 460,000, 

 and 467,000 are apparent (Fig. 1), corresponding to 



peaks in numbers of sets made on dolphins in 1961, 

 1965, and 1970 (Table 3). A total of about 4.8 million 

 dolphins is estimated to have been killed in the whole 

 period (Table 4). 

 The CVs of the annual estimates decline rapidly 



Table 4.— Estimated number of dolphins 

 killed by year (Equation (4)), with standard 

 errors (SE) and coefficient of variations 

 (CV). 



31 



