FISHERY BULLETIN: VOL. 85, NO. 3 



IB H ISO H 



lao II 110" a 



LONSITUre 



Figure 2. — Plot of hypothetical tracklines expected from use 

 of one (A), two (B), or three (C) ships for 120 days each. 



N=P,DS^PkAk. 



(3) 



k=i 



where m = number of strata (3 for the north area 



and 4 for the total area), 

 k = 1, 2, 3, or 4 denotes the inside, middle, 



west, or south stratum, respectively, 

 N = estimated number of spotted dolphins 



in the survey area, 

 D - density estimate of number of schools 



of all dolphin species in the survey 



area (schools/1,000 km^), 

 Dk = density estimate of number of schools 



of all dolphin species in the ^th 



stratum (schools/1,000 km^), 

 S = mean school size estimate for target 



species in the survey area (number of 



animals), 

 Stk = mean school size estimate for target 



species in the /eth stratum (number of 



animals), 

 Pi = proportion of all dolphins that were 



target species in the survey area, 



Pk = proportion of spotted dolphins in the 

 target schools in the /eth stratum, and 



Ak = area inhabited by all dolphins in the 

 kth stratum. 



The variance of N for Equation (2) was estimated 

 using Taylor series expansion (Seber 1973) as 



Var (N) = 2 [iStk Pt Pk ^^ )^ Var (Dk ) 

 k=i 



+ (DkPtPkAk)^'^kr(Sik) 

 + (D,S,,P,A,)2Var(A) 



+ (DkSfkPtAk)^ War iPk)] . (4) 



The variance of iV in Equation (3) was determined 

 using Equation (4), but density and school size 

 estimates that were calculated for the entire area 



438 



