FISHERY BULLETIN: VOL. 85, NO. 3 



of the 1983 surveys. However, rates of detecting 

 schools during good sun conditions were larger 

 than during poor conditions (Fig. 9) and no 

 schools were detected on the trackline during 

 poor conditions. 



(92) 



E 



o 

 o 

 o 



o 



i 4 

 u 



(0 

 UJ 



H 3 



< 



CE 



Z 



2 2 



I- 

 o 



UJ 



I- 



tu . 

 Q ' 



(94) 



(6) 



(8) 



I I Good sun 

 all schools 



|:::;'-| Poor sun 

 all schools 



^^Good sun 



trackline schools 



( ) Percent effort 



1982 



1983 



Figure 9. — School detection rates and relative density esti- 

 mates during good and poor sun glare conditions for 1982 and 

 1983 ship data. 



Density Estimates 

 Inshore Area 



Aerial observers during the 1977 and 1979 sur- 

 veys searched 34,006 km and detected 152 dol- 

 phin schools in the inshore area (Table 1). The 

 estimate of school density using aerial data was 

 4.18 schools/1,000 km^ with a standard error of 

 0.902. 



From 1977 to 1983, shipboard observers 

 searched 27,840 km in the inshore area and de- 

 tected 297 schools (Table 2). Ship data yielded an 

 estimate of density for the inshore area of 4.47 

 schools/1,000 km^ with a standard error of 0.514 

 (Table 1). This was only slightly larger than the 

 aerial inshore estimate. 



Oflfehore Area 



Observers aboard both vessels surveyed 46,567 

 km in the offshore area and detected 192 schools 

 (Table 2). The estimate of density was 2.04 

 schools/1,000 km^ with a standard error of 0.263 

 (Table 1). 



Total Area 



From 1977 to 1983, observers on both vessels 

 searched 74,407 km in all areas and detected 489 

 schools (Table 2). The density estimate for all 

 shipboard data was 2.95 schools/1,000 km^ with a 

 standard error of 0.253 (Table 1). The estimate of 

 density using the aerial inshore estimate and the 



Table 2.— School detection rates for 1977-83 ship data and for 1979-83 ship data stratified by sea state category in the 

 inshore, offshore and total areas. Data were truncated at 2.13 km perpendicular distance. 



430 



