FISHERY BULLETIN. VOL. 78, NO. 3 



much like that seen in the western North Atlantic. 

 This is because the general circulation patterns of 

 the North Atlantic and the North Pacific are simi- 

 lar, and the scattered records in the western mid- 

 latitudes in the North Atlantic are probably a re- 

 sult of the Gulf Stream. 



In the eastern tropical Pacific, H. micans does 

 not often occur south of lat. 10° S or north of lat. 20° 

 N (Figure 3). The southern border of its distribu- 

 tion is well defined by the EASTROPAC sampling 

 program. The northern border could be an artifact 

 of that sampling program, since distributions of 

 both samples and the species approximately coin- 



cide. However, many negative EASTROPAC sam- 

 ples were taken north of the edge of the species 

 distribution (Figure 3), a large number of Califor- 

 nia Current samples have also been negative for 

 the species (Cheng unpubl. data), and other sam- 

 pling programs have shown the same feature 

 (Figure 2). These combine to convince us that the 

 northern border shown in Figure 3 is not artificial. 

 Halobates sobrinus seems to be confined to the 

 equatorial upwelling regions off the west coast of 

 Central America, with some northward extension 

 along the Mexican coast (Figure 2). Although both 

 the North and South Equatorial Currents could 



30' 



130° 



120° 



100° 90° 



20' 



10° 



10° 



20' 



Halobates sobrinus 



130° 



120° 110° 100° 90° 



Figure 4. — Halobates sobrinus distribution, as in Figure 3. 



70° 



584 



