LOEB and ROJAS: ICHTHYOPLANKTON COMPOSITION AND ABUNDANCE 



90° 75° 60° 



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Figure 1. — Ichthyoplankton study area between Arica and Antofagasta, Chile (18°-24°S), 1964-83. 



tions of the OL. The OL are further separated into 

 myctophid, "other mesopelagic" and "coastal" 

 fractions. 



Ichthyoplankton abundances are expressed as 

 numbers per 10 m^ sea surface. Flow meters were 

 not used with the vertical Hensen net hauls; 

 numbers of larvae caught in each tow are multi- 



plied by 30 to provide numbers per 10 m^ esti- 

 mates. A flow meter used with WP2 nets provided 

 water volume measurements and more accurate 

 abundance estimates. Based on these measure- 

 ments the conversion factor applied to Hensen net 

 catches appears to be reasonable: water volumes 

 filtered by 100-0 m vertical WP2 net hauls aver- 



