Using information from Bruun (1935), Breder 

 (1938), Staiger (1965), Blache et al. (1970), and Miller 



and Jorgenson (1973), the following key was con- 

 structed and used for identifying juvenile flyingfishes: 



Key to Juvenile Flyingfishes 



Pectoral fins short, not reaching origin of dorsal fin Oxyporhamphus micropterus 



Pectoral fins long, reaching to or beyond origin of dorsal fin 3 



Pelvic fins short, less than 21% of SL 5 



Pelvic fins long, greater than 25% of SL 9 



Pectoral fins ca. 70% of SL; 13-14 dorsal rays; dorsal fin not extending to 



caudal base 6 



19-21 gill rakers on lower limb of first gill arch Exocoetus obtusirostris 



24-26 gill rakers on lower limb of first gill arch Exocoetus volitans 



Pectoral fins ca. 60% of SL or less; 10-13 dorsal rays; dorsal fin extends 



beyond caudal base Parexocoetus brachypterus 



More dorsal rays (12-16) than anal rays (8-12) 10 



Second pectoral ray simple Prognichthys gibbifrons 



Second pectoral ray branched 12 



Dorsal fin (at least partly) black 14 



Dorsal fin uniformly gray 16 



Less than 30 predorsal scales; 15 dorsal rays; mandibular barbels flap- 

 like, shorter than 46% of standard length Cypselurus exsiliens 



More than 30 predorsal scales; 12-13 dorsal rays; mandibular barbels 



cylindrical, very long, reaching past origin of dorsal fin Cypselurus cyanopterus 



Palatine teeth visible; 12 dorsal rays; 42 vertebrae (26-27 precaudal) Cypselurus comatus 



No palatine teeth; 13-14 dorsal rays; 45-47 vertebrae (29-31 precaudal) .... 18 

 First pectoral ray longer than 38% of standard length; 29-33 total caudal 



rays Cypselurus furcatus 



First pectoral ray shorter than 38% of standard length; 26-29 total caudal 



rays Cypselurus heterurus 



More anal rays (11-13) than dorsal rays (10-12) 21 



Second pectoral ray simple; 12 dorsal rays Hirundichthys rondeleti 



Second pectoral ray branched; 10-11 dorsal rays Hirundichthys affinis 



Of the three species of flyingfishes most commonly 

 taken, only Parexocoetus brachypterus demonstrates 

 marked seasonality in size of fish and numbers taken 

 (Table 3). 



The halfbeaks Hemiramphus brasiliensis and 

 Hyporhamphus unifasciatus were both more 

 numerous and larger in night tows than in day tows 

 (Table 4), attesting either to the ability of these fast- 

 moving predators to avoid the net during daylight or 

 to the fact that they avoid surface waters during the 

 day and actively feed there primarily at night. 



Table 3. — Number caught and length range (mm FL) of speci- 

 mens less than 100.0 mm for three species of flyingfishes. 



BELONIDAE 



Tylosurus acus Lacepede 



agujon 



D-67-4 May 



MM-2, 1, 206.0 

 D-67-8 Jul-Aug 



GG-7, 1, 197.0 

 D-67-16 Oct 



PP-1, 1, 208,0 

 Tylosurus sp. 

 D-67-16 Oct 



KK-5, 1, 35.5 



ATHERINIDAE 



Mem bras martinica 



(Valenciennes) 



rough silverside 



D-67-16 Oct 

 BB-1, 41, 29.9-51.4 

 FF-1, 25, 66.0-80.6 



D-68-1 Jan-Feb 

 EE-1, 1, 63.2 

 LL-1, 5, 71.0-76.0 

 LL-2, 72, 73.8-107.8 



Table 4. — Diel occurrences and maximum sizes of two species 

 of halfbeaks. 



19 



