AHLSTROM: FISH LARVAE IN EASTERN TROPICAL PACIFIC 



of the eastern tropical Pacific are as yet inad- 

 equately known. Most larvae taken between lat 

 10° and 20° N were those of Scopelarchoides 

 nicholsi Parr. 



17. SCOPELOSAURIDAE 

 (9 occurrences, 16 larvae) 



stations between the coast and the outer line 

 occupied by Argo. Leptocephali of Hildebrand- 

 ia were restricted to a broad coastal band, 

 but leptocephali of Bathyconger and Para- 

 conger were almost as widespread as those 

 of Ariosoma. Only one record was obtained of 

 Gnathopis. 



Two kinds of Scopelosaurus larvae were col- 

 lected in the EASTROPAC area, but neither has 

 been linked to its adult stages as yet; one of 

 these occurred in only a single collection. Most 

 of the specimens of the other form were taken 

 in an equatorial band, between lat 5° N and 5° S. 



20. EEL LEPTOCEPHALI 



(87 occurrences, 179 larvae in 1.0-m oblique net 



hauls; 58 occurrences, 553 larvae in 5.0-ft 



micronekton net hauls ) 



A total of 10 families of true eels of the order 

 Anguilliformes, suborder Anguilloidei, is rep- 

 resented in the EASTROPAC I collections. Eel 

 leptocephali were decidedly more common in 

 collections made with the 5-ft micronekton net 

 than in the 1-m net collections: 9.5 larvae per 

 positive haul as compared with 2.1 larvae. This 

 difference probably was due in large part to the 

 larger volume of water strained in taking micro- 

 nekton net hauls, but the faster towing speed 

 of these hauls, ca. 5 knots as compared with 1..5 

 to 2 knots for 1-m net hauls, also may have con- 

 tributed. In the discussion of eel families that 

 follows, I have utilized information on occur- 

 rence of eel leptocephali from the collections of 

 both nets. 



Congridae 



Leptocephali of congrid eels were taken at 

 more stations, 57, than those of any other fam- 

 ily, yet no congrid larvae were obtained to 

 the south of lat 6° S. Most congrid leptoceph- 

 ali could be identified to genus, of which five 

 were represented; some larvae, however, could 

 not be identified below the family level. Lep- 

 tocephali of Ariosovia were widely distributed 

 between lat 20° N and 3° S, occurring at 28 



Derichthyidae 



The only definite record is a metamorphosing 

 specimen obtained at station 11.167. 



Moringuidae 



Leptocephali of Neoconger were taken at five 

 coastal stations between lat 8° N and 1° S. 



Muraenesocidae 



Leptocephali were taken at four stations in 

 the inner pattern occupied by the Alaminos, all 

 within 3° of the equator. 



Muraenidae 



Muraenid leptocephali were taken at 17 sta- 

 tions; two were on the line of stations occupied 

 off Acapulco, Mexico, and the remainder in the 

 broad con-idor between Puntarenas, the Galap- 

 agos Islands, and the coast of Ecuador. 



Nemichthyidae 



Two genera of nemichthyid larvae were rep- 

 resented in the EASTROPAC area, Nemichthys 

 and Borodiniila. A specimen of Nemichthys, 

 310 mm long, was obtained at station 14.188. 

 Leptocephali of this family were taken at 24 

 stations scattered throughout the EASTROPAC 

 area, including the South Pacific central water 

 mass. 



Nettastomidae 



Taken at 17 stations in the inner half of the 

 EASTROPAC pattern between lat 9° N and 2° S; 

 two kinds of nettastomid larvae were obtained, 



33 



