KINDS AND ABUNDANCE OF FISH LARVAE IN THE EASTERN 

 TROPICAL PACIFIC, BASED ON COLLECTIONS MADE ON EASTROPAC I 



Elbert H. Ahlstrom' 

 ABSTRACT 



This paper deals with kinds and counts of fish larvae obtained in 482 oblique plankton hauls taken 

 over an extensive area of the eastern tropical Pacific on EASTROPAC I, a four-vessel cooperative 

 survey made during February-March 1967. On the basis of abundance of larvae, the dominant fish 

 group in oceanic waters are the myctophid lanternfishes (47 %), gonostomatid lightfishes (23 %), 

 hatchetfishes, Stemoptychidae (6 %), bathylagid smelts (5 %). Scombrid larvae ranked fifth, and ex- 

 ceeded 2 % of the count. 

 Two kinds of larvae were outstandingly abundant : larvae of the lantemfish Diogenichthys latematus 

 made up over 25 % of the total, while larvae of the gonostomatid genus Vinciguerria made up almost 

 20 %. More fish larvae were obtained per haul, on the average, in the eastern tropical Pacific than 

 were obtained per haul in the intensively surveyed waters of the California Current region off Cal- 

 ifornia and Baja California. 



EASTROPAC I was the first and most wide- 

 ranging of a series of cooperative cruises made 

 in tlie eastern tropical Pacific between February 

 1967 and April 1968. A vast expanse of the 

 eastern tropical Pacific was surveyed on EAS- 

 TROPAC I, extending from lat 20° N to 20° S, 

 and from the American coasts ofi'shore to long 

 126° W (Fig. 1). Four research vessels par- 

 ticipated in EASTROPAC I: Alaminos oper- 

 ated by Texas A & M, occupied the inner pat- 

 tern, while Rockaway operated by the U.S. 

 Coast Guard, David Star?- Jordan operated by 

 the Bureau of Commercial Fisheries (now the 

 National Marine Fisheries Service), and Argo 

 operated by the Scripps Institution of Ocean- 

 ography, occupied patterns successively seaward. 

 The oceanographic, biological, and meteorolog- 

 ical data collected on EASTROPAC cruises will 

 be graphically presented in a series of EAS- 

 TROPAC atlases, including generalized charts 

 dealing with fish eggs and larvae. 



The present paper is the result of a chain of 

 events that began 2 decades ago, at the initiation 

 of CalCOFI (California Cooperative Oceanic 

 Fisheries Investigations) in which a large-scale 

 sea program was set up to investigate the distri- 



' National Marine Fisheries Service Fishery-Ocean- 

 ography Center, La JoUa, Calif. 92037. 



bution and abundance of sardine spawning, and 

 the factors underlying fluctuations in survival 

 of the early life-history stages of sardines. The 

 plankton collections not only contained eggs and 

 larvae of sardine but those of most other pelagic 

 fishes in the California Current region. A de- 

 cision was made to attempt to identify and enu- 

 merate all fish larvae in the collections in order 

 to obtain more precise information about the eco- 

 logical associates of the sardine. At that time 

 few fish larvae, other than those of the sardine 

 and anchovy, could be identified. 



Within a few years most kinds of fish larvae 

 were identified to genus or species. Once the 

 larvae were identified and enumerated, it be- 

 came obvious that this was an exceptionally use- 

 ful tool for evaluating fish resources. Most 

 oceanic fishes have pelagic eggs and/or larvae 

 that are distributed in or just below the photic 

 zone, i.e. within the upper 150 to 200 m of depth. 

 At no other time in their life histories are so 

 many kinds of fishes associated together — deep- 

 sea fishes (mesopelagic and bathypelagic) as 

 well as epipelagic species — where they can be 

 collected quantitatively with a single type of 

 gear, a plankton net. 



Once the larvae of the pelagic fish fauna of 

 a region, such as those in the California Cur- 

 rent region, are known, there is a large trans- 



Manuscript received September 1970. 



FISHERY BULLETIN: VOL. 69, NO. I, 1971. 



