FISHERY BULLETIN: VOL. 70, NO. 4 



Table 14. — Percentage contributions of larvae of the 

 two most abundant species to the total catch of larvae 

 in the monitoring pattern. 



Cruise 



Percentage contribution of larvae of 



designation ^'"'^ °^ ^"'"^^ Vincigu^rna Diogenichthy: Combined 



lucetia laternatus 



reproduction in oceanic, tropical fishes. Except 

 for this, little more was gained from the repeated 

 coverages that was not evident from any one of 

 the six coverages. The same species composition 

 was observed in all six cruises, and even the rel- 

 ative abundance of the various constituents did 

 not change much. The similarity between cruis- 

 es also extended to the geographic distributions 

 of the various constituents which changed but 

 little over time. 



COMPARISON WITH RV 

 OCEANOGRAPHER ZIG-TRANSECT 



Although the average number of larvae per 

 haul was almost identical for the Oceanographer 

 collections and equivalent ETP II collections, 

 488.5 versus 487.8 larvae, and the kinds of larvae 

 obtained were strikingly similar, the relative 

 abundance of several categories was somewhat 

 more variable than in the monitoring pattern 

 (Table 15). 



Similarities and differences in relative abun- 

 dance of larvae during the two coverages can be 

 shown from a consideration of the 10 families 

 with highest abundance in the Oceanographer 

 collections (Table 16). 



Myctophfdae. — The difference in relative 

 abundance of Myctophidae larvae between 

 Oceanographer and ETP II collections, 194.1 

 versus 273.9 larvae per haul, is almost entirely 

 due to difference in relative abundance of larvae 

 of Diogenichthys laternatus. Over 509^ of D. 

 laternatiis larvae on ETP II were taken in four 

 contiguous stations between lat 5°40' and 

 7°44'N, with three collections exceeding 1,000 

 larvae and the largest with 2,505 larvae. In- 



terestingly, the two Oceanographer collections 

 containing more than 1,000 D. laternatus larvae 

 were taken between lat 6° and 7°N; these were 

 the only two stations occupied between lat 5°40' 

 and 7°44'N by Oceanographer in contrast to four 

 collections from this rich area on ETP II. 



Gonostomatidae. — The difference in relative 

 abundance of Gonostomatidae larvae in the two 

 occupancies of the zig-transect was again due 

 principally to a single species, Vinciguerria 

 lucetia. Although twice as many larvae of this 

 species were taken in Oceanographer collections, 

 an examination of the station record revealed 

 that one collection, OP.036 with 2,046 larvae, 

 accounted completely for the difference. 



Clupeidae. — It is necessary to examine the 

 species composition to evaluate differences be- 

 tween the two coverages (Table 17). Larvae 

 of the sardine, Sardinops sagax, were taken in 

 six contiguous stations near the Galapagos on 

 ETP II, and averaged 29 larvae per positive 

 haul, whereas only 1 sardine larva was obtained 

 from the same area by Oceanographer. This 

 species appears to have a period of peak spawn- 

 ing with reduced reproduction at other periods 

 of the year. The contrast between the two col- 

 lections of thread herring, Opisthonema sp., 

 made at the station nearest the Mexican coast 

 along long 92 °W is the largest observed in 

 EASTROPAC collections— 2,730 larvae in the 

 Oceanographer sample versus one larva in the 

 ETP II collection. The larvae in the Ocean- 

 ographer collection were intermediate-sized, 6 

 to 12.5 mm. Even allowing for the circumstance 

 that clupeid larvae often occur in patches, this 

 exceptionally large collection of larvae must 

 have been obtained at a peak period of spawning 

 of thread herring. 



Bathylagidae. — Larvae of the two species of 

 bathylagid smelts that occur in the area covered 

 by the zig-transect, were similar in distribution 

 and relative abundance in the two coverages. 

 Larvae of Bathylagus nigrigenys were taken in 

 all but three collections on each coverage, and 

 average abundance per haul was almost identi- 

 cal, 26.3 versus 26.6 larvae (Table 17). Larvae 

 of Leiiroglossus stilbius urotranus had a more 

 restricted distribution on both coverages, occur- 

 ring between about 7°S and the equator, at sta- 



1170 



