FISHERY BULLETIN: VOL, 77, NO, 4 



OTHER GONOSTOMATIDS.— The eight other 

 gonostomatid species caught were rare; together 

 <4% of the family total (Tables 2, 3). Diplophos 

 taenia had the shallowest distribution of any 

 gonostomatid species, occurring mostly at 0-25 m. 

 Gonostoma atlanticum, G. elongatum, Ichthyococ- 

 cus ovatus, and Woodsia sp. were present in the 

 75-350 m range, with maxima at 75-100 m. Mar- 

 grethia obtusirostra and Valenciennellus 

 tripunctulatus were caught only at 100-225 m and 

 100-350 m. 



Family Sternoptychidae 



The Sternoptychidae is the third most abundant 

 family in the central gyre in terms of total larval 

 abundance on a year-round basis (Loeb 1979b). 

 Peak abundances occur during winter months, 

 when this family makes up more than 6% of the 

 total larvae. Minimal catches occur in late sum- 

 mer, so the 40 individuals taken during the pres- 

 ent (late summer) cruise can provide only a very 

 sketchy description of the vertical distributions of 

 this otherwise abundant family. 



The two genera (Sternoptyx and Argyropelecus) 

 almost always occurred deeper than 100 m ( Figure 

 2) and were abundant relative to other larvae in 

 the 100-600 m depth range. Sternoptyx spp. ap- 

 peared to have a shallower distribution than Ar- 

 gyropelecus spp. (Table 2). All but 2 of the 35 

 Sternoptyx larvae were taken between 100 and 350 

 m, with largest catches at 100-225 m (24 larvae 

 distributed among all six samples). Four of the five 

 Argyropelecus larvae were caught at 350-600 m. 

 This is in contrast with the depth distributions 



MEAN NO PER 1,000m' 

 100 200 300 



PERCENT 



25 50 



Lomponyctinoe 



Myctophinae 



(b) 



600 J 



Figure 6. — Vertical distributions of larval myctophids m the 

 North Pacific central gyre during sununer. (a) Concentrations of 

 myctophid larvae (31 species combined) by depth interval, (b) 

 Percent of estimated water column abundances of Lampanyc- 

 tinae and Myctophinae larvae in each depth interval. 



found in the eastern Atlantic (Badcock and Mer- 

 rett 1976) where Argyrope/ecus larvae were found 

 from 100 to 500 m and Sternoptyx from 500 to 

 1,000 m. 



A variety of developmental stages of both gen- 

 era were found in the stratified samples. Sternop- 

 tyx diaphana from 100 to 225 m ranged from early 

 larvae (3.8 mm) to larvae with abdominal and 

 isthmal photophores (7.7 mm). The four Argyro- 

 pelecus spp. from 350-600 m ranged from very 

 small undeveloped larvae to one individual with 

 an almost complete photophore complement. 



Family Myctophidae 



The myctophids ( 14 genera, 31 species) contrib- 

 uted over 42% of the total larvae. Over 98% of the 

 estimated water column abundance was in the 

 upper 100 m with maximum abundance at 25-50 

 m (Figure 6a). Diversity was highest (21 to 23 

 species) between 25 and 100 m (Table 2). The lar- 

 val depth distributions of the two subfamilies dif- 

 fered (Figure 6b). Ninety-four percent of the Lam- 

 panyctinae estimated water column abundance 

 was in the upper 75 m, with peak abundance at 

 25-50 m; only two (Lobianchia gemellari and 

 Notolychnus valdiviae) of the 19 species were not 

 taken in the 25-50 m interval (Table 3). This sub- 

 family contributed 78% of the myctophid indi- 

 viduals and therefore greatly influenced the shape 

 of the family distribution curve (Figure 6a). Myc- 

 tophinae larvae were never caught in the upper 25 

 m, and contributed only 7% of the total myctophid 

 larvae in the 25-50 m interval. The subfamily was 

 most abundant from 50-225 m, contributing 49%, 

 58%, and 71% of the total myctophid larvae in the 

 50-75 m, 75-100 m, and 100-225 m intervals, re- 

 spectively; peak abundance occurred at 50-75 m 

 (Figure 6b). Only 4 of the 12 myctophine species 

 taken were found at 25-50 m, while 7 were taken 

 at 50-75 m and 11 at 75-100 m (Table 3). Sig- 

 nificant differences were found between the cumu- 

 lative frequency versus depth distributions of the 

 two subfamilies (Kolmogorov-Smirnov test, 

 P<<0.01). 



Aspects of abundance, size distributions, and 

 development of the more abundant species are 

 considered below. For some species a variety of 

 developmental stages was found. Because of the 

 diverse patterns of photophore development ex- 

 hibited by myctophid larvae (Moser and Ahlstrom 

 1970) only very general terminology is used to 

 denote these stages. These include: early larvae ( = 



786 



