LOEB. VERTICAL DISTRIBUTION OF LARVAL FISHES 



no photophore development); early photophore 

 development larvae ( = photophores developing); 

 late photophore development larvae ( = lacking 

 full photophore complement and still having lar- 

 val morphology); transforming, or meta- 

 morphosing, individuals (= those completing 

 photophore development and undergoing changes 

 in pigmentation and morphology); and trans- 

 formed, or early juvenile, stages ( = adult mor- 

 phology and photophore patterns, but still lightly 

 pigmented). Additional information from other 

 gyre cruises on developmental stages is included 

 here. 



Subfamily Lampanyctinae 



BOLINICHTHYS SPP. —Bolinichthys longipes 

 was the fifth-ranked species taken, occurring 

 primarily in the upper 50 m, with peak abundance 

 at 0-25 m; abundances in replicate tows within the 

 0-25 m interval were significantly greater 

 (Mann-Whitney U test, P<0.01) than in other 

 depth intervals (Table 3). Median standard 

 lengths increased with depth (Table 3) and 0-25 m 

 and 25-50 m cumulative size-frequency curves 

 were significantly different from each other. The 

 largest specimen (8.7 mm, from 50-75 m) was still 

 in early photophore development. The largest B. 

 longipes larva (10.8 mm) of the 670 taken from 

 IKPT samples was also in early photophore 

 development. No transforming individuals were 

 taken, although juveniles s 12.8 mm were caught. 

 Bolinichthys distofax had a narrower distribu- 



tion than did B. longipes; all individuals came 

 from 25-50 m (Table 3). Larval size ranges and 

 developmental stages found in bongo and IKPT 

 samples were comparable with those of B. lon- 

 gipes. 



CERATOSCOPELUS WARMINGI.-Cerato- 

 scopelus warmingi was the third-ranked species, 

 >5% of total larvae, and is also third-ranked 

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

 though present at 0-225 m (Figure 7), 94% of the 

 estimated water column abundance was at 25-75 

 m. Abundances in replicate samples within the 

 25-50 m interval were significantly greater 

 (P<0.01) than in other intervals; the species made 

 up 9% of the total larvae in this interval. Median 

 standard lengths increased with depth and cumu- 

 lative size-frequency curves for 0-25 m, 25-50 m, 

 50-75 m, and 75-225 m (Figure 8) were all sig- 

 nificantly different from each other. The three 

 largest larvae (8.6-12.8 mm), taken at 75-225 m, 

 were still in early photophore development stages. 

 No later photophore development stages or trans- 

 forming specimens of C. warmingi were found 

 among the 1,806 larvae (to 16.7 mm) examined 

 from 0-300 m IKPT samples; a few early juveniles 

 (S18.0 mm) were taken. 



DIAPHUS SPP. — Seven Diaphus species were 

 taken on this cruise. They fell into the two 

 morphological categories described by Moser and 

 Ahlstrom (1974): the "slender" form (which as 

 adults possess a suborbital photophore) and the 



MEAN NO. PER I.OOOm^ 



20 30 40 



600 



-Diaphus anderseni 

 - D elucens 

 -D "slender B" 

 -D rolfbolini 

 D brachycephalus 

  D "slencjer C" 



— Hygophum proximum 

 -- H. reinhardti 



Figure 7. — Vertical distributions of various myctophid species m the North Pacific central gyre during summer. Concentrations of (a) 

 Ceratoscopelus warmingi and Notolychnus valdiviae. ibl Diaphus spp., and (c) Hygophum spp. larvae by depth interval. 



787 



