LOEB; VERTICAL DISTRIBUTION OF LARVAL FISHES 



in other intervals (Table 3). Only early-stage lar- 

 vae (2.1-6.9 mm) were taken. Median standard 

 length increased only slightly with depth (Table 

 3). 



The three other Lampanyctus species caught in 

 stratified tows were rare. These included: L. "big 

 snout," probably of the L. niger complex; L. "lacks 

 pectorals," a larval stage of an undescribed Lam- 

 panyctus species IE. H. Ahlstrom''); andL. nobilis. 

 The larvae of L. "big snout" and L. nobilis were 

 most abundant at 25-50 m, while L. "lacks pecto- 

 rals" was taken mostly at 50-75 m (Table 3). All 

 three species showed a trend for increased size 

 with depth (Table 3); only early photophore 

 development stages were taken. No late larval or 

 transformational stages of any Lampanyctus 

 species were found in 0-300 m IKPT samples 

 (1,477 specimens examined). 



LOBIANCHIA GEMELLARI— The larvae of L. 

 gemellari occurred deeper than most lampanyc- 

 tine species, only at depths >50 m (Table 3). Over 

 94% of the estimated water column abundance 

 was between 50 and 100 m; larvae were similar in 

 frequency of occurrence in samples and in abun- 

 dance at 50-75 m and 75-100 m. Cumulative size- 

 frequency curves for 50-75 m and 75-100 m were 

 significantly different from each other and indi- 

 cated more small and fewer large individuals in 

 the deeper interval. The largest larvae taken in 

 stratified tows (6.7 and 7.9 mm) were in early 

 photophore development. Stages from early larvae 

 through transformation (10.8-12.7 mm) were 

 caught in 0-180 m IKPT hauls. 



NOTOLYCHNUS VALDIVIAE.— Both the adult 

 and larval N. valdiviae differ from other 1am- 

 panyctine species in several respects, and Moser 

 and Ahlstrom (1974) suggested placement of the 

 species in a separate subfamily. The larvae are 

 also unusual in their depth distributions as com- 

 pared with other lampanyctine species (Figure 

 7a). Notolychnus valdiviae was absent at 0-50 m 

 and rare at 50-75 m; maximum abundance (40 of 

 the 44 larvae caught) occurred at 75-100 m where 

 the species ranked fourth (Table 2). 



All stages of development of N. valdiviae were 

 found between 50 and 100 m. The largest pretrans- 

 formation specimen (8.0 mm) was from 75-100 m. 



'E. H. Ahlstrom, Southwest Fisheries Center, National 

 Marine Fisheries Service, NOAA, La JoUa, CA 92037, pers. 

 commun. 1977. 



A 10.5 mm transforming specimen plus nine other 

 individuals ranging from recently transformed to 

 adult (10.8-21.8 mm) were caught at 50-75 m. 

 Three other metamorphosed individuals were 

 found in other intervals: a recently transformed 

 individual ( 1 1.3 mm) at 25-50 m; and twojuveniles 

 (15.7 and 17.3 mm) at 75-100 m. 



TRIPHOTURUS NIGRESCENS.—Triphoturus 

 nigrescens was the fourth-ranked myctophid 

 (eighth ranked species overall) taken. The larvae 

 were distributed from to 100 m, with 88% of the 

 estimated water column abundance at 25-50 m; 

 abundances in replicate samples within this in- 

 terval were significantly greater (P<0.01) than in 

 other intervals (Table 3). Median standard 

 lengths increased below 50 m (Table 3) and 25-50 

 m and 50-75 m cumulative size-frequency curves 

 were significantly different from each other. The 

 1 1.8 mm larva, from 75-100 m (Table 3), was one of 

 the largest T. nigrescens larvae taken in any cen- 

 tral gyre plankton sample; it still lacked photo- 

 phore development. Nine metamorphosed indi- 

 viduals were also caught in stratified tows: six 

 ( 14.7-17.0 mm) at 25-50 m; one (17.9 mm) at 50-75 

 m; and two (17.0 and 21.3 mm) at 75-100 m. No 

 late-stage larvae have been found among the 612 

 specimens collected from central gyre IKPT sam- 

 ples. 



Subfamily Myctophinae 



BENTHOSEMA SUBORBITALE .—Benthosema 

 suborbitale occurred at 75-350 m, and was an im- 

 portant component of the deeper ichthyoplankton, 

 ranking third in 75-100 m samples and second in 

 100-225 m and 100-350 m samples (Table 2). 

 Largest numbers occurred at 75-100 m, but 46 of 

 the 48 larvae from this interval came from only 2 

 of 10 samples; frequency of positive samples was 

 highest at 100-225 m (five of six samples). Size 

 ranges, median lengths, and cumulative size-fre- 

 quency curves were similar for all depth intervals. 

 The largest larva (8.0 mm) was in early photo- 

 phore development. Seven recently transformed 

 juveniles were caught: five (11.1-12.1 mm) at 

 25-50 m and two ( 10.8 and 12.7 mm) at 50-75 m. 

 Developmental stages to early transformation 

 (10.8-11.3 mm) were found in 0-300 m IKPT sam- 

 ples. 



CENTROBRANCHUS SPP.— Three species of 

 Centrobranchus were caught at 75-100 m (Table 



789 



