FISHERY BULLETIN: VOL, 77, NO 4 



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STANDARD LENGTH (mm) 



Figure 8. — Cumulative size-frequency curves for Cerato- 

 scopetus warmingi larvae taken in 10 samples each from 0-25 m, 

 25-50 m, 50-75 m, and in combined samples from 75-100 m (10) 

 and 100-225 m (6) of the North Pacific central gyre during sum- 

 mer. 



"stubby" form (without this photophore). The 

 presence of transforming specimens of most of 

 these species in planitton samples facilitated their 

 probable identifications. The "slender" species 

 were D. anderseni, D. brachycephalus, and the D. 

 mollis complex. The "stubby" species were D. elu- 

 cens, D. rolfbolini, and the possible larvae of D. 

 schmidti. 



Diaphus anderseni had the shallowest distri- 

 bution among Diaphus species, with 96% of the 

 abundance from the upper 50 m and significant 

 (P<0.05) peak abundance at 0-25 m (Figure 7b; 

 Table 3). Median standard lengths increased 

 slightly from 0-25 m to 25-50 m, with a much 

 greater increase between 25-50 m and 50-75 m 

 (Table 3); cumulative size-frequency curves were 

 significantly different for all three intervals. The 

 largest individuals (11.3 and 11.6 mm), caught at 

 50-75 m, were transforming. One recently trans- 

 formed ( 10.5 mm) individual was taken at 100-350 

 m. The entire developmental sequence of D. an- 

 derseni was found in 0-300 m IKPT samples; 

 transforming individuals were 11.3-11.8 mm. 



Diaphus "slender C" (probably the "B" form of 

 D. mollis; Clarke 1973), D. brachycephalus, D. elu- 

 cens, and D. roZ/bo/jn;' all had similar distributions 

 centered around maximum abundances at 25-50 

 m (Figure 7b); for all but D. brachycephalus the 

 abundances in replicate tows within this interval 

 were significantly greater than in other depth 

 intervals (Table 3). Within the 25-50 m interval. 



D. elucens, D. rolfbolini, and D. "slender C" 

 ranked 4, 7, and 8, respectively, in total larval 

 abundance; D. elucens was the fourth-ranked 

 species taken overall during this cruise (Table 2). 

 For each species, median standard lengths in- 

 creased with depth (Table 3) and 25-50 m and 

 50-75 m cumulative size-frequency curves were 

 significantly different from each other. 



No transforming individuals of these species 

 were taken in tows considered here, although a 

 transforming D . "slender C" ( 10 .5 mm) was caught 

 in a 0-100 m sample, and one recently transformed 

 D. elucens (11.8 mm) was caught at 0-25 m. 

 Oblique IKPT hauls (ranging in depth from 0-180 

 m to 0-360 m) on other central gyre cruises have 

 caught late larval, transformational, and early 

 juvenile stages of all four species. Transforming 

 individuals of D. brachycephalus were 9.8-10.5 

 mm; D. elucens, 10.3-11.7 mm; D. "slender C," 

 11.2-12.7 mm; and D. rolfbolini, 11.7-12.5 mm. 



The two other Diaphus species taken were both 

 rare in stratified tows (Table 2). Most of D. "slen- 

 der B" (probably the "A" form of D. mollis; Clarke 

 1973) occurred at 50-75 m, the deepest distri- 

 bution of the genus (Figure 7b). Transforming 

 specimens (10.0-11.3 mm) have been caught in 

 0-300 m IKPT hauls. Diaphus "stubby C" may be 

 the larval form of D. schmidti; the larvae have 

 been taken in the central gyre only in small num- 

 bers and sizes. Most were caught at 25-50 m dur- 

 ing this cruise. 



LAMPADENA SPP. — Lampadena anomala and 

 L. luminosa were caught in low numbers within 

 the upper 50 m. Eleven L. luminosa larvae oc- 

 curred in four tows from both 0-25 m and 25-50 m; 

 one large larva (12.7 mm) was also taken at 75-100 

 m (Table 3). There was a trend for increased size 

 with depth. Lampadena anomala was taken (one 

 per sample) in five 0-25 m and three 25-50 m sam- 

 ples (Table 3). All Lampadena spp. individuals 

 were in early stages of photophore development. 

 No late-stage specimens of these relatively rare 

 central gyre species have been taken in any of the 

 samples examined. 



LAMPANYCTUS SPP. -Lampanyctus stein- 

 becki, most abundant of the larval Lampanyctus 

 species taken, ranked ninth for this cruise (Table 

 2). It was caught at 0-75 m, but 89% of the esti- 

 mated water column abundance was at 25-50 m; 

 abundances in replicate samples within this 

 interval were significantly higher (P<0.01) than 



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