CLARKE and WAGNER: VERTICAL DISTRIBUTION OF MESOPELAGIC FISHES 



RESULTS 



Table 1 gives length and capture data for 11 

 rare and sporadically taken species from our 

 collections near Hawaii. We also have included in 

 Table 1 capture data for two rather infrequently 

 collected species of argentinoid fishes which were 

 taken by a series of IK trawls in the central 

 equatorial Pacific (cruise 47 of the NMFS RV 

 Townsend Cromwell). Other species are considered 

 under individual headings below. 



Opisthoproctidae 



Opisthoproctus soleatus Vaillant (150; 28-84 mm) 



Almost all 0. soleatus were taken at 450-600 m 

 during the day; highest catch rates were at 500-550 

 m. Large (>50mm) fish were caught throughout the 

 day depth range, but smaller fish were taken 

 mostly above 550 m. Only six specimens were 

 taken at night-also in the same depth range. The 

 daymight ratio of total trawling time in this depth 

 range was about 4:1; thus the difference in catch is 

 only partially explained by differences in effort. 

 Since the night catches did not indicate that 0. 

 soleatus is spread more thinly over a broader depth 

 range, the difference in catch per effort indicates 

 that this species avoids the net better at night. 



Female 0. soleatus mature at about 60 mm. Data 

 for each season were few, but there was no in- 

 dication of seasonality in gonad ripeness, size 

 composition, or abundance. 



Opisthoproctus sp. (3; 11-17 mm) 



A 17-mm specimen, tentatively identified as 0. 

 grimaldii Zugmayer, was taken in a day tow at 

 500 m in September. Two smaller specimens (11 

 and 15 mm) taken in June are apparently 0. 

 soleatus. One was taken at night in an oblique tow 

 from to 350 m; the other was caught, possibly in 

 transit, by a day tow which fished at 725 m. 



Alepocephalidae 



Photostylus pycnopterus Beebe (12; 62-1 13 mm) 



Photostylus pycnopterus was taken within the 

 same depth range day and night. Five day catches 

 were at 750-975 m, and the two night catches at 750 

 and 875 m. Five other day catches were from 

 oblique tows which fished to 800-1,000 m. 



Photostylus pyncopterus appears to mature at 

 about 100 mm and to spawn relatively few but 

 large eggs. Goodyear (1969) recorded a 93-mm 

 female with eggs 1.4 mm in diameter and two 

 specimens (84 and 96 mm) with much smaller eggs. 

 Our three largest females (101-113 mm) carried 

 eggs about 1.75 mm in diameter. One undamaged 

 specimen had only 80 eggs in the ovaries. Another 

 apparently had spawned some already; there were 

 26 eggs— mostly in the anterior sections of the 

 ovaries. The gonads of two large males (106 and 

 110 mm) filled most of the body cavity. The 

 remaining specimens (62-89 mm) were clearly 

 immature. 



The eggs of P. pycnopterus, both absolutely and 

 relative to body size, were larger than those of any 

 other species examined from our collections. Mead 

 et al. (1964) have pointed out that other species of 

 Alepocephalidae also have large eggs. 



Giganturidae 



Bathyleptus lisae Walters (89; 49-195 mm) 



Although a few B. lisae were caught as shallow 

 as 500 m, the majority were taken at 750-1,000 m 

 both day and night. Of the 70 specimens taken in 

 horizontal tows, only 7 were taken above this 

 range and 3 deeper. There was no apparent trend 

 in size with depth. 



Female B. lisae appear to reach much greater 

 size than males. Of 26 fish sexed, there were 14 

 females of all sizes (67-195 mm) and 12 males-all 

 between 63-81 mm. All nine specimens over 81 mm 

 were females. Of these, only one (171 mm) ap- 

 peared mature. 



Eurypharyngidae 



Eurypharynx pelecanoides Vaillant 

 (34; 89-575 mm TL) 



Except for two day captures of small individuals 

 (126 and 155 mm at 425 and 550 m, respectively) E. 

 pelecanoides was taken between 650 and 1,300 m. 

 Twenty-five specimens were taken during the day 

 within this range. Of the 14 less than 300 mm, only 

 2 were taken below 1,000 m, and all over 300 mm 

 were taken below 1,000 m. Thus, the small fish 

 appear to occur shallower than the large ones. 

 There were only seven night catches in horizontal 

 tows, but these agreed with the size-depth pattern 

 apparent in the day data. 



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