FISHERY BULLETIN: VOL. 71. NO. 2 



night.) Both of the September 1970 estimates 

 were close to that for full moon in September 

 1971. Thus there appears to be less avoidance of 

 the IK during the day than at night during new 

 moon. 



For March 1971, the calculated total from 

 the CT series was only about 3.7 x that of the 

 day IK series, and the calculated size-frequency 

 curves for the two series agreed closely. Thus 

 the IK appears to sample H. proximum by day 

 better than the CT at night. Since day tows and 

 full moon night tows with the IK appear to 

 sample this species about equally well, the IK 

 may give better estimates of abundance and 

 size composition than the CT at full moon. 

 Kuba (1970) found that the IK sampled H. 

 proximum better than the CT in night tows in 

 equatorial waters. Most of his tows where this 

 species was caught were taken near full moon. 



The calculated day totals indicated that H. 

 proximum was distinctly more abundant in 

 September and March than in December or 

 June. The calculated size-frequency curves for 

 March 1971 and September of both years were 

 similar and indicated that most fish were 

 mature or nearly so. None less than 15 mm were 

 caught in September or December, but a few 

 10-15 mm were caught in March 1971. Fish 

 12-14 mm long were present in fair numbers 

 during the June 1971 series and abundant in 

 July 1970. This suggests that H. proximum 

 spawns principally in spring or early summer. 

 The percentages of mature females with de- 

 veloped ova were highest in March and June but 

 did not differ significantly from the other values. 



Hygophinii vehihardti 



H. reinhardti was less abundant and occurred 

 slightly deeper than its congener, H. proximum, 

 but the data indicated that similar sampling 

 problems existed. So few H. rei)ihardti were 

 caught in the March 1971 IK series that it was 

 impossible to make quantitative comparisons 

 with the CT data, but it appeared the IK 

 missed substantial numbers at 75-100 m and 

 sampled about as well as the CT in deeper 

 water. Though catches were low during both 

 September 1971 series, the full moon series 

 caught overall higher numbers and indicated a 



shallower night depth than the new moon series. 

 In all four regular series, catches of day tows 

 were generally higher than those of night tows. 

 Size-frequency curves from the CT series 

 indicated no trends in size composition with 

 depth. The curves for IK tows in September 

 1970 at 150 and 195 m differed significantly 

 with few fish >20 mm at 195 m and few <20 

 mm at 150 m. Three-day tows in September 

 1970 showed no individuals over 20 mm at 520 

 m and most over 20 mm at 775 and 900 m. There 

 were no obvious seasonal changes in abundance. 

 Juveniles ( < 15 mm) and females with developed 

 ova were present at all seasons. 



Alyctophmu spp. 



Three species of Mijctophum — M. iiitidulum, 

 M. ohtusirostrum,'^ and M. spiiiosum — ap- 

 parently occur at or near the surface at night. 

 They were regularly dipnetted at the surface 

 at night, but few were caught in the trawls, 

 even in preliminary tows at 10-m depth. In- 

 dividuals considerably larger than the trawl- 

 caught specimens were frequently taken by dip 

 net. These species are relatively solid-bodied 

 and are probably strong swimmers. They 

 probably avoid the trawl easily in the process 

 of avoiding the ship itself. 



The few day catches of these species were 

 mostly from 500 to 800 m but may well have 

 been due to contamination. These species are 

 distinctly countershaded, and in life the upper 

 color is quite blue, suggesting that they occur 

 at shallow, well-lighted depths during the day 

 where they can avoid the trawl. Nevertheless, 

 the rarity of even small individuals in the trawl 

 catches indicates that none of the three were 

 abundant. 



Myctophnm selenoides 



At night, small (<30 mm) M. selenoides were 

 taken mostly between 50 and 100 m. The larger 

 fish were below 100 m and mostly around 150 m. 

 Only three were taken during the day, one by 



* Myctophnm obtiisirostrum is the correct name for 

 the species called M. hranchv^iuuhiim by Nafpaktitis 

 and Nafpaktitis (1969) and others (B. G. Nafpaktitis, 

 pers. comm.). 



410 



