FISHERY BULLETIN: VOL. 72, NO. 2 



water column for each series were similar, but the 

 calculated size compositions indicated that during 

 full moon 909?^ of the population were larvae or 

 recently transformed juveniles as opposed to only 

 50% in the new moon series. Since the tows were 

 taken during the season of highest recruitment to 

 the trawlable population (see below), the differ- 

 ence possibly was due to recruitment during the 

 intervening 2 wk. 



When only the individuals over 15 mm were 

 considered (Figure 2B), it appeared that most of 

 the larger fish occurred about 50-75 m deeper at 

 full moon. The calculated total number for the new 

 moon series was about twice that for the full moon 

 series, and the calculated size-frequency curves 

 were similar. In addition to moving deeper, V. 

 nimharia also appeared to avoid the net better 

 during full moon. 



Vinciguerria nimbaria was by far the most 

 abundant of the fishes considered here. Among all 

 the species which occurred in the upper layers at 

 night, V. nimbaria ranked eighth after seven 

 species of myctophids, but because of its small size, 

 contributed little to the total estimated biomass 

 (Clarke, 1973). Calculated total numbers in Sep- 

 tember and December were about twice those for 

 March and June (about 30-35/102m2 vs. 

 15-18/10^m2). The calculated biomass was about 

 7-8 g/lO^m^ at all seasons. 



Vinciguerria nimbaria appears to spawn prin- 

 cipally in the summer and fall and reach maturity 

 (27 mm) within 1 yr. The calculated size composi- 

 tions indicated that about 759i: of the population in 

 June were less than 15 mm, while in March, 759^ 

 of the fish were over 20 mm and about 40^ were 

 mature. The September and December series had 

 substantial percentages of small fish, but about 

 5(Wr were 15-25 mm. Among the mature females 

 examined, the proportion bearing ripened ova was 

 higher in June and September (15/16 and 7/9, re- 

 spectively) than in December and March (5/10 and 

 4/11). 



Vinciguerria poweriae (365; 9-35 mm) 



Only 35 V. poweriae were caught during the 

 day by IK tows. These were mostly 25- to 30-mm 

 fish caught around 500 m. A daytime CT tow at 

 300 m caught seven individuals (15-29 mm), sug- 

 gesting that this species occurs rather shallow in 

 the water column during the day and avoids the 

 net due to higher light intensities. At night, V. 



poweriae occurred at 100-200 m. Few larger than 

 20 mm were caught above 150 m and practically 

 none under 15 mm were taken below 150 m. 



Seasonal changes in size composition indicated 

 that V. poweriae spawns in the spring and sum- 

 mer. All caught in March were over 15 mm and 

 over 5(Wc were larger than the size at maturity (27 

 mm). Ten of 11 mature females from the March 

 series carried ripe ova. In June, few of any size 

 were caught, but these included both juveniles 

 (< 15 mm) and mature fish. Three of the four ma- 

 ture females caught in June were ripe. In July 

 and September, the bulk of the fish were 9-20 mm 

 and very few mature. The few caught in December 

 were all over 15 mm. Of the five mature females 

 taken in September and December, only one was 

 ripe. 



Ichthijococctis ovatiis (45; 12-55 mm) 



All but nine /. ovatus were taken during the 

 day between 400 and 500 m. The night catches 

 consisted of two small fish (15 mm) taken near the 

 day depth, two larger ones taken at 350 m, and five 

 others (26-35 mm) taken at 150 m and 260 m. 

 Since it seems unlikely that this species occurs as 

 shallow as 150-260 m during the day, at least some 

 fraction of the population apparently moves into 

 the upper layers at night. /. ovatus matures at 

 about 35 mm. 



Gonostotna atlanticum (680; 10-66 mm) 



Gonostoma atlanticum was taken principally at 

 490-560 m during the day and at 150-300 m at 

 night. In several cases, the size-frequency curves 

 from samples at different depths within the same 

 series differed significantly and indicated that the 

 smaller fish occurred at shallower depths. In De- 

 cember, at night all fish from 170 m were less than 

 30 mm, most from 190 to 200 m were 30-45 mm, 

 and most from 250 to 300 m were 40-60 mm. 

 Catches from day tows in both March and Sep- 

 tember indicated that few fish less than 50 mm 

 occurred deeper than 500-525 m. 



Gonostoma atlanticum apparently spawns over 

 most of the year. Between 90 and 100% of the 

 mature females (over 50 mm) in each series car- 

 ried well-developed ova, and there were no evi- 

 dent seasonal changes in size composition of the 

 catch. 



340 



