FISHERY BULLETIN: VOL. 71. NO. 2 



1970, with 50% under 30 mm. In December 

 1970, most fish were still immature, but the 

 peak size group was 30-40 mm. In March and 

 June 1971, about 65 and 90% of the fish, 

 respectively, were mature. The percentages of 

 ripe females among mature females were highest 

 in March and June 1971 and were significantly 

 lower than all others in December 1970. Thus 

 L. steinhecki appears to spawn principally in 

 the spring and summer and to reach trawlable 

 size by September. Most fish appear to live 

 about 1 year. 



hitmpanyctus tenniforiiiis 



L. tenuiformis differs from L. steinhecki 

 principally in size at maturity and relative 

 positions of a few photophores. Counts of fin 

 rays, etc., for the two species were either 

 identical or overlapping. Individuals over about 

 40 mm could be distinguished by the relative 

 development of the gonads, but it is possible 

 that some smaller, damaged L. tenuiformis were 

 erroneously identified as L. steinhecki. Owing 

 to the former's rarity, as evidenced by the few 

 larger individuals, any error is almost certainly 

 negligible. 



Only four L. tenuiformis were taken at 

 night, and the larger two of these (120 and 138 

 mm) were taken in tows near the day depths. 

 Thus the night depth range given in Table 2 

 is quite uncertain. L. tenuiformis appears 

 to spawn near Hawaii; four females (123-138 

 mm) with ripened ova and two small juveniles 

 (28 and 32 mm) were collected. 



Triphotirrns riigrescens 



T. nigrescens <15 mm were caught only in 

 a night tow at 650 m in June 1971, suggesting 

 that small juveniles do not migrate. In December 

 1970, high catches of larger fish were made 

 during the night both in the upper layers and 

 at the day depths. Calculated totals indicated 

 roughly 60% of the population did not migrate. 

 Calculated size-frequency curves for shallow 

 night, deep night, and day samples all were 

 quite similar and also agreed closely with the 

 curve from fish taken in three short night 



oblique tows from to 300 m. Differences in 

 sex ratio and percentage of mature females with 

 developed ova between the deep and shallow 

 samples were small and nonsignificant. 



Large numbers of more than one size class 

 were caught only in July and September 1970. 

 There were significant differences between size- 

 frequency curves indicating that fish <20 mm 

 occurred mostly above 50 m at night and above 

 650 m during the day. Adults occurred mostly 

 below 50 m at night and below 650-700 m 

 during the day. 



Owing to low numbers in June 1971 and poor 

 timing of shallow night tows in September 

 1970, day and night comparisons could be 

 made only for December 1970 and March 1971. 

 The day calculated totals were larger in both 

 series, 1.3 x for December 1970 and 3.8 x for 

 March 1971. The larger discrepancy in March 

 1971 may have been due to missing nonmigrat- 

 ing fish at night. The calculated size-frequency 

 curves for day and night agreed closely. 



The CT tows in March 1971 caught only 

 2.5-4 X the IK tows; the calculated total for 

 the CT was 2.6 x that for the IK night series. 

 The calculated size-frequency curve for the CT 

 was nearly identical to both the day and night 

 IK curves, and most fish were over 30 mm. 

 Apparently T. nigrescens is better able to avoid 

 the CT, but it is possible that some fish of even 

 the larger sizes could have escaped through the 

 coarser CT meshes. 



T. nigrescens appears to have a 1-year 

 generation cycle with spawning principally in 

 spring and summer. Abundance was distinctly 

 highest in December and extremely low in 

 June and September 1971 with substantial and 

 roughly equal numbers present in September 

 1970 and March 1971. T. nigrescens was 

 also abundant in July 1970 with most of the 

 population either adults or <20 mm. In Sep- 

 tember 1970, 65% of the population was 20-28 

 mm with few adults, and in December, 85% 

 were over 25 mm. In March 1971, 85% were 

 over 30 mm and none <24 mm. In June 1971, 

 the catches were made up almost entirely of 

 adults or fish < 15 mm. The conditions of the 

 ovaries were correlated with the changes in 

 size frequency. The percentages of mature 

 females with developed ova (Table 2) were low 



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