FISHERY BULLETIN: VOL. 71, NO. 2 



spp., Hawaii is near the edge of their ranges. 

 Little can be said about Form C; it appears to 

 have a depth distribution and migration pattern 

 similar to those of the other two. 



LiUJipanyctus nobilis 



L. nohilis apparently does not begin migrating 

 until about 25-30 mm long. A few small fish 

 were taken in shallow tows at night, but most 

 were taken at 625 and 750 m at night during 

 September and December 1970. The absence of 

 small individuals in deep night tows during 

 March and June 1971 was probably due to 

 widely spaced sampling since substantial num- 

 bers of small ones were caught in day tows then. 

 There was no evidence that other sizes did not 

 migrate regularly. 



There were few instances where enough L. 

 iiobilw were taken to make comparisons of size 

 composition and depth, but several pairs of 

 size-frequency curves showed significant dif- 

 ferences. Individuals <30 mm were mostly 

 above 75-80 m at night, and most fish below 

 100 m were >40 mm. All night catches of 

 exceptionally large individuals (16 of >95 mm) 

 were below 100 m. During the day, catches 

 above 750-800 m were almost all < 25-30 mm, 

 and the only substantial catches offish >40 mm 

 were at 1,150 and 1,200 m in September 1970. 

 The only mature individual caught during the 

 day, 100 mm long, came from a tow at 1,250 m. 

 It is possible that the lower end of the day 

 depth range was not adequately sampled. 



L. uobilis avoids the IK in substantial num- 

 bers. In March 1971, the CT tows indicated a 

 depth range similar to that of the IK series 

 (Figure 8), except that a large catch was made 

 at 175 m, below a catch of almost none at 150 m. 

 The size-frequency curve from the 175 m CT 

 tow looked like a composite of the shallower 

 tows. This catch was likely due to excessive 

 contamination and was disregarded. The cal- 

 culated total for CT was 18 x that for the IK 

 principally due to catches at 100 and 125 m 

 which were 21.4 x and 24.8 x the IK catches 

 at these depths. The size-frequency curves for 

 individual pairs differed significantly and like 

 the calculated total curve indicated that the 

 IK missed individuals over 40-45 mm. Thus 



NUMBER /~105m3 



Q. 

 ill 

 Q 



200 



Figure 8. — Estimates of abundance of Lampanyctus 

 nobilis at different depths at night during March 1971 

 from samples with the Cobb trawl (CT) (solid circles 

 and lines) and Isaacs-Kidd trawl (IK) (open circles, 

 dashed lines). CT catches were adjusted to the same 



volume filtered by 2-hr tows with the IK, ca. 10-^ 



m-' 



L. nohilis was probably about twice as abundant 

 as the IK tows indicated. 



At new moon in September 1971, L. nohilis 

 occurred between 60 and 125 m with peak 

 abundances at 75 and 100 m. At full moon, the 

 only individual caught was from 190 m. Tows 

 below 200 m taken during full moon in' other 

 series made no substantial catches. Thus the 

 difference between the new and full moon series 

 was probably due to greatly increased avoid- 

 ance at full moon. 



There were no gross seasonal differences in 

 abundance or size composition apparent from 

 the IK data except that L. nohilis may have 

 been slightly less abundant in June 1971. Small 

 (<25 mm) fish were present in comparable 

 numbers in September 1970, December 1970, 

 and June 1971 (the proper depth zone was not 

 adequately sampled in March 1971 day or 

 night). 



With the exception of a 78-mm individual, 

 all ripe females were over 97 mm and were 

 rarely caught — once in September, once in 

 March, and twice in June. The presence of 

 juveniles indicated that spawning regularly 

 occurs in the area, and the presence of immature 

 sizes in fair abundance suggests that adults 

 should be more abundant than catches of 

 either IK or CT indicated. It seems likely that 

 these larger fish avoided both trawls in sub- 

 stantial numbers. 



418 



