FISHERY BULLETIN: VOL. 71, NO. 2 



NUMBER /TOW 

 20 40 60 80 



Figure 2. — Number of individuals of Benthusema stih- 

 orbitale (left) and Hygophiim proximum (right) caught 

 per tow at several depths in the upper layers at night 

 during new moon (solid circles and lines) and full moon 

 (open circles, dashed lines) during September 1971. 



Size composition and abundance showed a 

 definite seasonal pattern. In June 1971, about 

 70% were 10-15 mm; there were a few adults 

 and practically no intermediate sizes. The 

 calculated size-frequency curves (Figure 3) 

 shifted to the right from June to March indicat- 

 ing changes in size-composition due to growth. 

 Though calculated day totals were higher than 

 night totals for all but the June 1971 series, the 

 rank order was the same for both, abundances 

 being highest in December, lowest in June, and 

 intermediate and nearly equal in September 

 and March. 



It appears that B. suborbitale spawns prin- 

 cipally in the spring and summer. A few young 

 (10-15 mm) are present by March and many by 

 June. A substantial portion are 20-25 mm long 



100 



z 



UJ 



o 

 a: 

 111 

 o. 



> 50 



Z2 



o 



20 30 



STANDARD LENGTH (mm) 



Figure 3. — Cumulative size-frequency curves for Bcn- 

 thoscma suborhiiale at four seasons. Size composition 

 was calculated (see text) from samples taken throughout 

 the water column in June 1971 (A), September 1970 (B), 

 December 1970 (C), and March 1971 (D). 



by September, but apparently not all have 

 reached the minimum size caught by the trawl 

 until later. Most fish are mature by December 

 when maximum abundance occurs. There is 

 apparently little growth in size between Decem- 

 ber and March and a decrease in total numbers. 

 By June, most of the adults are gone and the 

 next generation has begun to reach trawlable 

 size. The percentages of mature females with 

 ripe ova (Table 2) correlate with these trends; 

 they were significantly higher in December and 

 March, before the periods when juveniles 

 appeared. 



Bent hose niii fibulatiiui 



B. fihnlatum is apparently epibenthic or 

 restricted to nearshore areas. In Hawaii, large 

 individuals (45-95 mm) are regularly taken in 

 bottom trawls at depths of 100-190 m at night 

 (P. J. Struhsaker, pers. comm.), and large 

 catches have been made by NMFS in CT tows 

 at 25-100 m over areas where the bottom depth 

 is about 600 m. Only eight of the individuals 

 taken during this study were of the size taken 

 by inshore trawls, 40-72 mm. The rest were 

 15-27 mm and mostly taken in the upper 100 m 

 at night. 



Diogetiichthys dthitit'niis 



D. atlaiiticua, although quite abundant in the 

 Equatorial Pacific (Hartmann, 1971), was 

 captured rarely in Hawaiian waters. About 80% 

 of the individuals collected were adults, but the 

 presence of 11- to 15-mm fish several times of 

 the year suggests some spawning may occur in 

 this area. 



Hygophuni proxhuiim 



In June 1971, nine small H. proximum (12-14 

 mm) were caught at about 650 m at night. As 

 low as this catch was, it was higher than any 

 shallow night catch and unlikely due to con- 

 tamination. Similar numbers of this size were 

 caught near this depth during the day and 

 none in the shallow night tows, suggesting that 

 the smallest H. proximum caught by the trawl 

 do not regularly migrate. Individuals of this 



408 



