FISHERY BULLETIN: VOL. 71. NO. 2 



Tcia)ii)igichthys mini tuns 



Other reports, e.g., Davy (1972), have stated 

 that T. minimus does not migrate, but all night 

 catches in this study were well above the day 

 depth range. Individuals 20-30 mm long were 

 caught between 150 and 250 m at night and 

 larger fish between 200 and 400 m. None were 

 taken in night tows below 475 m. Of 32 fish 

 caught in March 1971, 27 were 20-24 mm and 

 only 1 was over 50 mm. In other seasons, all 

 were over 30 mm, and most over 50 mm, 

 suggesting that T. mi)iimus spawns principally 

 in late winter or early spring. Too few mature 

 females were taken to correlate gonad ripeness 

 with the changes in size composition. 



La))ipa)iyctns niger 



Most L. niger less than 25 mm long were 

 taken at depth both day and night, indicating 

 that the majority of the smaller fish do not 

 regularly migrate. In December 1970, no 

 individuals under 50 mm were caught in the 

 upper layers, and large catches with about 50% 

 larger than 50 mm were taken near the day 

 depth at night (Figures 6 and 7). The mature 

 individuals taken in deep night samples did not 

 differ from those of shallower samples in sex 

 ratio or percentage of ripe females. Smaller 

 peaks at depth during the night were present 

 during other series, but catches of fish over 

 25 mm could not be discriminated from 

 contamination. 



In the upper layers at night, the size- 

 frequency curves from catches above 150-165 m 

 were usually significantly different from those 

 in deeper tows (Figure 7). Few individuals 

 over 50 mm were caught above 165 m, and 

 below 200 m, 50-100% of the catches were over 

 50 mm. Similar stratification by size was evident 

 in some day series and suggested, nonsignifi- 

 cantly, that individuals less than 50 mm rarely 

 occurred deeper than 750 m. 



The calculated totals for day and night agreed 

 well for all but the June 1971 series (day 

 was 1.6 X night). The calculated size-frequency 

 curves differed greatly for the September 1970 

 and June 1971 series. The difference for Sep- 

 tember 1970 may well have been due to missing 



NUMBER/~l05m3 



Figure 6. — Depth-abundance profiles for Lanipanyctus 

 ni^er from samples taken by Isaacs-Kidd trawl during 

 June 1971 (left) and December 1970 (right). Night 

 samples are designated by solid circles connected by 

 solid lines; day samples by open circles and dashed 

 lines. Numbers collected were adjusted to a 2-hr towing 

 time with volume filtered of ca. 10'' m^. 



juveniles at depth at night. The discrepancies 

 for June 1971 were principally due to an 

 exceptionally large catch of 30- to 36-mm fish 

 at 140 m at night. 



L. iiiger, especially the larger individuals, 

 apparently avoided the CT more than the IK. 

 The ratio of CT to IK catches was low (1.2-5.8) 

 for all depth pairs except at 100 m where the 

 CT caught 18 to only 1 in the IK. The calculated 

 total for the CT was only 2.3 x that for the 

 IK tows above 200 m. The individual size- 

 frequency curves were significantly different 

 in three of four pairs but not consistent in 

 direction. The calculated size-frequency curves 

 indicated that the CT caught lower percentages 

 of 50- to 70-mm individuals. 



During the new moon series, L. )nger was 

 caught at 145 and 165 m — the deepest samples, 

 but at full moon none were caught. It is not 

 known whether all of the population occurred 

 below 190 m, the deepest depth sampled at full 

 moon, or whether there was increased avoidance. 



416 



