GARTNER ET AL.: LANTERNFISHES 



monitored on all cruises by mechanical time-depth 

 recorders (TDR), meters of wire out and wire angle. 

 Additionally, on three RV Columbus Iselin cruises 

 (Table 1) depth was monitored by electronic deck 

 readout via a depth transducer and conducting 

 cable. Volume of water filtered per tow was calcu- 

 lated from flowmeters mounted in the mouth of the 

 plankton net and on the main trawl frame. Incli- 

 nometer measurements and underwater observa- 

 tions of the wire angle of nets towed just beneath 

 the surface indicated the mouth of the net fished at 

 an angle of about 30° from the vertical, which was 

 used as a standard angle when filtration volumes 

 were calculated. Trawl speed was 1.5 to 3 kn. 



Nets were fished obliquely over a depth range, or, 

 as on Columbus Iselin cruises, at specific depth 

 horizons. Vertical depth control during horizontal 

 tows was -I-/- 10 m from 0-300 m (except for the 

 surface and 5 m depth strata), -i- / - 25 m from 300- 

 700 m, -H/-50 m from 700-1,000 m. 



The trawl catch was initially fixed in 10% v:v sea- 

 water Formalin" and subsequently transferred to 

 50% isopropanol. Myctophids were measured to the 

 nearest millimeter standard length (mm SL) and 

 identified to species using Nafpaktitis et al. (1977). 



Diel vertical distributions for all species were 

 calculated using data pooled from all cruises. Sam- 

 ples which were taken within 1 hour before or after 

 sunrise and sunset were excluded from analysis, 

 because vertical migration is pronounced at these 

 times. Excluding the sunrise-sunset samples, a total 

 of 155 samples (82 days, 73 nights) collected dur- 

 ing the Columbus Iselin cruises from to 1,000 m 

 were used to construct vertical profiles for the abun- 

 dant species (Table 2). Abundance was expressed 

 as individuals per 10** m^. 



••Reference to trade names does not imply endorsement by the 

 National Marine Fisheries Service, NOAA. 



'Lunar phases: X - waxing. W - waning. 



83 



