CLARKE: ECOLOGY OF LANTERNFISHES 



species caught in abundance in the replicates 

 at 50 and 100 m during July 1970, there were 

 no significant differences between size-frequency 

 curves in seven and only one sample in each of 

 the other three sets differed significantly from 

 one or more of the other replicates. 



Not all individuals were sexed and no detailed 

 gonad studies were done. Size at maturity was 

 taken as the minimum size at which females 

 were found with obviously ripened ova. A vari- 

 able number of each species were examined. 

 For abundant species, sex was determined for 

 about 50 juveniles, and sex ratio of mature fish 

 and ripeness of mature females were determined 

 for samples from several depths and seasons. 

 If significant or nearly significant differences 

 between samples were noted, a larger series 

 was examined to determine trends. It was 

 assumed that the percentage of females among 

 mature fish and the percentage of ripe out of 

 total mature females were distributed as a 

 binomial and that the differences in percentages 

 were considered significant if the 95% confidence 

 limits did not cross zero. 



For species collected in low numbers, the 

 data from each series were simply pooled to 

 estimate overall size composition and relative 

 abundances. For abundant species, total num- 

 bers and overall size composition for the entire 

 water column were computed by a rectangular 

 integration of the depth-abundance curves. 

 Numbers collected were adjusted to a 2-hr 

 towing time. It was assumed that abundance 

 and size composition from the depth sampled 

 were the same for the layer between the mid- 

 points between that depth and the next shallower 

 and next deeper depth sampled; i.e., abundance 

 estimated from a sample at depth 2/ was 

 assumed constant throughout (2/ _ ^ + 2j-)/2 to 

 (2j + 2/ + i) 12 where 2/ _ i was the next shal- 

 lower depth sampled and 2/ + ^ the next deeper. 

 The number of individuals of each size in each 

 sample was weighted accordingly. 



Differences in the numbers and size com- 

 position of these calculated totals could not be 

 compared statistically since no estimate of the 

 variances of the data were available, but where 

 depth coverage was adequate, calculated totals 

 and size-frequency curves were used to roughly 

 compare whole series for day and night, sea- 



sonal, full and new moon, and IK and CT 

 differences. The calculated size-frequency curves 

 for December 1970 and June 1971 could be 

 compared with those of the oblique tows when 

 sufficient specimens of a given species were 

 taken in the latter. Unless there were obvious 

 deficiencies in depth coverage, etc., the cal- 

 culated curves agreed closely with those from 

 the oblique tows. 



RESULTS 



A total of 47 species of myctophids were 

 collected. The number collected, size range, size 

 at maturity for females, and day and night 

 depth ranges are given in Table 1. Unless noted 

 under individual species headings (below), the 

 individuals caught did not deviate from species 

 descriptions in Wisner (1971, manuscr.^), 

 Nafpaktitis (1968), or Nafpaktitis and Nafpak- 

 titis (1969).^ The percentage of ripe females 

 among total mature females examined for each 

 of the four quarterly cruises is given for several 

 abundant species in Table 2. 



The depth ranges given in Table 1 are the 

 best estimates based on all available data. 

 Because the trawl was open during descent 

 and ascent, some individuals were caught in 

 tows made below the levels where they occurred. 

 For abundant species, catches below the depth 

 ranges given were low and consistently close 

 to those of short oblique tows (see Appendix 

 Table 2). A few cases where substantial numbers 

 were caught near the day depth at night are 

 discussed below under the species headings. For 

 rarer species, where the chances of being caught 

 in a tow at their actual depth were not much 

 greater than the chances of being caught in 

 transit by deeper tows, catches due to contami- 

 nation could not be readily distinguished and 

 the lower depth limits in Table 1 may be 

 erroneous. In most cases, the values given are 

 conservative. 



■' Wisner, R. L. Unpubl. manuscr. Annotated and 

 illustrated key to the identification of fishes of the 

 family Myctophidae of the eastern Pacific Ocean, east- 

 ward of 160° West Longitude. 



^ Specimens of most species will be deposited at the 

 U.S. National Museum, Los Angeles County Museum, 

 Scripps Institution of Oceanography, and the Bernice 

 P. Bishop Museum in Honolulu. 



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