



4' 6' 



LATITUDE 



8" 



10* 



12" 



WN 



Figure l.-Temperature (in degrees Celsius) profile along long. 145°W. (Compiled by R. A. Barkley from data collected on cruise 43 of 



the RV Townsend Cromwell.) 



all stations at a given latitude does not, of course, 

 necessarily mean the species was not present. It 

 may have been present at low abundance and 

 missed by the collections or may have occurred at 

 depths greater than 75 m. With respect to the first 

 possibility, we have ignored zero values in a few 

 cases below, e.g., for very rare species and for the 

 data from lat. 3°30'S where total catches were so 

 much lower than elsewhere that it is likely some 

 fraction of the total species present were not 

 caught. With respect to the second possible source 

 of error, we exclude from further consideration six 

 species for which the upper limit of the depth 

 range is close to the depth of the deep CT tows. 

 Based on vertical distribution data from near 

 Hawaii (Clarke 1973), only slight changes in the 

 depth ranges of Diaphus brachycephalus, No- 

 tolychnus valdiviae, and Lampanyctus steinbecki 

 would determine presence or absence in the CT 

 collections. The IK data from lat. 3°30'N (Table 4) 

 indicates that the same may be true for D.jenseni, 

 D. longleyi, and D. splendidus. In the absence of 

 data to the contrary and in some cases with 

 reasonable evidence (see below), we assume that 

 the remaining 26 species have shallow nighttime 

 depth ranges wherever they occur in any abun- 

 dance and that zero catches were not the result of 

 changes in depth ranges with latitude. 

 In the presentation below, we attempt to relate 



patterns of distribution in the study area to other 

 data on the species. Unfortunately, we have felt it 

 necessary to disregard data from certain earlier 

 studies where species identifications are doubtful. 

 We have relied heavily on data from recent studies 

 by Clarke (1973) near Hawaii, by M. A. Barnett 

 (pers. commun.) near the center of the eastern 

 central Pacific gyre (ca. lat. 29°N, long. 155°W), 

 and by Ahlstrom (1971, 1972) in the eastern equa- 

 torial Pacific. For convenience, these will not be 

 cited formally each time; unless otherwise cited, 

 "near Hawaii," "gyre center," and "eastern equa- 

 torial," respectively, refer to the above three 

 studies. 



Eight species occurred across the entire 

 sampling area. These were: Hygophum proximum, 

 Diogenichthys atlanticus, Myctophum aurolater- 

 natum, M. spinosum, Symbolophorus evermanni, 

 Diaphus fragilis, Triphoturus nigrescens, and 

 Ceratoscopelus warmingi. Other records of these 

 species and of M. nitidulum and Bolinichthys 

 longipes, which were taken at all latitudes except 

 3°30'S, indicate that all 10 occur widely throughout 

 central water masses of the Indo-Pacific and, in 

 most cases, the world (Bekker 1965; Nafpaktitis 

 1968; Nafpaktitis and Nafpaktitis 1969; Gibbs et 

 al. 1971; Wisner footnote 3). All but M. aurolater- 

 natum are taken consistently near Hawaii and all 

 have been taken at the gyre center. 



635 



