CLARKE: ECOLOGY OF STOMIATOID FISHES 



depth-size plot indicated a trend for greater size 

 with increasing depth, but since 106 of the 133 

 specimens were 75-125 mm any trends for smaller 

 or larger fish are of dubious significance. The only 

 mature females collected were the four largest 

 specimens (172-186 mm). There was no seasonal 

 trend in size composition of the the catches. 



DISCUSSION 



In spite of the fact that the stomiatoids in the 

 study area were quite diverse and that there have 

 been no really comprehensive studies based on 

 extensive sampling programs in the Pacific, only a 

 few species are either undescribed or of uncertain 

 status (with the exception of the Eustomias spp.). 

 To paraphrase Gibbs (1960), it is indeed a reHef 

 that most specimens fit descriptions based pri- 

 marily on Atlantic material. 



Eight species were previously unrecorded in the 

 Facific: Astronesthes ge?7imifer, Neonesthes micro- 

 cephalus, Aristostomias grimaldii, A. lunifer, 

 A., polydactylus, Eustomias bibulbosus, Photo- 

 nectes achirus, and Bathophilus altipinnis. Three 

 of the more commonly collected species were pre- 

 viously known only from a few specimens. 

 Gonostoma ebelingi (Grey, 1960) and Eustomias 

 bifilis (Gibbs, 1960) were described on the basis of 

 two and one specimens, respectively, and no other 

 specimens have been reported since. Thysanactis 

 dentex, which was taken regularly by the present 

 study and by King and Iversen ( 1962), is listed by 

 Morrow and Gibbs ( 1964) as known from only five 

 captures in the North Atlantic. Further studies of 

 material from other tropical areas will be nec- 

 essary to determine if these species are for some 

 reason present in high numbers only in the 

 Central Pacific. 



Inadequate information from other areas of the 

 Pacific does not permit detailed consideration of 

 zoogeographic patterns of these species. Negative 

 records of several studies and reports cannot 

 necessarily be considered conclusive. It is likely 

 that the majority of the species recorded here 

 occur throughout the warm water masses. How- 

 ever, preliminary examination of samples from 

 the central equatorial Pacific indicates that at 

 least Vinciguerria nimbaria and Gonostoma 

 ebelingi do not occur continuously across the equa- 

 torial region and also confirm Gibbs' (1969) state- 

 ment that Stomias danae is replaced by S. affinis 

 ' in equatorial waters. Two species, Vinciguerria 

 lucetia and Idiacanthus antrostomus, which ap- 



pear to occur in eastern and equatorial waters, 

 were not taken during this study. Vinciguerria 

 lucetia has been recorded near Hawaii (King and 

 Iversen, 1962; Ahlstrom and Counts, 1958) and 

 Idiacanthus antrostomus may also be expected to 

 occur here occasionally, but their absence from the 

 material collected during the study indicates that 

 some warmwater species do not normally occur in 

 the central water mass. 



It is clear from the absence or extreme rarity of 

 mature fish, that neither of the trawls used were 

 adequately sampling the larger sizes of many 

 species — particularly the Astronesthes spp. Al- 

 though differences in day-night catches have not 

 been rigorously demonstrated, it also appears that 

 many large species and individuals avoid the IK 

 better during the day than at night. 



For most species, the numbers caught by the 

 paired series of IK and CT tows in March 1971, 

 were not sufficient for detailed analyses, but 

 rough comparison of the catches and size ranges 

 (Table 1) indicates some differential avoidance. 

 The total volume sampled by the CT tows was 

 about 10 times that of the IK tows in the same 

 depth range. In 10 species, the ratio of CT/IK 

 catches was considerably lower than 10 (1.3-6.0) 

 suggesting that the IK's greater towing speed was 

 more of an advantage than the greater size of the 

 CT. In these cases, the CT/IK ratio was httle af- 

 fected by considering only the fish larger than the 

 smallest caught by the CT; i.e., the passage of 

 smaller fish through the coarser CT meshes did 

 not seem to be an important factor. 



Three species, Diplophos taenia, Gonostoma 



Table 1.— Total numbers and size ranges of 15 species offish 

 taken in nine tows with the IK and eight tows with the CT in the 

 upper 200 m at night during February-March 1971. The tows 

 with each net were roughly equally distributed between 25 and 

 200 m. The total volume sampled by the CT tows was about 10 x 

 that of the IK tows. 



347 



