CLARKE: ECOLOGY OF STOMLATOID FISHES 



Eustomias bifilis (128; 41-170 mm) 



All but 5 of the 92 night catches of £:. bifilis (40 

 by IK, 51 by CT) were at 15-200 m. The day depth 

 range appeared to be 635-800 m; only 5 of the 29 

 day catches were at greater depths. There was no 

 obvious trend in size composition with depth. Size 

 at maturity was about 140 mm. 



Eustomias gibbsi (28; 55-131 mm) 



All but three E. gibbsi were taken at night. 

 The night depth range was about 50-200 m, and 

 the three day catches were at 680-800 m. There 

 was no obvious trend in size composition with 

 depth among the night catches. None of the speci- 

 mens were mature. 



Eustomias spp. 



Of the remaining specimens of Eustomias, 

 about 130 were too badly damaged to be identified 

 with certainty. The great majority of these had 

 pectoral ray and photophore counts within the 

 range of the three species considered above (most 

 were probably E. bifilis). Some 150 other speci- 

 mens include about 20 different forms, most of 

 which cannot be reliably identified due to present 

 uncertainties in the systematics of the genus. 

 These along with other specimens from the Cen- 

 tral Pacific will be considered in a later, more 

 systematically oriented report. 



Thysanactis dentex (340; 39-177 mm) 



Thysanactis dentex, the most frequently col- 

 lected melanostomiatid, occurred principally at 

 75-200 m at night. A few individuals were taken 

 as shallow as 40 m, and there were scattered night 

 catches throughout the water column. The princi- 

 pal day depth range was 600-800 m with a few 

 caught between 400 and 600 m or scattered deeper 

 than 800 m. Within both ranges, the larger fish 

 tended to occur deeper and the smaller shallower. 

 At night few over 100 mm occurred above 150 m, 

 and catches of those smaller than 80 mm below 

 125 m were low and probably due to contamina- 

 tion. During the day those over 100 mm were 

 caught mostly below 700 m and those less than 

 100 mm mostly between 600 and 700 m. Size at 

 maturity was about 160 mm. 



Bathophilus spp. 



Seven species of Bathophilus were taken. Al- 

 though data are incomplete for most, it seems that 

 all occur at about 500-700 m during the day and 

 migrate to the upper 250 m at night. Bathophilus 

 kingi (23; 24-95 mm) was taken most frequently. 

 At night, 18 specimens were taken between 50 and 

 225 m. Three specimens were taken at 590-725 m 

 during the day and one each at 1,000 and 1,100 m. 

 Bathophilus brevis (3; 12-43 mm) was taken only 

 at night between 200 and 225 m. Bathophilus di- 

 gitatus (9; 23-91 mm) was taken seven times at 

 night at 125-175 m and twice during the day at 

 520 and 550 m. Bathophilus longipinnis ( 10; 25-97 

 mm) was taken seven times at night scattered 

 throughout the water column (100-1,175 m) and 

 three times between 520 and 590 m during the 

 day. Bathophilus pawneei (7; 30-90 mm) was 

 taken at night between 40 and 195 m and once at 

 690 m during the day. Bathophilus cf. altipinnis 

 ? (3; 26-59 mm; pectoral rays 26-28, pelvic rays 

 15-18) was taken at 170 and 265 m at night and at 

 640 m during the day. A singleB. schizochirus (76 

 mm) was taken at 265 m at night. 



Other Melanostomiatidae 



Pachystomias microdon (33 mm) was taken once 

 in a day tow at 660 m. Two small (55-56 mm) 

 Flagellostomias boureei were taken at 500 m (day) 

 and 750 m (night). Five juvenile Echiostoma bar- 

 batum (29-89 mm) were taken, four at 30-185 m at 

 night and one in an oblique day tow to 800 m. Four 

 species of Photonectes which were collected could 

 be identified with reasonable certainty. Photo- 

 nectes achirus (9; 43-146 mm) was taken at 

 125-225 m at night and at 400, 550, 620, and 1,400 

 m during the day. A single Photonectes caerules- 

 cens (127 mm), which is likely to be proven indis- 

 tinct from Photonectes achirus, was taken in a day 

 tow at 800 m. Photonectes albipennis (8; 22-87 

 mm) was taken once at 620 m during the day and 

 between 60 and 165 m at night. Photonectes 

 fimbria (34 mm) was taken once at 620 m during 

 the day. The above specimens ofPhotonectes fit the 

 descriptions given in Morrow and Gibbs (1964) 

 reasonably well. In addition, two specimens (208 

 and 255 mm), taken at 650 m at night and 490 m 

 during the day, were close to, but not identical 

 with, Photonectes margarita. 



Leptostomias spp. (15; 68-134 mm) were taken 

 predominantly at night between 100 and 250 m; 



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