FISHERY BULLETIN: VOL. 85, NO. 1 



Table 4.— Abundance data for dominant myctophid species from 

 the eastern Gulf of Mexico. CI - Columbus Iselin cruises I, II, III; 

 other - all other cruises. 



orbitale was somewhat more prevalent in our day 

 than our night catches. 



Common Species 



Ten species were represented by 101 to 500 speci- 

 mens (Table 3). With the exception of two species 

 (Lampanyctus lineatus and Diaphus lucidus), sizes 

 ranged from postmetamorphic through sexually 

 mature adult stages. The maximum sizes for all 10 

 species, however, were smaller than reported in 

 Nafpaktitis et al. (1977). 



Diel distribution patterns showed that all species 

 in this group were migrators (Table 3). During the 

 day, the maximum abundance of all but one species 

 occurred between 400 and 700 m. Lampanyctus 

 lineatus was found between 600 and 1,000 m. 



At night, three vertical patterns were evident. 

 Centrobranchus nigroocellatus entered the surface 

 (0-5 m) waters, while L. lineatus remained at lower 

 epipelagic-upper mesopelagic depths (110-300 m). 

 The other eight species primarily concentrated be- 

 tween 50 and 150 m, though Hygophum benoiti and 

 H. taaningi were often captured as shallow as to 

 10 m, which suggests that these species may have 

 disjunct night distributions similar to Myctophum 

 affine. 



The entire populations of Diaphus lucidus, D. 

 problematicus, Bolinichthys photothorax, and 

 Centrobranchus nigroocellatus apparently migrated 

 nightly while some individuals of the other six 

 species remained at depth at night (Table 3). Data 

 were insufficient to discern size-depth trends in 

 these species. 



Uncommon and Rare Species 



Twenty-six uncommon species were represented 

 by 10 to 100 specimens in our collections. Compari- 

 son of the sizes captured vs. size at metamorphosis 

 and sexual maturity (where known) indicated that 

 six species (Lampadena luminosa, Lampanyctus 

 ater, L. cuprarius, L. nobilis, L. tenuiformis, Noto- 

 scopelus resplendens) were represented only by 

 juveniles. Nine species {Bolinichthys supralateralis, 

 Diaphus effulgens, D. perspicillatus, D. subtilis, D. 

 termophilus, Hygophum macrochir, Myctophum 

 asperum, M. obtusirostre, M. selenops) occurred only 



Table 5.— Mean size (mm SL) of dominant species with respect to depth. 



88 



