GARTNER ET AL.: LANTERNFISHES 



nobilis) were captured as shallow as 50 m, and Hygo- 

 phum taaningi was occasionally taken in surface (0-5 

 m) waters. Individuals of nine species were taken 

 deep at night, between 450 and 950 m, indicating 

 incomplete migration of the populations (Table 3). 

 Six species were considered rare (<10 individuals). 

 Both Taaningichthys species were taken below 600 

 m during the day while the other four species came 

 primarily from night samples between 50 and 200 

 m (Table 3). 



NE and SE Sampling Areas 



A total of 1,943 specimens from 42 of the 49 east- 

 ern Gulf myctophid species were captured in the NE 

 sampling area, while 40 of the 49 species were re- 

 corded from SE samples (813 specimens; Table 3). 

 The seven most abundant species in both areas are 

 the same as for EC with the exception ofMyctophum 

 affine, which was infrequently captured because of 

 a lack of surface night samples. Diaphus mollis was 

 in the top seven species in the NE locale; Hygophum 

 taaningi in the SE. The top seven species comprised 

 81.0% of the total number of specimens collected 

 from NE samples and 75.2% from SE. 



DISCUSSION 



Vertical Distribution 



Despite spatial overlapping, the vertical profiles 

 of the eastern Gulf of Mexico myctophids show dis- 

 crete stacking of species groups, which presumably 

 enhances partitioning of spatial and trophic re- 

 sources. Based on minimum depths of occurrence 

 (MDO), vertical ranges and zones of abundance, 

 groups of clearly associated species can be defined 

 (Table 6). Five day and five night groups were con- 

 structed. Each day group consists of at least one 

 abundant species plus one or more common species. 

 However, because of differential migration ranges, 

 only the three shallowest night groups contain abun- 

 dant species. 



During the day, almost all species have an MDO 

 within their zone of highest abundance. All Diaphus 

 species are typically upper mesopelagic inhabitants, 

 while Lampanyctus and Taaningichthys species 

 primarily dwell in the lower mesopelagic zone. Hygo- 

 phum and Myctophum species are divided among 

 upper and middle zones. 



The daytime distribution of the abundant species 



Table 6.— Species groups based on minimum depth of occurrence (MDO) and zones of abundance by day (36 spp.) and night (43 spp.). 

 Underline indicates abundant species. Species in parentheses are outside of zone of maximum abundance; number after name indicates 

 zone. 



'Based on single capture; included because of additional unpublished data. 



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