THE LANTERNFISHES (PISCES: MYCTOPHIDAE) OF 

 THE EASTERN GULF OF MEXICO 



John V. Gartner, Jr./ Thomas L. Hopkins,' Ronald C. Baird,^ 

 AND Dean M. Milliken^ 



ABSTRACT 



Forty-nine species from 17 genera of Myctophidae were taken in mid water trawl samples from the eastern 

 Gulf of Mexico during March through October between 1970 and 1977. Seven abundant species 

 (Ceratoscopelus warmingii, Notolychnus valdiviae, Lepidophanes guentheri, Lampanyctus alatus, Diaphus 

 dumerilii, Myctophum affine, and Benthosema suborbitale) comprised 74.4% of the total number (13,369) 

 of myctophids captured. Of the remainder, 10 species were common, 26 were uncommon, and 6 were 

 rarely collected. Diel vertical profiles showed that all species except Taaningichthys vertically migrated. 

 Daytime vertical ranges for the entire assemblage were between 300 and 900 m, while at night myc- 

 tophids were most abundant between the surface and 150 m. A deep group remained below 600 m at 

 night and was composed of mostly juvenile nonmigratory individuals of 19 species and Taaningichthys 

 bathyphilus. Five daytime and five nighttime groups of associated species were defined based on ver- 

 tical ranges, minimum depths of occurrence and zones of abundance. Species of tropical and tropical- 

 subtropical zoogeographic affinities comprised the largest percentage of the total number of specimens 

 and were about equal in their percentage contributions. The presence of many tropical species in the 

 collections may have been due to the transport of the Florida Loop Current. Comparison of the species 

 list with those reported for other myctophid assemblages from tropical-subtropical latitudes shows 

 panoceanic distribution of 10 species. 



Myctophid fishes are one of the dominant compo- 

 nents of oceanic mesopelagic ecosystems (McGinnis 

 1974; Maynard et al. 1975; Badcock and Merrett 

 1976; Nafpaktitis et al. 1977; Hulley 1981; Hopkins 

 and Lancraft 1984; Hulley and Krefft 1985). With 

 the exception of Clarke's (1973) work in Hawaiian 

 waters, there have been no comprehensive studies 

 on faunal structure and ecology of this family in 

 subtropical-tropical oligotrophic regions where myc- 

 tophids are exceptionally diverse (Backus et al. 

 1977). 



The Gulf of Mexico is one such regime. Backus et 

 al. (1977) noted that although there are no endemic 

 myctophid species in the Gulf of Mexico, it is zoo- 

 geographically unique and faunistically separable 

 from other regions of the western North Atlantic. 

 Unlike the adjacent Caribbean Sea, which it hydro- 

 graphically resembles (Nowlin and McLellan 1967), 

 the Gulf of Mexico undergoes a marked change in 

 surface water temperatures over an annual cycle 

 (Jones 1973). In addition, circulation patterns are 



'Department of Marine Science, University of South Florida, 140 

 Seventh Avenue, S.E., St. Petersburg, FL 33701. 



^Director of Corporate Relations, Worcester Polytechnic In- 

 stitute, Worcester, MA 01609. 



^Florida Institute of Oceanography, 830 First Street S., St. 

 Petersburg, FL 33701. 



strongly influenced by the Florida Loop Current, 

 whose penetration into the Gulf of Mexico is both 

 geographically and seasonally variable. The central 

 Gulf of Mexico, despite seasonal variability, has 

 many characteristics typical of low latitude oligo- 

 trophic gyre systems. 



This paper details the taxonomic composition, zoo- 

 geographic affinities, and vertical structure of the 

 mesopelagic (sensu Marshall 1971) myctophid fauna 

 in the eastern Gulf of Mexico (hereafter as Gulf) dur- 

 ing the warm months of late March through early 

 October. The results are based primarily on collec- 

 tions with opening-closing midwater trawls made 

 from 1970 to 1977 in the eastern central Gulf in the 

 vicinity of lat. 27°N, long. 86°W. Additional data 

 from other stations in adjacent northeastern and 

 southeastern Gulf areas are included. 



MATERIALS AND METHODS 



The data are from 526 stations occupied during 

 12 cruises made between 1970 and 1977 (Fig. 1). The 

 majority of samples were taken within a 20 nmi 

 diameter circle centered around lat. 27°N, long. 

 86° W in the eastern central Gulf of Mexico, an area 

 referred to as the "Standard Station". Samples 

 were also taken from the northeastern and south- 



Manuscript accepted August 1986. 



FISHERY BULLETIN: VOL. 85, NO. 1, 1987. 



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