Bregmacerotidae: Development and Relationships 

 E. D. HouDE 



THE codlets are small, gadiform fishes of pelagic habit found 

 in neritic and oceanic water of tropical and subtropical 

 seas. The family Bregmacerotidae (Gill, 1872) includes the single 

 genus Bregmaceros (Thompson, 1840), in which there are sev- 

 eral species. In recent reviews six (Belyanina, 1974) or seven 

 (D'Ancona and Cavinato, 1965) valid species have been rec- 

 ognized. The systematics remain confused, although Belyanina 

 (1974) has partly clarified species relationships. Larvae often 

 are among the ten most common families occurring in both 

 oceanic and coastal ichthyoplankton surveys in subtropical and 

 tropical waters (e.g., Ahlstrom, 1971; Moser et al., 1973; Houde 

 etal., 1979; Loeb, 1979; Richards, 1981). The species are mor- 

 phologically similar but most have distinctive meristics, from 

 which specific identifications usually are possible. Differences 

 in vertebral number and median fin ray counts serve to distin- 

 guish larval to adult stages while pigmentation differences and 

 the size at appearance of the single, first dorsal fin ray serve to 

 identify small larvae. Larval characters, particularly those of the 

 smallest individuals (1.5-3.0 mm SL), often are the best char- 

 acters for identification purposes. A careful examination of on- 

 togenetic evidence indicates that some species are still unde- 

 scribed and that misidentified Bregmaceros frequently have been 

 reported in the literature. Based on evidence from larval char- 

 acteristics there may be ten or more valid species in the world 

 oceans. 



Species distributions. — Larvae of Bregmaceros commonly occur 

 between latitudes 40°S and 40°N (Table 83). D'Ancona and 

 Cavinato (1965) and, more recently, Belyanina (1974), have 

 reviewed distribution data on the known species. Centers of 

 abundance have been observed in the western Indo-Pacific and 

 Indian Oceans (Munro, 1950; D'Ancona and Cavinato, 1965; 

 Kotthaus, 1969; Belyanina, 1974), in the eastern Pacific (Ahl- 

 strom. 1971; Belyanina, 1974) and in the Caribbean Sea and 

 Gulf of Mexico (Belyanina and Lopes, 1974; Milliken, 1975; 

 Belyanina, 1980; Houde, 1981). Bregmaceros macclellandi is 

 circumtropical with areas of apparent high abundances in the 

 Caribbean Sea, western Indian Ocean and Indo-Malayan region. 

 It also occurs in the eastern Pacific. Bregmaceros atlanticus. 

 including the closely related Pacific Ocean form B. japonicus 

 (D'Ancona and Cavinato, 1965) also is circumtropical with an 

 apparent center of abundance in the western Atlantic. ' The latter 

 sometimes occurs in neritic waters. Several neritic species are 

 known, including B. nectahanus, B. arahicus, B. rarisquamosus, 

 B. bathymaster, B. caw/or; (Milliken and Houde, 1984) and the 

 Type A larva described by Houde (1981). 



Neritic species vary in the breadth of their distributions. It 

 now seems certain that the Indo-Pacific B. nectabanus does not 

 occur in the western Atlantic and its occurrence in the eastern 

 Atlantic Ocean is uncertain. The species B. cantori. described 

 by Milliken and Houde (1984), is the most common bregma- 

 cerotid in the western Atlantic. It occurs in the Caribbean Sea 

 and Gulf of Mexico (Milliken, 1975; Houde, 1981), in the south- 

 west Atlantic Ocean off Brazil- and along the East Coast of the 

 United States.' The common bregmacerotid in the Gulf of Ca- 

 riaco, initially referred to as B. atlanticus (Mead, 1963) and 

 subsequently as B. nectabanus (Baird et al., 1973, 1974; Bely- 

 anina and Lopes, 1974) and that referred to as B. nectabanus 

 from the Caribbean Sea and Gulf of Mexico (Belyanina, 1980) 

 is B. canton (M\\\\ken, 1975; Houde, 1981; Milliken and Houde, 

 1984). Bregmaceros bathymaster has been collected only in the 

 eastern Pacific. It is abundant in the Gulf of Panama (D'Ancona 

 and Cavinato, 1965) and in the Gulf of California (Moser et al., 

 1973). Bregmaceros rarisquamosus occurs in the Indian Ocean, 

 Bay of Bengal, Arabian Sea and western Pacific Ocean. It also 

 is present in the Persian Gulf'' where it occurs with B. necta- 

 banus and B. arabicus. Previously, B. arabicus had been re- 

 ported from the Arabian Sea, Bay of Bengal and East China Sea. 

 Larvae of an undescribed species, B. Type A, have been collected 

 in the western North Atlantic (Houde, 1981)' ^ 



Bregmacerotids reportedly occur from the surface to depths 

 of approximately 4,000 m, but are most common in the upper 

 300 m. Larvae generally occur from surface to 600 m depth, 

 neritic species tending to be closer to the surface than oceanic 

 species (D'Ancona and Cavinato, 1965). Some reported catches 

 from great depths may be in error. Adults and subadults of some 

 Bregmaceros undertake extensive vertical migrations and one 

 species (B. cantori) inhabits anoxic water during a part of the 

 day (Mead, 1963; Wilson. 1972; Baird et al., 1973; Milliken, 

 1975). 



Family characteristics. — CharaclcTs defining Bregmacerotidae 

 were summarized briefly by Nelson ( 1 976) and more extensively 

 by D'Ancona and Cavinato (1965) and by Belyanina (1974). 

 Fahay and Markle (this volume) have tabulated meristic data 

 and discussed ontogenetic characters of Gadiformes, including 



' Late larvae and juveniles that I examined from the eastern Pacific 

 appeared to be typical B. atlanticus but small larvae, which may have 

 been younger specimens of this species, did not resemble typical B. 

 atlanticus from the Atlantic. The eastern Pacific specimens were less 

 pigmented, with a prominent melanophore on the ventral midline, be- 

 tween the anus and the lip of the tail. Specimens were provided by Dr. 

 H. G. Moser, Southwest Fisheries Center, National Marine Fisheries 

 Service, La Jolla, California. 



- I examined specimens of B. cantori from coastal waters of Brazil, 

 collected from latitudes of 22°S to 27°S, provided to me by Dr. Y. 

 Matsuura, Instituto Oceanografico, Universidade de Sao Paulo, Brazil. 



' 1 examined specimens from R/V DOLPHIN cruises, taken from 

 Florida to the Carolinas, provided to me by M. P. Fahay, Sandy Hook 

 Laboratory, National Marine Fisheries Service, Highlands, New Jersey. 



■■Houde. E. D., J. C. Leak, S. Al-Matar, and C. E. Dowd. 1981. 

 Ichthyoplankton abundance and diversity in the weslem Arabian Gulf. 

 Kuwait Institute for Scientific Research, Mariculture and Fisheries De- 

 partment, Final Report, Project MB- 16, 3 volumes. (This report was 

 not available for distribution at the time the present paper was written.) 



' The Type A larva was present in collections from two R/V AL- 

 BATROSS cruises into the Caribbean Sea. 1 examined larvae provided 

 by Dr. W. J. Richards, Southeast Fisheries Center, National Marine 

 Fisheries Services, Miami, Florida. 



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