368 



Abstract — Evolutionary associations 

 among the four North American spe- 

 cies of menhadens (Brevoortia spp.) 

 have not been thoroughly investi- 

 gated. In the present study, classifica- 

 tions separating the four species into 

 small-scaled and large-scaled groups 

 were evaluated by using DNA data, 

 and genetic associations within these 

 groups were explored. Specifically, 

 data from the nuclear genome (mic- 

 rosatellites) and the mitochondrial 

 genome (mtDNA sequences) were 

 used to elicit patterns of recent and 

 historical evolutionary associations. 

 Nuclear DNA data indicated limited 

 contemporary gene flow among the 

 species, and also indicated higher 

 relatedness within the small-scaled 

 and large-scaled menhadens than 

 between these groups. Mitochondrial 

 DNA sequences of the large-scaled 

 menhadens indicated the presence of 

 two ancestral lineages, one of which 

 contained members of both species. 

 This result may indicate genetic diver- 

 gence (reproductive isolation) followed 

 by secondary contact (hybridization) 

 between these species. In contrast, 

 a single ancestral lineage indicated 

 incomplete genetic divergence between 

 the small-scaled menhaden. These 

 results are discussed in the context 

 of the biology and demographics of 

 each species. 



Systematics of the North American menhadens: 



molecular evolutionary reconstructions 



in the genus Brevoortia (Clupeiformes: Clupeidae) 



Joel D. Anderson 



Email address: Joel.Anderson@tpwd.state.tx.us 



Perry R. Bass Marine Fisheries Research Station 

 Texas Parks and Wildlife Department 

 HC02 Box 385 

 Palaclos, Texas 77465. 



Manuscript submitted 28 July 2006 to the 

 Scientific Editor's Office. 



Manuscript approved for publication 



12 January 2007 by the Scientific Editor. 



Fish. Bull. 205:368-378 (2007). 



The North American species of men- 

 haden (Brevoortia spp. Gill, 1861) sup- 

 port large commercial fisheries on the 

 eastern Atlantic and Gulf of Mexico 

 (hereafter, Gulf) coasts. Historically, 

 this industry represented as much 

 as 40% of all commercial landings in 

 the United States (Vaughan and Mer- 

 riner, 1991), and the Gulf menhaden 

 (B. patronus Goode, 1878) supported, 

 by weight, one of the largest single 

 fisheries in the United States. In addi- 

 tion, menhaden are one of the most 

 important participants in estuarine 

 and nearshore food webs along the 

 Atlantic coast (Gottlieb, 1998) and 

 support various recreational fisheries 

 in the Gulf and Atlantic (Kroger and 

 Guthrie, 1972; Scharf and Schlicht, 

 2000; Bethea et al., 2004). 



There are four species of menhaden 

 present in North American waters, 

 three of which are found in the Gulf 

 of Mexico (Fig. 1). These species are 

 further classified into two general 

 groups, the small-scaled and large- 

 scaled menhadens. These groups are 

 named according to the relative size 

 of scales adjacent to the lateral line 

 but also reflect contrasts in other 

 morphological characteristics (Dahl- 

 berg, 1970), population demographics 

 (Christmas and Gunter, 1960), and 

 migratory behavior (Gunter, 1945; 

 Simmons, 1957; Tolan and Newstead, 

 2004). The Gulf menhaden (B. pa- 

 tronus) and Atlantic menhaden (B. 

 tyrannus Latrobe, 1802) are members 

 of the large-scaled group. Brevoortia 

 patronus occurs wholly in the Gulf 

 of Mexico, and dominates the men- 



haden fishery in the Gulf, with other 

 menhaden species representing less 

 than 1% of the annual catch (Ahren- 

 holz, 1981). Brevoortia tyrannus is a 

 semimigratory species found in large 

 schooling populations and is targeted 

 by a second reduction fishery. This 

 species is found only on the Atlantic 

 coast, and does not inhabit the Gulf 

 (Ahrenholz, 1991). The small-scaled 

 menhadens, yellowfin menhaden (B. 

 sniithi Hildebrand, 1941) and fin- 

 escale menhaden, (B. gunteri Hilde- 

 brand, 1948), are present in smaller 

 population sizes and have slightly 

 overlapping distributions in the Gulf. 

 Brevoortia gunteri has a distribution 

 range restricted entirely to the north- 

 ern and western Gulf coastal region. 

 In contrast, B. smithi exists mainly in 

 the eastern Gulf, although it ranges 

 north on the Atlantic coast to Cape 

 Lookout, North Carolina (Reintjes, 

 1959; Ahrenholz, 1991). Brevoortia 

 sniithi overlaps the eastern range of 

 B. patronus, and also overlaps the 

 southern range B. tyrannus. Consider- 

 able hybridization is thought to occur 

 between B. patronus and B. sniithi 

 along the west coast of Florida, and 

 between B. tyrannus and B. sniithi 

 along the east coast of Florida (Turn- 

 er, 1969; Heftier, 1984). 



Although the evolutionary relation- 

 ships among the four North American 

 menhaden species have not been ex- 

 plicitly examined, early investigations 

 in species morphology indicated that 

 B. tyrannus and B. patronus were At- 

 lantic and Gulf complements of one 

 another, and that B. gunteri and B. 



