DELINEATION OF TILEFISH, 



LOPHOLATILUS CHAMAELEONTICEPS, STOCKS ALONG 



THE UNITED STATES EAST COAST AND IN THE GULF OF MEXICO 



S. J. Katz, 1 C. B. Grimes, 2 and K. W. Able 3 



ABSTRACT 



Tilefish, Lopkolatilus chamaeleonticeps, are an important commercial species in the Mid-Atlantic 

 Bight and the focus of developing fisheries in the South Atlantic Bight and the Gulf of Mexico. 

 Attempts were made to delineate stocks over this range by analyzing for variation in morphology 

 (28 meristic and morphometric characters) and electrophoretic migration of eye, liver, and muscle 

 proteins. Morphological and electrophoretic data (liver isocitrate dehydrogenase and liver esterase) 

 consistently supported a separate Mid-Atlantic Bight stock. Electrophoretic data suggested that 

 South Atlantic Bight and Gulf of Mexico samples belonged to a separate, single stock. This was not 

 consistently supported by the more variable morphometric characters. It was suggested that Mid- 

 Atlantic Bight populations be treated as a separate stock and, as a working hypothesis, that South 

 Atlantic and Gulf of Mexico populations be considered as a second stock. 



Tilefish, Lopholatilus chamaeleonticeps, are dis- 

 tributed from southern Nova Scotia (Leim 1960; 

 Markle et al. 1980) south to off Surinam, South 

 America, (Wolf and Rathjen 1974) and through- 

 out the Gulf of Mexico (Bigelow and Schroeder 

 1947; Hoese and Moore 1977) but exclusive of the 

 Caribbean Sea (Dooley 1978). The tilefish is the 

 basis for a valuable bottom longline fishery in the 

 Mid-Atlantic Bight (Grimes et al. 1980), and this 

 fishery is developing elsewhere along the east 

 coast of the United States and in the Gulf of 

 Mexico. This paper investigates tilefish popula- 

 tions to determine if separate stocks can be iden- 

 tified over this range. 



There are several reasons to suspect that dis- 

 tinct stocks of tilefish may occur. Tilefish prob- 

 ably have a restricted habitat. They are reported 

 from rather narrow temperature ranges (9°- 

 14°C) at the edge of the continental shelf along 

 the east coast (Goode 1884; Rathburn 1895; Bige- 

 low and Schroeder 1953) and in the Gulf of Mexi- 

 co (Nelson and Carpenter 1968; Wolf and Rath- 

 jen 1974). Also, preliminary tagging studies 

 (Grimes et al. in press) suggested that individual 



'Ecology Graduate Program, Rutgers University, New 

 Brunswick, NJ 08903. 



2 Forestry and Wildlife Section and New Jersey Agricultural 

 Experiment Station, Rutgers University, New Brunswick, NJ 

 08903. 



3 Biological Sciences and Center for Coastal and Environ- 

 mental Studies, Rutgers University, New Brunswick, NJ 

 08903. 



tilefish moved <2 km in over 1 yr. These obser- 

 vations are supported by submersible observa- 

 tions which suggest that tilefish are resident 

 in temporally stable burrows of their own con- 

 struction (Able et al. 1982). In the Mid-Atlan- 

 tic Bight, tilefish are caught the year-round 

 which also suggests that these may be resident 

 populations. In addition, the prevailing current 

 patterns, temperature regimes, and species dis- 

 tribution patterns along the east coast suggest 

 that important faunal boundaries may exist at 

 Cape Hatteras and around the Florida peninsula 

 (see Briggs 1974 for discussion). This study re- 

 ports on morphological and electrophoretic char- 

 acteristics of tilefish from the U.S. east coast and 

 the Gulf of Mexico. The distribution of the char- 

 acters were used to test the null hypothesis that 

 there are no differences among these popula- 

 tions. 



MATERIALS AND METHODS 



Tilefish samples were obtained from commer- 

 cial fishermen or collected by hook and line on 

 exploratory fishing cruises (National Marine 

 Fisheries Service RV Oregon ID during 1978 and 

 1979 (Fig. 1) (Katz 1982). Information on physi- 

 cal conditions at collection were unavailable, but 

 temperature is known to be relatively constant 

 throughout the range (see above). Fish were 

 transported fresh, on ice, or frozen, depending on 

 distance of collection from the laboratory. 



Manuscript accepted July 1982. 



FISHERY BULLETIN: VOL. 81. NO. 1. 1983. 



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