McEACHRAN and MUSICK: DISTRIBUTION AND RELATIVE ABUNDANCE OF SKATES 



Raja garmani probably does not occur regu- 

 larly on the eastern slope of Georges Bank, con- 

 trary to Schroeder (1955), because no specimens 

 were captured there during the Albatross IV 

 cruises. The depth and temperature ranges of 51 

 to 494 m and 5.3° to 15°C given by Bigelow 

 and Schroeder (1953) are close to those for the 

 area north of Cape Hatteras in the present study. 

 It has more limited depth range and is found 

 in warmer water in the southern part of its range 

 than in the northern part as stated by Bigelow 

 and Schroeder (1953). Staiger (1970) stated that 

 it is found between the 119- and 366-m isobaths 

 on Pourtales Terrace, and north of Pourtales 

 Terrace it occurs in 183 m up the coast of Florida. 

 This species appears to have separate popu- 

 lations, one north and the other south of Cape 

 Hatteras. North of Cape Hatteras mature speci- 

 mens are 335 mm TL (McEachran 1970) to 439 

 mm TL and south of Cape Hatteras they are 

 mature between 250 and 314 mm TL. The dif- 

 ferences in temperature ranges north and south 

 of Cape Hatteras may be due to differences in 

 physiological requirements of the two populations. 



Raja laevis 



Raja laevis was captured from the Gulf of St. 

 Lawrence, along the northeastern coast and off- 

 shore banks of Nova Scotia, to the northeastern 

 coast of Florida. During the Albatross IV cruises 

 it was taken from the Nova Scotian shelf to the 

 southern section of the mid-Atlantic Bight and 

 was most frequently taken in the northern sec- 

 tion of the mid-Atlantic Bight, the eastern part 

 of Georges Bank, eastern Gulf of Maine, and 

 the Nova Scotian shelf. No specimens were ob- 

 tained from the western Gulf of Maine. Seasonal 

 changes in abundance were not evident. In the 

 Gulf of St. Lawrence, i?. laevis was found in 315 m 

 at 4.7°C. Off northeastern Nova Scotia it was 

 caught at depths of 24 to 375 m at 1.2° to 10.7°C. 

 Depths and temperatures at capture for the area 

 from southern Nova Scotia to Cape Hatteras 

 ranged from 38 to 351 m and 3° to 20°C. Raja 

 laevis was caught in 302 to 368 m off northeastern 

 Florida. 



Raja laevis is the most widespread of the 

 species studied, but too few were taken during 

 this study to elaborate on its distribution. Bigelow 

 and Schroeder (1953) stated that this species 

 occurs from the tidemark to about 750 m at 

 1.2° to 20°C. The southern limit of its range 



remains in doubt because of the apparent con- 

 fusion of this species with R. floridana which 

 has been captured from Cape Lookout, N.C. to 

 Dry Tortugas, Fla. (Bigelow and Schroeder 1968). 

 Raja floridana is very similar to R. laevis (Bige- 

 low and Schroeder 1962) and the specimens used 

 to describe R. floridana came from some of the 

 same stations at which Bullis and Thompson 

 (1965) listed R. laevis. The senior author has 

 examined the specimens identified as R. laevis 

 at the United States National Museum and 

 University of Miami School of Marine and At- 

 mospheric Sciences, and all of those from south 

 of Cape Hatteras have proven to be i?. floridana. 

 Also R. laevis does not occur in the species lists 

 of Struhsaker (1969) or Staiger (1970). Thus it is 

 likely that many or all of the records ofR. laevis 

 from south of Cape Hatteras refer toR. floridana. 



Raja erinacea 



Raja erinacea was recorded from the Gulf of 

 St. Lawrence; off Cape Breton, Nova Scotia; 

 Western Bank; and two specimens were posi- 

 tively identified from Sable Island Bank. It was 

 the most abundant species captured on Georges 

 Bank and in the northern section of the mid- 

 Atlantic Bight. It was rarely taken in the western 

 Gulf of Maine (Figure 7). Raja erinacea was 

 most abundant in Chesapeake Bight during the 

 winter and those that remained there during 

 the summer moved into deeper water. 



Throughout its range, R. erinacea was gener- 

 ally caught at depths less than 111 m, but was 

 occasionally taken at depths greater than 183 m, 

 especially in the northern section of the mid- 

 Atlantic Bight and on Georges Bank where it 

 occurred as deep as 329 m. Edwards et al. (1962) 

 captured R. erinacea as deep as 384 m off New 

 Jersey, thus the species is not as restricted to 

 shallow water as stated by Bigelow and Schroeder 

 ( 1954) who reported that 159 m was the maximum 

 depth of the species. Temperatures at depth of 

 capture ranged from 2° to 19°C with most captures 

 occurring between 2° and 15°C. The recorded 

 temperature range of the species is 1.2°C (Tyler 

 1971) to 21°C (Bigelow and Schroeder 1953). 



Raja erinacea is a Virginian to boreal species 

 whose center of abundance is in the northern 

 section of the mid- Atlantic Bight and on Georges 

 Bank. Only in these areas was it found year- 

 round over almost the entire range of tempera- 

 tures recorded for the areas (Figures 8-10). In 



^y 



119 



