DISTRIBUTION AND RELATIVE ABUNDANCE OF SEVEN 



SPECIES OF SKATES (PISCES: RAJIDAE) WHICH OCCUR 



BETWEEN NOVA SCOTIA AND CAPE HATTERAS^ 



John D. McEachran^ and J. A. Musick^ 



ABSTRACT 



Data collected during eight groundfish surveys of the area from Nova Scotia to Cape Hatteras, 

 North Carolina, and during five seasonal surveys of Chesapeake Bight were used to define the 

 distribution and relative abundance of Raja eglanteria, R. garmani, R. laevis, R. 

 erinacea, R. ocellata, R. senta, and R. radiata. Ancillary distributional data for the 

 area from the Straits of Florida to Cape Hatteras and the areas off northern Nova Scotia and the 

 Gulf of St. Lawrence were used qualitatively to extend the distributional study. 



Raja eglanteria is a Carolinian species abundant north of Cape Hatteras only during the 

 warmer months. Raja garmani, a skate of the outer continental shelf and upjjer slope, consists 

 of two populations which have different temperature preferences. Raja laevis is the most wide- 

 spread species studied and does not appear to be as abundant as the other skates in any region 

 of the study. Raja erinacea, a Virginian to boreal species, occurs from southern Nova Scotia 

 to Cape Hatteras in shallow water but is present at depths down to 384 m. Raja ocellata is a 

 Virginian to boreal species distributed similarly toR. erinacea except that the former is widespread 

 in the Gulf of St. Lawrence and off northern Nova Scotia. Raja senta, a boreal species, fre- 

 quently occurs on the northern offshore banks of Nova Scotia and at temperatures as low as 

 -1.3°C. Raja radiata is a boreal to arctic species. 



Raja erinacea and R. ocellata are sympatric over the greater part of their ranges as 

 are R. senta and R. radiata. The two pairs of species have complementary distributions. 

 Raja ocellata has slightly lower temperature preferences than R. erinacea, and R. radiata 

 is more widespread and has wider temperature tolerances than R. senta. 



The genus Raja is represented by R. eglan- 

 teria, R. garmani, R. laevis, R. erinacea, 

 R. ocellata, R. senta and R. radiata along 

 the continental shelf of North America between 

 Nova Scotia and Cape Hatteras, NC. Notes on 

 the occurrence and distribution of these species 

 have been summarized by Bigelow and Schroeder 

 (1953, 1954), Leim and Scott (1966), and 

 McEachran (1973); however, most of this infor- 

 mation is based on scattered regional studies. 

 The present study presents data gathered during 

 comprehensive groundfish surveys of the area 

 from Nova Scotia to Cape Hatteras and defines 

 the distribution and relative abundance of each 

 species, as well as cooccurrence among species. 



MATERIALS AND METHODS 



Data used in this study were divided into two 

 categories: 1) quantitative data used to deter- 



'Contribution No. 651 Virginia Institute of Marine Science. 



^Department of Wildlife and Fisheries Sciences, Texas A & M 

 University, College Station, TX 77843. 



'Virginia Institute of Marine Science, Gloucester Point, 

 VA 23062. 



mine relative abundance of the skates, and 

 2) qualitative data used only to determine the 

 temperature, depth, and geographical ranges of 

 the skates. 



Data supplied by National Marine Fisheries 

 Service (NMFS) Biological Laboratory at Woods 

 Hole, Mass. (now Northeast Fisheries Center) 

 and by the Virginia Institute of Marine Science 

 (VIMS) at Gloucester Point, Va. were used to 

 determine relative abundance. The former data 

 consisted of eight groundfish surveys of the con- 

 tinental shelf (27-366 m) from LaHave Bank, 

 off southeastern Nova Scotia, and the Gulf of 

 Maine to Cape Hatteras. A total of 2,247 stations 

 were made during the winters of 1968-70, the 

 summer of 1969, and the autumns of 1967-70 

 (Table 1) by the RV Albatross IV, except that 

 part of 70-06 was conducted by the RV Delaware 

 II. The survey area was divided into 58 strata 

 according to depth and geographical area, and 

 three or more stations were randomly selected 

 within each stratum per cruise (Figure 1) (Gross- 

 lein 1969). A No. 36 Yankee trawl equipped 

 with a cod end liner of 0.25-inch bar mesh and 



Manuscript accepted March 1974. 



FISHERY BULLETIN: VOL. 73, NO. 1, 1975. 



110 



