262 Memoir Sears Foundation for Marine Research 



and broken shells, sand and gravel, or gravel and pebbles, we have also taken it at many- 

 stations in the Gulf of Maine where soft mud floors the deeper troughs. It does not occur 

 regularly at any locality where the bottom temperature rises above 9-10° C (48-50° F) 

 for more than short intervals, though it can survive brief exposure to temperatures 

 much higher than those to which it is subjected in any part of its range.i^s At the other 

 extreme, many have been taken in Newfoundland waters where the temperatures go 

 down to 1.1° C (34° F), or nearly as low as temperatures are in the open sea off the 

 eastern American seaboard. Nor does it show any apparent preference for either the 

 upper half of its thermal range or for the lower. However, the polar temperature of 

 the ice-chilled Labrador Current may be responsible for its scarcity along the north- 

 eastern coast of Newfoundland north of the offing of Conception Bay and along Atlantic 

 Labrador as contrasted with its abundance along southwestern Greenland, where the 

 temperature of the bottom water at depths where it occurs are upwards of 2-3° C 

 (36-37° F) for the most part during late summer and early autumn. 1-' 



R. radiata is seldom (if ever) encountered in water less saline than 3 1.2-3 1.5 °/oo 

 (shoaler parts of Gulf of St. Lawrence ; also Passamaquoddy Bay) ; the recorded max- 

 imum for it is about 35.3 "/oo, and the great majority of the American population 

 throughout its latitudinal range exists in salinities ranging from about 32-34.5 "/oo- 



Numerical Abundance. In September 1929, 37 trawl hauls on Georges Bank yielded 

 a catch of 325 R. radiata, and trawling on the Newfoundland Banks yielded a maximum 

 catch of 54 per hour. As further evidence of its abundance we may quote catches of 

 12 R. radiata in 30 minutes in the western side of the Gulf of Maine with a beam 

 trawl that was only eight feet across at the mouth, and of i-ioo specimens in 26 trawl 

 hauls between Mt. Desert Island and Massachusetts Bay.^^s Oflf the coast of southern 

 New England, 21 were taken in 17 half-hour trawl hauls in 71-260 fathoms, but 

 none were taken in 46 hauls made in 22-69 fathoms on the same cruise. ^^^ 



Relation to Man. No commercial use is made of this particular Skate in American 

 waters, but a few are dried and salted in Iceland."" 



Range. Continental waters in both sides of the northern North Atlantic in boreal 

 and subarctic latitudes. On the east, from the White and Barents seas, Bear Island, 

 Spitzbergen, Iceland, Norway, and the western part of the Baltic to the Dutch Coast, 

 and reported doubtfully from Belgium and the Bay of Biscay ;i3i in the west from Labra- 



126. The lethal upper temperature for it is 26.5-26.9° C, according to experiments by Huntsman and Sparks (Contr. 

 Canad. Biol., N. S. 2, 1924: 102). 



127. The bottom water at depths of 25-50 fathoms is colder than 0° C (32° F) for the most part from July into Septem- 

 ber along northeastern Newfoundland and Atlantic Labrador. See Iselin (Proc. Amer. Acad. Arts Sci., 66, 1930: 

 3-25) and Smith, Soule and Mosby (Sci. Res. Marion-Gen. Greene Exped., U. S. Cst. Guard, 2, 1937: fig. 56) 

 for bottom temperatures along northeastern Newfoundland and Atlantic Labrador; for the Grand Banks region, 

 see tables and charts in Rep. Newfoundland Fish. Res. Comm. [i [4], 1932; 2 [i], 1933; 2 [2], 1934; 2 [3], 

 1935); for the West Greenland fishing grounds, see Beauge (Rev. Trav. Off". Sci. Techn. Peches marit., 4 [i], 

 1931: 111-112; 5 [i], 1932: 59-68; 6 [i], 1933: 97-100) and Smith, Soule and Mosby (Sci. Res. Marion-Gen. 

 Greene Exped., U. S. Cst. Guard, 2, 1937: figs. 13, 15, 20). 



128. July-November, 1927-1930. 129. Albatross III, May ii-iS, 1950, between Long. 67°io' and 72°2o'W. 



130. Saemundsson, Skr. Komm.' Havunders. Kbh., 5, 1909: 126. 



131. For a recent summary (with references) of the distribution oi K. radiata in the eastern Atlantic and tributary seas, 

 see Clark (Rep. Fish. Bd. Scot. [1926], i, 1926: 29). 



