2 24 Memoir Sears Foundation for Marine Research 



have a specimen, taken on Nantucket Shoals in mid-July, that is so small (193 mm 

 long) that it could not have been set free long before its capture. 



Barndoors are usually taken on sandy or gravelly bottom, but individuals that 

 live in the deepest water are often on muddy ground. In the Gulf of Maine, for example, 

 we have trawled them in the deep mud-floored troughs in company with R. senta and 

 R. radiata. 



The depth range for R. laevis covers the whole breadth of the continental shelf, 

 from tide-mark down to 235 fathoms ;^^ the 5-fathoni and the 70— 80-fathom contours 

 approximately enclose the zone of greatest abundance and of most regular occurrence. 



It has been reported off northern Nova Scotia and on the southwestern part of 

 the Newfoundland Banks in water as cold as 1.2 and 2.2° C (about 34 and 36° F). 

 The facts that many more are taken in autumn than in summer in shoal water along 

 southern New England and that they are reported as not entering Sandy Hook Bay 

 near New York City until the water has cooled to about 17° C (63° F), suggest that this 

 is near the upper limit of the optimum range of the species. However, the individuals 

 that live closest inshore (i. e., shoalest) along southern New England and southward 

 may be in water as warm as 18—20° C (about 64—68° F) in summer, if not warmer. 

 Especially interesting in this connection is the report of small R. laevis being taken 

 in 18 fathoms off Cape Lookout, North Carolina in mid-August^* when the bottom 

 temperature there was probably not less than 22-24° C (72—76° F). 



R. laevis occurs in salinities that range from about 35 "/oo along the continental 

 edge to 31—31.5 "/oo inshore along the open coast and to as low as 21—24 "/oo within 

 the mouth of Chesapeake Bay. One specimen has even been reported from so far up 

 the Delaware River (above Philadelphia) as to suggest that R. laevis may occasionally 

 run up into water that is only slightly saline or even fresh. 



The fact that R. laevis is taken much more regularly and in larger numbers 

 close inshore along southern New England, New York, and New Jersey in autumn and 

 spring than in summer suggests that the inshore fringe of the population tends to move 

 out into slightly deeper water during the warmest season and to move shoreward again 

 as the water cools with the onset of autumn. It is likely also that such individuals as 

 come into water less than a fathom or so in depth during autumn tend to withdraw 

 again during the winter as the water chills. But there is no reason to suppose that these 

 thermal migrations involve such of the stock as live deeper than 5—10 fathoms (includ- 

 ing the great majority of the population), for Barndoors are taken regularly on the 

 offshore fishing banks in winter as well as summer.^^ 



53. The records of greatest depth are 120 fathoms on the southwest slope of the Grand Banks of Newfoundland; 235 

 fathoms along the continental edge off Nantucket, Massachusetts; 105 fathoms in the western side of the Gulf of 

 Maine; no fathoms in the central basin of the Gulf; and 159 fathoms off Charleston, South Carolina. 



54. Radcliffe, Bull. U. S. Bur. Fish., j.#, 1916: 273. 



55. It is taken throughout the year in the vicinity of Nantucket Lightship where it is especially plentiful in winter in 

 depths of about 30-50 fathoms and in summer in about 20 fathoms (reported by Captains Jared Vincent and H. W. 

 Klimm, catches from 1945-1950). And we saw many trawled in midwinter south of Rhode Island in 47-67 fathoms 

 (by the Eugene H., January 27 to February 3, 1950), as well as along the southern New England Coast in May 

 (by the Albatross III). 



