432 



FISHERY BULLETIN OF THE FISH AND WILDLIFE SERVICE 



couple of inches long tend to hold close enough 

 to the bottom in our Gulf for great numbers of 

 them to be caught in otter trawls. But some may 

 also live pelagic over the deep basins as they are 

 known to do in the Gulf of St. Lawrence; also, 

 in the Norwegian Sea, where there is a population 

 of all sizes living mostly at depths of about 50 

 to 100 fathoms, over much greater depths. 19 

 When they are on bottom the rosefish are chiefly 

 on rocky or hard grounds or on mud, seldom on 

 sand, if ever. Their depth range on the bottom 

 is from within a few feet of tide line (p. 434) down 

 to 350 fathoms at least; perhaps to 400 fathoms 

 (p. 434) with the greater part of the commercial 

 catch trawled at about 40 to 175 fathoms; and 

 fry, living pelagic, have been taken as deep as 270 

 fathoms in north European waters. 



Our rosefish inhabit a wide range of temperature. 

 The maximum may be set at about 48° to 50° F., 

 and probably it is the low temperature of parts of 

 the Bay of Fundy, where the upper 10 fathoms or 

 so may be as cool as 50°-52° even in midsummer 

 that allows them to remain in shoal water there 

 the year round (p. 435). At the other extreme 

 they winter in Massachusetts Bay and in Passa- 

 maquoddy Bay in water as cold as 33° to 35°, and 

 perhaps colder, though they could easily avoid 

 these low temperatures by a short offshore migra- 

 tion. In fact, the rosefish has often been described 

 as an Arctic species. But while this is true to the 

 extent that its range extends to Arctic Seas, it is 

 a misnomer if taken to mean that it is character- 

 istic of Polar temperatures, for the records of its 

 occurrence, horizontal and bathymetric, prove 

 that the great majority of them inhabit waters 

 warmer than 35°-36° over the greater part of their 

 geographic range. 



The distribution of the rosefish 20 in the Gulf of 

 St. Lawrence is especially instructive in this 

 respect, for it inhabits the comparatively warm 

 water (39° to 42° F.) in the bottoms of the deep 

 channels, and not the icy intermediate layer (about 

 32°) which, generally speaking, is so nearly an 

 impassable barrier to its upward migration that 

 it is seldom if ever taken on the shoal banks. 

 And its vertical range in relation to temperature 

 seems to be much the same as this off the south- 



>• For studies of the pelagic occurrence of S. marinus in northeastern 

 Atlantic waters, see Murray and Hjort (Depths of the Ocean, 1912, pp. 

 647-648) and especially Tailing (Journal du Conseil, Cons. Internat. Explor. 

 Mer., Vol. 16. 1949, No. 1). 



» Huntsman, Trans. Roy. Soc. Canada Ser. 3, vol. 12, Pt. 4, 1918, p. 63. 



west coast of Greenland, where rosefish are taken 

 chiefly deeper than 90 fathoms, in water of about 

 37°-39°, not in the icy layer above, and where 

 numbers of them (says Jensen) sometimes come 

 to the surface dead in winter, apparently having 

 succumbed to cold. 21 In the Norwegian Sea, how- 

 ever, rosefish of this species are caught only in the 

 overlying layer of water of Atlantic influence at 

 temperatures of 37°-39° or higher, never deeper 

 in the icy cold Polar water. 



Temperatures of 37°-39° are the lowest in which 

 young rosefish are born in any numbers in our 

 Gulf; there is no water there colder than this by 

 the time production is well under way, say late 

 June or early July. At the opposite extreme, 

 practically the entire production of rosefish takes 

 place in water colder than 46°-48°, this being the 

 maximum to which the water warms at the 20- 

 fathom level and deeper, except in regions of active 

 vertical mixing where the temperature may rise a 

 degree or two higher. In the Gulf of St. Lawrence, 

 rosefish have been found breeding in 39°-42°. 

 Cursory examination of station data might suggest 

 that young are born in colder water on the Grand 

 Banks as well as along the south and east coasts 

 of Newfoundland, for they have been taken there 

 in tow nets at many localities where the tempera- 

 ture was lower than 32°, either on the bottom or 

 at some intermediate depth. But it is more likely 

 that the parent fish, and the young fry also, were 

 living above this icy layer, not in it; i. e., in water 

 at least as warm as about 35° (1.5° C.), and 

 warmer than about 36°-37° for the most part. 



Thus the range of temperature within which 

 American rosefish fry are produced in one place or 

 another is from about 37° to 47° or 4S°, which is 

 about the same as for north European waters. 22 

 In fact it is not likely that rosefish breed success- 

 fully in temperatures lower than 35° anywhere in 

 either side of the Atlantic. 



The salinity in which rosefish breed in our Gulf 

 is as definitely limited in one direction as is the 

 temperature, if not in the other, for its joung are 

 produced for the most part in salinities upward of 

 32 per mille. 



»' See Jensen (Vid. Meddel. Dansk Naturhist. Foren. Copenhagen, vol. 74, 

 1922, pp. 89-109, for an interesting study of the occurrence of the rosefish in 

 Greenland waters. 



» See Taning (Journal du Conseil, Cons. Internat. Explor. Mer, vol. 16, 

 No. 1, 1949) for a recent discussion of the thermal relationships and breeding 

 range of S. marinus. 



