THE OYSTER-INDUSTRY. 221 



The scattered oysters lying on tlie sands and those bods in the vicinity of sand-shoals and in shallow ^vatcr, the Mnddy marsh and 

 Beach island rocks ]iarticnhirly, are exposed to damage by "sanding" in a manner similar to certain beds in Tangier sonnd, and which 

 has already been ilescribed. The large amount of grass, sponge, and sea-weed growing on the sand-shoals, especially the one to the east 

 of Heme island and south of the Guilford channel, is frequently torn up by the heavy gales and deposited on the beds with the same 

 injurious elfect that it had in Tangier sound. Hea\-y southerly gales will sometimes cover the beds above the Buoy spit and Shell rocks 

 with mud for a short time, but not sufiticieutly long, it is said, to atl'ect the oysters seriously. 



Effects op ice on the beds. — This account is typical of wbat might be said of oyster-beds in general along 

 the whole coa.st. Al)out the only other iujurious agency is that of ice. In the Chesapeake heavy winter gales 

 from the northward have the eft'ect of diminishing the depth of water by piling up any floating ice upon the leeward 

 shores and cutting away parts of the shores. Few beds are exposed, however, by the lowest of these tides, and it is 

 rare that ice grounds, doing damage at these times only to a small extent, unless it remains for a long time in contact 

 with the beds. lu respect to this, Winslow has some interesting remarks : 



If it [the ice] only touches in a few places, not much harm is done; indeed, it is supposed to protect the majority on the bed by 

 covering them, but where there is a contact all over the "rock", the oysters are killed in a short space of time. • * • 



The winter gales break up the ice-fields and i)ile them up in immense masses on the leeward shores and over the adjacent beds. Tho 

 Shark's Fin bed suU'ers particularly in this respect. A good deal of damage is done to the shores by the ice, and the oysters feel the eft'ect, 

 showing it by becoming what is called "winter killed", or poor and weak, having a slimy, sickly appearance when opened. Many die on 

 the beds from this cause, and after the disapiiearauce of the ice, ten days or two weeks must elapse before they are fit for marUetablo 

 purposes. Ordinary cold weather and a moderate amount of ice is said to improve tho iishing, tho oysters aiipeariug to be drawn more to 

 the surface of the bed and the shells to sink more toward tho bottom. My informants said this elfect was quite noticeable. No one that 

 I was able to interrogate had ever seen an oyster frozen in tlie water, and the impression was, that so long as the oysters were covered they 

 would recover from any ill effects of ice or ordinary cold weather. 



In northern waters, such as Long Island sonnd and Karraganset bay, the oysters seem much more hardy in 

 the endurance of cold than those of the Chesapeake. This would naturally be expected. Nevertheless, drifting 

 ice often plows up the beds, both natural and artificial, to a ruinous extent in exposed situations, or, resting upon, 

 freezes great areas of loose, single oysters into its under surface, and then, on a rising tide and before a brisk wind 

 or strong current, moves off, bearing thousands of bushels away to scatter them over new ground, or Jiold them 

 until they perish. This sort of action is an agency to be remembered in studying the geographical distribution of 

 oyster-beds, since the molhisks will survive a long journey of this kind, and, finally, by the grounding or thawing 

 of the floe, may be dropped all together iu some favorable si>ot at a long distance from anj- other colony. The 

 existence of such an isolated bed might easily be used as an argument, to show the great distance to which spawn 

 travels, when, in fact, the colony owed its origin to nothing of the kiud, but to having its progenitors carried there, 

 as adults, by floating ice. 



The question of the iufluence which ice has upon the existence of oysters as a race, in a certain region, becomes 

 of great moment, when the locality is as nearly arctic as the gulf of St. Lawrence. I asked many questions on this 

 point when at Prince Edward island, and also as to the effect of low temperature generally on the mollusks of 

 that coast. 



Tempeeatuee obseevations. — The only observations on temperature that I could learn of having been 

 made in the gulf of St. Lawrence were in 1872, by Prof. J. F. Whiteaves, of Montreal, who recorded them in an 

 article in volume VI of the Canadian Naturalist.* After describing the character of the bottom, this writer goes 

 on to say : 



Attempts were made to endeavor to ascertain the approximate temperature of the deep-sea mud. When the dredge was hauled up, its 

 contents wore emptied as quickly as possible into a large shallow tub, and this was covered with a tarpaulin and placed in the shade. An 

 ordinary thcrmometor, with a metal case and perforated base, was then plunged into the mud, and the whole was kept carefully shaded 

 for a time. With one exception the temperature of the mud was found to bo from 37° to 38° Fahr., and this not alone in deep water ; for 

 sand brought up from 25 fathoms on the north shore of the St. Lawrence also made the mercury sink to 3S° or 37° Fahr. 



Again, the same author writes : 



In the deepest parts of the river, on the south shore, between Anticosti and part of the Gasp6 peninsula, the thermometer registered a 

 few degrees higher. Sand dredged on the north shore in 25 fathoms also made the mercury sink to 38° or 37°. 



Elsewhere he mentions that oft' Port Hood, Cape Breton, the temperature of the bottom ranged from 40° to 

 42° Fahr. ; but adds, that not a truce of oysters are found living on that part of the coast. These are summer 

 records. 



Such notes were unsatisfactory, since they referred to an area outside of the oyster's range, and I therefore 

 essayed to learn something of the temperature of the water upon the beds themselves — but I had no better means 

 than an ordinary thermometer, which I believed to be not far from true — at various points where it was possible. 

 It will be seen by the record of these observations below, that the temperature is higher than would naturally bo 

 suspected on a coast where the Gulf Stream is the other side of a polar current, that brings hosts of icebergs to the 

 northern shores of Prince Edward and Cape Breton, and fills Northumberland sound with immense flows of dense, 



* Whiteaves, J. F. Notes on a deep-sea dredging exjiedition round the island of Anticosti, in the gulf of St. Lawrence. Canadian 

 NaturalM, VI (new series), pp. 86-100. 



