LOBSTER I'LAXTIXa AREAS 123 



SESSIONAL PAPER No. 38a 



and this at a time when the temperature at the surface was not high. The range 

 here would easily fall within the extremes 32° to 70° as given for the Atlantic waters, 

 for unless for a fathom or two at the surface or on long slojiing beaches, it would 

 seem from the little data that we have that the temperature is not likely to go below 

 45° or above 65° at any depth in the strait of Georgia and the straits and channels 

 among the islands. Moreover, in cases where it is stated that the lobsters live in 

 localities where there may be somewhat extreme surface temperatures, it is commonly 

 stated as well that the lobster migrates to the deeper water to escape the cold of the 

 shallow water. This is only a surmise, however, and not necessarily a correct one, 

 as the migration is just as liable to be due to the necessity of going to deeper water 

 for requisite food material which at this time of year might be scarce in shallow 

 water areas. It has been proved time and again that the lobster seems to be in no 

 way harmed by being kept at a low temperature during transportation, hence if the 

 low temperature alone came into play the winter migration might not be necessary. 

 •At any rate there seems to be little doubt but that the lobster can adapt itself to con- 

 siderable variation in temperature provided it is not too high, and a danger fro_m 

 high temperature is not likely to be a factor in the waters of the strait of Georgia. 



I have found that there is very little difference in temperature in water at 100 

 fathoms or even at 50 fathoh'is in July and October, hence there is not likely to be 

 very great difference during the rest of the year. I have no data as to the tempera- 

 ture at these depths in the Atlantic, but would be surprised to find that it diifered 

 much from the temperature at the same depth here. It would seem, therefore, 

 although we may not have such extrenies of surface temperature as in the Atlantic 

 where the lobsters are now at home, yet at the depths that the lobsters are likely to 

 be located at any particular time of the year there is not likely to be very much differ- 

 ence, not enough to be of any serious obstacle to their welfare. 



8. Conditions of Density and Salinity of Water. 



Another feature to which scarcely any attention has been i^aid by those who have 

 written about the lobster, viz., density or salinity, would appear to me to be much 

 more important than the temperature and yet from this lack of attention it is impos- 

 sible to give any satisfactory comparison. Herrick in his large work of over 250 

 pages does not consider the question at all. Prince says: ''Lobsters avoid localities 

 where fresh-water streams run in unmingled Avith salt water," but that does not help 

 out a great deal. Rathbun does not think it worth mentioning in his comparison. 

 Eeiwrts on destiny in t\\^ localities on the Atlantic coast where lobsters are found 

 may give some idea of what density is required. In the paper already mentioned on 

 the biological survey of Woods hole (cf. pp. 433--43C)) four density charts are given for 

 Buzzards bay and Vineyard sound. The water is all so shallow in the area surveyed 

 that it is scarcely comparable to the waters of the east coast of Vancouver island, and 

 yet as lobsters live and thrive in these waters, the degree of salinity must be favour- 

 able. The water at the bottom has practically the same density as that at the surface 

 in nearly all cases, with but few instances where the densitj^ is lower than 10230 or 

 higher than 10240, very uniform throughout the year. In a paper on "The Tem- 

 peratures and Densities of Passamaquoddy bay and its Environs " ^ the density 

 measurements were all made during the summer months and most of them were at 

 the surface or not more than 5 fathoms from the surface. These' readings fall fairly 

 well between the same limits as do those at Woods hole, although there is noticeable 

 variation due to the excessive change of the tide. If it is necessary to have a salinity 

 represented by such density right to the surface of the water then it is useless to 

 attempt to grow lobsters along the east coast of Vancouver island, because it would 

 be a difficult matter to find a spot between Haro strait and Queen Charlotte sound 



iCopeland, G. G. Contributions to Canadian Biology, 1906-1910, pp. 2S1-294.' 



