PREFACE. 



By Professor Edward E. Prince, LL.D., M.A., D.Sc, F.E.S.C. Dominion Commis- 

 sioner OF Fisheries; Chairman of the Biological Board; Chairman of the 

 Canadian Arctic Expedition Committee; Member of the Advisory Board on 

 Wild Life Protection, Ottawa; Chairman of the Food Refrigeration Com- 

 mittee, CaiNadian Research Council; Vice-President of the International 

 Fisheries Congress, Washington, D.C, 1907. etc. 



The present volume of Contributions to Canadian Biology is composed of a series 

 of separate reports by trained scientists who have taken advantage of the facilities 

 generously provided by the Dominion Government at the Atlantic Biological Sta- 

 tion, St. Andrews, N.B., and the Pacific Station, Depai'ture Bay, near Nanaimo, 

 B.C. The subjects treated cover a wide range, but they all have, like marine 

 research in general, a very important practical bearing upon fisheries and fish 

 resources of Canada. 



It may be pointed out that the problems which occupy the attention of the staffs 

 of technical investigators at both stations consist either of questions which the Depart- 

 ment of Naval Service finds it urgently necessary to have e^tact and adequate inform- 

 ation upon, or of problems determined by the Biological Board as of importance in 

 the general advancement of knowledge relating to fish life in our seas, or they 

 are lines of investigation which members of the scientific staff have selected as likely 

 to yield valuable technical and practical results. 



Of departmental problems which have arisen in connection with the conserva- 

 tion of the British Columbia salmon fisheries, and especially in the devising of wise 

 regulations, as well as the effective restoration of the supply by fish-culture, the 

 problem of the rate of growth, which Dr. jVIcLean Fraser has still further advanced, 

 in the first report, is of signal interest. It carries to a further stage the work which 

 he summarized in a prev^'ous report, and which he has treated in a number of scat- 

 tered memoirs and papers. 



The second report in the series, by Dr. Fraser, deals with the effects which 

 seem to be associated with severe weather as they influence organisms on which fish 

 directly and indirectly depend for food. The observations were made in the winter 

 and spring of 1915-16, and they show that marine animals in certain instances shifted 

 into deeper water owing to the cool temperature, and fish and other forms had to 

 follow them, and thus change their local hahitat. Not only was much life actually 

 destroyed ; but higher forms such as migratory fishes had the incubation of the eggs 

 delayed, and the fry migrated later than usual. 



The third report, also by Dr. Fraser, emhodies systematic observations, for five 

 yearei, 1914-19, on tTie temperature a-nd specific gravity variations at the sea's surface 

 near Nanaimo. B.C.. 



Miss Fritz's report, forming the fourth in order, gives the results of patient and 

 laborious work in the culture of Diatoms, which form a staple food of the minute 

 crustaceans called Copepods by which young fishes and a multitude of other organ- 

 isms are sustained. 



The fifth report on Plankton Diatoms near St. Andrews, also by Miss Fritz, is 

 a study of material obtained from October, 1916, to October, 1917, and includes eighty- 

 two species. Their relative abundance and scarcity over extensive areas, and at 

 various depths, are detailed and the numbers at various specified stations are given 

 in detail. Counts up to many millions were made, thus in spring (on May 1), 8,750,000 



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