CANADIAN FISHERIES EXPEDITION 



ATLANTIC VVATEKS OF CANADA 



REPORT OS THE COPEPODA OBTAINED IN THE GULF OF 

 ST. LAWRENCE AND ADJACENT WATERS, 1915. 



BY 



PROFESSOR ARTHUR WILLEY, D.Sc, F.R.S., F.R.S.C, etc. 



Professor of Zoology^ McGill University, Montreal. 



PART I. 



The pelagic Copepoda are small Crustacea averaging less than five millimetres in 

 length, whose abundance in the sea is the measure of their importance as a direct 

 source of food-supply for the young of the commercial fishes. In addition, they are 

 pre-eminently the food of the herring which in its turn is preyed upon by larger fi.<5he8 

 such as the cod and halibut. Accordingly, the investigation of their distribution as 

 governed by depth, season, currents, salinity, and temperature, is generally recognized 

 as having an economic bearing, for fishes will necessarily assemble in places where 

 their food is plentiful. Much work has been devoted to this subject in recent years, 

 especially in European waters, the general purpose of such investigations being to 

 correlate the movements of these organisms with the seasonal migrations of fishes and 

 with the seasonal variations of currents. In the IS'aples monograph of the pelagic 

 Copepods (1892), the author. Dr. W. Giesbrecht, remarks that very little information 

 was at that time available for the northern part of the Pacific ocean and for that part 

 of the Atlantic ocean which lies between the 35th and 48th parallels of north latitude. 

 It is convenient to remember that cape Cod is situated a little above 42° 'N. In Cana- 

 dian waters there had been no quantitative study of the zooplankton up to the year 

 1915, but the gulf of Maine and the coastal waters between Nova Scotia and Chesa- 

 peake bay have quite recently been thoroughly explored during two seasons, the sum- 

 mers of 1912 and 1913, by the United States fisheries schooner Grampus, under the 

 direction of Mr. Henry B. Bigelow. 



The investigation has to be conducted along two lines : systematic and hydrogra- 

 phical, which in this case is tantamount to saying qualitative and quantitative. The 

 object of the first method is to identify the species, in itself a matter of no little diffi- 

 culty, involving many microscopic examinations. The second method seeks to deter- 

 mine their relations to the physical and biological conditions of the local environment. 

 In 1901, Dr. W. ^[. Wheeler published a systematic report on the free-swimming 

 Copepods of the Woods Hole region. The delimitation of this region was interpreted 

 in a liberal sense so as to include not only Vineyard sound but also Plymouth harbour, 

 Mass., and that part of the Gulf Stream which lies 60 to 80 miles due south of Martha's 



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