Report on the Marine Copepoda collected during the Cana- 

 dian Arctic Expedition. 



By Abthue Willey, D.Sc, F.R.S. 



McGill University, Montreal. 



The marine copepod Crustacea, collected by Mr. Frits Johansen during the 

 Canadian Arctic Expedition from 1913 to 1916, covers a wide extent of coast- 

 line from Vancouver island to Coronation gulf in the Northwest Territories of 

 Canada, the whole embracing an area which has been only slightly explored 

 in regard to its micro-crustacean fauna. The comparison of this fauna with 

 that of the Atlantic coast of North America offers remarkable similarities mingled 

 with dissimilarities, as indeed does every other division of the North Pacific 

 fauna. _ The facts discovered justify the expectation that further data will 

 throw light upon the relation of the pelagic copepods to the currents prevaiHng 

 off the west coast. These insignificant arthropods form the basis of the food- 

 supply for pelagic fishes, especially for young fishes, whilst the littoral and 

 bottom-dwelling species have nutritive value for the flat-fishes, either directly 

 or indirectly. 



The copepod contents of Mr. Joh&nsen's samples were generally scanty, 

 so that it was not always possible to indicate their percentage composition. 

 In the present report several species are identified for the first time from the 

 west and northwest coasts, but perhaps the most memorable marine copepod 

 record for the entire expedition is that of Limnocalanus grimaldii from Collinson 

 point, Alaska. It will be found that the collection secured by Mr. Johansen 

 under such arduous circumstances presents several other features of interest. 

 A notable deficiency is the absence, from all the gatherings, of Calanus cristatus 

 which, according to Giesbrecht, is the most characteristic species of the Behring 

 sea and has not been found south of that area. The explanation of its 

 absence is to be looked for in the comparatively small number of stations made 

 by the expedition on the voyage to the Arctic Ocean where their main 

 objective lay.^ 



The number of copepods of the subdivision Harpacticoida taken pelagically 

 by horizontal towing of the plankton nets at or near the surface, in water lanes 

 amid pack-ice, or by vertical hauls through holes in the ice, makes a rather 

 striking commentary on this collection. Just as the pelagic Calanoids make 

 daily excursions to and from the deeper strata of water, so the benthonic or 

 bottom-dwelling Harpacticoids evidently rise toward the surface from time 

 to time. Only one pelagic Harpacticoid was recorded from the east coast waters 

 during the Canadian Fisheries Expedition, 1914-15, namely, Halithalestris croni. 

 This species has not yet been found on the west coast. The clear-cut specific 

 divergence of Danielssenia stefanssoni, in comparison with its Siberian congener, 

 is another point worthy of special mention. 



A. Calanoida. 

 1. Calanus finmarchicus (Gunnerus, 1765). 



This prolific species is common to the North Pacific, North Atlantic, and 

 Arctic oceans. According to the latitude, season, time, depth, and proximity 

 to land or ice, in which it may be taken, it is found associated with very different 

 companions. 



iNoTE. — Most of the macroscopic forms in the Zooplankton (Fishes, Crustacea, Annelids, Medusae, 

 etc.), were picked out before the samples were sent to Prof. Willey. — Frits Johansen. 



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