xxviii DEPARTMEyr OF THE J AVAL HEltVICE 



ever, from the present investigations, to come to any final decision here, but the work 

 done has certainly raised questions of the greatest importance for future Canadian 

 fisherj^ investigations. 



These waters are, of course, extremely interesting from the most general biological 

 jDoint of view. We find here, in one and the same area, and with only a water layer of 

 a score of fathoms between, cod spawning on the floor of the banks, in water of absolu- 

 tely arctic temperature, while at the surface, directly above, spawn southern forms such 

 as the mackerel, wliich have possibly migrated from the water layers just off the Con- 

 tinental Shelf where the last remains of the Sargasso weed are still to be found. And 

 a single haul at the surface will be seen to contain pelagic eggs of both these species of 

 fish. 



Of tlie remaining plankton, only two groups have been dealt with up to the present, 

 viz., the Cha3tognaths, by Dr. A. G. Huntsman, and the Copepods, by Prof. Arthur 

 Willey. These two studies afi^ord, however, in themselves, excellent examples of what 

 plankton investigations can yield in the way of results, and of the methods which 

 must doubtless best be employed until better implements are available for ciuantitative 

 study. Of the comparatively large and not so very numerous Chsetognaths, Huntsman 

 has given estimates for the total number of individuals in the samples. In the case of 

 the small and numerous Copepods, this was impossible, and the method here adopted 

 v.'as therefore to determine, from a small selected sample, the percentage of com- 

 position represented by the separate species. In the case of some few more important 

 forms (especially Calanus finmarchimis) , Willey has given also the percentages of the 

 various principal stages of development in the sample. 



Thus the two papers illustrate the occurrence of various biological types, viz., 

 those pertaining to the oceanic water of the Atlantic, those of the colder boreal water 

 layers, and finally those of the fresher coastal layers And a study of these plankton 

 reports, compared with those of the hydrographical work, will give an idea'of the 

 marked agreement between the distribution of the animal forms concerned and that 

 of the various water layers. 



The results of the fishery investigations proper, i.e., investigations as to the actual 

 life and occurrence of the fish themselves, cannot yet be given in their entirety, as the 

 treatment of part of the material is not yet concluded. Up to the present, we have 

 only Mr. Einar Lea's description of all the herring samples; this section is, however, 

 after all, the most important part of the work from a biological point of view, and the 

 primary object of the expedition is thereby attained. 



Mr. Lea has in his paper given a thorough explanation of the methods employed 

 in age and growth determinations, based on examination of the scales, and the work 

 will therefore, it is hoped, prove useful in future Canadian fishery investigations. 



For the rest, I would merely point out that Mr. Lea's careful researches have satis- 

 factorily demonstrated what the results of my preliminary investigations had already 

 indicated, viz., that there are in the Canadian waters distinct types of herring, 

 excellently characterized by their maimer of growth and the difference in age com- 

 position. His thoroug-h treatment of the material likewise shows that the various areas 

 exhibit the same peculiarity as has been found so markedly apparent in several Euro- 

 pean (and especially Norwegian) waters, to wit, the pronounced fluctuation in the 

 increment of young individuals from year to year, whereby the age composition of the 

 stock reveals an enormous predominance of some few extremely rich year-classes, while 

 others hardly contribute in any appreciable degTee to the numerical value of the whole. 

 The conclusions here arrived at, regarded together with the like results which are 

 becoming, apparently, more and more common in various spheres of biological research, 

 force us to admit that hitherto prevalent views not only on leading fishery questions, 

 but also of general biological problems as to the maintenance of species, and all that is 

 comprised in the old Malthusian ideas, will need to be essentially revised. 



