100 Transactions of the Royal Canadian Institute 



We have undertaken to investigate this matter more thoroughly, in 

 the behef that it has a very general import, and that it vitally affects 

 the distribution and abundance of many of our commercial fishes. 

 We purpose using Sagitta elegans as a type, inasmuch as it is of very 

 general occurrence, and is of such sizes as to be obtained easily in plank- 

 ton hauls in all stages of its life history. 



We are indebted in this, as in many other instances, to Professor A. 

 Willey of McGill University, for much advice and assistance, particularly 

 in the matter of the discovery and identification of the eggs of Sagitta 

 elegans. 



Vertical Distribution. 



The adults are usually confined to the deeper levels of the water. 

 This is shown by the results of hauls made in deep water some distance 

 from land, as at "Prince" stations nos. 2 and 3 (Huntsman, 1919, p. 463). 

 Vertical hauls from near the bottom yielded a considerable number of 

 individuals, whereas tows made near or a slight distance below the sur- 

 face (down to 20 metres) gave none, or only one small specimen. In 

 channels and near shoals where the strong tidal currents effect a con- 

 siderable vertical movement of the water, all stratification is lost. Not 

 only do the tows made at any depth almost invariably yield Sagittae, 

 as at "Prince" station 1 (Huntsman, 1919, p. 463), but also it is a cus- 

 tomary experience to see the animals darting to and fro near the surface 

 of the water in the channel (Quoddy river) where this station is situated. 



We may quote from a previous account (Huntsman, 1919, p. 465) 

 based upon conditions not only in the Bay of Fundy but in our Atlantic 

 waters generally. ''Sagitta elegans is confined to water of comparatively 

 low salinity. It is affected by light, coming nearer the surface at night. 

 It is affected by temperature, keeping to the colder water. The young 

 behave differently from the adults, living in the lighter, warmer surface 

 water. With increasing age it becomes gradually restricted to the 

 darker, colder water, which is deeper." 



The waters of the Bay of Fundy on the whole exhibit little stratifi- 

 cation, the mixing action of the strong, tidal currents resulting in a 

 comparatively uniform condition from surface to bottom. This tends 

 to eliminate the factors of temperature and salinity in the vertical 

 distribution. It would seem that light remains as the dominating 

 factor. 



The following records show the vertical distribution for the latter 

 part of the summer of 1916 at several points in the Bay of Fundy. 

 Station No. 3 is between Grand Manan island and Nova Scotia; station 

 no. 5 between Campobello island and the Wolves; and station no. 23 



