20 



DEPARTMENT OF THE NATAL SERVICE 



Length — Weight Ratio. — Concluded. 



In (Comparing the cohos of 1917 according to tlie groivps into which they have 

 been placed, those from Quathiaski and those from Lasqueti have practically the same 

 rate of growth throughout the three years, while those from Na.naimo and still more 

 those from the Fraser river, have greater growth in each year than these. In all 

 probability some of the Fraser river coho, if not all of them, had been out to the open 

 (Sea, and some of the late caught Nanaimo fish may have been, or may have been 

 living in the deeper water of the strait, since i-n. 1917, as in previous years, most of 

 the larger fish were caught late in the season. Since these fish have greater growth in 

 each year, it seems that in the case of the coho, as in the case of the spring salmon, 

 those that go out to the open sea get better feed and are larger fish than those that 

 remain within the confines of the strait throughout their marine life. On the other 

 ha-nd the data available for 1917 indicate that there is comparatively little difference 

 in the fish that remain in the inner waters, no matter what river or creek they pass 

 np to spawn, or at any rate that the fish from the various riversi and creeks roam about 

 the strait, so that a cosmopolitan lot is likely to be caught in any one locality unless 

 this locality is at the mouth of a river or creek, where the members of an individual 

 race have congregated before the final migration begins. The relatively small iiumibeT 

 of males in the fish from Quathiaski is unusual in the cohos as far as observation has 

 gone. All the others more nearly retain the equilibrium, although the males are in the 

 majority in every instance. Seldom anywhere among the Pacific salmon has the 

 average length of the female been fouiid to be greater than that of the male as it Was 

 h\ the case of the coho from Lasqueti and from the Fraser river. In the ratio of 

 weight to length there is no indication of any definite difference between male and 

 female or between those in the different groups. 



The Nanaimo group may be. compared with those of 1916 and 191.5. The first 

 .vear's growth corre.«iponds exactly with the growth of those caught i-a 1916, and is 

 somewhat greater than in those caught in 1915. The second year's growth is the least 

 of the three years, 1915 and 1916 beiufg nearly equal. The greatest difference is shown 

 in the third year's growth, that of 1917 being considerably greater than that of 1916 

 but much less than that of 1'915. Since there is the greatest difference here the total 

 length varies in much the same proportion as the third year's growth. 



The ca.t<?h of coho i-n the strait is getting less year by year. One might suppose 

 that there might be more food more easily procured for those that remain and that 

 these should grow larger. Since they do not do so, there must be other limitations 

 to growth than those depending on the amount of available food. 



Humpback. 



Of the 925 humpbacks examined from the 1917 run, 181 were caught in Deep- 

 water bay, 231 in the Fraser river and 513 near Pender island in the vicinity of Haro 

 strait. The first lot was obtained at the Quathiaski cannery, Jjily 21 and S-S, and 

 the other two at the Nanaimo cannery, August 15 to August 30. As many would 

 have been taken from the Fraser river as from Pender island if it had not been that 

 after the first few were caught the scales were too badly disintegrated at the margin 

 to make growth calculation possible. All of the scales used for calculation were in 

 ficood condition. 



