52 



Truasactious. 



that they are the result of some peculiarity in that fish's growth. Whilst 

 very puzzling, these peculiarities are encouraging, for they open up possi- 

 bilities for fresh discoveries in scale-reading. 



The Back-country Lakes. 



The material examined comprises ten fish from Marymere, fifteen from 

 Lake Heron, three from Lake Coleridge, and two from Lake Alexandrina. 

 Marymere. — The average growth in this lake is as follows : — 



The full figures are set out in Table IV (A), and the growth-curve is 

 shown in fig. 5. The most striking feature of the curve is the large growth 

 made during the second year, which exceeds even that of the first year ; 

 and not only is this the case in the average curve, but it is true of every 



Fig. 5. 



one of the ten fish examined, except one, in which the growth was equal 

 for the first and second years. Such a state of aft'airs would generally be 

 explained by saving the fish migrated at one year old to more favourable 

 conditions. This cannot be the explanation in Marymere, as there are no 

 streams running either into or out of the lake. It must be remembered, 

 however, that the insects in our back-country districts are mostly large in 

 size, and it seems probable that the true explanation is to be found in the 

 fact that the main bulk of the food-supply is of a nature more suitable to 

 fish after they have passed the yearling stage. Gilbert (2) has shown that 

 quinnat and sockeye salmon which have migrated to the sea as fry a few 

 months after hatching have very similar scales. 



