GoDBY. — Growth of Brouni Trout in Canterbury. 57 



growth has set in the growth follows the normal curve again, getting less 

 every year. This break or jump is probably caused by migration to more 

 favourable surroundings. 



6. Trout which have been stunted by unfavourable conditions for four 

 or even five years, and possibly longer, are still ca])able of rapid growth. 



7. Any particular water seems to have' a fairly definite maximum size 

 of fish. In waters where this is large, such as Lake Ellesmere and the back- 

 country lakes, the maximum size will be reached no matter what the age of 

 migration, and the age of migration seems to have little or no effect u])on 

 the size ultimately attained. 



8. Lake Ellesmere has a maximum size in the neighbourhood of 23 in., 

 but some fish considerably exceed this. Whether this is due to an mherited 

 tendency to rapid growth or to some specially favourable circumstances 

 I cannot at present say. It is certainly a point worthy of investigation. 



9. In Canterbury trout grow much more rapidly in the early stages than 

 in Norway, but the growth slows down earlier. The very large Mjosen 

 trout are mostly very old, and still growing vigorously. The average age of 

 migration is also much higher there than in Lake Ellesmere, for instance. 



10. Yearling trout average about 5 in. in Canterbury, as calculated from 

 the scales. From Victoria Lake 112 yearling trout averaged 6 in., but the 

 conditions there are certainly more favourable than the average. In 

 Norway yearling trout average about 2 in. (Dahl). 



11. Lake Coleridge seems to favour the most rapid growth of all. The 

 sea is slightly more favourable than Lakes Heron, Marymere, and Ellesmere, 

 which are about the same. 



12. Except in very complicated waters, a fair idea of the average growth 

 can be obtained by examining small parcels of ten to twenty fish, provided 

 they aie of fair age and fairly representative. 



I take this opjjortunity of expressing my thanks to Dr. Chilton for much 

 kindly instruction in microscopy, and to the North Canterbury Acclimatiza- 

 tion Society and many anglers for assistance in collecting scales. The 

 photographs are by Messrs. Leghorne and Colgan, of the Radia Studio, to 

 whom I am much indebted for their infinite pains and trouble to secure the 

 best possible results. 



References to Literature. 



(1.) Knut Dahl, The Age and Growth of Salmon and Trout in Norway, as shown by their 



Scales (translated from the Norwegian by Ian Bailee), Salmon and Trout Asso- 

 ciation, London, 1910. 

 (2.) C. H. Gilbert, Age at Maturity of the Pacific Coast Salmon of the Genus 



Oncorhynchus, Bulletin U.S. Bureau of Fisheries, vol. 32 (Document No. 767). 



1912. 

 (3.) C. HoFFBAUER, Die Altersbestimmung des Karpfen an seiner Schuppe, Allgemeiite 



Fischerei Zeitunq, Jahrg. 23, pp. 341-43, 1898 ; Jahrg. 25, pp. 135-39, 150-56, 



297, Miinchen, 1900. 

 (4.) H. W. Johnston, The Scales of Tay Salmon as indicative of Age, Growth, and 



Spawning-habit, Fishery Board for Scotland, Ann. Rep., vol. 23, pt. 2, 1904 : 



vol. 25, pt. 2, 1906 ; vol. 26, pt. 2, 1907. 

 (5.) A. T. Masterman, Rejjort on Investigations upon the Salmon, with Special 



Reference to Age-determination by Study of Scales, Board of Agriculture and 



Fisheries, Fishery Investigations, Series 1, Salmon and Fresh-ivater Fisheries. 



vol. 1, London, 1913 . 

 (6.) H. P. Taylor, The Structure and Growth of the Scales of the Squeteague and the 



Pigfish as indicative of Life-history, Bulletin U.S. Bureau of Fisheries, vol. 34 



(Document No. 823), 1914. 



