Arthur. — On the Broivn Trout introduced into Otago. 493 



I commonly find a large quantity of shell-fish (Limnaa) in the stomachs of 

 the trout ; and many of our rivers are teeming with these curious little 

 molluscs. That the milky- like and sometimes yellow mud from gold 

 diggings is unwholesome for trout, and destructive to a great extent of insect 

 larvae, I have no doubt. The upper waters of the Shag, the Waitahuna, 

 and Pomahaka are more or less so affected ; and there the trout are com- 

 paratively poor in condition, particularly at the beginning of summer ; 

 notably also on the Deep Stream, for half a mile or so below where some 

 Chinamen were digging five years ago or more, the trout all disappeared, 

 and I question whether any have come back again ; I have seen none at all 

 events. At the same time, I am aware that there are trout in the muddy 

 parts of the Taieri Eiver ; but these are large fish which, I think, have gone 

 there not from choice, but seeking heavier water and more range than 

 existed in the streams they had left. Trout of half a pound, I find, can 

 swallow other fish, as whitebait and crayfish, and feed on them just as 

 comfortably as fish of 5 lbs. or 10 lbs. weight. As to smaller trout than 

 half a pound here, I have never investigated the contents of their stomachs. 

 As no food has yet been found by me in most Wakatipu trout opened, the 

 mystery of their fat condition and excellent taste cannot easily be made 

 out, and its solution must be deferred. 



It is difficult to say what proportion between the sexes of our trout exists ; 

 the question, however, has been forced on my attention owing to the males 

 which I have caught being so few compared with the females. During one 

 season I estimate the males taken by me did not exceed a quarter of the 

 females ! For the last two or three years, therefore, I have made special 

 notes of the sexes ; but while this is comparatively easily done as regards 

 trout over 2 lbs. in weight from their external markings, those of half 

 a pound to a pound I very often found puzzling, and when dissected even, 

 had not sufficient sexual development to make the sex certain. On two 

 occasions in the Deep Stream I killed one male and five female trout, but 

 six days scattered over 1880-81-82 gave 11 males and 17 females. In the 

 Lee Stream also, in four days, from 1879 to 1882, the results were also 11 

 males and 17 females. On the other hand, when I have fished the Shag 

 Eiver at night the trout taken were always males, so far as I recollect. Mr. 

 W. S. Pillans, when taking spawning fish in Lovell's Creek in 1882, got 7 

 males and only 3 females ! Mr. Deans explains this latter case by the cir- 

 cumstance of the females always going away from the redds when spawned, 

 while the males hang about long afterwards. Whatever may be generally 

 the rule here, at present I am of opinion that the females greatly out- 

 number the other sex. The effect of the disproportion, in whichever way it 

 really lies, on the stock in a river would probably be the same, that is, 



