Arruur.—On the Brown 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 
larve, 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 River; 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]bs, 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 
River at night the trout taken were always males, so far as 1 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 Í 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, 
