278 The N.Z. Journal of Science and Technology. [Jan. 
These could be set free in the larval condition in the streams selected as a 
sanctuary under recommendation 2 following this below. 
2. It is of the greatest importance that one lake, together with the 
streams flowing into it, should be set aside as a sanctuary for the natural 
food-supply. Most unfortunately, this aspect of the question was not 
considered when the stocking of the streams with trout was undertaken. 
The result is that there is at present no lake in the Rotorua district 
which does not contain trout. In the Taupo district, an undertaking 
was given by the Government to the Maoris that Lake Roto-Aira should 
be kept free from trout. Unfortunately, trout were surreptitiously intro¬ 
duced into this lake two years or more ago, and have grown to a considerable 
size. Roto-Aira is at present the only possible lake that could be main¬ 
tained as a sanctuary. 
* 
A. Double trap-net with leaded bottoms, suitable for river with unstable pumice-bed, 
and set so as to catch trout running down-stream. 
B. The same net set with two extra pairs of steel-rope braces, so as to catch trout 
running up-stream. 
The arrows indicate the courses taken by the trout. 
N.B.—The nets should be so designed that plenty of slack is allowed for above the 
leaden weights, so that if a flood washes the pumice bottom out the slack will 
allow the net to sink without lifting the weights from the bottom. 
