1038 REPORT OF COMMISSIONER OF FISH AND FISHERIES. [2] 



from their greatest enemies — the larger ones — by keeping them assorted 

 according to size, irrespective of age; directing and equalizing the in- 

 flow of water proportionate to the number and size of the fishes in each 

 pond; guarding all possible avenues of escape of the fishes from one 

 pond to another, as well as into the waste channel, and in removing the 

 masses and collections of the ever-generating algse floating against and 

 clogging the screens — a source of great annoyance on hot, sunny days 

 that are especially favorable to its formation. 



At the hatchery, but little preparation for the hatching season was 

 necessary, everything having been put in order at the close of this 

 branch of work in April, 1881, and left in readiness to resume opera- 

 tions again at the proper time. The few essential preliminaries in this 

 direction, as well as in connection with the water facilities and adjuncts, 

 were therefore arranged in September and October, cotemporaneously 

 with the work of revising the trout ponds. 



As the estimates contemplated increased work in the way of propa- 

 gating whitefish, increased hatching capacity was provided by displac- 

 ing a double row of hatching-boxes with a tier of tanks, which were 

 subsequently equipped with hatching-jars. 



Possible and manifestly weak places in connection with the spring 

 pond and its three outlets were repaired and strengthened to better guard 

 against leakage and imminence of danger of outbursts. The discharg- 

 ing channels alluded to provide for drainage, for overflow, and for con- 

 veying the water to the reservoir from which the tank room is supplied. 

 Being made of wood and laid underground, they have usually lasted not 

 to exceed 4 or 5 years, and, in spite of their being thoroughly caulked 

 when laid, leak more or less after a time. Then, the draught-pipe be- 

 tween the spring pond and reservoir must, of necessity, pierce the dam 

 near its surface to give suflicient head of water in the hatchery, and, 

 being so near the surface, has been lifted from its bed by upheavals of 

 frost, the water percolating underneath. The overflow being still nearer 

 the toj) of the dam is even more liable to be thus forced from ])osition; 

 and nothing short of constant vigilance at times has prevented the 

 water getting suflicient start in this way to wash a gorge across the 

 highway that creates the dam, which would soon draw the pond below 

 the draught pipe, and thus discontinue the supply for the hatchery. 

 The overflow in use having become quite unserviceable through age, I 

 decided to guard against further insecurity at this point by replacing 

 it with pipes of iron firmly imbedded in cement and gry.vel. This was 

 accordingly done, and no further trouble from this source is anticipated. 

 The drainage and draught pipes, after being thoroughly caulked, were 

 considered safe for another season — the one just closed. But as there 

 is now more or less leakage, which is a constant menace to the safety of 

 the dam, and as it is important to secure immunity from danger of de- 

 stroying the water power during the hatching period, these must also 

 be replaced by iron conductors of sufficient caliber for the purpose, 



