REPORT OF COMMISSIONER OF FISH AND FISHERIES. 49 
barely sufficient in the ponds north of the hatchery to sustain life, 
consequently this loss was unavoidable. 
The breeding stock of rainbow trout on hand at the beginning of the 
year numbered about 4,000, their age ranging from one to ten years. Of 
these, about 2,500 were classed as spawners. The seasonextended from 
November 4 to February 10, and resulted in the collection of 1,255,800 
eggs from 1,224 fish, an average of 1,025. The size of the eggs was 
more uniform than last season, the variation being from 355 to 438 to 
the ounce, though the majority ran about 381. About 25 per cent of 
the eggs collected were unfertilized or lost during incubation, 417,000 
were shipped to other stations and foreign applicants, and 524,000 
were hatched. 
The loss of brood-fish was more than double that of any previous 
season, amounting to nearly 700, or about 33 per cent of the fish 
handled. This was unquestionably due to the inexperience of the 
spawn-takers, the foreman and fish-culturist both being absent during 
the spawning period. Most of the fish lost were the larger females. 
In January two consignments of brook-trout eggs were purchased 
from New England dealers, and reached the station in apparently good 
condition, though there was a subsequent loss of several thousand. 
For the first three weeks after hatching the rainbow and_ brook- 
trout fry were fed six times a day on canned herring roe. From that 
time they were fed four times a day until they were ten weeks old, 
when the roe was gradually discontinued and liver substituted. At 
the age of three months the usual mixture of liver and mush was 
given to them. 
The water was unusually muddy during the summer months, which 
was of course very injurious to the young fish of all kinds and espe- 
cially to brook trout. The death rate increased from 40 to 50 per day 
to several hundred, and on two or three occasions, when the water was 
very muddy, over a thousand were lost. 
The rainbow trout were not so seriously affected from this cause, 
but late in June they were attacked by parasites in large numbers. 
This parasite (Gyrodactylus elegans) is described by Livingston Stone 
in his book on the Domesticated Trout, also by J. J. Armistead, in 
Angler’s Paradise. After trying a number of remedies it was finally 
destroyed by the use of common apple vinegar. The vinegar was 
diluted with water to a 25 per cent solution, and in this the fish were 
dipped, a net full at atime, and allowed to remain from 2 to 4 seconds, 
according to the size and age. This treatment does not injure the 
fish and is an absolute remedy for the parasite. Care should be taken, 
however, not to have the solution too strong nor allow the fish to 
remain in it too long. 
Early in April the brood rock bass were placed in suitable ponds 
and a number of gravel nests provided for them. On April 19, just as 
F. C. 1901—4 
