of the Fishery Board for Scotland. 121 
the number of the adult fishes furnishing eggs, and therefore of the 
eggs collected, was considerably under what it was in 1903. As pointed 
out in previous reports, a certain number of the plaice confined in the 
pond die each year, and this loss is ordinarily made up by a renewed 
supply of living adult fishes in the autumn, which are obtained from 
the trawlers employed for scientific purposes in Aberdeen Bay or the 
Moray Firth, the vessels being provided with large tubs for the 
collection of the fish, and a constant circulation of water maintained until 
port is reached. In the autumn and winter of 1903 the same practice 
was followed, but it was found that large adult plaice, suitable for the 
hatchery, were exceedingly and unusually scarce, and thus the stock in 
the pond was only partially replenished. 
The total number of eggs collected from the spawning pend through- 
out the season was 39,600,000, as compared with 65,940,000 in the 
previous year. Most of them, as is usually the case, were obtained in 
March, which is the chief spawning month of the plaice. The numbers 
collected in the various months, and the percentages on the total 
number, are given in the following table, which also contains for com- 
parison the corresponding monthly percentages for the previous season 
in 1903 :— 
Number of Eggs Percentage, Percentage, 
Collected. 1904, 1903. 
January, . 660,000 16 0:3 
February, - 10,320,000 26:1 18:0 
March, - - 22,040,000 5D°7 56:2 
April, - : 6,580,000 16°4 24:1 
ay, - : a 1:3 
Tt will thus be seen, as above indicated, that spawning was, on the 
whole, a little earlier in 1904 than in 1903, nearly 28 per cent. of the 
aggregate number of eggs being collected before March in the former 
year, as compared with 18 per cent. in the same period in the latter year. 
The estimated number of fry which were obtained from the eggs 
amounted to 34,780,000, and they were liberated in seven lots at 
various dates in March, April, and May, off Aberdeen Bay, a fishing 
yawl being employed for the purpose. 
Particulars as to the collection of eggs from the pond and the libera- 
tion of the fry will be found in the tables which are appended. 
The expense of the hatching operations as carried on at the Bay of 
Nigg is small, compared with the number of fry produced. Thisis ~ 
owing to the fact that the hatchery is worked in conjunction with the 
Marine Laboratory, for which pumping operations are required 
throughout the year. The annual expenditure that may be ascribed to 
the hatching work is about £100, the principal items being the main- 
tenance of the apparatus, food for the fishes, and extra coals. 
The hatchery was visited by delegations of fishermen sent for instruc- 
tion by the County Councils of Aberdeenshire and Argyllshire, to whom 
a series of demonstrations was given. 
| TABLES. 
