of the Fishery Board for Scotland. 



Ill 



mentioned below, four delegations of fishermen attended these demons- 

 trations in the course of last spring. 



During the season last year the eggs of the plaice were first discovered 

 floating in the pond on 20th January, which is about the ordinary time 

 when they first occur. Examination of the water some days earlier failed 

 to reveal their presence, and only a few hundreds were obtained on the 

 20th. The number gradually increased up to about the middle of March, 

 and after that declined, the last collection, of a few hundreds of eggs, being- 

 made on the 16th May. 



The duration of the spawning in the pond was therefore about 117 

 days, which may be taken as approximately the period in the sea. The 

 total number of eggs obtained was estimated at 40,110,000. The greater 

 number were collected in March ; the collections in February and April 

 were nearly equal in quantity to one another ; while in January and May 

 comparatively few were obtained. The figures showing the quantity for 

 each of the months, and the percentages in each month for the last three 

 years, are as follows : — 





Number 

 Collected. 



Percentages. 





1903 



1904 



1905 



Mean. 



January, 



1,080,000 



0-3 



1-6 



2-6 



1-5 



February, 



9,242,000 



18-0 



26-1 



23-0 



22-3 



March, 



19,475,000 



56-2 



55-7 



48-5 



53-5 



April, - 



9,431,000 



24-1 



16-4 



23-5 



21-3 



May, - 



882,000 



1-8 





2 - 2 



1-2 



In two Tables which are included in this paper, the particulars are 

 given from day to day of the number of eggs collected and the tempera- 

 ture and specific gravity of the water in the pond, in the hatchery, and 

 on the beach, and of the quantities of fry which were placed in the sea. 



It will be seen that the temperature of the water in the pond when the 

 eggs were first obtained was about 3 , 5°C. (33*8°F.) ; that it remained low 

 to about the end of March, and that towards the end of the spawning it 

 had risen to 10°C. (50°F.) and over it, the highest reading being on 15th 

 and 19th May, when the temperature was 10-6°C. (5M°F.). 



During the season trouble was occasionally caused by the filters, and 

 the death-rate was larger than usual. The number of dead eggs (including, 

 however, the shells of the eggs which had hatched), amounted to about 

 15,790,000, which gives a rate of 39 per cent. The estimated number of 

 fry put out into the sea, as given in Table II (p. 115) may be stated at 

 24,500,000, when allowance is made for the shells of the eggs and the 

 debris contained in the boxes. 



Most of the fry were put out off Aberdeen in March, April, and May, 

 the first lot on the 8th of March, and the last on the 23rd May. One 

 lot, by the request of the fishermen of the district, was taken to St. 

 Combs, further up the coast, on the 24th of April. The fry in this lot 

 were estimated to number about 3,517,000, which were dispatched by 

 rail under the charge of the attendant, the water in which they were 

 placed having been previously cooled to a temperature of 1 , 5°C. (34-7°F.) 

 to obviate risks in carriage. The number of adult plaice found in tha 

 pond, when it was cleaned out after the hatching season was over, was 282, 

 and a fair number of dead fish and the remains of some others were 

 removed. 



