68 Part III. — Twenty-seventh Annual Report 



II.— REPORT ON THE OPERATIONS AT THE MARINE FISH 

 HATCHERY, BAY OF NIGG, ABERDEEN, m 1908. By Dr. 

 T. Wemyss Fulton, F.R.S.E., Scientific Superintendent. 



In last year's report, in describing the work of the hatchery in 1907, it 

 was stated that, owing to the small numbers of adult plaice in the spawning- 

 pond, the number of fertilised eggs obtained was the smallest since the 

 hatching operations were begun. In previous years it was the practice to 

 engage a steam-trawler to fish for the plaice for the hatchery either in 

 Aberdeen Bay or the Moray Firth, but this arrargement was terminated 

 at the end of 1905. In the latter part of 1907, through the co-operation 

 of Professor D'Arcy Thompson, a considerable number of plaice suitable for 

 breeding purposes were procured by the Goldseeker in the Moray Firth, and 

 were brought to Aberdeen in tubs in the ordinary way. Although a 

 tolerably large proportion of these died en route, or shortly after being 

 landed — caused in large measure by the bufieting to which the vessel was 

 exposed — the supplies were sufficient substantially to increase the quantity 

 of eggs for the hatchery, and therefore the number of fry which was 

 hatched. The quantity was still, however, far below what was available in 

 former years under the old system, or what the capacity of the pond is 

 adapted for. 



The fii-st eggs were obtained on 13th January, which is about the usual 

 time, whereas in 1907 they were first collected on 25th February, the stock 

 of fishes then being very small. The last lot of eggs was taken from the 

 spawning- pond on 14th May, which is also about the usual time. 



The total number of eggs which were collected in the course of the season 

 was about 15,332,000, as compared with an estimated quantity of 1,626,000 

 in 1907. The number obtained in each month and the percentages to the 

 aggregate are shown as follows : — 



The quantity of dead eggs removed from the hatching apparatus (including, 

 however, the shells of those which were hatched) was estimated at 3,056,000, 

 or 19'9 per cent., which is a lower percentage than usual. In 1907 the 

 death-rate was 21 per cent. ; in 1906, 41 per cent. ; and in 1905, 39 per cent. 

 The reason for the lessened mortality is referred to below. 



During the season the specific gravity of the water remained fairly con- 

 stant at from 27' 2 to 27-4. The water drawn fi-om the beach (examined 

 from the flow from the pump after a time) on two days in April fell to 26'0 ; 

 while the highest reading at any time was 27'6. That in the pond was 

 much the same, the highest reading being 27-6 and the lowest 26*8. In 

 the hatching apparatus it was usually well above 27, but on one day (10th 

 April) it fell to 25-6, and to 26 on the two following days. 



