SCIENTIFIC REPORTS. 



I.— REPORT ON LARVAL AND LATER STAGES OF CERTAIN 

 DECAPOD CRUSTACEA (with Five Plates). By H. Chas. 

 Williamson, M.A., D.Sc, F.R.S.E., Marine Laboratory, Aberdeen, 

 Issued separately as Stationery Office Publication, j^rice 2s. 3d. 



IL— REPORT ON THE OPERATIONS AT THE MARINE FISH 

 HATCHERY, BAY OF NIGG, ABERDEEN, in 1909. By Dr. 

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



In the course of the autumn of 1908 several hundreds of live plaice were 

 added to the stock of adults in the spawning-pond, the fish having been 

 caught by the Fishery Investigation steamer Goldseeker in the Moray Firth 

 and brought to Aberdeen. The mortality among these fishes, owing often 

 to the rough passage from the fishing-grounds, was sometimes considerable 

 after they had been placed in the pond, and, as the fact is not without 

 importance with reference to the methods adopted in the " marking 

 experiments " (to ascertain the migrations of fishes), it may be mentioned 

 that of 193 placed in the pond on 12th September, 55 had died before the 

 29th of that month, and of 267 put in on 23rd October, 30 had succumbed 

 by the nest day, and other 36 within a week. 



In consequence of the increased supplies of spawners, the number of 

 eggs collected from the spawning-pond in the course of the season was 

 larger than in the previous year, amounting to about 19,749,000, as 

 compared with 15,332,000 in 1908, the increase thus being about 

 4,417,000. 



The first eggs were collected on 21st January, which is about the usual 

 time for them to appear, and collections were made thereafter almost daily 

 until 26th May, when a few thousands were obtained. The spawning of 

 the plaice thus extended over eighteen weeks, but, as usual, by far the 

 greater projportion of the eggs were shed in March, and particularly just 

 after the middle of the month. It will be observed from the appended 

 table that the spawning was considerable at the end of February, when the 

 temperature of the water was unusually high for the season, and that it 

 was checked later when the temperature fell several degrees lower. The 

 numbers of eggs obtained in each month of the season, and the percentages, 

 are given in the subjoined table : — 



Month. 



January. . 

 February 

 March . . 

 April 



The number of dead eggs which were removed from the hatching 

 apparatus (including, however, the shells of those which had hatched) was 

 estimated at 3,134,000, or a little under 16 per cent., which is a very low 

 B 



