SEA-FISHERIES LABORATORY. 125 



Throughout the whole period the fish were in the tanks 

 they were fed on lug worm (Arenicola), which is plentiful 

 in the vicinity of the hatchery. Mussels with the shells 

 removed were tried at first, but were not eaten by the fish, 

 and were discontinued after a few days. 



The first fertilised eggs were collected on February 28th. 

 From that date onwards the numbers gradually increased, 

 until the maximum was reached in April. After that the 

 numbers rapidly decreased, and the spawning was over by 

 May 10th. During the spawning period nearly fifteen and 

 a half millions of eggs were collected and placed in the 

 boxes for incubation. These eggs produced over thirteen 

 and a half millions of fry, which were set free about the 

 centre of Morecambe Bay. The period of incubation varied 

 from eleven days at the beginning to six days at the end of 

 the season — a reduction of time entirely due to the in- 

 creasing temperature of the sea water, which is shown by 

 the table of temperatures and specific gravities given below. 

 It will be noticed from the table that the specific gravity 

 during the hatching was satisfactory, and never fell below 

 1*026 till after the middle of May. The loss of eggs during 

 incubation from all causes averaged about 11*5 per cent., 

 practically the same as last year. A number of attempts 

 were made to rear flounder larvae, but these experiments 

 failed owing to the difficulty of getting minute natural food 

 in the waters of the channel. 



The following tables show the numbers of eggs collected 

 and fry set free, and also the specific gravity* and tempera- 

 ture of the water during the spawning season. 



*The figures given are simply the uncorrected readings taken with the 

 Kiel areometers. 



