MARINE PISCICULTURE 307 



Plaice . . .;.. -. 340,455,000 



Lemon soles .... 5,727,000 



Turbot. . . . . 5,160,000 



Cod . . . . . 4,010,000 



Other fishes . . , . 2,000,000 



Since 1897, sea-fish hatcheries have also been 

 established in England, at Piel, in Lancashire, 

 by the Fisheries Committee of that county ; and 

 at Port Erin, Isle of Man, by the insular govern- 

 ment. 



The methods adopted in the artificial culture of 

 sea-fish differ somewhat in the various establish- 

 ments. This is particularly the case in the manner 

 in which the eggs are obtained. Commonly sea- 

 fish eggs for incubation in hatcheries are obtained 

 direct from fishes kept on the establishment. 

 Several months before the onset of the breeding 

 season a sufficient number of fish are obtained, of 

 such sizes that they may be expected to yield 

 spawn at the next spawning season. Generally one 

 male produces sufficient spermatozoa to fertilise 

 the eggs of several females, so in obtaining the 

 fish this is taken into account a somewhat 

 difficult matter, as it is not always possible to 

 distinguish between immature females and mature 

 males. The stock of breeding fish are either 

 specially fished for, short drags with a fish trawl- 

 net being made, so as to obtain the fish in as healthy 

 a condition as possible, or they are purchased from 

 the vessels engaged in the commercial fishery. 



