SEA-FISHERIES LABORATORY. 377 



It has been suggested that much the same results 

 would be attained by the removal and fertilization of the 

 ripe eggs from Plaice caught in the course of commercial 

 fishing and the immediate return of these to the sea with- 

 out having undergone treatment in the hatchery. We do 

 not know whether this is practicable, and at any rate, the 

 number of ripe eggs in the ovary of a Plaice at any one 

 time is only a small proportion of the total number pre- 

 sent. This method of obtaining eggs for the hatchery has, 

 however, been adopted at times. The trawling vessels 

 have been boarded on the fishing grounds and ripe fish 

 have been " stripped," the eggs fertilized and taken to 

 the hatchery. 



As we have seen the most striking fact in the life 

 history of the Plaice is its limited range of migration, 

 and this has suggested the possibility of recruiting a 

 limited fishing ground in process of exhaustion, by plant- 

 ing artificially hatched larvae on it. The most economical 

 method of obtaining the eggs would be from fish caught 

 in the course of commercial fishing. Obviously the scale 

 on which the hatchery would most effectively work would 

 be determined by a knowledge of the annual reduction cf 

 the fish population by fishing operations. 



