SEA-FISHERIES LABORATORY. 131 



Board for Scotland, spawning takes place under similar 

 conditions. Our small fish tanks at Piel are only about 

 four feet deep, and we find the fish mature quite 

 normally. During the spring of 1906 we found that 

 some of the adult plaice, collected in Luce Bay in the 

 autumn of 1905, matured when kept in water fourteen 

 inches deep. The fish actually spawned in that depth of 

 water, but the eggs were not fertilised. Very ripe female 

 dabs collected in March, and brought alive to Piel, 

 discharged their eggs in shallow tanks only ten inches 

 deep. In the latter case the eggs were probably too far 

 advanced to be retained by the fish when subjected to the 

 greatly altered conditions of pressure. In the other case, 

 so far as reproduction is concerned, the only apparent 

 difference due to confinement is a slight retarding of th<e 

 maturation of the eggs. We find from the tow-nettings 

 taken in the open sea that plaice eggs were taken in 

 Cardigan Bay on January 23rd, 1906, and off the 

 Liverpool North-west Lightship on the 31st. The 

 occurrence of one plaice egg in Cardigan Bay on 

 December 15th, 1905, and the capture of a spent female 

 plaice in the same bay on January 26th, 1906, has already 

 been recorded by us. Fertilised eggs under artificial 

 conditions were secured at the Bay of Nigg Hatchery on 

 January 20th, t and at Port Erin Hatchery on February 

 20th, 1906.J 



The following tables give the number of eggs 

 collected and of the fry hatched at Piel, and set free on 

 the dates specified : — 



f Twenty-fourth Annual Report Fishery Board for Scotland, part hi, p. 112. 



J Twentieth Annual Report of the Liverpool Marine Biology 

 Committee, p. 17. 



