194 TRANSACTIONS LIVERPOOL BIOLOGICAL SOCIETY. 



grounds iii Menai Straits and in the shallow water 

 immediately offshore from this area, these only contribute 

 a part of the plaice population forming the material for 

 the fishery offshore from them. A study of the statistical 

 data of this Report, as well as that of the marking experi- 

 ments, will show that this stock of fish is derived to a 

 considerable extent from that present on the grounds to 

 the North-East during the few months prior to the date 

 of the fishery. 



Thus the fishery is mainly an autumn and winter one. 

 Plaice are (commercially) absent from these grounds 

 during the months of March, April, May, and June. A 

 certain amount of fish are taken during July, August, 

 and September, but this is small, and it would probably be 

 found from a careful study of the Board of Agriculture 

 and Fisheries " D 2 " form that the plaice in these months 

 were caught in and about " Channel Course," that is, 

 anywhere between Point Lynus and Liverpool North- 

 West Light Vessel. About October the fishery begins to 

 be a commercially productive one, and from this month 

 until January, the plaice are mainly caught between 

 Colwyn Bay and Red Wharf Bay. There are well-marked 

 differences from year to year in the mean positions of 

 the grounds from which the bulk of the fish are taken, and 

 even a study of the results of the fish-marking experiments 

 in this and former Reports will show that sometimes the 

 main fishery lies offshore from Great Orme's Head, while 

 in other years it is concentrated in Red Wharf Bay, or is 

 scattered over the deeper grounds offshore from this Bay 

 down towards the 20-fathom contour line. 



About the end of the year the fishery ceases. The 

 precise date of its commercial cessation varies from year 

 to year, sometimes, as in 1912, it began to fall off in 

 November, in other years, as in 1909, it only began to 



