96 TRANSACTIONS LIVERPOOL BIOLOGICAL SOCIETY. 



same form as during the past five years : — (1) The lengths 

 of the plaice caught, given in centimetre groups; (2) the 

 values of the length- weight coefficient h, that is, the index 

 of the average condition of the fish, on the various grounds, 

 and at different seasons; (3) the age, sex, and phase of 

 sexual maturity of the plaice examined in the laboratory. 



Dr. Johnstone also adds to this report a summary of 

 the investigations of the same kind carried on during the 

 years 1909-1913. This includes statements of the average 

 sizes of the plaice found on: — (1) The summer fishing 

 grounds between Blackpool and Liverpool Bar ; (2) off the 

 Estuaries of the Mersey and Dee; (3) on the shrimping 

 grounds in the Mersey Estuary; (4) on the winter fishing 

 grounds off the coasts of Carnarvon and Anglesey; and 

 (5) in Luce Bay (for the years 1908-1912). Tables showing 

 the actual numbers of fish at each centimetre of length, in 

 each month of the year, and also the percentage of the 

 whole catches per month and ground, at each centimetre 

 of length, are given, and also summary statements as to 

 the weight and length, and also the age and length, of the 

 plaice examined. 



This statement for the quinquennial period 1909-1913 

 has been made in order to find, if possible, any deficiencies 

 in our methods, and any possible ways of improving our 

 scheme of investigation. It seems to show that the 

 measurements are useful so far as they go, but are not 

 numerous enough. The plaice fisheries in certain parts 

 of the district are still uninvestigated, although the 

 inclusion of these fisheries was provided for in the scheme 

 approved by the Development Commission. Also, we are 

 of opinion that these measurements should be extended to 

 all soles caught, and that the investigation of the sole 

 spawning grounds should be made during the coming 

 summer. 



