86 TRANSACTIONS LIVERPOOL BIOLOGICAL SOCIETY. 



and for each centimetre group have also been found, but 

 the tables are not published, since they can be 

 summarised in a future report. In this connection I add 

 a short note relative to the length-weight function in 

 the plaice. 



The Length and Weight Relation in Plaice. 



In 1903* Professor A. Meek showed that the weight in 

 ounces of a plaice is given by the relation w = al 3 , 

 I being the length in inches and a a coefficient, which 

 was found in the series of figures considered to be about 

 00067. Subsequently Professor D'Arcy Thompson 



suggested that the formula 



. n . . 7 (length in centimetres) 3 

 weight m grams = k X — — — 



should be used in fishery investigations. It was adopted 

 by Henking and Heincke in 1907, t and has since been 

 generally employed. 



The coefficient k ranges in value from about 0*7 to 

 about 1*2 according to the fishing ground, the season, 

 and the length of the fish. It is a reliable index of the 

 vague attribute known as the " condition " of the fish. 

 When a plaice is plump and well nourished, and full of 

 roe, k is big; when it is thin, " watery," or spent, k is 

 small. 



Generally speaking it is greatest in the early 

 summer months, and least in the late winter, since at the 

 latter season plaice usually cease to feed. In the case 

 of a summer fishery, such as that carried on during the 

 months, June to August, near Nelson Buoy and its 

 vicinity, this is the way in which k varies ; but in the 

 case of a winter fishery, such as that carried on off the 

 coast of North Wales during the months of October to 



♦Northumberland Sea- Fish. Committee. Kept, on Sci. Invests, for 

 19C3. Newcastle, 1903, p. 40. 



f " Schollen u. Schollenfischerei." Beteilig, Deutschlajids a. 4- Ipt, 

 JKeerepfqrsch., IV, V, Berlin 1907. 



