of the Fishery Board for Scotlavd. 335 



the end of tlie second summer the average weight of the haddock is 

 about 6| ounces (188 grammes), while the average weight of the plaice 

 of coiTesponding age is only a little over one ounce (30'5 grannnes). 

 The smallest haddocks weigh about 3| ounces, and the largest about 10 J 

 ounces ; the smallest plaice weigh a little over a quarter of an ounce 

 (9*5 grammes), and the largest about 1| ounces (50 grammes). 



After the third summer's growth the average length of the haddock 

 is about 360 mm., or Hj inches, and its weight about 14| ounces (415 

 gi-annnes), while the plaice of corresponding age has a length of about 

 217nnn., or8| inches, and weighs scarcely 3| ounces (97 grammes). 

 The smallest liaddocks weigh about 10| ounces, and the smallest plaice 

 scarcely 1| ounces. 



The difference between the whiting and the common dab is not so 

 pronounced, but is still very considerable. The average length of the 

 whiting at the end of the first summer is about 125 mm., or 4J-|^ inches, 

 and its weiglit 14 grammes, or half-an-ounce. The average length of 

 the common dab is about 60 mm., or 2~ inches, and its weight is 1-7 

 grammes, not j^ of an ounce. Some of the young whitings measui-e 

 2| inches and others as much as 6| inches, and the variation in weight 

 may be from -^ of an ounce (3 grammes) to lyL ounce (31 grammes). 

 The variations in the dabs may range from 28 mm. (1^ inches) and 0'2 

 grammes, to about S^ inches and 5 4 grammes, or scarcely a fifth of 

 an ounce. 



After the second summer's growth the average length of the whiting 

 is about 8 1 inches, and its weight about 2| ounces, or 77 grammes. At 

 the same date the dab of corresponding age measures about 5^ inches, 

 and weiglis under three-quarters of an ounce (19 grammes). The range 

 in the whitings may be from about 7 to 11 inches, and from under 1^ 

 ounces to about 6 ounces (168 grammes). The range among the dabs 

 of corresponding age luns from about 3| to 6^ inches, and from a 

 quarter of an ounce to nearly 1| ounces. 



These observations in regard to the compar-ative rate of growth of the 

 plaice and haddook, and the common dab and whiting, hold also in regard 

 to other sjjecies. The slow growth of the flat-fishes is especially marked 

 in the first year, and is no doubt then in part directly accounted for by 

 the transformation which they undergo ; and it is throughout life 

 clearly correlated with their change in structure and conformation. 

 Compared with what it is in the round fishes, the whole of the digestive 

 system of the flat-fishes is small relatively to the mass of the body, and 

 the amount of nutriment available for growth is correspondingly less. 

 They have been described as flattened cod-fishes, and it would be equally 

 applicable to say they were dwarfed cod-fishes. 



The Influexoe of Temperature upon Growth. 



Tlie growth of fishes is closely related to the temperature of the water 

 in which they live, the maximum increment taking place when the 

 water is warm and the minimum when it is cold ; and the greatest 

 yariatioiis occur where the range of temperature is greatest. The 

 influence of the temperature of the water on growth is no doubt twofold, 

 directly aflecting it by accelerating or retarding metabolism, and 

 indirectly by increasing or diminishing the abundance of the lower 

 organisms wliich form a large part of the food of fishes. The direct 

 eflect is probably much the more impoi^tant of the two. The informa- 

 tion available as to the temperature of the bottom water in tlie deeper 

 parts of the North Sea tluougliout tlie year is imperfect ; Init it is 

 evident from the scattered observations which have been made bv 



