180 



Part III. — Twenty-fourth Annual Report 



series of papers in the Annual Reports of the Board.* The numbers of 

 the various species measured for this work, and already dealt with, are as 

 follows : — 



Plaice, - 



17,950 



Gurnard, 



5,495 



Common Dab. 



26,230 



Norway Pout, 



7,192 



Flounder, - - 

 Lemon Dab, 



231 



Hake, 



571 



2,201 



Herring, - - 



19,806 



Witch, - - 



3,422 



Sprat, 



6,473 



Long Rough Dab, 



20,261 



Grey Skate, 



432 



Turbot, 



212 



Angler, 



722 



Brill, - - 



807 



Armed Bullhead, 



1,312 



Cod, 



7,176 



Lesser Weever, 



417 



Haddock, - 



28,760 



Lumpenus 



738 



Whiting, - 



58,164 





Numerous measurements of other forms, as halibut, megrim, ling, pollack, 

 coalfish, tusk, catfish, have also teen made, and will be dealt with later. 



Most of the fish were measured on board commercial steam-trawlers, 

 engaged either in trawling investigations in territorial waters or in 

 commercial fishing in the North Sea. 



Methods. 



In a previous papert I gave a full account, with illustrations, of the 

 method adopted in collecting and measuring the fishes. Besides this 

 method, there is no doubt that much may be learned by keeping 

 fishes in confinement, and measuring and weighing them from time 

 to time, for comparison with those obtained on the fishing grounds, and 

 this has been done. Another method, referred to above — viz., labelling 

 the fish — has also in certain cases given good results, most, perhaps, with 

 flat-fishes. Recently a fourth method has been employed, especially in 

 Germany, by the examination of the markings on the scales, otoliths or 

 ear-stones, and bones. It has also been used in the international investi- 

 gations in this country by Garstang and Wallace, with reference particularly 

 to the growth of the plaice, and the results agree with those obtained by 

 a study of the measurements.^ 



Comparison Between Different Species. 



While one general result of the investigations on the rate of growth of 

 fishes has been to show that they do not grow so fast as was generally 

 believed, it has been made clear that different species may increase at 

 different rates, apart from differences in size. In fishes which undergo a 

 marked metamorphosis, growth is sometimes, and perhaps always, slow, 

 especially at early periods. It is thus with the plaice and other fiat-fishes, 

 with the eels, and with the herring and sprat. Among round fishes, as 

 the cod, the haddock, and the whiting, on the contrary, growth is com- 

 paratively rapid. A young haddock grows many times faster than a 

 plaice. 



With regard to the age at which fishes attain mature size and begin to 

 reproduce, similar differences exist. So far as the investigation has gone, 



*19th, 20th, 21st, 22nd. 



f Twentieth Annual Report, Part III., pp. 228-334. 



X North Sea Fisheries Investigation Committee. Report (No. 2, Southern Area) on 

 Fishery and Hydrographical Investigations in the North Sea and Adjacent Waters. 



