460 SOME RESULTS OF THE INTERNATIONAL FISHERY INVESTIGATIONS. 



essential if we wish to understand ihe conditions of the sea fisheries. 

 If we wish to know, for instance, whether small plaice are more 

 ahundant near the shore than in the ofluig, or whether they are more 

 abundant in shallow than in deep water, or whether the plaice near the 

 shore are larger or smaller than those off-shore, or what is the pre- 

 dominant kind of fish present from time to time on any part of the 

 sea bottom ; in all these, and in many other cases, it is only by 

 making experiments with nets of different forms that we can obtain the 

 desired information. 



Such fishery experiments, made chiefly by means of the large com- 

 mercial otter-trawl net, have been carried out by both the British and 

 continental exploring vessels. It would be unprofitable at the present 

 time to attempt to make exliaustive analyses of the results obtained. 

 These are still incomplete — indeed, the results of the Scottish experi- 

 ments are not yet published. It is when the results of the five years' 

 experiments are collected that they can most usefully be discussed. 

 But while this is the case, some results of interest are already apparent. 

 The English fishery experiments show that small plaice are much more 

 abundant in the shallow waters near the land than in the deeper 

 w'aters off-shore. Plaice of less than 8 inches in total length were, as a 

 rule, restricted to a strip of sea lying between the laud and the 

 10-fathom line. There they were relatively very abundant. On the 

 shallow grounds off the coasts of Holland they were much more 

 abundant than in corresponding depths of sea near the English coasts. 

 On the " Eastern Grounds," that is, the shallow-water area off the 

 islands of the Zuider-Zee, off Heligoland and the coast of Denmark, 

 some distance from the land, the English steamer Huxley took average 

 catches of from 180 to 2500 plaice of this size per hour of trawling.* On 

 the fishing grounds of the same depths off the English coasts the Huxley 

 never took more than 65 plaice per hour. Again, medium-sized 

 plaice 10-12 inches long " were altogether absent on many of the 

 English in-shore grounds " ; but on the fishing grounds well off the 

 land, in fact, over the greater part of the southern part of the North 

 Sea, south of latitude 53° 30', in what may be called the Flemish 

 Bight, these plaice formed an extensive portion of the catch. A legal 

 size limit, if this should be adopted on an international scale, could not 

 be greater than 12 inches if trawling for plaice were to continue on 

 these grounds. Up to 12 inches in length the plaice is very generally 

 an immature fish, that is, it has not yet produced spawn. The pre- 

 dominant plaice population of the southern part of the North Sea is 

 therefore an immature one. 



Mature plaice in the North Sea are very generally fishes of over 



* Garstang, Fishery and Hydrographical Invatigations, etc. (cd. 2670), 1905, p. 102. 



