HOEK— INTRODUCTORY — XVIII — 



plaice taken by the fishermen under the ordinär)' conditions of the trawl-fishery 

 will live when returned again to the sea. 



Passing to the trawling experiments carried out by the investigation-steamers, 

 Mr. G.\RSTANG reports, that the material placed at his disposal enables him to 

 calculate the following factors for many of the lOO North Sea fishing grounds estab- 

 lished by him and for the four quarterly periods (January — March, April— June, 

 July— September, October — December), viz. : 



a. the average size of the plaice captured; 



b. the average catch per hour, for plaice above and below 30 cm.; and 



c. the proportion of small plaice, under 20 cm., in the catches. 

 The author calls special attention to the following general results: 



(i) In the whole region between the Dogger Bank and the coastal grounds, the 

 average size of the plaice taken is considerably greater in the winter quarter] than 

 in the summer quarter, especially than in autumn when the size is at its minimum. 

 On the other hand, the impression is gained, that the maximum size on the Dogger 

 Bank occurs in summer and the minimum in winter. 



(2) It appears from the fisheries experiments, that the small plaice are in much 

 greater quantity on the eastern part of the North Sea than on the western, even 

 in one and the same depths. 



Mr. Garstang concludes his report by referring' to the importance of the 

 results obtained by him for the problem of the undersized fish; so far as can be 

 judged as yet, in his opinion, an increase in the number of small plaice on the 

 coastal grounds would still further retard their growth there; the question then 

 arises, whether such results would be of general advantage to the fisheries or not. 

 Redckc's report Dr. Redeke traccs the variations in size etc. of the plaice taken on certain 



fixed stations as uniformly as possible throughout the year. He describes the 

 migrations undertaken by these fishes and discusses their causes. He has come to 

 the general conclusion, that the distribution of the plaice in the North Sea near the 

 Dutch coast is a function of or varies with the size, and is so regular, that one can 

 almost say the size of the plaice varies in centimeters as the depth varies in meters. 



Fisheries To Committcc C, which was established somewhat later than the other com- 



investigations jjj^^^ggg .^^g entrustcd the fisheries investigations relating to the Baltic. Its work 



m the Baltic ' . 



was really introduced with the meeting at Stralsund m July 1903, where programs 

 were discussed and determined as to the main lines. The work has begun with 

 the preparation of a work, in which reviews over the fisheries (fish-grounds, apparatus, 

 statistics, laws and regulations etc.) are to be given for the various countries 

 participating in the Baltic fisheries ; the intention being, to form afterwards a general 

 work on the Baltic fisheries from these separate reports. Two of these reviews 

 (for Denmark and Sweden) have been sent in and published by the Bureau i; that 

 for Germany is almost completed; those for the other countries are in preparation 

 and will appear soon. 



Distribution With regard to the actual investigations, no final reports are yet to hand. 



of the plaice /pj^Qgg fQj. ^jjg western part of the Baltic have been specially concerned with the 



in the Baltic ^ -^ ^ 



I See: Publications de Circonstance Nr. 13 A. (p. 5 of this General Report). 



