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rate of growth: the ''Southern Plaice", which is restricted to the southern and south- 

 eastern parts of the North Sea, and which grows more slowly, being therefore, smaller 

 at an equal given age, and the "Nortliern Plaice", found in the northern waters of the 

 North Sea, which is a quicker-growing and larger form. The boundary between them 

 would be a line drawn approximately from Flamborough Head on the English coast, 

 north east round the Dogger Bank to the Liimfiord. The territory of the Southern 

 Plaice, lying south of this line, is by far the richest plaice-ground of the North Sea, 

 being the home of certainly 90 % of the total number of plaice in the North Sea, and 

 forming the real seat of its plaice fishery. One of its characteristics is the wide 

 extent of the coastal zone up to 40 metres deep. The territory of the Northern Plaice 

 is considerably deeper than that of the Southern Plaice, and is in its western part, off 

 the coast of North England and Scotland, distinguished by the extraordinary narrowness 

 of the shallower coast belt up to a depth of 60 metres. The spawning grounds, for 

 instance in the Moray Firth, and the narrow coastal zone, inhabited by the young 

 plaice-spawn in their first year, are here very close together, and the whole life of the 

 plaice is thus lived within a much more restricted space. As the depths of over 80 

 meters are already generally very poor in plaice, this also explains the much greater 

 paucity in numbers of the stock of plaice in the northern North Sea. 



The density and composition of the stock of plaice in different areas being thus 

 extremely variable, and the nature, extent and yield of the plaice fishery correspondingly 

 so; and as both are dependent on the depth of the fishing grounds and their distance 

 from the coast, it is necessary, in order to give a comprehensive view of these condi- 

 tions, to suitably subdivide the North Sea into areas. With this end in view, we 

 have here employed the method of division of the North Sea into depth zones (Areas 

 A, B, C, D, E, F, G) as first adopted in England, and proposed at the meeting of the 

 Central Council in Copenhagen, July 1905, together with the geographical subdivisions 

 of these zones, as shown on the chart appended. This method of division, besides 

 agreeing well with the natural conditions pertaining to the distribution of the plaice, 

 also permits of the place of capture for the landings of plaice at the fishing-ports being 

 located in these areas without any serious error, thus determining the exact place of 

 origin of the landings from the individual areas of the North Sea. 



If we designate all plaice under 25 cm. in length, (and under 150 grammes in 

 weight) as ''young" plaice, — since they include fish of the first three to four years of 

 age — and as "undersized" , in view of the fact that their value as an article of human 

 consumption is only small, we can then use the term "young-fish grounds'' to designate 

 those fishing grounds where such plaice occur in greatest numbers, amounting for in- 

 stance, to more than the half of the plaice taken in a trawl catch. These young-fish 

 grounds are naturally, from a practical point of view, the most important in considering 

 the plaice question: it is here that the greatest catches and at the same time the 

 greatest destruction of young undersized plaice occur. The International Investigations 

 have therefore paid special attention to the exact location of these young-fish grounds 

 and the investigation of their population of plaice, as well as of other fish and plaice- 

 food. In the southern part of the North Sea, which practically comes first in consi- 

 deration of the plaice question, these young-fish grounds lie in the broad shallow 

 coastal zones, at a depth of from 10 to 40 metres: indicated here as Areas A and B 

 (with the exception however, of Area Bi, the Dogger Bank, which is an open sea 



