— 6o — 



would only be obliged to change their fishing grounds, these sailing vessels, which are 

 fitted for the capture of live plaice, would soon be forced, by the introduction of a 

 comparatively low size-limit, to give up fishery entirely as unprofitable, or alter their 

 methods of fishing, for instance, by introducing the Danish "Snurrevaad" and building 

 larger vessels with motor engines. Conducted on these lines, plaice fishing can be made 

 to pay, even with a size limit of 26 cm., at least in the areas As and B4, as is clearly 

 shown by the results of the Danish plaice fishing in the North Sea. 



If it were possible, by means of the introduction of an international size-limit (e.g., 

 of 26 cm.) to render unprofitable, and thus entirely prevent the trawling of the coastal 

 areas of the southern North Sea, or at any rate the young-plaice grounds therein con- 

 tained, for a great part of the year, this would certainly mean an effective protection 

 of the younger stages, not only of the plaice, but also of other important food fishes, 

 such as the common sole and the turbot. The protection would mean practically the 

 same thing as the introduction of close seasons and closed areas, with this essential 

 difference however, that it is left entirely to the fishermen themselves how far they 

 will respect the close seasons and closed areas, this being for them only dependent on, 

 whether the fishery pays or not. 



The height of the size-limit must then be determined, on the one hand, by the 

 probability which it affords for the protection of the young plaice as stated above, and 

 on the other hand, by the loss caused to the fishery of the different countries by the 

 introduction of such size- limit. 



The loss which would be suffered by the different countries owing to size-limits of 

 various height, can only be calculated from those series of measurements which we have 

 obtained as to the composition of the landings based on market measurements. We 

 can designate as loss the quantity of those plaice which lie below the length of the size- 

 limit given, expressed as percentage of the total landings. And we must here distin- 

 guish between loss in number, loss in weight, and loss in value. The two last may to 

 a certain degree, though not entirely, be regarded as proportional to each other. The 

 weight percentage of loss will probably always be somewhat higher in reality the loss 

 in value, and thus represent its maximum. On the other hand, the actual loss both 

 in number and weight, will generally turn out somewhat higher, as shown in the cal- 

 culations from the landings, as, if the size-limit is strictly observed, there will always 

 be a number of plaice which are not landed, although they may be of the required 

 size or even larger. Thus the difference between the weight per cent and the true 

 percentage value should be more or less equalised, so that the weight per cent can 

 be regarded as a good indication of the loss. 



In the comparison given below, the lengths of 20, 21, 22, 23, 24, 25, 26 and 29 

 cm. are taken as possible size limits, and the loss in number [n) and weight (w) shown 

 for each country with each size- limit. The loss values are in many cases more or less 

 uncertain, owing to the lack of sufficiently extensive market measurements to allow of 

 their exact determination. This is the case for instance with Holland and Scotland, 

 while Belgium for the same reason cannot be taken into consideration at all. The un- 

 certainty is not however, so great in the case of any of the countries here shown, as 

 to render the figures valueless; they can and will no doubt be altered by renewed and 

 more accurate inve.stigation, which must, in particular, be extended so as to obtain 



