There has to be an exception obsertred in the regulation of 

 minimum mash width in the trawl fishing for herring, raackerelj sprat 

 aad shrimp© It has to be shown by the catches that only these species 

 are being fished© No fishery must be left outside the regulation 

 for Hiinimian sizes since it is a control on tha use of the right net 

 for a certain species o It has been brought out, especially by German 

 sourceSj, that it is impossible for the shrimp fishers to pick the 

 trasho One source has pleaded that shrimp fishermen should be allowed 

 to land their trashj, which consists of the very youngest year classes© 

 This plea was defended with the argument that it is not tinvrise to thin 

 the 0= and 1= groups of the plaiceo This is only true for plaice and 

 certainly not for the young sole which is also caught and perhaps 

 also not for the young turbot which appears near the coast. Insofar 

 as these fish come in with the shrimp, they cannot be avoided© 

 Many shrimp fishermen;, however^ took part in the deliberate fishing 

 for trash and it must be assured that this will ao^t bappeas agaiaie All 

 landings of fish below the minimum size must be forbidden© 



bo The Probable Effect of the Protection 



We now have to estimate the decrease in the catch of undersized 

 fish after these reg-ulations have become effective o 



The i'esults of setting a minimvim size for fish will be two= 

 foldj, 1) the deliberate catching of small fish will be discontinuedi 

 and 2) the fishermen will try to stay away from those areas where 

 undersized fish chiefly appear© Before 1930, about 15 percent of 

 the haddock catches (in weight) consisted of non=marke table fish© 

 We will assume that the same amounts of undersized fish would be 

 caught now, if minimum sizes only were established© However, 

 if a minimijm mesh width were established also, the catch of under- 

 sized fish would be reducedo The effect of this large-mesh width 

 can be estimated© 



The quantity of undersized fish caught with the 8 centimeter 

 net in proportion to the quantity of undersized fish caught with 

 the 5 1/2 centimeter net is estimated in table 17© In both cases 

 a fishing standard of 50 percent is assumed© It is also ass'jmed 

 that the chance to be caught is the same for each length group 

 of a certain year group© From the "selection curve* it then can be 

 estimated what percentage of each length group remains in the nets© 



For" instanca, by fishing with the 5 l/2 centimeter cod ehd 

 the haddock reaches a length of 16 centimeter in its first yearo 

 Of 1,000 haddock existing at the beginning of the year, 500 

 (50 percent) get into the nets during the year© That is^ of each 

 length (centimeter) group 500 g- 16 haddock© According to the 

 selection curve in figure 5b„ none below 14 centimeters remaini 

 at 14 centimeters, Ij at 15 centimeters, 2^ and at 16 centimeters. 



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