It has been stated repeatedly that undersized fish will always 

 remain in the nets and that the possibility is very small that these 

 fish get back in the sea in a good enough condition to remain alive© 

 Therefore, there -will always be a vocal protest on the part of the 

 fish^meal industry and the duck farmso They will want these fish, 

 which are lost anyway, to be landedo Thsrefore, it needs to be em<= 

 phasized that the minimum size is precisely the only satisf actory 

 control on the compliance with the regulations for mesh widthSj, as 

 well as for the avoiding of~ the protec ted areaso ' 



It is impossible to control the use of cod ends at sea, because 

 the possibilities for avoiding the mesh=width regulations are very 

 simple o (For ins tan ce^ by setting two cod ends over each other, 

 or by using a cod end authorised for pelagic fishing for herring or 

 mackerelo) Even the catch of some species of less importance for 

 hximan consumption will have to be limited in order that the value 

 of these fr.sh will not be large enough to constitute a reason for 

 an avoidance of the mesh=width regulations„ or that the fishing in 

 the protected areas will be attemptedo 



Finally I want to remark that naridersized fish, even if thrown 

 back dead, will be of some use to the fish stocko Part will be 

 eaten by organisms which in turn will become food for the fisho 

 Part, through bacterial action will free inorganic salts of 

 phosphates, nitrates and other essential nutrients which will build 

 up the productivity of the sea© This is profitable for the fishery, 

 since we have already stated that the productivity of the North Sea 

 is insufficient for the maximum growth of all fishes o 



4o Projected Measures to Minim:.ge the Catch of 

 Non=marke table Fish in the Norttr"S(9& 



ao Motivation of the proposed plans o 



In the North Sea, the haddock and the plaice were overfished* 



aao Haddock 



To begin with we have to establish a minimum catchable sise 

 for haddocko This shoiild be established with regard to the fishing 

 intensity which may be expected in the future, to enable the egg 

 production to retain the stock at the proper density level before 

 overfishing occurs o This point can be established fairly accurately e 

 Through the work of Thompson and Raitt (Raitt, 1939) the relative 

 strength of the year classes 1918=36 is knowrio The strengths change 

 enormously from year to year due to factors still largely unknown, 

 which we have called fluctuation factors (ppoiSO^ SS)o The class of 

 1918, for instance, is 8S times as large as the weak 1922 class© 



SI 



