114 TRANSACTIONS LIVERPOOL BIOLOGICAL SOCIETY. 



cipal object of the present investigation. A knowledge 

 of these sizes is no less important when considering the 

 question of the migrations of the fish than when practical 

 regulations have to be elaborated. I would point out, in 

 the meantime, that no attempt can yet be made to inquire 

 into the causes of the migrations : it is obvious that 

 investigation of this nature must await fuller knowledge 

 of the annual hydrographic changes in the water of the 

 Irish Sea. The data collected in the present Report do, 

 however, possess much value when trawling regulations 

 are being considered, and may be discussed from this 

 latter point of view. I think the Committee now, for the 

 first time, possess definite data with regard to the size of 

 plaice on the various grounds within their jurisdiction. 

 If such an investigation as the present one had been 

 carried out at the beginning of the nineties the results 

 of a comparison of the sizes of fish caught then and now 

 would have been of the greatest practical value. But the 

 trawling experiments made in the past, however valuable 

 they may have been in the circumstances which dictated 

 them, are too indefinite to be of much use now. 



It is therefore most useful that the data of the 

 present Report should be published in detail, so that the 

 condition of the fishing grounds during the period 1908- 

 1910 should be recorded for comparison for future work. 

 Obviously the " lumping together " of the results of the 

 hauls cannot be practised to a great extent, since one 

 cannot foresee the purposes for which the figures may be 

 used. But it would require a great amount of space to 

 record the results of each haul of the trawl net separately, 

 and I think that little, if anything, is sacrificed by 

 combining the results for each month, in each of the 

 areas. In many cases only one haul is recorded for the 

 month, but when the figures are large — exceeding 1,000 

 —they represent from two to five separate hauls. 



