SEA- FISHERIES LABORATORY. 177 



(A few cases where the lengths of liberations, positions of 

 recapture, etc., have obviously been mis-recorded are omitted.) 



Condensing this table we get : — 



Ranges 



of 



Lengths. 



Numbers 

 Liberated. 



Numbers 

 Reported. 



Less than 19 cms. 







/o 

 5 



/o 

 



20 „ 





13 



1 



21 „ 





34 



9 



22 „ 





54 



16 



20 to 23 cms 





no 





21 to 25 „ 



50 













This means that the smaller fish do riot stand the marking- 

 operation well (and, of course, that they grow between the 

 time of liberation and that of recapture). The two lower lines 

 of the last table are read as follows : Half of all the fish liberated 

 were between 20 and 23 cms. in length and half of all those 

 reported were between 21 and 25 cms. in length. 



One must remember that the position of recapture reported 

 is always approximate, for the skipper cannot tell, to a mile or 

 two, exactly where he is, and also the fish may have been 

 caught anywhere on a ten to twenty-mile drag. We have no 

 reason to suspect any misleading information as to the places 

 of recapture : on the other hand skippers were always most 

 willing to give full details, and very often eager to know where 

 the fish had been marked. We assume, generally, that the 

 plaice moved straight from where they were set free to where 

 they were caught, but this must hardly ever be the case : 

 the fish, doubtless, " backs and fills " in its movements. For 

 small periods of a month, however, it is quite permissible to 

 assume that the migrations path is directly from the one spot 

 to the other. 



The J u n e -Jul y Migratio u s . 



The data from which these are to be deduced are given 

 in the following synoptic chart : — 



