227 



with large trawls, heavy catches and long- drags, most fish 

 are dead when the net is hauled. The success of such a 

 measure would therefore depend to some extent on the 

 possibility of devising a mesh of such form and dimen- 

 sions as would capture only moderately large Plaice with- 

 out prejudice to the capture of other (round) fish trawled 

 for. 



As far as inshore fishing is concerned the " vitality " 

 experiments made by Mr. Dawsonf for the Lancashire Sea 

 Fisheries Committee have shewn that with moderately 

 short drags (one or two hours) both with fish and shrimp 

 trawls a great proportion of Plaice (81 per cent.) recover 

 when taken from the contents of the net and placed in 

 running sea water. The relative catching powers of nets 

 with different sizes of meshes have also been ingeniously 

 illustrated by the same writer. An ordinary fish trawl of 

 25 feet beam and with a square m.esh of Tin. periphery 

 was used. E-ound the catching portion of this net a 

 similar net but with a mesh of 4|^in. periphery was laced. 

 The combined net was dragged in the ordinary manner. 

 Fishes which passed through the inner wide meshed net 

 were retained in the outer one. In one such trial the 

 inner Tin. net captured 41 Plaice of about 9 inches in 

 length, while the outer 4^in. net caught 349 Plaice of 

 about 5^ inches in length which had passed through the 

 inner net. In another trial of this combination net the 

 Tin. net caught 142 Plaice T|-9|^ inches long, and the 

 outer 4|in. net 390 fishes of 4|^ inches long. Correspond- 

 ing results were obtained with the other fishes captured.t 



Petersen's " growth-theory," it will be seen, proposes 

 to remedy the exhaustion of the Plaice fishery by raising 



t See Lancashire Sea Fish. Laby. Rep. for 1893, p. 23. 

 I See Holt— Journ. Mar. Biol. Ass., vol. iii., pp. 437-441, 1895, for a 

 discussion of the probable results of regulation of the trawl mesh. 



