144 Mussel Beds; theli' Product'u'ltij and Maintenance 



more than half this quantity per tide. But if, as we have supposed to 

 be the case, twenty men were working at the fishery, and that all of them 

 assisted in the transplantation, removing one ton per tide per man, 

 the whole amount could be removed in, roughly, ten journeys per boat. 

 The scar may be supposed to dry for about four or five days during 

 low spring tides, or, even if it does not actually dry, the depth of water 

 covering it will be negligible, and, therefore, the whole operation could 

 be carried out in the space of two spring tides. If additional assistance 

 were forthcoming, the time occupied would be further lessened. Thus 

 boats from a neighbouring pgrt might be requisitioned for a few days, 

 their owners assisting; such services to be repaid in kind later. The 

 mussels should be transplanted prior to spawning. 



Some Destructive Influences, etc. 



It has been mentioned before, that mussel beds, when affected by 

 strong currents, are liable to much destruction through becoming under- 

 mined, when large masses become detached. These felted masses are 

 swept out to sea and destroyed. The wastage of spat is simply incredible, 

 if, indeed, it is to be regarded as wastage. Myriads of creatures feed 

 upon the larvae, both in the brief free-swimming stage and after fixation. 

 I believe that frost has been known to destroy large numbers of mussels 

 in beds subject to its influence, but I am unable to quote any authority 

 for this statement, at the moment. I have not remarked such an effect 

 in Cardigan Bay. 



The chief fish consumers of young mussels are those belonging to 

 the Pleuronectid family, — Plaice, Dab and Flounder. Skate are caught 

 near the seed areas at Aberdovey, and it is not unlikely that they feed 

 upon the thin-shelled population of these areas. 



Fishermen assert that Herring Gulls, Oyster Catchers, etc., favour 

 a dietary of mussels, and, certainly, whenever the Ro-ddu area becomes 

 dry, large numbers of these birds resort to it. Scott adduces evidence 

 confirmatory of this statement, and found traces of mussels in gulls' 

 excreta, while Field gives a list of birds feeding on mussels in America^. 



Several carnivorous molluscs attack the mussel, but the only one 

 that need be mentioned here is the Dog Whelk {Purpura lapillus L.), 

 which may sometimes be detected in the act. Mussel shells bearing a 

 neatly drilled hole are not uncommonly found^, — clear testimony of the 

 attacks of a gastropod culprit. 



' b*ee article by J. A. Field in The American Museum Journal, October, 191G. 

 - Ibid. 



