346 



Part III. — Seventh Annual R&poft 



of glacial deposits. The muddy interval is barren of molluscan life and 

 presents an unfavourable resting place and feeding ground for the active 

 scallop. The single pecten or so dredged in this part of the Firth was 

 doubtless caught on its journey from one bed to another, or on its wander- 

 ing in search of new feeding grounds. 



The greatest depth of water over the beds is, as stated, 10 or 12 fathoms, 

 and the bottom shallows gradually to the flat shores on either side of the 

 Firth. The water, moreover, is deeper on the northern than on the 

 southern bed, and the sea eastwards or seawards from Inchkeith is much 

 deeper than between that and Inchmickrie. On the whole, the conditions 

 of water, as regards depth, are the best possible for a vigorous growth of 

 clam life. The bottom, too, is composed for the most part of dead shells 

 of scallops lying on the top of sandy mud which, though somewhat finer 

 than the sandy gravel on which pectens usually occur, yet affords a suit- 

 able habitat for the species. 



The clams are most plentiful to the north-east of Inchkeith, and the 

 number of dead valves are proportionally fewer than on the southern bed. 

 On the latter, the dead shells are, at least, three times as numerous as 

 the living, but the proportion of dead to living shells on the smaller bed 

 is something like two to one. Besides, the dead shells of the southern are 

 more worn than those of the northern bed, a fact that lends support to 

 the suggestion that the northern is the younger bed. 



From the nature of the bottom on the north side of the Firth it may 

 be expected that the north bed will go on increasing. On the south side, 

 however, the available ground is pretty well covered by pectens and unless 

 expansion goes on towards and to the east of Gullane Ness there is not much 

 room for an increase of the area of this bed. The expansion of either 

 bed seawards will be retarded by the less sheltered nature of the ground 

 to the east of Gullane Ness. In addition to ground suitable, from a 

 physical point of view, to the development and increase of the scallops, 

 ground where there is abundance of food is a necessity to a vigorous 

 growth. Only a limited quantity of pecten food is contained within a 

 given cubical space, so that the quality and size of the scallop depends on 

 the crowding or otherwise of the species within a restricted area. The 

 proper cultivation of the beds is also dependent on the ' thinning ' of the 

 scallops, and on the removal of great numbers of them, in order that 

 those left behind may obtain a rich supply of crustacean and other micro- 

 scopic forms from the surrounding water. In this way 1 the struggle for 

 existence ' may be considerably modified by a judicious system of dredging 

 and the value of the beds enhanced. 



IV. The Clam as a Source of Bait Supply. 



The beds provide a constant supply of bait during ten months of the 

 year to the fishermen of Port Seton, Cockenzie, Prestonpans, Leith, and 

 Newhaven. The fishermen of Fisherrow, Burntisland, Largo, St Monance, 

 Anstruther, and other Fifeshire fishing villages, where a greater variety of 

 bait is used, bait their lines with clams at different seasons of the year. 

 The quantity of clams landed in 1887, within the limits of the Leith 

 district, amounted to 16,020 cwts., and 1374 cwts. were secured in the 

 Anstruther district. These quantities are greatly in excess of the produce 

 of the clam fishing in 1886, when the total weight in both districts only 

 amounted to 9100 cwts. In 1888 the total yield of clams was 20,774 

 cwts., so that, with care and attention, it is quite possible that the produc- 

 tiveness of the beds may be still further increased and the annual supply 

 of clams augmented. 



When the fishermen are absent at the herring fishing during the months 



