of the Fishery Board for Scotland. 



65 



stiller than over the stone-covered ridges. This conclusion was arrived 

 at after the various parts of the bank had been repeatedly sounded and 

 dredged, and after some of the basin-shaped portions had been examinod 

 by a diver. While small groups of eggs were found coating the stones (PI. 

 IX. figs. 1 and 2), on various parts of the bank, it was only in gravel-coated 

 basins that spawn was found in great abundance, where it covered many 

 square yards with a layer nearly half an inch in thickness (PI. IX. figs. 3 

 and 4). In addition to covering the gravel, the eggs were, however, often 

 found arranged in low conical masses over the surface of the long stems 

 of laminaria (PI. IX. fig. 5). 



An indication of the position, form, and depth of the Ballantrae Bank 

 will be obtained by a reference to the chart (PI. VI.), prepared by Sub.- 

 Lieut. H. T. Hibbert of H.M.S 'Jackal.' This chart shows that the 

 bank, which is of an irregular elongated form, is covered with from 7 to 

 13 fathoms of water, and that while within the bank the water is shal- 

 lower, it soon increases to over twenty fathoms on the outer edge 

 of the bank. Between the bank (i.e. the portion enclosed by the dotted 

 red line) and the shore, the bottom consists chiefly of fine sand, while on 

 the north, south, and east of the bank, the bottom is muddy, or covered with 

 a mixture of mud and sand. The surface of the bank consists chiefly of 

 polished stones, fine gravel, and coarse sand, the stones being especially 

 abundant at the middle and lower portion of the bank (Stations IX., XL, 

 XII., and XIII.), while the gravel and sand were especially abundant at the 

 upper end, in a basin-shaped area extending between the stations, marked 

 XVIII., XXIII., and XXIV. on the chart, XVIII. being near the centre 

 of the basin, with 11 fathoms of water. 



On the east coast, judging from the specimens of eggs brought up by the 

 long line fishermen, the herring seem to select hard ground covered with 

 a plentiful growth of sea-firs, especially with hydrallmannia (PI. VII.), 

 and antennularia (PI. VHP); but, as on the Ballantrae Bank, the greater 

 portion of the spawn may be deposited on flat areas covered with coarse 

 sand or gravel. 



The temperature and saltness of the water seem to have little influence 

 with the herring when selecting a spawning ground, for they spawn equally 

 readily whether the temperature is at 40° Fahr. or 60° Fahr., and whether the 

 specific gravity of the water is high or low— the Baltic herring depositing 

 their spawn in almost fresh water. Further, the depth of the water 

 within certain limits seems not to be of vital importance, for in the Schlei 

 the herring spawn in half a fathom of water, while in the North Sea some 

 of the sea-firs, with eggs attached, are said to have been taken in forty 

 fathoms of water. But though the depth may neither influence the 

 herring in selecting the spawning ground, nor when over thirty fathoms 

 do more than slightly retard development, it may have a great influence 

 over the young fry. The fry, as will be afterwards pointed out, begin to 

 ascend as soon as they are hatched, in order apparently to reach 

 the upper waters, in which their food is to be found ; but it is possible 

 that with their limited powers they may be exhausted by the attempt to 

 rise from 50 to 100 fathoms, and ultimately falling to the bottom, suc- 

 cumb for want of nourishment. 



It may be mentioned that any given spawning ground may be influ- 

 enced by a great increase of the fish, and other forms which feed on the 

 herring spawn, or by the impurity of the water covering it. On the Ballan- 

 trae Bank the spawn seemed to lie almost unmolested, while the water 

 was remarkable for its purity. 



In nearly all the inquiries made by Royal Commissions, fishermen and 

 others indicated that they believed there was some relation between the 

 disappearance of the herring from any given spawning ground and the 



I 



