The Spawning Areas of Sand-Eels in the North Sea. 9 
depth in the neighbourhood of Orkney. Strodtmann (1906) found 
that similar conditions prevail in the Hastern Baltic. The small 
larve are fewest in the vicinity of the Bornholm Deep, where the 
condition of the bottom is not favourable for the deposition of the 
eggs. The tables show that the area of. greatest frequency in the 
Moray Firth lies off the coast of Caithness. Here the 30 fathom 
line lies very close to the coast, and beyond it the bottom deposits 
are very similar to those in the immediately adjacent area to the 
north. But the depth gradually decreases southwards along this 
coast, and it is significant that there is a corresponding decrease in 
the frequency of the larve. It would appear that the conditions in the 
very shallow coastal waters are similar to those found by M‘Intosh 
in St. Andrews Bay in the spring months of the year. At Burghead 
and Nairn, in depths of less than seven fathoms no larval sand-eels 
were found, although the bottom deposits in these bays are 
composed of very fine sand. So, too, within the Cromarty Firth 
and in the shallow waters just outside, no young sand-eels were 
found in the plankton. In short, therefore, young sand-eels are 
found in the March plankton all over the Moray Firth area, with 
the exception of the very shallow zone close to the shore and over 
those places where there is excess of mud in the bottom deposits. 
Further, the frequency increases greatly in the north along the 
Caithness coast. 
Over the area to the east of Scotland within the 40 fathom 
contour line the frequency of occurrence of larval sand-eels in the 
plankton in the month of March is very uniform. Variations in 
frequency do undoubtedly occur, but in no case is the difference 
notable. The following figures are typical of this area :— 
Poses Vertical Horizontal Hauls, 
: Hauls. Half-hour duration. 
Lat. Long. lm. cheese cl. Surface. Mid-water. Bottom. 
DOceaieeGa, Lo 35) W.., 5 2 82 80 
57 eet BS 2) W.., 21 144 324 426 
56° ae Ne auc 10’ W.., 26 76 466 606 
whilst the general average for the East Coast of Scotland is given by 
9 53 624 326 
The frequencies for the East Coast of Scotland show, on the whole, 
a slight increase on those of the coastal areas of the Moray Firth, 
at at no station do they approach those of the area of greatest 
ensity. 
The Firth of Forth area, including the locality just outside the 
estuary or east of May Island, has now to be considered. The 
observations within the Firth itself did not extend beyond the island 
of Inchkeith. In this neighbourhood the frequency is generally 
very low, as is shown by the following averages : — 
Vertical Horizontal Hauls, half-hour duration. 
Haul. 1 metre cheese cloth net. 
1 metre ch. cl. Surface. Mid-water. Bottom. 
1 19 69 96 
but the numbers obtained on the 27th of March, 1909, viz., 
1 80 204 934 
