374 



Part III. — Fifteenth Annual Report 



From a consideration of the movement of the surface water off our 

 eastern coast as explained in the first part of this paper, and the facts 

 reviewed above, it may be concluded that the great spawning areas 

 Lying off that coast stand in normal relationship, not to the inshore 

 waters opposite to them, but to those situated further to the south. 

 The millions and billions of eggs which are annually shed into the 

 waters above these spawning areas — each with its potential market- 

 able fish within it — are normally carried by the surface waters south- 

 wards to a more or less distant area where they hatch, and the larval 

 fishes continue to be borne in the same direction. Thus the spawning 

 grounds in the northern part of the Moray Firth, at Smith Bank, and 

 neighbourhood, and which are known to be frequented by great shoals 

 of the food fishes, must be looked upon as the main source of supply of 

 larval and post-larval fishes to the areas off the north coast of Aberdeen, 

 the coast of Banff, and by the normally deflected current passing west- 

 wards, to the inner reaches of the Moray Firth, perhaps also partly to 

 the east coast of Aberdeen. The spawning grounds lying off the latter 

 coast and the coast of Kincardineshire can only exceptionally supply the 

 territorial waters of these coasts ; normally the floating eggs will be 

 borne southwards, and may reach the coast of Fife or even Berwickshire. 

 So also the offshore spawning areas situated to the eastwards of the Isle 

 of May can only exceptionally furnish larval and post-larval fishes to the 

 Firth of Forth and St Andrews Bay. They must be regarded as stand- 

 ing in relationship rather to the coasts of Berwickshire and Northumber- 

 land. Similar generalisations may be made in connection with the 

 spawning areas off the east coast of England. 



The importance of these conclusions with respect to proposals for pro- 

 tecting spawning fishes is obvious. If, for example, it was deemed to be 

 desirable (as in my opinion it is desirable, as a corollary to the experi- 

 ments already made, and described in last year's Report), to protect, for 

 part of the spawning season, the offshore grounds which stand in relation 

 to the Firth of Forth and St Andrews Bay, then it would be neces- 

 sary to deal with the areas lying to the north-east. Owing, however, to 

 the want of investigations of the offshore spawning grounds, it is not 

 possible at present to define their exact extent or position. 



If the movement of the surface water and of the pelagic eggs floating 

 in it is normally in the direction indicated, to the south, one would 

 expect a corresponding migratory movement of the growing or adult 

 fish in the opposite direction, or otherwise there would tend to be, so to 

 speak, an aggregation of fish in the southern parts of the North Sea. 

 This would especially tend to happen with forms whose eggs and larva) 

 float for long periods, as those of the plaice, cod, and haddock. With 

 the summer-spawning species, the distance between the place where the 

 eggs are shed and the nurseries of the young fishes derived from them 

 is comparatively small, and the reversed migratory movements of the 

 growing or adult fishes would accordingly not require to be great. Now, 

 it is an interesting fact that the experiments on the migration of fishes 

 show that a definite movement of plaice occurs northwards along the 

 east coast of Scotland. In the Eleventh Annual Report (Part iii. p. 

 185) I described the movement of marked plaice in the Firth of Forth 

 and St Andrews Bay, and showed that this movement was in a westerly 

 direction along the southern shore of the Firth of Forth, then easterly 

 along the northern shore, and then northerly towards St Andrews Bay 

 and towards the coast of Forfarshire, as shown in a diagram, here repro- 

 duced (Fig. 5). Since that account was published I have received a number 

 of marked plaice caught in the Moray Firth, which were liberated a year 



