of the Fishery Board for Scotland. 



223 



closer to the coast at spawning time in this area, and it appears to be the 

 only fish whose eggs are pelagic that does so. It resembles the herring in this 

 particular. The other fishes with pelagic eggs which spawn in the inshore 

 waters on the East Coast, as well as in the offshore waters, are the common 

 dab, the long rough dab, the flounder, and the sprat. In the case of the 

 flounder there is distinct evidence of a movement at the spawning time into 

 deeper water than the usual habitat of this fish. In the case of the dabs 

 there does not appear to be any marked movement of the kind. The migra- 

 tion of the gurnard in April and May from the open sea towards the shores 

 is therefore primarily connected with reproduction ; but that it is not 

 solely connected with reproduction is shown by the fact that great num- 

 bers of small immature fish, which do not develop eggs in the same 

 season, follow the larger mature gurnards in May. A study of the com- 

 ponents of the migrating shoals makes these points clear ; and for tins 

 purpose the sizes of all the gurnards have been tabulated. 



The size at which the gurnard reaches maturity is about nine inches, 

 sometimes a little less.* The great majority under nine inches may be 

 regarded as immature, and the great majority above nine inches as mature. 

 Ail under eight inches may be considered immature, and all over 10 inches, 

 at the spawning period, may be looked upon as mature spawning fish. It 

 has already been stated that the gurnards caught in the Forth area in 

 February and March, when the inshore migratory movement commences, 

 were of large size (Table, p. 219). Only one was under 10 inches — viz., 

 one of the four caught at Station VII. at the end of March 1891, which was 

 only six inches long. Of the fourteen obtained in St. Andrews Bay in 

 March, only one was under eleven inches — viz., seven inches. With these 

 two exceptions, the March gurnards, the pioneers of the migrating shoals, 

 were all spawners. The numbers caught in March were small. Of the 

 fourteen caught in the Forth area, ten, or 71*4 per cent., were twelve 

 inches or more in length, and thirteen, or 93 per cent., over ten inches. 

 Of fourteen caught in March in St. Andrews Bay, thirteen, or 93 per 

 cent., were twelve inches or more in length. Of the 545 caught in April, 

 whose sizes were measured,J 412, or 75*6 per cent., were over nine 

 inches in length; 359, or 65 '9 per cent., were over ten inches; and 171, or 

 31-3 per cent., were over 12 inches in length. The gurnards under nine 

 inches, the great majority of which were no doubt immature, numbered 133, 

 or 24*4 per cent. ; those under eight inches numbered only 53, or 9*7 per 

 cent. Only two gurnards at five inches were caught in April (0*3 per cent.), 

 and none smaller. 



We therefore see that in April, while the great majority of the migrating 

 gurnards are adults, moving to the inshore waters to spaw 7 n, immature 

 forms begin to accompany or follow them. All the gurnards caught 

 from four inches to seventeen inches have been tabulated for each month, 

 according to their length, into groups differing from each other by 

 intervals of an inch, and curves constructed, which need not be reproduced 

 here. They show that in April the largest number caught were ten inches 

 in length, then came those of twelve inches, very nearly as numerous ; 

 the next most numerous were those at eight inches, and then those 

 at six inches. In the next month this feature became strongly 

 marked, the majority of the gurnards caught in May being under nine 

 inches in length. Instead of 31*3 per cent, being twelve inches or over, 



* Fulton, Eighth Annual Report, Part III., p. 161. Tenth Annual Report, Part III., 

 p. 240. Holt, Journal Marine Biological Association, Vol. II., p. 218. Royal Dublin 

 Society, Report of Council, 1891, p. 275. 



X The fish were first measured in 1888. 



