of the Fishery Board Jor Scotland. 



227 





9 Inches. 



10 Inches. 



12 Inches. 



.. 



April, 



7-6 





3-2 



May, ' 



17-3 



12-4 



4-3 



June, 

 July, 



13-9 



7-8 



2-7 



11-0 



8-0 



3-8 



August, - 



13-5 



10-1 



G-l 



September, 



8-1 



7-1 



40 



October. - 



4-3 



3-7 



2-3 



November, 



0-8 



0-7 



0-3 



It will be observed that in August the number of those at or over nine 

 inches in length approaches the number in May and June, and that the 

 increase is chiefly in the larger sizes. The average per haul of those at 

 or over 12 inches is the highest of the year. It will also be noticed that 

 the absolute numbers of the larger sizes, as well as their ratio to the 

 other components of the shoals, increase somewhat in July. We possess 

 at present very little definite information as to the duration of spawning 

 in the individual fishes of any species; but it is known from the condition 

 of the ovaries and the comparatively small proportion of eggs that become 

 matured at the same time that the period in many cases for all the eggs 

 to be shed is considerable. This is especially so in fishes which produce 

 pelagic eggs, and it is a marked feature in the reproduction of the 

 gurnard.* It is no doubt partly for this reason that the spawning period 

 of the gurnard as a species is so prolonged ; but it is unlikely that the 

 gurnards which begin to spawn in April and May continue spawning in 

 July and August. The spawning fishes at the latter part of the period 

 more probably do not begin to spawn until the season is well advanced, 

 and this opinion is supported by a study of the proportions of ripe gur- 

 nards in different, months. In the diagram (Fig. 2) it will be seen that 

 the downward slope of the curve from June is interrupted in July and 

 August, so that it is prolonged into September, and this agrees with the 

 curves representing the proportion of adults at the same time. In all 

 cases, whether the average per haul or the percentage is considered, there 

 is seen to be a rise in the numbers of the larger adults in July and 

 especially in August; and this increase is common to the other areas— 

 viz., St. Andrews Bay, the Moray Firth, and the Firth of Clyde. More- 

 over, it is found on analysis of the data referring to the different stations 

 in the Firth of Forth area that in July there is a rise from June at the 

 outer stations (VIII. -IX.), and a fall there from July to August and 

 September. At the inner stations (I.-I.V.) there is, on the other hand, a 

 rise from July to September, which might be accounted for on the suppo- 

 sition that spawning adults had then moved inwards. 



The migration of the immature gurnards is obviously due to some other 

 cause than reproduction, and may be owing to more abundant food supply, 

 the shoaling instinct, or simply to the increasing temperature of the 

 inshore waters. It seems reasonable to suppose that the movement of the 

 adult gurnards to the inshore grounds at the spawning time would be 

 followed by the smaller gurnards also moving inwards, provided the 

 supply of food was at least equally abundant. The average numbers 

 caught per haul of the net in the various months are as follows : — 



*The Comparative Fecundity of Sea Fishes. Ninth Annual Rrwrl Fishery Board for 

 Scotland, Part III., p. 250. 



