210 



Part III. — Seventeenth Annual Report 



V.— ON THE MIGRATORY MOVEMENTS AND RATE OF 

 GROWTH OF THE GREY OR COMMON GURNARD. By 

 T. Wkmyss Fulton, M.D., F.R.S.E., Scientific Superintendent. 



CONTENTS. 



1. Introduction, . . . . . . . . 210. 



2. The .Migratory Movements, ....... 210. 



3. The Relation between the Migrations and the Temperature of the Water, 216. 



4. The Relation of the Migratory Movement to Reproduction. . . 222. 



5. The Rate of Growth, 228. 



Introduction. 



Among the fishes caught by the " Garland " there appears to be none 

 whose migratory movements are more marked and definite than the 

 common gurnard ; nor is there any in which this migratory movement can 

 be more distinctly correlated with the seasonal changes in the temperature 

 of the sea water, and with the instinct of propagation, than in this fish. 

 The circumstance that the common gurnard approaches the inshore grounds 

 at the spawning time and leaves them in great numbers late in autumn 

 was pointed out in 1892;* and subsequent investigation has shown that this 

 movement is one of great regularity, and is associated with other phenomena 

 of interest. The facts set forth in the following pages are based on a study 

 of the catches of gurnards made by the " Garland " during the past ten 

 years ; but the more detailed and systematic part deals principally with the 

 garnards caught in what may be termed the Firth of Forth area, which 

 includes not only the Firth itself and the estuary, but also the open sea 

 to a distance of twelve or fourteen miles east of the Isle of May. Some 

 hauls were also taken at a bankt twenty-two miles east by south of the 

 Isle of May. In this area the occurrence of gurnards at each station has 

 been studied in relation to (1) their appearance and numbers in the various 

 months of the year; (2) their sizes in relation to maturity and age; (3) the 

 temperature of the sea water in the various months at the different 

 stations ; (4) the spawning period. The number of gurnards dealt with 

 in this area is over 10,000, and the period comprises ten years. The 

 gurnards caught in the other areas where the " Garland " has carried on 

 trawling work — viz., the Moray Firth, the Firth of Clyde and Loch Fyne, 

 St. Andrews Bay, Aberdeen Bay, Montrose Bay, and Lunan Bay — over 

 14,500 in number, have also been dealt with; and some of these areas, 

 and especially the Clyde and the Moray Firth, have furnished important 

 data in connection with the conclusions reached for the Firth of Forth. 



The Migratory Movements. 



In considering the migratory movement, we shall first of all deal with 

 the gurnards as a whole, irrespective of their grouping into sizes or of the 

 slight variations that occur in different years. For this purpose the 

 collective data referring to each particular month in all the years have 



* Fulton : "Observations on the Reproduction, Maturity, and Sexual Relations of the 

 Food Fishes." Tenth Annual Report Fishery Board for Scotland, Part III., p. 235. 



f Liston Bank, so named from the experienced trawler who has had charge of the actual 

 trawling operations on the "Garland " from the first. 



