236 



Part III.- — Twenty-fourth Annual Report 



In my previous paper I showed that an extremely close relation 

 existed between the changes of the temperature of the water and the 

 abundance and migration of the gurnard, none of them entering the Firth 

 of Forth until the temperature reached about 40*5° F. The average 

 number of gurnards taken in that Firth per haul of the net in the various 

 months of the year, and the mean bottom temperature, are as follows : — 





Jan. 



Feb. 



Mar. 



Apr. 



May. 



June. 



July. 



Aug. 



Sept. 



Oct. 



Nov. 



Dec. 



Gurnards, 



•02 



•04 



•29 



11-1 



44-2 



30-2 



24-0 



21-6 



18-9 



8-4 



1-1 



•2 



Temperature, 



42-2 



40-6 



40 0 



42 2 



45-6 



47-6 



50-8 



53*5 



53-3 



51-4 



48-1 



44-8 



On the other hand, in the Moray Firth and the Firth of Clyde, where 

 there is deep water, the gurnards moved out into the deeper water. Here 

 are the similar details for the deep-water stations in the Moray Firth 

 and for the Clyde : — 





Jan. 



Feb. 



Mar. 



Apr. 



May. 



June. 



July. 



Aug. 



Sept. 



Oct. 



Nov. 



Dec. 



Moray Firth — 



























Gurnards, . 

 Temperature, 











21-0 

 45-5 



19-2 

 477 



23-1 

 o0'2 



37-3 

 52-1 





39-4 

 52-6 



29-6 

 49*4 





Clyde- 



























Gurnards, . 



13-6 



o-o 



26-5 



22-2 



18-6 





10-6 



63-6 



11-8 



27 



19 



31-1 



There are not complete observations in regard to the Clyde to enable 

 the mean temperature to be given, but they show that in January at the 

 deeper stations, where the gurnards were chiefly caught, the temperature 

 is from 47-48 F., and in December it is about 6 F. higher than in the 

 Firth of Forth at the same period. 



It is thus to be inferred, from what is known in regard to the relation 

 between the temperature of the water and the growth of fishes, that the 

 young gurnards do not cease growing in winter, but that, migrating to 

 regions where the winter temperature is high, they continue to grow and 

 are found to be larger in spring. The explanation is necessary to account 

 for the different groups in the collections. 



In a number of Tables appended to this paper the collections of gur- 

 nards have been tabulated in one-centimetre groups, but in many cases the 

 limits of the groups are much better brought out by a *5cm. arrangement 

 of the measurements, and some of these will now be given. 



I have arranged in the following Table the measurements of certain 

 collections from Aberdeen Bay, the Firth of Forth, and the Dornoch Firth, 

 in '5cm. up to 34cm. The columns refer to the collections, as follows: — 



Col. 



I. 

 II. 

 III. 

 IV. 

 V. 

 VI. 

 VII. 



Aberdeen Bay, Summary of July collections. 



,, ,, ,, September collections. 



,, ,, ,, October collections. 



Dornoch Firth, Summary of November collections. 



Burghead Bay, „ September collections. 



Firth of Forth, ,, May collections. 



„ ,, ,, July collections. 



