66 



Appendices to Fourth Annual Report 



tho mesh has on the size of fish taken, was supplied me by the Fishery 

 officer at Lybster, who sent up two samples of herring taken on exactly 

 the same fishing ground three miles off Dunbeath, and at the same time in 

 August last, but by boats using nets with a different size of mesh. The 

 herrings in one sample, caught in a net which had been in use earlier in 

 the year, and having been rebarked seven or eight times, was consequently 

 shrunk, ranged in length (to end of scales) from 217 mm. to 228 mm., the 

 average length being 224*5 mm. to end of scales, 25 8 '6 mm. to tip of tail. 

 The other sample, caught in a net which had been little used and was con- 

 siderably wider in the mesh, shows a range in length among the fish of 

 from 230 mm. to 257 mm. (to end of scales), the average being 249 mm. 

 to end of scales, 284 mm. to tip of tail. I need scarcely quote further 

 examples here, for the result appearing in the above is that which we 

 should expect. Nevertheless, in fairness, I must quote an apparent excep- 

 tion, which, however, only shows that with the same size of mesh there 

 may be taken fish having a considerable difference in size, and that the 

 mere presence of a preponderating quantity of large fish in a take does not 

 necessarily though generally point to the employment of a mesh which will 

 not capture small fish. 



This example comes from the Fishery officer at Anstruther, and the 

 samples, though taken at different places (in the Firth of Forth) and on 

 consecutive nights, were taken by the same boat and the same net. The 

 length of fish in the first sample ranged from 219 mm. to 248 mm. (to 

 end of scales), the average size being 235 mm. to end of scales and 269 

 mm. to tip of tail ; while the second sample gave a variation in length of 

 from 173 mm. to 220 mm., with an average of 195*7 mm. to end of scales 

 and 226 mm. to tip of tail. It is quite conceivable that circumstances 

 either as to mass or movement of the shoal, weather, tide, kc, may 

 influence the meshing of fish in a net which is rather small for them. But 

 nothing of the kind accounts for the fact apparent in the Lybster sample 

 that small and big fish being certainly present at the same time and place, 

 each net took those fish which were suited to the size of the mesh and let 

 most of the others escape. I have stated the different effects of the net in 

 these cases in terms of the length of the fish, as being more readily under- 

 stood than would be a comparison of the girth of the fish at the operculum, 

 which of course is the principal factor in this question, and one which I 

 shall hereafter have to refer to ; but the rule applicable to the size of the 

 fish in the special cases instanced applies to the size of these fish at the 

 back of their heads also. We must then not be too certain that our con- 

 clusions as to the size to which our herring grow, and the relative numbers 

 in which the larger of them are present on our coasts are absolutely correct. 

 That they are so as to the' fish actually caught goes without saying. 



As to the influence which the common employment of what I may call 

 a small meshed net — for, of course, the use of this term ' small ' is rela- 

 tive to the size of the adult fish — may have on the general size of the 

 herring, it can readily be understood that if all fish were meshed, however 

 large, or even if the herring only spawned after reaching their full develop- 

 ment (which, as I shall show below, is probably not the case), then there 

 could be little doubt about the ^eat advantage of employing only those 

 nets which, while both bringing the largest fish only to the market, would, 

 by allowing the smaller and younger to escape, not only permit theni to 

 grow up, and thus increase the supply of the larger, but also have a fair 

 chance of doing so by the increased number of spawners. But as things 

 are, it is questionable whether by a moderate size of mesh we are after all 

 doing anything to deteriorate the size of our fish ; whether indeed we are 

 not directly helping to increase their size. For if we employ a mesh which 



