109 



PRESENT STAGE OF THE SALMON EXPERIMENT. 

 Bj Morton Allport, F.L.S., F.Z.S., &c. 



[Bead November 12th, 1877.] 



Thougli grilse weighing from 31bs. to 71bs. have during 

 the last four years been taken in the Derwent, how is it that 

 no mature salmon, that is, fish weighing from 151bs. to 301bs., 

 have been captured ? This is a question frequently asked 

 both here and in the neighbouring colonies, but it will be 

 necessary before attem^^ting to answer it to refer to what is. 

 known of the early life history of the salmon in Europe and 

 Tasmania. 



It has been calculated by able British authorities that in 

 specially good salmon rivers, such as the Tay in Scotland, 

 not more than one egg in every 1,500 deposited ever becomes- 

 a salmon, the diminution in number taking place chiefly 

 during the earlier stages of life, and especially during tho 

 journey of the smolt to the sea, and the first few weeks of 

 their residence there, though even the grilse aj^pear liable to 

 have their numbers considerably decreased by the attacks of 

 marine enemies before their return as veritable salmon. 



The limited number of mature salmon we can yet have in the 

 Derwent might therefore alone account for their non-capture,, 

 but we must add to that disadvantage the want of adequate 

 appliances to ensnare large sized fish. The chance of taking 

 one with the rod is infinitesimal while the fish are scarce, the 

 fishermen scarcer, food very abundant, and the difficulties 

 with which the angler in the Upper Derwent has to contend 

 great. The one or two fine meshed seine nets worked down 

 the river, though well adapted to scraj^e out smolts, are quite 

 unfitted for the capture of salmon, as they are shot so as to 

 leave a considerable space between the net and the shore, and 

 take so long to haul that the wary old salmon would, before 

 the ends of the net reached the land, pass round one or the 

 other, and so escape. 



The majority of the 18 or 20 grilse caught have been taken 

 in an ordinary grab-all net, having a mesh of such a size that 

 only the fish of from 31bs. to 51bs. weight can mesh themselves, 

 and no larger salmon is at all likely to be taken by the same 

 net, as in this method of fishing it is essential that the fish 

 should be able to get the gill covers through the mesh or by 

 backing it can at once free itself. If a grab-all net, having a 

 mesh of two and a half inches from knot to knot, was used, 

 the chance of catching a mature salmon would be largely 

 increased, provided only such mature salmon are there to be 

 caught, which has yet to be proved. 



We know that in our own waters the capture of sea- going; 



