THE SALMON EXPERIMENT IN TASMANIA. 821 



nous small fry, whicli are then constantly hatching out. As the female 

 of these grilse taken in earlj^ autumn invariably exhibit the ova consid- 

 erably more matured than when taken in the spring, there can be no 

 doubt that they are finding their way to the fresh- water spawning-beds, 

 and would reach them in the early floods of winter, though among the 

 wealth of suitable streams running througli scores of miles of uninhab- 

 ited, mountainous, and inhospitable country we have never yet (except, 

 perhaps, in one instance) been able to ascertain the exact locality of such 

 spawning-beds. 



It is quite jjossible that the grilse after spawning, and on its return 

 with the last of the winter floods to salt water, requires some greater 

 change and a longer journej^ seawards than when it was passing from 

 the smolt to the grilse stage. And, if so, it may have to encounter more 

 formidable marine enemies than on its first journey, or some unfavora- 

 ble physical features of our coast of which we, as yet, know nothing. 

 Unfortunately, the most scientific ichthyologists and the most practical 

 fishermen are still equally ignorant of the precise habits of the mature 

 salmon when at sea, and exj)erience can alone prove whether the final 

 stage is to be successfully reached, and, if so, when f 



During the last few years, and since the commencement of the salmon 

 exijeriment, large numbers of specimens of our coast fish have been 

 forwarded to and examined by Dr. Albert Gunther, of the British 

 Museum, whose determination of the species proves that many of our 

 fish are not merely representatives of but identical with British forms, 

 such, for instance, as the John Dory {Zeus faher), the horse-mackerel 

 {Trachurus trachurus), the dog-fish {Acanthias vulgaris), the sprat {Clu- 

 pea sprattus), and the conger [Conger vulgaris). And this fact goes far 

 to show that there can be no vast difference between the physical fea- 

 ture? of the Tasmanian and British coasts. 



If, therefore, there is any truth in the doctrine of natural selection and 

 survival of the fittest, we may rest assured that as the grilse are rapidly 

 increasing in number, some few out of the thousands sent time after 

 time to sea will be able to adapt themselves to their altered circum- 

 stances, escape their foes, and find their way back as salmon. After 

 the second migration is accomjilished, the increased speed and cunning 

 of the fish will materially improve its chance of successfully overcom- 

 ing tlie dangers of all subsequent journeys. 



For each of the grilse which have been taken in one minute spot of 

 the wide estuary of the Derwent, by a net ill-suited for the purpose, 

 there must be hundreds, and more probably thousands, passing of 

 which we hear and see nothing; and if this is true of the grilse after the 

 manifold risks to which they have been exposed on our coasts, what 

 must be the number of smolts that have passed down the Derwent, and 

 what the still greater luimber of fry in the eailier parr stage on the 

 gravelly rapids of some tributary or tributaries of the Upper Derwent ? 

 Can we set such numbers down at less than hundreds of thousands ? 



