64 



Having now, to tho best of my ability, completed the list of our fresh water 

 enemies, I would call attention to tho fact that, with but one or two exceptions, 

 the attacks of all the creatures yet mentioned would be directed only against 

 the ova or the fish during their early and inactive stage, the lesson to bo 

 learnt from which is, that to ensure success we must never leave off protecting 

 the ova and young fry by artificial propagation, and from the interest hitherto 

 taken by the Fellows of the Eoyal Society in this great work, I feel certain 

 that they will do their utmost to sxipport the Salmon Commissioners in their 

 determination to carry on the artificial rearing till all suitable Australian 

 rivers swarm with the King of fish. 



With regard to the creatures inhabiting our brackish and salt waters, tho 

 diflRculty of estimating the degree of injury they may do to the salmon is very- 

 great, from two obvious causes, one is our ignorance of the habits of the salmon 

 when he leaves the fresh water, the other I regret to say, is our want of 

 reliable information concerning the creatures inhabiting our coasts and estuaries. 

 With reference to this last cause, I would urge the Fellows, to communicate to 

 this Society any observations they may have made upon the habits of our vora- 

 cious fish or other animals. Such information would add greatly to the value 

 of our published transactions, and might prove of very great service to those 

 who are personally superintending the salmon experiment. 



If we knew whether the smolts, on their way to the sea, swim near the 

 surface or near the bottom, along the banks or in mid-stream, we might predict 

 with more accuracy, what their foes would be, but in the absence of this 

 knowledge, all I can do is to take care that none of our predaceous animals, 

 with which I am acquainted, and which could possibly interfere with the salmon, 

 are omitted. 



One fact in the natural history of the salmon in salt water, is well esta- 

 blished, and that is the rapidity of his gi'owth and corresponding increase in 

 strength and speed, — and this increase in size, strength and speed will effectually 

 remove him from the attacks of a host of enemies to smaller and more sluggish 

 fish. 



To commence, as before, with the mammals, Seals ; {Sfenorynchics lejitonyx 

 and Arctocej)halus lobatus) once common on our coast, are now all but extinct, 

 two or three only having been seen in the Derwent duriug the last twenty 

 years. It is not diflficiilt to estimate this advantage, when we remember that 

 amongst the worst enemies of the full-grown salmon of the Scotch and Irish 

 rivers, are the troops of small seals which still periodically visit their rocky 

 headlands. 



I have already mentioned that the beaver- rat is found on the banks" of rivers 

 below the fresh water, but in these situations his nefarious practices are con- 

 fined to rushgrown tidepools, and backwaters, rather than to the open river, 

 and he is consequently little to be feared. 



Of toothed cetacean the only one much to be dreaded is our common 

 porpoise (Phoccena sp. t) A shoal of these is always to be found in some part 

 of the Derwent and I greatly fear they will often levy a toU on each batch of 

 salmon passing up or down the river. Yet porpoises are no more numerous 

 here than on the British coasts, and it must be borne in mind, that vast shoals 

 of our indigenous fish, far less active than salmon are periodically subjected to 

 the attacks of this foi-midable enemy without becoming extinct ; indeed, any 

 one who has watched from the rocks at the confluence of the River? Jordan and 

 Derwent, the myriads of bream, mullet, and other estuary fish, passing up and 

 down with each tide, must be aware that the porpoises are amply supplied with 

 the food to which they are accustomed, and that a large majority of the salmon 

 will therefore certainly escape. 



Outside the Derwent, in Storm Bay and on our coasts, another toothed whale, 

 attaining a length of from 12 to 15 feet, and known to southern whalers as the 

 " Black-fish" ( Glohiocephalus macrorynchus) occasionally makes its appearance 

 in large shoals. Whether this " Black-fish" will prove an enemy or not will 

 depend on how far the salmon proceed seawards. For my own part, I do not 

 believe they will ever travel beyond the arm of the sea which forms the entrance 

 to the Derwent, as the time occupied in the journey from the fresh water to 

 the sea and back is so short, often not more than six weeks, and a large part 

 of that time must necessarily be taken up in the search for food. 



From sea-birds salmon would have little to fear. During a week or ten days 

 of their first marine excursion, the smolts, if they swim near the surface, may 

 be subjected to the attacks of gannets (»S't<?a AustraUs), but after that time 

 the increased size of the fish will render them safe. Herons, terns, sea-gulls, 

 icC, are not powerful enough to interfere with the smolts, even when they 



