56 OBSERVATIONS ON ACCLIMATISATION OP THE TRUE SALMON. 



over-crowding, abnormal temperature, or by direct pollution, 

 represents a very if not the most important factor. Notwith- 

 standing, however, the apparently exhaustive onslaughts of this 

 formidable epidemic it is satisfactory to know that the returns 

 of the fish captured in these previously affected rivers within 

 later years has been in no way diminished, but even increased. 

 It is indeed advocated by some authorities on fisheries 

 matters that good is accomplished through the visitations of 

 this epidemic, since it operates as a check by which the old 

 male fish or kelts, which systematically lay in wait for and 

 prey upon the young salmon smolts when descending to the 

 sea, are periodically eliminated. 



Whatever good ends in the scheme of Nature may 

 be attained through the advent of this fungus disease in 

 association with the salmon rivers and the natural spawning 

 beds, it cannot be denied that where it invades and affects 

 those artificial conditions brought about by human interven- 

 tion, the consequences may be altogether disastrous. In 

 illustration of this, I may now refer to the circumstances 

 and phenomena attending the presence of this disease at the 

 salmon and trout breeding establishment on the River Plenty. 

 For many years, or in fact ever since artificial breeding 

 operations have been conducted there, a greater or less number 

 of the breeding fish have been attacked by this parasitic phase 

 of the fungus, 8a'prolegnia, and many fish have died. This 

 mortality, however, has hitherto been associated with ordinary 

 trout, Salmo fario, and salmon trout, 8. trutta, both of which 

 species, being firmly established in this colony, can be easilj 

 replaced at the breeding ponds. With the true salmon, 

 Salmo solar, however, the case is different. The only breeding 

 stock of this species that has been available this past winter 

 for artificial propagation has been a series of thirty fish 

 developed from the salmon ova brought out by the s.s. 

 Abingdon, in 1884, hatched out that same year, and since 

 retained in the Ponds. These fish, or rather what remain of 

 them up to the present time, not having migrated 

 to salt water, are in a relative dwarfed or undeveloped 

 condition. The largest of them scarcely exceeds q, foot in 

 length and they still retain their immature or parr markings. 

 The majority of them have nevertheless manifested a tendency 

 to propagate, and from the entire series a number of ova little 

 short of 4,000 have been artificially expressed and fertilised. I 

 should rejoice to be able to congratulate the colony upon 

 having in this most auspicious anniversary of Her Majesty's 

 reign, and after many years of indefatigable and self-denyiug 

 perseverance on the part of that very worthy body of gentle- 

 men, the late Salmon Commissioners, succeeded in es- 

 tablishing in Tasmania a race of this noble fish that would 



