MARINE AND FRESH WATER PISCICULTURE. 25 



entrance a line of tramway has been constructed across the 

 mouth of a bay for the purpose of conveying ballast to the 

 breakwater at the Heads. This viaduct, while it encloses 

 j^erhaps 200 acres of water, provides communication with the 

 tide through a bridge 100 feet long — the water already teems 

 with fish fry of various kinds, thus proving its suitability as a 

 nursery and feeding ground. The proj)riety of setting it 

 apart for the purj^oses of experiment and observation in the 

 propagation of fish, and perhaps Crustacea and mollusca too, 

 will be obvious. Some few large estate proprietors back 

 from the coast have certainly introduced trout and other 

 fresh water non-indigenous fish into theu' own artificially 

 conserved waters, but no extensive or general movement in 

 this direction has taken place. 



It must not, however, be concluded that marine fish 

 culture, such as is here suggested, will apply to all species 

 of marine fish — scientific research has revealed the fact that 

 in European waters certain species breed in the open sea ; 

 their ova, according to its specific gravity, finding a location 

 either on the surface, or at various gradations of depth, or on 

 the ocean bottom. It would be difficult perhaps to control 

 such species within the limits of enclosed tidal waters, at 

 least those of them which pass their whole lives at sea ; but 

 some, the sole for instance, and indeed the 2^^^^^'onectid(S 

 generally, gravitate at quite an early age towards the quieter 

 waters of bays and inlets, and remain there until they reach 

 the adult stage, when in turn they seek the sea and perform 

 their office of reproduction. 



To what extent Australian fish species are subject to this 

 routine is not known, such can only be determined by 

 systematic observation and experiment, and these have not 

 yet been attempted. 



But in this connection Mr. Alexander Oliver, in an article 

 on the " Correlation of the inlets to the migratory and other 

 species of our sea fishes," affirms that the red bream, the 

 progeny of the schnapper, generally hatched at sea, becomes 

 from its cock schnapper period a denizen of inlets until, in a 

 more adult stage, it reaches out again to the ocean depths. 



This similarity of habit between at least one principal 

 species of Australian fish and many of the edible fislies of 

 the Northern Hemisphere is interesting in the extreme. 



The value of authentic knowledge respecting the life history 

 and hal)its of our food fishes can scarcely be over-estimated. 



Mr. Oliver's paper will be found amongst the Appendices. 



