MARINE PISCICULTURE 327 



to show on what an enormous scale economic 

 hatching operations would have to be conducted. 



Finally, it may be observed that our relative 

 ignorance, both scientific and statistical, of the 

 condition of the fisheries, and of many portions of 

 the life-histories of economic fishes, is so great as 

 to prevent us from undertaking sea-fish culture in 

 what may be called an intelligent manner. It has 

 been assumed, in this discussion of the matter, that 

 impoverishment of the fisheries with regard to any 

 one species can be made good by adding to the 

 number of fry (fishes at the stage of the meta- 

 morphosis) of that species already present in the sea. 

 But it is not even certain that by doing so we 

 should be making any sensible increase in the 

 number of fishes of marketable size on the fishing 

 grounds ; for we do not know that the mortality 

 at about this stage is of so much significance as 

 that between it and the stage at which the fish 

 becomes of value to the fishermen. (It is much 

 more probable that protection of the immature, 

 but just marketable, fish is the step most likely 

 to be of direct economic value.) There are so 

 many things to be considered before we can under- 

 take fish-culture in any particular locality, with 

 any degree of confidence of success, and we 

 know so little of them, that lengthy scientific 

 investigation must, in each case, precede the 

 purely economic work. 



