144 THE STORY OF FISH LIFE. 



and when the fishing is suspended for a short 

 time, a river of nearly four hundred feet in width 

 and five-and-twenty in depth has been known to 

 be completely blocked by a solid mass of fish." 

 Sturgeon fishing is prosecuted for the sake of the 

 flesh, the ova, from which caviare is made, and 

 the air-bladder, from the inner lining of which 

 isinglass is prepared. 



The sturgeon and the salmon afford us 

 instances of a universal migration of adults 

 from the sea into the rivers for the purposes 

 of making provision for the future generation. 

 But besides these armies of adults, the rivers are 

 also invaded by hosts of young fishes hatched in 

 the sea, but which complete their growth in the 

 rivers. The common eel is one of the most 

 interesting of these hosts. " In the course of the 

 summer," writes Dr Giinther, " young individuals 

 from three to five inches long ascend rivers in 

 incredible numbers, overcoming all obstacles, 

 ascending vertical walls or flood-gates, enter- 

 ing every larger and smaller tributary, and 

 making their way even ov^r terra firma to waters 

 shut off from all communication with rivers. 

 Such immigrations have been long known by the 

 name of Eel-fairs. The numbers participating in 

 these migrations are so vast as to be almost 

 incredible. Upwards of three tons of " elvers " 

 as these young eels are called were de- 

 spatched in one day from the Gloucester district 

 in the spring of 1886, and it has been estimated 

 that over fourteen thousand of these elvers go to 

 make a pound weight. " In the previous year," 

 writes Mr Lydekker, " the annual consumption 



