FISHERY INDUSTRIES. 



33 



very little in excess of 50,000, and the egg take was fewer than 

 3,000,000; in 1912 the catch was again slightly increased and the egg 

 take increased proportionately to nearly 4,000,000, showing a spawn- 

 ing escape of about 4 per cent. This high degree of efficiency of the 

 seiners is brought about by the conformation of the bay. It wiU 

 probably be impossible for them to take all the fish without barricad- 

 ing the stream, but their present effectiveness will prove a sufficiently 

 close approximation to exterminate the run commercially in a few 

 more years. 



HATCHERIES AS A CONSERVATION PROVISION. 



Perhaps the best example of results to be obtained from hatcheries 

 is to be found in the Fortmann hatchery at Loring, on the Naha 

 stream. At this station, since its establishment in 1901, the entire 

 run of redfish has been devoted to propagation uses. In 1903 the 

 hatchmg plant was extended to its present size and, with the excep- 

 tion of one season, 1911, the entire number of redfish entering the 

 upper lake has been artificially spawned, so the number of eggs taken 

 eacli year indicates with fair accuracy the number of fish entering 

 the stream. These figures are shown in the following table: 



Redfish Eggs Taken and Fry Liberated, 1901 to 1912. 



o Product in each case of eggs taken the previous year. 



The factor of error introduced by these figures as an exponent of 

 the number of fisli entering the stream lies in the fact that an uncer- 

 tain number of fish spawn each year below the upper lake. In 1911 

 these were numerous and not counted; in 1912 a considerable portion 

 of the eggs secured were taken in the lower lake, thus entering the 

 count. But in general, the number of fish may be arrived at approx- 

 imately by omitting the last three places in the figure for eggs. For 

 example, in 1912, 23,160 fish ma}^ be credited to the stream. From 

 1887 to 1891 this stream yielded to the canneries an annual average 

 catch of 78,000 fish; in the next five years it dropped to half of that, 

 or 39,000; in the next four years to less than half of this, or 15,000. 

 Under hatchery operations on a closed stream, the run the first four 

 years averaged annually about 33,000; in the next four years it 

 reached 60,000, but in the last four years it has fallen again to an 

 average of 54,000. In the initial period of four years, of course, only 

 the natural run was produced; that is, the product of the hatchery 



