42 REPORTS OF THE DEPARTMENT OF COMMERCE. 



saving of these valuable food rosources by systematic annual rescue 

 work is of vital importance to the maintenance of the fisheries of the 

 region. The Bureau will expand its efforts to the full limit of finan- 

 cial possibility, and should bo reinforced by all the States, some of 

 which up to the present time have exhibited no interest and assumed 

 no responsibility. 



SOME NEEDS OF THE FISH-CULTURAL SERVICE. 



Among the more urgent needs in the Bureau's fish-cultural work 

 is an increase in the number of hatcheries. The new establishments 

 are desired for States or regions not now provided with hatcheries 

 or only inadequately served by existing hatcheries. In addition to 

 the foregoing, there should be several salmon hatcheries provided for 

 Alaska. 



There should be congressional recognition of the invaluable service 

 rendered by the Bureau in salvaging food fishes in the overflowed 

 districts of the Mississippi Basin, and li})eral financial provision should 

 be made for its continuance and extension. 



Tlu-oughout the fish-cultural service there is an imderpaid per- 

 sonnel. If the standard of efficiency is to be maintained there must 

 be provided at once a revised salary scale that will retain desirable 

 men and induce others to enter the various grades. Noteworthy 

 results in the artificial propagation of aquatic animals and in the 

 stocking of our interior and coastal waters can not reasonably be 

 expected from a staff that in many cases is changing more quickly 

 than appointment papers can be prepared and delivered. 



ARTIFICIAL PROPAGATION OF FRESH-WATER MUSSELS. 



The active efforts taken by the Bureau to maintain by artificial 

 means the supply of pearly fresh-water mussels, on which depend 

 important fisheries and an extensive button-making industry, 

 have presented the usual aspects. The work is conducted under 

 the supervision of the fisheries biological laboratory at Fairport, 

 Iowa, at various favorable points in the Mississippi Basin from 

 Arkansas northward. 



During the fiscal year 1919 about 136,907,365 young musselj, 

 or glochidia, in a condition of parasitism on fishes, were liberated 

 in public waters as compared with 209,132,825 liberated in the 



{)revious year. This decrease was duo chiefly to unsatisfactory 

 abor conditions, which made it difficult to keep efficient seining 

 crews steadily employed, with a resulting reduction in the fish catch. 

 The principal reduction was in the Lake Pepin field, the output of 

 which was 35,423,125, as compared with 91,226,800 in 1918. 



Four species of commercial mussels were propagated, the leadhig 

 ones l)eing the common mucket (Latnpsilis ligamentina) and the 

 Lake Pepin mucket (Lampsilis luteola), the others being the yellow 

 sand-shell (Lampsilis anod(mtoides) and the pocketbook (Lampsilis 

 ventricosa). The inoculated fish hosts were liberated in the Missis- 

 sippi River off Fairport, Iowa; in Lake Keokuk, Iowa; at New 

 Boston and Oquawka, 111.; in the Mississippi River at Lake Pepin, 

 Minn, and Wis.; in Lake Pokegama, Minn.; and in the Black River 

 in the vicinity of Pocahontas and Clover Bend, Ark. 



