REPORT OF COMMISSIONER OF FISH AND FISHERIES. LIX 



one messenger could carry all the young procurable in a given time, a 

 car holding ten or twenty times that amount is at present easily filled. 

 Too much, however, must not be expected from artificial propagation, 

 as it has to contend, not only with the depletion by excessive fishing, 

 but also with chaiiges of physicf-il condition, such as temperature, etc., 

 that require increased eftbrts to meet and overcome, and possibly, in 

 some instances, the substitution of other species better able to resist 

 the changes in question. In some cases the preventable difficulties 

 mentioned above successfully antagonize all the eflbrts made. 



22. — NEED OF A FISH-WAY AT THE GREAT FALLS OF THE POTOMAC. 



The importance of maintaining at their maximum of production the 

 valuable fisheries of the Potomac can hardly be over-estimated, in view 

 of the extent to which they furuish food for home consumption and for 

 transportation, and also of their agency in reducing the expense of 

 living to the poorer portion of the population. The fish involved in 

 this consideration are the shad, herring, rock, white perch, and black 

 bass, together with other fish coarser in quality and lower in price. 



Old records dating back to colonial times bear testimony to an abund- 

 ance of production, whic]i,read in thelight of present experience, seems 

 little short of marvelous, although after all credible when we con- 

 sider the favorable conditions for natural production which were then 

 afforded. 



The broad estuary of the Potomac E-iver, extending for a distance of 

 more than 100 miles, from Point Lookout to the Great Falls, oflered 

 through its whole length numerous flats and bars where the shad could 

 spawn, rarely molested by the intrusion or device of man. Its reedy 

 shores and extensive tracts of marsh land, covered with aquatic grasses, 

 furnished eveiy where a nidus and a nursery for the countless million 

 of eggs of the glut herring {Pomolobus aestivalis). 



Into the numerous creeks tributary to the main river, which have their 

 origin in the swamps of the interior, the branch herring {Pomolobns 

 lernalis) entered to find at their sources a suitable resting place for its 

 eggs and a safe habitat and temporary abiding place for its young. 



How the hand of man has changed all this will be evident from the 

 following considerations : Access to the sources of the smaller tributa- 

 ries of the Potomac, which drain the tide- water region, has been almost 

 universally barred hy mill-dams placed at the head of tide. The con- 

 version of the woodland along their banks into arable fields has rendered 

 turbid their once clear waters, and with every rain a muddy torrent is 

 sent down, loaded with fine sediment, which settles upon and stifles 

 every embryo of shad or herring which may have found a resting place 

 in the reaches below tide level. In addition, fykes and stake nets, weirs 

 and pound or trap nets bar access of mature fish to these streams al- 

 most as effectually as the dams prevent their ascent. 



In the main river the favorable natural conditions which formerly ex- 



