REPOET OF COMMISSIONER OF FISH AND FISHERIES. LVII 



tlieir way up an obslructiou iiusurmountable by the shad, or ev'en by 

 the salmou ; so that there are very few waters in the eastern portion of 

 the United States where descending eels cannot be captured. 



All these methods of protection of fish and of enabling them to carry 

 out their mission, whether adults or young, are usually the subjects of 

 legislation ; and in some countries very stringent laws are in existence, 

 and enforced by the constant vigilance of wardens. 



The general principles just presented have relation for the most part 

 to the protection of the fish, and to the enabling them to perform their 

 reproductive functions undisturbed at the critical time. 



JEreetion of Jish-irays. — It is not my i3urpose at present to go into the 

 more detailed discussion of the various methods of protection of fish, 

 or into the question of suitable laws to establish such protection ; but 

 I confine myself to the subject of " fish-ways," which has always occu- 

 l)ied a good i)art of the attention of the Commission. 



In the report for 1872-'73, pp. 591-616, 1 have published an elaborate 

 account of the different methods of constructing fish-ways for facilitat- 

 ing the ascent of fish over obstructions in the rivers, including all that 

 were known, or in common use, at the time, and some which were de- 

 vised by assistants of the Commission. 



Numerous forms of fish-ways have been more or less successful, 

 especially in connection with the movements of the salmon. This fish 

 is very vigorous, and able, by leaping, to surmount vertical falls of 

 quite a number of feet in altitude, the number varying with the strength 

 of the fish. No height less than 6 or 8 feet is believed to be insuper- 

 able to the salmon ; but other fishes, especially the shad, are less power- 

 ful, and for these fish-ways are needed in many cases where they are 

 not necessary for salmou. 



It is but fair to state that, so far, the ordinary methods of fish- ways 

 have not been successful in facilitating the upward run of the shad, and 

 in spite of a great deal of ingenuity and much expenditure of money 

 and experiment, the problem cannot yet be considered as entirely solved. 



The device of Col. Marshall McDonald, one of the principal assist- 

 ants of the United Slates Fish Commission, holds out very great promise 

 of success in this respect, and it is proposed to test this apparatus at the 

 Great Falls of the Potomac Eiver, Congress having made an appropri- 

 ation for the purj)ose. 



There is no locality where a successful fish-way would do more in the 

 way of increasing the supply of shad than on the Potomac Eiver, as the 

 stream below the Great Falls now represents a most productive locality 

 for shad, and the waters above the Falls would furnish the most favorable 

 opportunities imaginable for the spawning of eggs and development of 

 the young. The general character of the device selected will be found 

 under the head of the Great Falls Fish- way. 



