[13] EXPLORATIONS ON COLUMBIA EIVER. 24D' 



a dam was put across the river, but where the settlers are so numer- 

 ous above that such an obstruction would not be tolerated. 



6. Facility for catching parent fish. — This is not so essential 

 a condition as the preceding ones, because labor and dynamite can usu- 

 ally create a good seining ground almost anywhere. It is an important 

 condition, however, because a poor seining ground is a great drawback 

 and a very serious annoyance at a salmon hatchery, and in many places 

 it would cost a great deal of money to make a good seining ground with 

 labor and dynamite. Moreover, such artificially prepared grounds are 

 torn to pieces, so to speak, every winter by the violence of the high wa- 

 ter during floods. This difficulty of securing a good natural seining 

 ground is more often encountered than one would suppose. An inex- 

 perienced person might perhaps think that a net could be dropped any- 

 where in a river where fish abounded, and be drawn in successfully. 

 .But it is not so. Indeed there are many things which bar out seining 

 in a river. For instance, a seine cannot be hauled with any success in a 

 swift and shallow place, for the net cannot be drawn inshore with any 

 success, even supposing the river bottom to be comparatively smooth 

 and level. Neither is it of any use to haul where there are deep holes 

 in the river bed, for the fish will go into the holes as the seine passes 

 over them, and will escape. Again, it is impossible to haul a seine 

 where there are large bowlders, or worse still, projecting points of rock 

 in the seining ground, as these obstructions will foul the net every time^ 

 and if the fishing is persisted in will soon tear the net to pieces. As 

 suggested above, a sufficient expenditure of time and money will make 

 a good seining ground out of a poor one, but it is often a very exi^en- 

 sive undertaking, and when accomplished the seining ground that has in 

 this way been artificially made will never be so good a ground for fishing 

 as one that has been prepared, or nearly prepared for use, by nature. 



As an example of the difficulty of finding a good seining ground I 

 might mention the McCloud Eiver, (California, where, I suppose, there 

 is not in the whole sixty miles of the course of the river a single place 

 Avhere there is a good seining ground or where a first-class seining" 

 ground could be made, except at the salmon-breeding station of the 

 United States Fish Commission two miles from the mouth of the river. 



7. Facility for arresting the progress of the breeding 

 SALMON UP THE RIVER — As evcrv oue knows, migratory fish, partic- 

 ularly those of the salmon family, develop an irrepressible instinct tO' 

 ascend the rivers which contain their spawning grounds. So strong and 

 violent, indeed, is this instinct in salmon that they will force their way 

 over all obstacles not absolutely insurmountable, in their endeavors to- 

 reach the sources of the rivers which they enter to- deposit their spawn. 

 Taking advantage of this instinct, the salmon-breeder finds an ensy 

 method for holding them at the particular place where he wants them 

 to stay, by throwing across the river a dam or fence, which allows the 

 water to pass down but prevents the salmon from going up. Their in- 



