392 American Fisheries Society 



Rutter that the fish alternated in movements, traveling up and 

 then again somewhat downstream as the tide shifted. This 

 may be a uniform response to the current stimulus, for in 

 these regions the current changes with the change of tide, but 

 as the descending stream is stronger and its influence is felt 

 for longer periods of time, so the ascending movements of the 

 fish are superior to its reverse movements, and the salmon 

 ultimately pass into the river above the tidal influence and then 

 mount steadily upwards. The portion of the migration of 

 the red salmon in tidal waters has not yet been followed defi- 

 nitely so far as I know. Once the fish have started to ascend 

 the part of the stream which lies above tidal influences, they 

 press steadily onward. The rate of migration has not been 

 observed for the red salmon with a definiteness to determine, 

 even in general terms, the rate of progress. 



I have also made many observations with reference to the 

 character of the water, without being able to find any uni- 

 formity in the conditions that conforms to the course of the 

 migrating red salmon. In some places they pass from turbid, 

 silt-laden waters to clear tributaries. In other places they 

 seem to have selected that branch of the stream which carried 

 the larger amount of sediment or was of the milky-white color 

 so characteristic of glacial- fed waters. Furthermore, in south- 

 eastern Alaska, where there are so many short and highly- 

 branched streams, one can find cases where the entire basin 

 of the stream is underlaid by a single rock formation, so that 

 the materials in solution must be identical in chemical char- 

 acter, and no doubt also in the amount of mineral substances 

 in solution; moreover, the plant growth is uniform in char- 

 acter, if not in amount, throughout the entire basin of the 

 stream, and it is difficult to formulate a theory which could 

 in any way account for chemical dififerences in waters of such 

 a limited and uniform area. 



The rapid, turbulent character of the salmon streams indi- 

 cates clearly their extreme poverty in minute organisms and 

 the lakes are strikingly plankton poor so that there is only a 



