ORIGIN OF LAKE SALMON. 145 



In his conclusions he writes: 'In the hght of all the evidence one may conclude: The 

 landlocked salmon in a lake were not influenced or held in restraint by the formation of 

 any mechanical barrier that cut off access from the ocean but by some factors within the 

 lake itself which changed primitive conditions. Some change brought about the dis- 

 appearance of the current stimulus that would have led them on down-stream to the 

 ocean. These new conditions caused them to hesitate and finally to abandon their journey 

 to the sea. In the Baker River it was the erection of the dam which created a great 

 body of quiet water and thus eUminated the current stimulus. Following that it was the 

 warming up of surface waters which led the young fish to seek deep, cool waters. One 

 should recall also that when in the old unmodified river the migrators had reached the sea, 

 the next move of the young fish was to turn there into deeper, cool waters. The succes- 

 sion of responses is the same in both cases. The changes brought about by the erection 

 of the dam were rapid and the results immediate.' 



If Ward's interpretation of the situation at Baker River is correct, other things being 

 equal, any obstruction happening at any time m a sockej^e salmon stream, which pro- 

 duces an area of deep quiet water having the surface warmer than the river water was 

 prior to the intervention of the obstruction, would result in the landlocking and dwarfing 

 of the salmon. Accordingly Uke conditions might have the same effect on Atlantic 

 salmon. Thus it would be possible for the salmon to have become landlocked at any 

 time, since the glacial period up to the present time, or to become landlocked in the future 

 if subjected to those conditions. But from the author's argument it is to be inferred that 

 he regards some cases of the 'landlocked habit', especially in the older landlocked fish, 

 as having become hereditary and non-reversible. 



A specific instance may be cited in support of the view that the 'landlocked' habit is 

 hereditary. In 1897 I was privileged to spend several months at Wallowa Lake, Oregon. 

 In this lake was a permanently resident 'dwarfed' Sockeye locally known as 'yank.' 

 The migratory sockeye, there called 'redfish,' ascended to that lake to spawn. Many of 

 the former and a few of the latter were collected, also young of the large form were col- 

 lected for me, as they were descending the Wallowa River below the lake. If the resident 

 Uttle redfish originated in any such way as Ward suggests, when the passage again 

 became clear, the fish had lost the impulse to go to sea and the migratory fish returned 

 to the lake to spawn and its young retained its sea going habit. 



Many generations of the 'Quinnat' or 'king salmon' were retained and propagated at 

 the Trocadero Aquarium at Paris, France. Apparently no one has regarded them as 

 landlocked salmon. The same species has been introduced into several lakes of New 

 England, where it grew up and in some instances attained breeding condition. But 

 lacking suitable conditions they never reproduced. 



Ward is doubtless correct in regarding temperature as one of the determining factors 

 in the natural landlocking of salmon, but it was probably only one of many. The 

 phenomenon at Baker River is merely suggestive of that fact and has no other signifi- 

 cance in its relation to the natural 'landlocked habit'. 



