98 SALMON AND TEOUT IN ALASKA. 



mon spawning at a temperature of 54°, and Steelhead Creek contained 

 many spawning humpbacks August 25, 1903, at about the same tem- 

 perature. It is probable that the optimum temperature for the 

 humpback is about the same as for the king. The dog salmon seems 

 to accept a slightly lower degree; a few were spawning in a creek of 

 Moira Sound as early as August 18 in 48°. 



NATURE OF SPAWNING BEDS SELECTED. 



With the exception of the coho, the salmons appear to require a 

 depth of water and a fuieness of bed material somewhat in corre- 

 spondence with their relative size. The king salmon spawns in water 

 of a depth up to 2 or 3 feet, with a bottom of gravel and coarse sand. 

 No exact conditions seem to be required. In the Salmon River, 

 Idaho, the kings are reported to avoid the coarser gravel and swift 

 currents; in the Sacramento they will spa^\^l on bowldery rapids. 



The sockeye affects shallower water for spawning than the king. 

 On most Alaskan beds many occupy water which does not completely 

 cover the male fish. In the selection of spawning beds this species 

 is unique in requiring the adjacency of a lake; also it is the only 

 species of the genus that ever spawns in still water. The lake shores 

 chosen are more frequently portions through which a small rill flows 

 or where seepage comes through, but sockeyes are known to spawn 

 where no inflow of any kind is apparent. 



In the streams the beds chosen are similar to those well known for 

 various species, but, as mentioned above, in water of less depth than 

 is usual for the king. Sometimes bottoms of fine gravel are occupied, 

 sometimes bottoms of larger bowlders where the current is so swift 

 as to make the holding of position precarious. No observations are 

 recorded as to whether the first comers occupy the more accessible 

 grounds. They apparently distribute from the beginning, and there 

 is no evidence that a spa\\Tier ever recedes from a position once chosen 

 and occupied. Unless carried out by the current, even the spawned- 

 out fish remain until they die about the pool where they have spawned. 

 At Yes Bay stream in 1903 fish could be found throughout the stream 

 as far as the falls, but strikingly few examples were attempting to pass 

 higher. The writer has seen no fish attempt the dam on the Naha 

 just above the spawning beds, though cohos are said to do so. A few 

 individuals usually enter all the small unsuitable brooks during times 

 of freshets, apparently returning wdth the subsidence of the water. 



In the Karluk tributaries many fish occupy beds where none of the 

 material is of a size they can move, hence the naked eggs are swept 

 do\^^l the current and doubtless most of them lost. In' bottoms of 

 finer material occupied by many fish dead eggs in abundance are 

 usually to be seen in the eddies behind the hillocks formed by the 

 spawners working up the gravel. 



