134 U. S. BUREAU OF FISHERIES. 
Inspection of the above table shows the slowest rate of travel in 
the first hundred miles of the river above its mouth. From the en- 
trance of the South Mouth to Pilot Station is approximately 130 
miles, but it was five days after the run began in the mouth of the 
river before the first king salmon appeared at Pilot Station, indi- 
cating a rate of about 30 miles per day. Between Pilot Station and 
Tanana, on the other hand, the rate of travel was slightly more than 
80 miles per day. This discrepancy is probably due to the habit of 
playing back and forth in brackish water, on entering the river 
mouth, before beginning their serious ascent of the river. It is well 
known to the fishermen at the mouth of the river that salmon enter 
the gill nets as numerously from the upstream as from the down- 
stream side. They pass back and forth on the tides, lingering within 
the fishing district, thus giving the nets many more opportunities to 
capture them than would be the case if they pursued a direct course 
on entering the stream. 
Three records below Tanana, those of the camp 51 miles below 
Kaltag, Kaltag itself, and Koyukuk, do not align themselves with 
the remainder of the series. At the average rate of travel king 
salmon should have reached Kaltag by the 24th instead of the 28th 
and Koyukuk by the 25th instead of the 29th. In both of these 
localities the capture of king salmon was considered of little relative 
importance, and the records are doubtless defective. 
Above Tanana the current of the river increases materially, rapids 
are encountered, and the intricate channels of the Yukon Flats are 
to be threaded. It is not surprising to find that the rate of travel in 
the upper portion of the river becomes reduced. Not only are the 
difficulties of ascent increased but the potential store of energy in 
the fish approaches exhaustion. When they enter the mouth of the 
river they are the richest in oil of any salmon known, but by the 
time they reach Dawson their flesh is comparatively dry and flavor- 
less, the oil having been expended to supply the energy needed in 
ascending 1,500 miles against the current and in carrying forward 
at the same time the sexual changes which precede the act of spawn- 
ing. The average rate of travel from Tanana to Dawson was 
slightly less than 45 miles per day, while from Pilot Station to 
Dawson, involving practically the entire length of the river below 
Dawson, the average rate was 57 miles per day. 
No record of any other river approaches this in completeness nor 
in the high rate of travel indicated. The unexampled speed with 
which salmon ascend the Yukon is doubtless associated with the 
great distances to be traversed before reaching their upper spawning 
areas, taken in connection with the shortness of the northern summer. 
Inasmuch as the investigators were compelled to restrict their 
attention to the main river, they are unable to designate the prin- 
cipal spawning areas of the king salmon. Limited numbers of kings 
are reported to turn aside into all the principal tributaries of the 
lower and middle sections of the river, but it is believed that a rela- 
tively large proportion of the run passes beyond the mouth of the. 
Porcupine into the upper portion of the basin. 
CHUM OR DOG SALMON. 
Although the king salmon is an important source of food to the 
natives and the white population, it is far surpassed in value by the 
