INVESTIGATION OF THE SALMON AND SALMON RIVERS OF ALASKA. 
PHYSICAL CHARACTERISTICS OF THE ENVIRONMENT OF THE SALMON. 
KARLUK BAY. 
(Plates XLV and l-lix.) 
The marine life of the Alaskan salmon is entirely unknown except when the vari- 
ous species approach the mouths of certain rivers to ascend to their spawning grounds. 
We do not know whether the ocean currents influence the movements of the schools 
of salmon, and we are not acquainted with the capacity of the salmon for enduring 
variations of temperature at sea. It appears from the best information we can obtain 
that the schools of salmon have not been observed at a greater distance than a mile 
and a half off shore. The direction of their ocean movements has not been determined, 
but Mr. Hirsch informs us that in approaching Karluk they come from all directions 
and continue in compact schools until they are close to land, when the schools break 
up. It is assumed as an established fact that the great body of the salmon come up 
from the sea at a certain time of the year and ascend streams for the imi’iiose of repro- 
duction. We know that at the time when the salmon approach the Alaskan shores 
certain species of small fishes constituting their food are abundant at sea near the 
land. Among these are the capelin, herring, and lant. Salmon continue to feed upon 
these species until they are ready to forsake the sea and enter the fresh waters. 
We could not learn that variations in temperature had much effect upon the daily 
catch of salmon. The lowest temperature of the water noted at the surface in Karluk 
Bay during our visit was 50°, and the highest 60°, the latter observed at noon, 
August 12. The greatest variation in temperature observed in any one day occurred 
August 13. At 7 a. m. the surface water was 50° and at noon it had reached 59°. 
The ordinary variation from 7 in the morning to 6 in the evening was from 2J to 4.J 
degrees. 
One of the sources of safety for the salmon at Karluk is the presence of beds of 
the bull kelji, Macrocystis giganteus, in which the fish find shelter from the seiners. 
Karluk Bay is merely a shallow arm of Shellikofif Strait, limited on the southwest 
by Cape Karluk, or Karluk Head, and on the northeast by high bluffs at the head of 
Karluk Spit. The outlook from Karluk Bay is towards the northwest. The beach 
descends very gradually from a low spit, and is composed of coarse gravel and large 
granite bowlders. The bottom slopes down gradually until, at a distance of 100 fathoms 
from the shore, the depth is several fathoms. There is very little good holding-ground 
for vessels. Some of the firms have fixed moorings at which their vessels ride out 
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