420 
BULLETIN OF THE BUREAU OF FISHERIES 
differences were noted in the different streams, as well as between the upper and lower 
courses of the individual streams. The maximum quantity of ammonia nitrogen was 
found in the sample obtained at the mouth of Moraine Creek on July 25, 1927, namely 
0.4 milligram per liter of water; the next in rank was a sample from the mouth of 
Upper Thumb River which contained 0.328 milligram of ammonia nitrogen per liter. 
The smallest amounts of free ammonia were found in the upper courses of some of the 
streams, such as none in the upper part of Moraine Creek and only traces in the upper 
parts of Canyon, Falls, and Little Lagoon Creeks, and the north fork of Upper Thumb 
River. 
The maximum quantity of nitrite nitrogen was found at the mouth of Upper 
Thumb River, namely 0.018 milligram per liter, while none was found in the 
samples taken in the upper courses of three streams. The other samples on which 
determinations were made yielded from 0.001 to 0.01 milligram of nitrite nitrogen 
per liter. 
The largest amount of nitrate nitrogen found in the stream waters was obtained at 
the mouth of Moraine Creek, namely 0.085 milligram per liter. In the other stream 
samples the quantity of nitrate nitrogen ranged from 0.005 milligram in the north 
fork of the Upper Thumb River to 0.072 milligram per liter in Upper O’Malley River. 
In Canyon, Cascade, and Falls Creeks there was a somewhat larger amount of nitrate 
nitrogen in the samples from the upper courses than in those from the mouths of these 
streams. In Moraine Creek, on the other hand, there was a little more than twice 
as much nitrate nitrogen in the sample obtained from the mouth as in that from the 
upper course of this stream. In the Upper Thumb River there were 12 times as 
much in the sample taken at the mouth as in that taken in the north fork of this stream 
above the falls. 
The red salmon which come into these lakes and streams to spawn have a very 
important effect upon the chemical status of their waters. After spawning these 
salmon die and the carcasses decompose either in the water or along the shores of the 
lakes and streams. The greater part of this decomposition takes place in the streams. 
In an average year more than a million red salmon, each weighing from 2 to 3 kilo- 
grams or more, migrate into these waters for the purpose of spawning, and their sub- 
sequent death adds probably in excess of 2,000,000 kilograms of decomposable organic 
matter to the waters of the Karluk drainage system. The decomposition of this 
material makes a very important contribution to the quantity of both organic and 
inorganic substances that are held in solution by these waters. 
Some observations made during the summer of 1927 serve to give an idea of the 
abundance of dead salmon in some of the streams. On July 17, Canyon Creek was 
listed as having comparatively few dead salmon; on July 21 it was estimated that 
there were 50,000 to 60,000 dead salmon in the two forks of Upper Thumb River. 
On July 25 Moraine Creek was listed as having about 10,000 dead fish. 
Shostrom, Clough, and Clark (1924) give the following results for chemical 
analyses of bone-free samples of the red salmon of Karluk River: Moisture, 69.5 
per cent; fat, 5.6 per cent; protein, 21.6 per cent; and ash, 1.3 per cent. They state 
that bone constitutes 2.2 per cent of the total weight of the fish. On this basis more 
than 400,000 kilograms of the total estimated decomposable matter contributed by 
the dead salmon would consist of protein material, and the decomposition of this 
protein furnishes a supply of nitrogen compounds to these stream and lake waters. 
In their final stages of decomposition these compounds yield ammonia, nitrites and 
