PROGRESS IN BIOLOGICAL INQUIRIES, 1939 39 
to handling were small. The recovery of these marked fish as adults 
will afford data on life history, points of capture in the commercial 
fishery, and mortality in the ocean. 
Fingerlings were taken in the Wood River from June 4 to August 
22, and marking was carried on between July 3 and August 14. Ab- 
normal water levels i in the river during the month of June followed 
the late break-up of ice on the Wood River lakes. A peak rise of 
more than 45 inches during this period reduced the number of loca- 
tions suitable for fishing “activities appreciably. The water level 
dropped gradually thereafter throughout the season, a condition ex- 
actly opposite to the normal occurrence in the Bristol Bay streams. 
The total release in this area was 11,338 fingerlings, marked by the 
excision of the adipose and left ventral fins. ‘The Wood River finger- 
lings were much smaller than those of the Naknek area, their gen- 
eral condition was poor, and they were further weakened by a high 
degree of infestation by’ cestodes. Losses due to handling agere- 
gated nearly 20 percent of the fish taken; an exceptionally ‘high 
mor tality for wild fish. 
During the commercial-fishing season 1 man was stationed at each 
of the main rivers to obtain veoular scale samples, body measure- 
ments, weights, and sex propor tions from the catches of the commercial 
drift-net fishery. Additional samples were taken from the fish 
caught by set nets within the rivers. These data will provide in- 
formation concer ning the age of the mature fish, material for racial 
comparisons, and a ‘basis for the determination of gear selectivity. 
The field parties were moved to the tributaries of the respective 
rivers during August for the purpose of making surveys of spawning 
grounds. In the course of the sur veys, actual “numbers of spawhers 
were counted in various streams and their tributaries. The rate of 
water flow, temperatures, stream-bed characteristics, and the extent 
of the spawning areas were determined. Body measurements, scale 
samples, and data on various morphological characters were obtained 
from spawners in these areas for racial comparisons. Of the spawn- 
ing tributaries thus investigated, 3 were rivers, 7 were major streams, 
and 19 were creeks. The field parties returned to Seattle via the 
Iliamna Lake portage on September 6 
In addition to the above-mentioned activities, several lakes were 
surveyed by Mr. Kelez as possible sites for survival studies on eggs 
and young fich. All major spawning areas were covered at least 
twice during the season by aerial survey, and spawning-ground esti- 
mates thus made were correlated with the work of the field parties. 
A new method of making a population census by means of aerial 
photographs was begun. While still in the experimental stage, this 
method holds much promise in that it makes possible a determination 
of the distribution of spawners in inaccessible areas, or in those areas 
where the cost of ground surveys is prohibitive. 
For Bristol Bay in general, the escapement of 1939 was consider- 
ably less than that of “1938, the Kvichak area showing the greatest 
proportional decrease. The Naknek and Egegik areas indicated 
uneven distributions and decreased total numbers of spawners, while 
the Wood River and Nushagak escapements were more nearly equal 
to those of 1938. The Ugashik area had a somewhat better escape- 
ment than that of 1938, although the spawning ground in this dis- 
trict was still not adequately seeded. 
