28 U. S. BUREAU OF FISHERIES. 
gravel from 1 to 4 inches in diameter. Here the eggs were buried from ap- 
proximately 8 to 16 inches deep. When the eggs were reached, the gravel was 
found to be absolutely clean, more especially where the good eggs were secured, 
with a coating of fine sediment on top, indicating a circulation of fresh spring 
seepage water at all times. Anticipating this condition, a common trough 
was installed in the slough, with a circulation of fresh water assured at a low 
tide, but which at flood periods would be covered from 13 to 4 feet with salt 
water without any circulation. The trough was filled with gravel, through 
which about 25,000 eggs were carefully mixed. A tight cover was then 
fastened on the top, with sufficient space left at both ends for proper circula- 
tion. The eggs were placed in the gravel on December 18, 1919, immediately 
after being fertilized, and on examination, on March 5, 1920, they were found 
to have hatched with an estimated loss of about 30 per cent. The fry appeared 
to be extremely active and healthy. The bad eggs were nearly all decayed 
and broken but had the appearance of having been fertilized and the embryo 
partially developed. 
This would lead us to believe that an entire salt-water supply, with as low 
a density as 1.010 for an extended period, is injurious but not absolutely fatal, 
and it strengthened our belief that where fish spawn naturally within tidewater 
area the eggs are deposited where they receive a circulation of fresh water, as 
-before stated. Samples of eggs were taken from each nest, and, contrary to 
Mr. Robertson’s theory and observations in hatching eggs in gravel, the infertile 
eggs were chalky white when first observed in the gravel. The alternating 
salt and fresh water may be a contributing cause, though where a continuous 
circulation of fresh water seeps through the gravel it would appear difficult 
for salt water to penetrate sufliciently to have much influence on the eggs. 
Our observations led us to believe that the infertile eggs might be accounted 
for largely by a scarcity of male salmon. However, there is a possibility that 
spawning might have occurred wholly in salt water, which may prevent the 
action of the eggs necessary to proper fecundation. As all but a few of the 
fish entering the slough were taken in the trap, and as the males are usually 
the first to ascend, it is not improbable that most of the males entered the 
trap, thus reducing the possibility of successful natural spawning at the points 
where observations were made. The table would indicate enormous losses 
through natural spawning, but aS conditions were not absolutely normal, we 
would not care to be too emphatic from this meager survey. 
To obtain full information relative to the foregoing it would be necessary 
to extend observations over the entire spawning season. Each nest should be 
marked and accurate data produced as to the number of fish depositing in each 
nest, together with all natural and unusual occurrences noted. 
RESULTS OF EXAMINATIONS OF FisH NESTS, WALCoTT SLOUGH, BRINNON, WASH., 
Marcu 5, 1920. 
Distance] Height Vorti Esti- 
= ertical 
sae ECO yates | eee eee ee 
Nests. | water | nest at sens ee tide | ber of age cae Remarks. 
at mean a tid e. | ing | Covers | eggs BBS. 
tide. Sa Hest. ae ee 
Yds. |Ft. In. Fé. In.) Hrs. * 
No.0 box! SOY des A OLS aie caet 8 3 225,000 | Hatched...) Estimate 70 per cent hatched. 
No. 11,3... 500|}2 5] 1.022/6. 8 6 46 | Good......| 41 good; 5 dead. 
No. 21,3... 450 | 2 Le MO 225 |v 0 43 100 | Total loss.| Unfertile. 
INiosd.1, 855% 450 | 2 1 | 1.022 | 7 0 44 151 | Perfect....| 1 dead, but all fertile. 
No. 4 #..... 420 | 3 Wit aeeeie 6 0 64 500 | Total loss.| Unfertile. 
No. 54..... ATO Gig 1a eee 6 0 63 ATI ae nny soe Do. 
INKS 300 | 4 7 eet et 5 6 63 402 | Very poor. a ee 2 good (bad, un- 
ertile). 
No: 7 4..2 2. 250 t4 ty Wiel acaeened Dies 6 62 Newbee Bl epetectan e015 Nest looked good, but con- 
tained no eggs. 
No. 8 4..... 200 | 5 if |Soeocnue 3 6 8 | e he AR eS haere. Sh ais Do. 
1 The silt water density was tested by pumping water from bottom over nests at flood tide and ranged 
aus ie a box location to 1.022 at nests Nos. 1, 2, and 3, and 1.025 naturalsea water in Hood Canal. 
anted. 
3 Nests 5 feet apart. 
4Current swift and water badly discolored; numbers estimated from those seen in the water and caught 
innet and baskets set below the nests on the riffles when disturbing eggs; good eggs are not as buoyant as 
dead ones, and therefore some may have escaped our notice. 
