! 
Vili DEPARTMENT OF THE NAVAL SERVICE 
7 GEORGE V, A. 1917 
4. Own the Lire-History or THE Cono.—(Dr. McLean Fraser.) 
The author points out that the increasing commercial value of the Coho or Silver 
Salmon (Oncorhynchus kisutch) in recent years justifies a thorough investigation of 
its life-history, rate of growth, etc. The spawning grounds are usually a short distance 
from the sea, and not at the head waters, as in the case of the Sockeye and the Spring 
Salmon. The eggs hatch in three months and the young fry wriggle up through the 
gravel early in April, and work down the rivers as the yolk is absorbed, and early in 
May many are near the mouth of their natal streams and creeks, but do not appear to 
migrate into the sea until the following March, or even later. The alevins measure 
13 inches; but when they are about to enter salt water (nearly a year old), they 
measure 2 to 23 inches about; and eight or nine months later are 10 to 12 inches long 
and of a weight of 12 to 14 ounces. When 2% years old or thereabout, they may be 
3% to 164 pounds in weight, and from 18 to 31 inches long, so great is the variation 
in growth. They are now mature and make the short ascent to their spawning grounds. 
Dr. Fraser proves that the opinion, which has been frequently expressed, that coho 
live for two or three years in rivers feeding 6n trout is absurd, and the reverse is 
much nearer the truth, for trout gorge themselves with coho eggs and devour the fry 
mercilessly. The Dolly Varden trout (S. malma) is the chief culprit. The mature 
coho feed actively until ready to ascend for spawning purposes; the shrimp-like 
Schizopods being their main food, but larval crabs, young herring, launce, and ecapelin, 
form also part of their diet. Dr. Fraser’s investigations correct the conclusions of 
previous workers as to the migrations and development of the coho, and three points, 
with which his report concludes, are of the highest interest to practical fish-culturists, 
viz., that the hatching of coho in fish-culture establishments is most desirable to avoid 
the wastage due to trout-depredations; and, secondly, that the retention of coho fry 
in rearing ponds must bring the best results, as almost .the whole of the fry hatched 
naturally remain for a year or more in fresh water before descending to the sea. 
Lastly, early coho fishing operations are a loss to the fishermen and the canners, as the 
eoho vastly increases in weight during the summer of its third year. 
5. INVESTIGATION OF OysTER PROPAGATION IN Ricumonp Bay, P.E.I., purine 1915.— 
(Dr. Julius Nelson.) 
The author, who was long prominent as a State Expert in New Jersey, U.S.A., 
agreed to carry on some special work in 1915 on the Richmond Bay Oyster Beds, 
P.E.1., and obtained some very remarkable results. These are difficult to epitomise 
owing to the very detailed nature of the investigation. The decline and extinction of 
certain areas are due not to the elevation of the beds, geologically, or by annual accu- 
mulations of debris, but to other causes. If the coast has been sinking, as seems prob- 
able, the intrusion of colder northern water may have lowered the temperature and 
the salinity may have been affected. Too much stress, says the author, has been prob- 
ably laid on salinity, for oysters can endure much variation in that respect; but 
temperature, oxygen, and currents, are of importance. 
Ice and snow also are unfavourable. Shallow water is favourable for propagation; 
but, in winter, results in oyster destruction; hence man can aid by oyster culture, 
especially by transplanting young oysters from shallow flats to deeper water, before 
winter comes. The main cause of destruction of beds has been improper fishing. 
Were private culture general each man would conserve the oysters, and fish them 
properly. 
Dr. Nelson calls attention to the fact that a large spawning oyster produces 
annually 60,000,000 eggs, and he estimates that an oyster bed readily produces ten to , 
fifteen millions of young for each adult present. In five years a bed should be ten 
million times larger; yet beds are decreasing and decaying. 
