58 
BULLETIN OF THE UNITED STATES FISH COMMISSION. 
Cod (Gadus morrliua). 
At Gloucester, Mass., November, December, and January are the best months for 
collecting cod eggs. 161 female cod furnished on an average 279,000 eggs. 
At Woods Holl, Mass., according to the report of the superintendent, the period 
of incubation in the McDonald tidal box averaged 18 days; in the Chester box, 20 days. 
Mr. Bichard Dana counts 18 cod eggs to 1 inch, from which basis he obtains : 
In 1 quart 336, 798 
In 1 pint 168, 399 
In 1 gill 42,099 
In 1 ounce 10, 254 
In 1 cubic inch 5, 832 
In 1889 the first cod for breeding purposes were received at Woods Holl on October 
27 ; by November 19, 3,403 had been received, sufficient for the season’s work. The 
fish were placed in live cars except 700, which were confined in a basin wherein the 
tide ebbs and flows. In this basin the mortality was great, probably owing to the 
high temperature, 55°, and the want of shelter from the sun. The eyes of many of 
the fish protruded from their sockets, and the fish became blind in six or seven days 
after their receipt. Board floats were then placed in the basin, after which the 
condition of the fish improved. When the temperature of the water fell to 46° the 
mortality decreased. 
The first ripe eggs were taken November 18, and from this time until February 
18, 1890, the number of gravid females handled was 91, which furnished about 8,500,000 
eggs. From these upward of 5,750,000 fry were produced, which were liberated in 
the harbor from three to six days after hatching. The percentage of eggs hatched was 
68. On February 11, 1890, were received from the Gloucester station 2,374,200 eggs. 
About 23 per cent of those received alive were hatched, the injury in shipment having 
been very great. On April 14, 1890, another shipment of 621,600 eggs was received 
from Gloucester, and of the number received alive 66 per cent were hatched. The 
hatching apparatus consisted of 40 Chester tidal boxes with a capacity of 6 hatching 
jars, each holding from 150,000 to 200,000 eggs, besides 47 McDonald tidal boxes each 
having a capacity of 500,000 eggs. 
The temperature of the water in the hatchery ranged from 47° to 33° with no 
sudden changes and with unusual immunity from slime and sediment. The small 
supply of eggs alone prevented a large output of fry. The experiment of keeping cod 
in aquaria after the sac was absorbed proved again unsuccessful. The cod fry were 
generally liberated on strong ebb tide in Buzzards Bay or Vineyard Sound, so that 
they might quickly be carried into deep water. The average yield of the female cod 
at this station was nearly 94,000 eggs. In fertilizing these eggs the milt of 102 males 
was used. The shortest hatching period was 107 hours, from eggs obtained November 
18, 1889, which were hatched November 23. The longest period was 696 hours, from 
eggs taken January 27, 1890, and hatched February 14. The average temperature 
during the hatching of the first lot was 47°. The maximum temperature during the 
incubation of the second lot was 38°, the minimum 34°, and the average 36°. 
While the Grampus was obtaining cod eggs in October, 1889, it was found that 
few ripe fish were taken with hand lines as compared with those caught with the nets 
and trawls. 
