FISH HATCHERIES 
77 
Spawning habits vary greatly. Some fish, like the sal¬ 
mon, make long journeys from the sea to the head waters 
of rivers and streams to deposit their eggs. The Colum¬ 
bia River is famous for the number of salmon which spawn 
there. Other fish, like shad, go up a river only a short 
distance to lay their eggs. Many shad, for instance, go 
up the Hudson River in New York state. In the case of 
herring, the eggs are laid in the sea and float on the surface. 
64. Life History of the Eel. — This well-known fish of 
the inland streams and lakes has had so many stories and 
myths in connection with its development that much effort 
has been made to learn the facts. Eels migrate down¬ 
stream to the larger rivers and eventually to the ocean in 
the fall of the year. Here in the region of mud banks the 
females lay their eggs in great numbers and the sperm cells 
of the males fertilize them. In some cases the females lay 
as many as 10,000,000 eggs at one time. After the eggs are 
laid the adult eels remain in the ocean a few weeks and die. 
The young eels pass through the larval stage in about three 
weeks after the eggs s!;art to hatch. 
At the beginning of the second spring the young eels start 
on their trip back to fresh water. Great numbers of them 
may be seen in the spring at the foot of Niagara Falls where 
they are blocked by the great cataract. By crawling over 
stones and along the banks, young eels are able to get above 
ordinary falls in the streams and rivers. 
The eel is a food fish. The commercial value of the eel 
is well known to fishermen. They are rich in oil and highly 
nutritious. Eels vary in weight from three and a half to 
six and a half pounds and often exceed three feet in length. 
65. Fish Hatcheries. — In the natural state, many eggs 
are laid that never hatch because the sperm cells do not 
come in contact with them; and of the fishes that are 
hatched only a small proportion reach maturity. As it 
is a matter of great economic importance that fishes be 
