110 FISHES 



laws which protect the fish during their egg-laying period 

 when they are easily caught and when the destruction of 

 even a few fish means the loss of thousands of eggs. 



Spawning habits vary greatly. Some fish, like the sal- 

 mon, make long journe} r s from the sea to 4;he 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 



Figure 110. — Eggs of Land-locked Salmon. 



up the Hudson River in New York state. In the case of 

 herring, the eggs are laid in the sea and float on the sur- 

 face. Eels go down from the rivers and streams to the 

 sea to lay their eggs, the young eels, when small, migrat- 

 ing up the river. Millions of small eels no larger than 

 needles are found in the Hudson at certain seasons. 



111. 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 saved 

 from extermination and their numbers largely increased, 



