46 Instincts, Habits, and Adaptations 
in the rivers, and a few pass more or less indiscriminately 
from one kind of water to another. 
Migratory Fishes.—The movements of migratory fishes are 
mainly controlled by the impulse of reproduction. Some pelagic 
fishes, especially those of the 
mackerel and flying-fish families, 
swim long distances to a region 
favorable for the deposition of 
spawn. Others pursue for equal 
distances the schools of men- 
haden or other fishes which serve 
as their prey. Some species 
are known mainly in the waters 
they make their breeding homes, 
as in Cuba, Southern Cali- 
fornia, Hawaii, or Japan, the 
individuals being scattered at 
other times through the wide 
seas. i 
Anadromous Fishes. — Many 
fresh-water fishes, as trout and 
suckers, forsake the large streams 
in the spring, ascending the 
small brooks where their young 
can be reared in greater safety. 
Still others, known as anadromous 
Fie. 32. — Portuguese Man-of-war fishes, feed and mature in the 
Fish, Gobiomorus gronovii. Family sea, but ascend the rivers as the 
Boe impulse of reproduction grows 
strong. Among such fishes are the salmon, shad, alewife, stur- 
geon, and striped bass in American waters. The most remark- 
able case of the anadromous instinct is found in the king salmon 
or quinnat (Oncorhynchus tschawytscha) of the Pacific Coast. 
This great fish spawns in November, at the age of four years 
and an average weight of twenty-two pounds. In the Columbia 
River it begins running with the spring freshets in March and 
April. It spends the whole summer, without feeding, in the 
ascent of the river. By autumn the individuals have reached 
the mountain streams of Idaho, greatly changed in appearance, 
