The outer appearance of this species shows that it is a pelagic fish that
spends most of its life in movement. A typically gregarious fish, it is
born to live and die surrounded by its own ilk. A solitary specimen would
fall into a state of stress, stop feeding and quickly perish. Herring life
essentially involves consecutive movement from fattening and wintering
sites to spawning sites, often quite remote. Observers used underwater
equipment to register the state of herring at nighttime as something similar
to sleep, during which the fish rest, having dispersed in various postures
(belly or tail up).
In summer, the herring intensely fattens
near the coastline, feeding on small plankton organisms. After fattening,
their fat content reaches 18-25%. Large specimens of up to 50 cm long are
especially fat, sometimes weighing 0.7 kg each.
The Pacific herring population fluctuates
considerably. The fish become sexually mature in the second-third year
of life. Herring makes its first approaches to the coastline under ice.
In Peter the Great Bay, it spawns from March through May when water temperatures
range from +1.5 to +8oC on shallows of 1-15 m deep. It lays
roe on rocks, sea grasses and algae. The Pacific herring is a highly valuable
commercial species. To enhance its productivity, biologists have developed
methods for creating artificial spawning grounds.