No sardine, no fun

Has in Portugal, moreover in the Atlantic, the sardine is an important fish in the Pacific.
But not only for people.
It is an important food for other marine animals, as birds and mammals.
There is not enough information why, but the sardine stock seems to be declining in the California coast.
As it happens to other top predators as tuna, that have been intensively harvested, the sardine fishery can also have irremediable consequences for the marine ecosystem.
Sardine is in a low level of the marine trophic web but they have an important role for other predators.
If we fish too much, there is less sardine to feed other animals and it is more difficult to recover.
If we look back, we can learn from the past.
Without fish, there is no fishery, no food...and in the end no sea life.

The decline has prompted steep cuts in the amount fishermen are allowed to catch, and scientists say the effects are probably radiating throughout the ecosystem, starving brown pelicans, sea lions and other predators that rely on the oily, energy-rich fish for food. 
The reason for the drop is unclear. 
Sardine populations are famously volatile, but the decline is the steepest since the collapse of the sardine fishery in the mid-20th century. 
And their numbers are projected to keep sliding. 
...
It was one of those seemingly inexhaustible swells that propelled California's sardine fishery to a zenith in the 1940s. 
Aggressive pursuit of the species transformed Monterey into one of the world's top fishing ports. 
And then it collapsed. 
By mid-century sardines had practically vanished, and in the 1960s California established a moratorium on sardine fishing that lasted 18 years. 
The population rebounded in the 1980s and fishing resumed, but never at the level of its heyday.