Upwelling and Anchovies off Peru
How does upwelling affect an important fish species? Is it possible to see a
fishery decline when upwelling fails?
What lessons are learned when El Niño calls a halt to upwelling off Peru?
O
ff the coast of Peru, cold, deep
water rises in the pattern
typically seen off the western coasts
of continents. The upwelling that
delivers nutrients to the surface there
has created one of the world’s richest
anchovy fisheries. Microscopic
organisms known as phytoplankton
bloom in the nutrients sent from
below. Anchovies feed directly on the
phytoplankton instead of eating
smaller fish. This unusually efficient
feeding method that shortcuts the
food chain explains the abundance of
anchovies off the coast of Peru.
In the 1950s, a huge commercial
anchovy fishery was begun off the
coast of Peru. Boats towing seine nets
harvested the anchovies at sea.
Anchovies processed into fishmeal
were sold all around the world as
feed for livestock and poultry.
Millions of sea birds fed on the
anchovies, too. Bird droppings on
coastal rock outcroppings not only
attested to the bounty of fish but also
were harvested for use as fertilizer on
Peruvian farms.
Trouble came in 1972, however,
when El Niño struck. Diminishing
trade winds halted the upwelling. The
phytoplankton supporting the
anchovies vanished, while the fishing
fleet kept on fishing. The anchovy
fishery collapsed, with global
repercussions. Meat prices rose
around the world; poultry prices in
the United States jumped more than
40 percent. When the birds that had
fed on the anchovies died, farmers in
Peru lost the source of fertilizer for
their fields. Eventually, the
trade winds resumed and
restored the upwelling,
and Peruvians began
managing the fishing
fleet to prevent
overfishing.
FISHERMEN pull a load of anchovies onto
their boat off the coast of Peru.
Image not available.
Please refer to the
image in the textbook
or in the eEdition CD.
540
Unit 6 Earth’s Oceans
Despite several more El Niño
events, anchovy stocks have slowly
recovered. Marine scientists hope that
the hard lesson learned after the
1972 El Niño will help preserve the
fish species that depends so heavily
upon coastal upwelling.
Extension
SCIENCE N OTEBOOK
In the event of another El Niño,
what do you think would be
Peru’s best strategy for protecting
the anchovy fishery? Explain what
you would suggest and why.
CLASSZONE.COM
Observe how upwelling occurs.
Keycode: ES2405