The most fished species in the world, anchovy stock is at historic highs in Peru that may be short-lived due to climate change and overfishing.

Peru's fleet can catch around 20,000 tonnes each day in a four-kilometer (2.48-mile) radius.

In contrast, a European zone where a ban is in effect through at least 2010, the catch level has been set at between 20,000 and 30,000 tonnes of adult anchovy.

For the past four years, anchovy stock has enjoyed protected status in the Bay of Biscay along the western coast of France and the northern coast of Spain.

In Peru's Pacific fringe, fed by cold, rich waters of the low-salinity Humboldt Current, the Peruvian anchoveta -- Engraulis ringens -- is king.

With some six to eight million tonnes fished each year, the Andean country and its 2,800 kilometers (1,740 miles) of coastland reap the lion's share of the tiny fish, ahead of Chile's one million tonnes annually.

Anchovies, which measure 12 to 19 centimeters (4.7 to 7.5 inches) as adult fish, account for eight percent of global catch, including all species and types of water.

But a study by the Peruvian Marine Research Institute (IMARPE) late last year found that anchovies were not always so abundant in Peru, where they were scarce four centuries ago.

During this mini-ice age, a slight drop in temperature that lasted from around 1400 to 1820, warmer water conditions paradoxically prevailed in the Humboldt ecosystem, explained researchers led by marine biologist Dimitri Gutierrez.

There were less cold water currents and thus less anchovies.

"We can of course think that one day, we will fall back into unproductive conditions, that everything could fall apart," said Arnaud Bertrand, oceanographer at Lima's Research Institute for Development.

Climate change has already made a dent on this portion of the Pacific Ocean, where 10 percent of global fishing takes place on less than one percent of its surface.

In 1972-73 and then 1981-82, aggressive cycles of the El Nino weather phenomenon -- which causes abnormal warming of the Pacific Ocean -- coupled with overfishing of up to 12 million tonnes per year led to a collapse of the anchovy stock and industry.

Studies have shown that civilizations that prospered along this deserted coastline thanks to maritime resources have come and gone according to major climate variations.

The Caral-Supe civilization, the earliest known urban settlement in the Americas, thus thrived for nearly 1,500 years until some 3,500 years ago.

Peru, which produces half of the world's fish flour -- pulverized fish protein, is now taking steps to protect its precious resource.

It is reducing its fishing fleet to 1,400 boats, adjusting its fishing practices, as well as closely following catches and scientific observations.

This year, Peru imposed individual quotas per boat and on the amount of fish that can be netted over several days. It is part of a move to respond to warming that tends to take place in oceanic zones lacking oxygen.

Betrand noted that despite accounting for the biggest stock in the world, anchovies are seldom used for human food, crushed instead into a fine flour to make animal feed for fowl, pigs and farm-raised fish.