Piles of dead whales, salmon, sardines and clams blamed on the El Nino freak weather phenomenon have been clogging Chile's pacific beaches in recent months.

Key points: Algae surge kills 40,000 tonnes of salmon

Algae surge kills 40,000 tonnes of salmon 8,000 tonnes of sardines and thousands of clams dead

8,000 tonnes of sardines and thousands of clams dead El Nino and farming growth being blamed

Last year, scientists were shocked when more than 300 whales turned up dead on remote bays of the southern coast — it was the first in a series of grim finds.

A surge in algae in the water earlier this year choked to death an estimated 40,000 tonnes of salmon in the Los Lagos region — equal to about 12 per cent of Chile's annual production of the fish.

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This month, about 8,000 tonnes of sardines were washed up at the mouth of the Queule river and thousands of dead clams piled up on the coast of Chiloe Island.

Chilean authorities blamed a "red tide" of algae and banned fishing in the affected region — putting thousands of fishermen out of work.

"We have red tides every year in southern Chile, but this time it reached further north," said Jorge Navarro, a researcher at the marine institute IDEAL.

"It affected bivalve populations (such as clams) that had never before been exposed like this [to the algae]," he said.

On the shores of Santa Maria Island off the centre off Chile's long coast, cuttlefish have been washed up dead in the thousands.

Various beaches in the centre of the country were closed as the specimens of the dreaded Portuguese Man-of-War jellyfish, normally foreign to the area, floated nearby.

El Nino 'most intense' in 65 years

Thousands of clams beached on the shores of Chiloe Island in May. ( AFP: Alvaro Vidal )

Scientists largely blame the anomalies on El Nino, a disruptive weather phenomenon that comes with warming sea surface temperatures in the equatorial Pacific.

With its 4,000 kilometres of Pacific coastline, Chile is particularly exposed to the effects of El Nino, which strikes every few years.

Chilean authorities blamed a "red tide" of algae. ( Facebook: Armada de Chile )

"We think that a common factor in the deaths of creatures in southern Chile, in the salmon farms and in fish off the coast is the El Nino phenomenon,"experts at the Chilean fisheries institute IFOP said.

The research centre has classed the current El Nino as "one of the most intense in the past 65 years".

Warmer sea water can lead to greater quantities of algae, which kills others species by consuming oxygen in the water or filling it with toxins.

"The Chilean ocean is shifting and changing," said Sergio Palma, an oceanographer at Valparaiso Catholic University.

"There has been a series of events that indicate an El Nino which is making its presence felt in many ways."

About 8,000 tonnes of sardines were washed up at the mouth of the Queule river. ( Facebook: Armada de Chile )

Fish farming could cause 'toxic blooms'

Scientists also suspect other causes for the mass destruction of the sea creatures.

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Laura Farias, an oceanographer at Chile's Concepcion University, said last year's huge toll of whales could have been caused by "natural ecological process".

"There is no ecological, oceanographic or climatic explanation" linking the whales to the other incidents, she said.

Ms Farias suspects the growth of fish farming in Chile's southern Patagonia region is to blame for killing the salmon and clams.

"There are studies indicating that in Patagonia the greater occurrence of toxic blooms could be a consequence of aquaculture," she said.

Some scientists have said the current El Nino seems to be subsiding, causing the surface of the sea to cool slowly.

Valesca Montes, a fisheries specialist at the Chilean branch of the World Wildlife Fund, said Chile still "lacks information" about the sea.

Thousands of dead clams piled up on the coast of Chiloe Island. ( Facebook: Armada de Chile )

AFP