All of the animals had fractured skulls and were missing teeth. The males' sexual organs had been removed.

"We estimate there are 35 male sea lions that were killed and that have had their genital organs removed," said Environment Minister Lourdes Luque.

In a government press statement, a Galapagos park official said that "the genitals are presumably extracted to be commercialised in Asian markets as an aphrodisiac".

The archipelago, located 600 miles (1000 km) west of Ecuador's shoreline, is known throughout the world as a home to unique wildlife, including exotic birds and sea lions.

The wildlife formed the basis for British naturalist Charles Darwin's theory of natural selection.

According to Ms Luque, 12 sea lions were found dead last year in similar circumstances.

Seals are also threatened by pollution from oil tankers

"It has to be people from the area. It's linked to the decline in the price for sea cucumber and the few catches local fisherman have had," she said.

The islands' sea lions have no natural predators on land and generally do not fear humans.

Investigators believe they were dumped in the ocean after they were mutilated and washed up on shore.

Police said they found what they believed was the poachers' abandoned camp site, littered with soft drink bottles and leftover food.

Shark fins

At the same time as the sea lions were discovered, two boats were intercepted that had been fishing in the protected waters around the Galapagos Islands.

On board the boats were 24 sharks, whose fins are another delicacy that fetches a high price.

The islands are famous for their unique wildlife

Whilst authorities have proclaimed the areas a national park with routine patrols there are not the resources available to prevent poaching.

Ecuador has tried to limit the number of visitors to the islands, but there were more than 71,000 last year - far too many, say environmental groups.

There is also a threat from pollution, brought into harsh focus in January this year when an oil tanker ran aground just off the island, spilling over 200,000 gallons of fuel.

An environmental catastrophe was avoided only because a change in the current swept the oil slick out to sea.

Shipping block

Environmental groups are calling for more protection for the unique habitat and the blocking of the major shipping lane that passes by the islands.

Ecuador is one of the poorer countries in South America, with more than half the population living in poverty. The sort of environmental protection required is considered to be too expensive for them.