Spanish rice farmers fight invasive snail

Island apple snail is destroying crops and threatens to spread into other southern European wetlands

Snail invasion in Spain

Shells of the invasive island apple snail in the Ebro Delta, Spain. Photograph: Dani Forcadell

The EU has “washed its hands” of an invasion of snails in a Spanish river delta that are destroying crops and threaten to spread into other southern European wetlands, farmers say.

Rice-growers in the Ebro Delta on southern Catalonia’s Mediterranean coast have reported losing up to half of their crops since the island apple snail (Pomacea insularum) was first seen in 2009. The worst-affected fields have 12 snails per square metre, with each snail capable of eating the roots of up to 15 rice plants each day.

Authorities are attempting to destroy the snails by drying out their fields over winter and flooding some with salt water. The EU has supported the experiment by sharing the cost with the Spanish and Catalonian governments. But it will recoup €378,000 of this money from the delta’s struggling farmers. The EU pays farmers a subsidy to keep their fields flooded during the winter months and preserve wetland habitat for birds and fish. The EU gave growers permission to drain 7,000 hectares of fields this winter, but this meant losing their subsidies.

“The EU has washed its hands of the problem,” said Albert Pons, a rice farmer from the delta village of Camarles. “I have spent hours and hours setting up systems to catch and eliminate the snail, cleaning out filters and irrigation channels and physically searching for and killing the snails one at a time.”

The Ebro River’s delta of rice fields and wetlands provide habitat and breeding sites for a large range of bird species. More than 7,000 hectares is protected under the Ramsar convention on wetlands. The wetlands currently remain free of the snail.

The European Food Safety Authority (Efsa) says the snails could destroy wetland ecosystems if they spread across southern Europe. The vice-chair of Efsa’s panel on plant health, Joop van Lenteren, said juvenile snails, only millimetres across, could attach to the feathers of migrating birds and spread to wetlands hundreds of kilometres away. The hulls of local fishing boats could be covered with eggs, raising concerns the snail could hitch a ride to other waterways.

Efsa research indicates that the snail could thrive in large parts of Spain, southern France, Italy and Greece and the Danube. If this happens, the snail could push already fragile ecosystems into irreversible decline as it has done in Thailand and other countries in south-east Asia.

“When the snail establishes in rivers and wetlands the consequences can be serious. Because it is so voracious, there is a high risk to biodiversity,” he said.

According to tthe Global Invasive Species Database, the snails have an ability to reproduce at extraordinary rates. Between April and November, females will lay 400 bright pink eggs every five to 15 days.

Pons said when the snail first appeared on his farmland, he did not realise what an insidious threat it posed. “I first saw the snail in an irrigation channel in 2010. The following year we found them in my rice fields. This last year has been catastrophic and our struggle to remove or control them [is] extremely expensive.

“The plague has spread like wildfire. Now farmers and the public bodies cannot keep up with it. Seeing the extent of the damage, I feel anxiety for the future of my livelihood and family,” said Pons.

The South American species is a popular aquarium pet because of its size and can grow as big as an apple. Its release into the Ebro has been linked with Promotora Bama, an exotic animal importer, which bred the snails at a facility in the village of L’Aldea on the north side of the delta. The snails were first detected in a drainage channel in the town. Shortly afterwards, the company relocated its facility to the town of Tarragona, 80km to the north.

Promotora Bama, who were unavailable for comment, were taken to court by the Catalonian government in 2012 but a judge dismissed the action because it had passed the three-year statute of limitations. Efsa said the snails in the delta had genetic traits consistent with cultivation in the pet industry.

Snail invasion in Spain
 Eggs left by the snails. Photograph: Dani Forcadell

In November 2012, the EU banned the import of all snails in the genus pomacea.

An European commission spokesperson said: “The commission is very concerned about the economic and environmental damage caused by the apple snail and for that reason, under the EU plant health legislation, the snails of the genus pomacea are subject to emergency measures to prevent its introduction into and the spread within the Union.”

The EU has made €2.64m available to the Spanish authorities from 2010 until 2013 for control actions against the harmful organism. But the EU says the subsidy contracts farmers received for flooding their fields, which were suspended during 2013, expired at the end of last year and would not be reinstated because the fields no longer represent good habitat for birds.

“The commission does not consider appropriate to extend these commitments until 2014, given the economic and environmental damage caused by the apple snail.”

One Response

  1. […] Spanish rice farmers fight invasive snail International Association for the Plant Protection Sciences, 19th February 2014 […]

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