Lead shot was forbidden in 2001 in Spanish wetlands on the Ramsar List of these areas of international importance. Ten years later, this prohibition -and the consequent use of steel shot by hunters- has started to bear fruit, according to a report in the journal 'Environment International'.
"The most important part of our work is that it shows that, despite it's still covering a partial area, the change of material from lead to steel shot has reduced waterfowl poisoning and the contamination of hunted meat," Rafael Mateo Soria of the Hunting Resources Research Institute (IREC) and co-author of the study, told SINC.
Lead shot accumulating in wetlands, with over 100 per square metre in many areas, remains in the sediments for decades.
Its main damage is to the health of waterfowl. When the shot is eaten it is retained in the gizzard and is worn down in the stomach, freeing lead that reaches the animal's tissues.
"The birds start to develop neurological problems, they cannot move and they also suffer from anaemia. Normally, if they ingest lead, they die with notable emaciation after days or even weeks after starting to ingest the shot," explained Mateo.
In species such as the mallard, 30% caught at the start of the 1990s in the Ebro delta had ingested lead shot, a figure which has now dropped to 15%. The same trend has been seen in other species such as the northern shoveller, the Eurasian teal and the common pochard.
On the other hand, the case of the northern pintail caught continues to cause alarm since over 70% have shot in their gizzards, a rate similar to that seen three decades ago.
The scientist notes that to discover the reason for the high percentage of poisoning in this species, they will start to fit birds with transmitters. "What we do know is that, because of its type of diet, this is a species with a high risk of ingesting shot. Nevertheless, in others that also have these risk f
FECYT - Spanish Foundation for Science and Technology