Last week we conducted the first stage of the year within the reintroduction programme of the Iberian frog (Rana iberica) in the Hoya de Peñalara. This frog is one of the few Iberian amphibians strongly associated with watercourses, and for decades was present in all the rivers of the Hoya of Peñalara. Unfortunately, in the 70s someone came up with the idea to introduce Brook Trout (an American salmonid) in the Laguna Grande of Peñalara for recreational fishing. The Brook Trout colonized all of the downstream waters, decimating the population of Common Midwife Toad and the Common Salamander of the Laguna Grande, and the entire population of the Iberian Frog of the Hoya of Peñalara.
In the 90s, managers of the Peñalara Natural Park began a successful initiative to remove the fish from the lake. However, we found that hundreds of Brook Trout still inhabited the rivers of la Hoya, so in 2003 we started to remove the Brook Trout from the streams, one by one, by low intensity electrical fishing.
In 2006, when the number of remaining Brook Trout was very low, we started the program to reintroduce the Iberian frog in the Hoya de Peñalara. We collected the frogspawn from areas of the nearby Hoya de Pepe Hernando where usually they would desiccate quickly without time for the tadpoles to develop. We took care of these eggs until the tadpoles metamorphosed and we released the little frogs in the Hoya de Peñalara where they could no longer be predated on by the Brook Trout. Since 2006 we have released more than 1,000 specimens bred in captivity, and two years ago we found that the frogs had bred successfully in the Hoya de Peñalara for the first time. At last, we have the Iberian Frog in the Hoya de Peñalara where it has been absent since the 70s!
In 2013 we finished removing the Brook Trout, and now that this area is free from these predators we can now reintroduce larvae, instead of small frogs which need a phase in captivity. Last Friday we were in the Hoya de Pepe Hernando and collected 150 frog tadpoles, which we released in the stream of Dos Hermanas in the Hoya de Peñalara.
During these years the exemplary management of Peñalara, the heart of the current National Park, has made it possible to return this fascinating endemic species to La Hoya where it should never disappear, and this should be the start of an ambitious program to reintroduce the species in all of the Guadarrama Mountains.