• Involvement of recreational anglers in the eradication of alien brook trout from high altitude lakes

      Tiberti, Rocco; Ottino, Michelle; Brighenti, Stefano; Iacobuzio, Rocco; Rolla, Matteo; von Hardenberg, Achaz; Bassano, Bruno; Gran Paradiso National Park, University of Pavia, Università degli studi di Trento, Fondazione E. Mach, Università degli Studi di Milano, Swansea University, University of Chester (Gran Paradiso National Park Agency, 2017)
      Stocking programmes for recreational angling are primarily responsible for the spread and ecological impact of introduced sh in high-altitude, originally shless lakes. In 2013, the Gran Paradiso National Park started an eradication campaign of brook trout by intensive gill-netting. Local anglers were invited to attend two angling sessions to start the eradication before gill-netting in an experimental lake, as part of an education action devoted to these critical stakeholders. The angling sessions turned out to be a valuable help for the eradication campaign and the aim of this study is to report on the outcomes of these angling sessions. Angling techniques were highly size-selective, removing a substantial part of the adult population and of the sh biomass, but their contribution to the eradication of small sh (<15cm) was irrelevant. Therefore, angling cannot completely eradicate age-structured populations. However, there is scope to use angling sessions as a support for eradication campaigns and as an emergency measure for recent sh introduc- tions. Similar actions should be considered whenever a sh eradication programme is planned. These ndings, however, do not imply a general endorsement for angling within protected areas.
    • Recovery of high mountain Alpine lakes after the eradication of introduced brook trout Salvelinus fontinalis using non-chemical methods

      Tiberti, Rocco; Bogliani, Giuseppe; Brighenti, Stefano; Iacobuzio, Rocco; Liautaud, Kevin; Rolla, Matteo; von Hardenberg, Achaz; Bassano, Bruno; University of Pavia; Gran Paradiso National Park; University of Trento; Fondazione Edmund Mach; Swansea University; University of Chester (Springer, 2018-10-31)
      Fish stocking is a serious threat to originally fishless mountain lakes. We used non-chemical eradication methods (i.e. gillnetting and electrofishing) in four high mountain lakes in the Gran Paradiso National Park (Western Italian Alps) to eradicate alien brook trout Salvelinus fontinalis. Data of amphibians, macroinvertebrates, zooplankton, chlorophyll-a, nutrient concentrations, and water transparency were used as indicators of the recovery process. All treated lakes were returned to their original fishless condition in spite of their different sizes and habitat complexity, without permanent negative side-effects for native species. Several ecological indicators showed that many impacts of introduced fish can be reversed over a short time period following eradication. The present study adds to a still growing body of specialized literature on the recovery of habitats after the eradication of alien species and provides further evidence that physical eradication methods are effective and can be part of a more general strategy for the conservation of high mountain lake biota.