Chapter 8
Why Should We Preserve Fishless
High Mountain Lakes?
Marc Ventura, Rocco Tiberti, Teresa Buchaca, Danilo Buñay,
Ibor Sabás and Alexandre Miró
Abstract High mountain lakes are originally fishless, although many have had
introductions of non-native fish species, predominantly trout, and recently also
minnows introduced by fishermen that use them as live bait. The extent of these
introductions is general and substantial often involving many lakes over mountain
ranges. Predation on native fauna by introduced fish involves profound ecological
changes since fish occupy a higher trophic level that was previously inexistent. Fish
predation produces a drastic reduction or elimination of autochthonous animal
groups, such as amphibians and large macroinvertebrates in the littoral, and crustaceans in the plankton. These strong effects raise concerns for the conservation of
high mountain lakes. In terms of individual species, those adapted to live in larger
lakes have suffered a higher decrease in the size of their metapopulation. This
ecological problem is discussed from a European perspective providing examples
from two study areas: the Pyrenees and the Western Italian Alps. Species-specific
studies are urgently needed to evaluate the conservation status of the more impacted
species, together with conservation measures at continental and regional scales,
through regulation, and at local scale, through restoration actions, aimed to stop
further invasive species expansions and to restore the present situation. At different
high mountain areas of the world, there have been restoration projects aiming to
return lakes to their native fish-free status. In these areas autochthonous species that
disappeared with the introduction of fish are progressively recovering their initial
distribution when nearby fish-free lakes and ponds are available.
M. Ventura (&) Á T. Buchaca Á D. Buñay Á I. Sabás Á A. Miró
Integrative Freshwater Ecology Group, Center For Advanced Studies of Blanes
(CEAB-CSIC), Accés a la Cala St. Francesc, 14, Blanes, Girona, Catalonia, Spain
e-mail: ventura@ceab.csic.es
R. Tiberti
Dipartimento di Scienze della Terra e dell’Ambiente (DSTA), University of Pavia,
Via Ferrata 9, 27100 Pavia, Italy
R. Tiberti
Alpine Wildlife Research Centre, Gran Paradiso National Park,
Degioz 11, 11010 Valsavarenche, Aosta, Italy
© The Author(s) 2017
J. Catalan et al. (eds.), High Mountain Conservation in a Changing World,
Advances in Global Change Research 62, DOI 10.1007/978-3-319-55982-7_8
181
Why Should We Preserve Fishless
High Mountain Lakes?
Marc Ventura, Rocco Tiberti, Teresa Buchaca, Danilo Buñay,
Ibor Sabás and Alexandre Miró
Abstract High mountain lakes are originally fishless, although many have had
introductions of non-native fish species, predominantly trout, and recently also
minnows introduced by fishermen that use them as live bait. The extent of these
introductions is general and substantial often involving many lakes over mountain
ranges. Predation on native fauna by introduced fish involves profound ecological
changes since fish occupy a higher trophic level that was previously inexistent. Fish
predation produces a drastic reduction or elimination of autochthonous animal
groups, such as amphibians and large macroinvertebrates in the littoral, and crustaceans in the plankton. These strong effects raise concerns for the conservation of
high mountain lakes. In terms of individual species, those adapted to live in larger
lakes have suffered a higher decrease in the size of their metapopulation. This
ecological problem is discussed from a European perspective providing examples
from two study areas: the Pyrenees and the Western Italian Alps. Species-specific
studies are urgently needed to evaluate the conservation status of the more impacted
species, together with conservation measures at continental and regional scales,
through regulation, and at local scale, through restoration actions, aimed to stop
further invasive species expansions and to restore the present situation. At different
high mountain areas of the world, there have been restoration projects aiming to
return lakes to their native fish-free status. In these areas autochthonous species that
disappeared with the introduction of fish are progressively recovering their initial
distribution when nearby fish-free lakes and ponds are available.
M. Ventura (&) Á T. Buchaca Á D. Buñay Á I. Sabás Á A. Miró
Integrative Freshwater Ecology Group, Center For Advanced Studies of Blanes
(CEAB-CSIC), Accés a la Cala St. Francesc, 14, Blanes, Girona, Catalonia, Spain
e-mail: ventura@ceab.csic.es
R. Tiberti
Dipartimento di Scienze della Terra e dell’Ambiente (DSTA), University of Pavia,
Via Ferrata 9, 27100 Pavia, Italy
R. Tiberti
Alpine Wildlife Research Centre, Gran Paradiso National Park,
Degioz 11, 11010 Valsavarenche, Aosta, Italy
© The Author(s) 2017
J. Catalan et al. (eds.), High Mountain Conservation in a Changing World,
Advances in Global Change Research 62, DOI 10.1007/978-3-319-55982-7_8
181