The growth of the fish is monitored on a daily basis by the surveillance staff and Dr. Iacobuzio. The first two introductions were performed in two sections of the torrent identified previously.
The development of juvenile trouts is monitored on a daily basis by the surveillance staff and Dr. Iacobuzio. Technicians from the Park of Ticino visited the incubator as provided for by the agreement entered into with the Organisation. Based on the collaboration agreement stipulated with the Metropolitan City of Turin and the Low Orco Valley Fishermen’s Association, about 2100 fry with their yolk sacs fully absorbed were sold to the aforementioned Organisation that had supplied the spawners. Timber planks were purchased and moved to the site for the construction of a provisional barrier across the Valsoera torrent that will prevent the upstream area of the watercourse from being recolonised by the brown trout, and will also ensure greater genetic isolation to the marble trouts introduced. Electrofishing activities in the Campiglia and Valsoera torrents were carried on.
Il periodo autunnale segna l’inizio delle attività riproduttive della Trota marmorata nei fiumi della
fascia pedemontana piemontese e la situazione idrologica (regime di magra) del Torrente Orco,
stabile da circa un mese all’inizio di Novembre, ha consentito l’organizzazione di due giornate (3-
6/11) esplorative alla ricerca di individui riproduttori da spremere in loco o da trasportare mediante
appositi contenitori ossigenati presso la vasca esterna adibita alla stabulazione dei riproduttori
dell’incubatoio di Ghiglieri, Locana (TO) al fine di consentire la maturazione delle gonadi e la
spremitura presso la struttura.
Precedentemente la vasca esterna in cemento è stata naturalizzata al fine di minimizzare
l’inevitabile stress al quale sono sottoposti i riproduttori (soprattutto se selvatici) quando vengono
traslocati in un altro ambiente.
Per questa ragione il pavimento della vasca è stato coperto con un consistente strato di ghiaia
proprio per evitare ai pesci temporaneamente stabulati abrasioni da contatto con il cemento della
vasca. Zone di rifugio sono state create mediante l’utilizzo di tubi di plexiglas e si è provveduto alla
copertura dell’intera vasca per evitare ai riproduttori l’esposizione diretta alla luce.
Il giorno 3 e 6 Novembre si sono quindi svolte le sessioni di pesca elettrica che hanno impegnato il
Personale di Sorveglianza del PNGP, la Città Metropolitana di Torino e l’Associazione Lenzatori di
In the Gran Paradiso National Park, the Ghiglieri fish hatchery has begun raising marble trout. The hatchery belongs to the category of “Valley floor fish hatchery,” a definition which links the fish rearing activities carried out at the facility to the valley and the river basin of which the structure is part. The Ghiglieri hatchery is comprised of two sections: an inner part dedicated to eggs hatching and fish growth, and an outer part where marble trout individuals intended for breeding are hosted and raised.
The hatchery also meets didactic purposes, addressing conservation issues and defining measures for the improvement of aquatic habitats in general. The hatchery receives water directly from the water supply system overflow outlets, a solution that ensures virtually pure water and provides for a sustainable use of water resources. The water leaving the facility is discharged into the Piantonetto Torrent after feeding a small pond used for teaching purposes and designed to encourage the presence of amphibians.
The artificial breeding of a fish species of conservation concern often works as an effective protection measure, since the number of individuals that can be raised is appreciable; for the marble trout, production is said to range from 1,500 to 2,500 eggs per kg of weight.
The extremely small marble trout larvae, about 1.5 cm long at this point, are fed with Artemia salina, an aquatic crustacean whose size is compatible with the mouth of the juvenile trout. These zooplankton organisms will also be bred at the Ghiglieri hatchery in ad hoc hatching structures: Artemia salina is a species originating from salt water bodies, and its tiny eggs require continuous hydration and the proper temperature to hatch. Once separated from the shells, the crustaceans are fed to the growing trout.
During the 2015 summer season, within the framework of the initiatives in favour of the marble trout, a total of 1291 brown trouts were removed, and namely:
- from the Piantonetto torrent: 870 trouts in the course of 3 removal sessions
- from the Valsoera torrent: 421 trouts in the course of 3 removal sessions
Samples were taken from some of them for the analysis of oxidative stress, an issue which is being investigated within the framework of a doctorate program.