Artificial reproduction and breeding: actions C.1, C.2 and C.3

Expected results

Project target fish species are: marbled trout (Salmo marmoratus), bullhead (Cottus gobio), italian riffle dace (Telestes muticellus), pigo (Rutilus pigus) savetta (Chondrostoma soetta); to them is added the white-clawed crayfish (Austropotamobius pallipes complex). The protection of these species is the main objective of IdroLIFE. The first prerogative is to have a public structure that is functional to the production needs for repopulation, the second, no less important, is the production of wild animals that are able to effectively repopulate rivers.

Progress of the interventions

The local public ittiogenic structure, which is useful for the purposes of the project and to give continuity beyond the Life has been identified in the incubator owned by ISE-CNR, refurbishment and accommodation that made it efficient for the production of 60,000 juvenile specimens of marbled trout, 5,000 of pigo and savetta and 1,000 bullhead. The property is able to ensure indifferently the weaning of species that love cold or temperate waters, to independently produce the zooplankton necessary for feeding the larvae, as well as to host environmental education activities. Currently the incubator is home to several thousand juvenile specimens of pigo and savetta, produced with the artificial reproduction of captured subjects and then released again in the natural environment, and a small nucleus of scuffle players, already reproduced in captivity for the first time, recording the first successes of the breeding tests of this extraordinary species. As far as the italian riffle dace is concerned, it has already been the subject of an initial repopulation campaign carried out through the collection of stock of founding individuals from sites adjacent to the project area, from abundant and well-structured populations of the same basin, then released, after a period of temporary housing at the hatchery and after marking with PITtag (adults) or by fin clip (cutting of a fragment of fin), in environments of the Val Grande Park, previously inhabited by the species and results to date eligible to host it. Regarding the marbletrout, a first breeding and repopulation campaign will be performed in the coming winter.

From the beginning of the project until 2020 a total number of 60,000 marbled trout (mainly juvenile and about 150 adults and sub-adults) has been produced by the incubator owned by ISE-CNR and released in the SPA “Fiume Toce”. In addition, the number of 1,000 italian riffle dace, thus reaching the project target, and 850 specimens of bullhead was reached that were used to repopulate the waters of the SCI “Valgrande”. Of these last two species 500 italian riffle dace and about 100 bullheads were marked with PIT Tags.

Also, in 2020, 508 specimens of with-clawed crayfish were captured from valley bottom areas and released into areas of the SIC “Valgrande”, which were also subjected to genetic analysis which confirmed their belonging to the species Austropotamobius italicus, var. carithiacus.

In the context of Action C.3, important results have been achieved, in fact, overall since the start of the project, 5.050 specimens have been released in the SPA “Lake Mergozzo and Mont’Orfano between savetta and pigo.

Longitudinal connectivity restoration: action C.4

Expected results

With the IdroLIFE project about 45 km of River Toce upstream of the mouth in Lake Maggiore and 8.5 km of Torrente San Bernardino will be defragmented. Through the construction of new fish passages or the adaptation of pre-existing structures, five obstacles to fish migration (4 on Toce and 1 on the San Bernardino), due to the presence of artificial barrages, will be removed allowing again to move freely in the river.

Progress of the interventions

Currently changes to the fish passage on the T. San Bernardino have been completed, and on the same structure  an action of monitoring is ongoing in order to check the transit of fish by marking and recapture.

In January 2020, the construction site for the first fish passage on the Toce River, near Lake Tana, was opened, the first of four infrastructures to be built to facilitate the migration of fish species.

Control of invasive alien species in project sites: action C.5

Expected results

The action C.5  involves the control and eradication of invasive alien aquatic species. Target species include wels catfish (Silurus glanis), ruffe (Gymnocephalus cernuus), catfish (Ameiurus melas), crucian carp (Carassius spp.), exotic crayfish (Procambarus clarkii) and other aquatic species.

Progress of the interventions

The containment activities, carried out in particular in the channel connecting Lake Mergozzo with Lake Maggiore and in the mouth of the Toce River, allowed to capture about 620 kg of exotic specimens, including 500 kg of catfish, the most abundant exotic species, about 40 kg of pumpkinseed and about 12 kg of roach. Also were captured 35 young wels catfish specimens, a species that is not yet very abundant but whose presence imposes a serious risk for the conservation of the entire native fish fauna.