Activity in progress regularly until 31/10/2020, Huso huso continues to be raised at the centers of the Park and the inputs foreseen by the project have been done.
2019 saw the acquisition and breeding of 1700 0+ specimens, the growth of 10,000 fertilized eggs to hatch, weaning of a new stock of 100 0+ recruits. Genetic studies on purchased stocks are still ongoing and involve 47 examples 2+ and 0+ to finish the phylogeographic study so as to have no contraindications in the use of acquired and bred specimens.
The difficulty encountered in the recruitment of sturgeons to be included in the reintroduction program, this problem was overcome thanks to two new breeders identified.
Breeding activities at Cassolnovo and the release and marking of Huso huso specimens continue. We point out the detection of a Huso huso individual released with the project activities at the Isola Serafini ascent ladder (carried out with the Con.FLU.Po project).
In this second year of activity, the action continued on several fronts:
- stock breeding of 60 specimens of about 2-3 years old, already kept in the semi-natural tanks of Cassolnovo;
- purchase with Life funds and breeding of 80 specimens of about 30-35 cm (0+);
- weaning tests on a new stock of 100 specimens of the year (0+), purchased with the Park’s own funds;
- genetic insights on the fish material purchased.
The action aims to reintroduce Huso huso into the Ticino river and consists of two phases:
- PREPARATORY PHASE to search for potential stock suppliers
- REINTRODUCTION PHASE
Up to now, the experimental hatching and first growth of the 10,000 Huso huso sturgeons purchased by the Park has continued at the Parco della Fagiana Center.
The species has proved extremely difficult to wean, in relation to its highly predatory attitudes. The available experiences are however very limited, having been reproduced this year for the first time in captivity among the breeders surveyed, a fish aged 23 years. The eggs have hatched in an estimated percentage of 80%, and then reabsorb the calf sack in the following days, with an additional mortality of about 10%.
From that moment, weaning began, based on Artemia salina in abundance. But the strong predator character of this fishing has determined a very rapid and progressive depletion of the stock, despite all the efforts put in place and the contacts with the breeder, who suggested to thin out the fish and to supply food in abundance, but confirming the same difficulty even in its installation.
The stock, which reduced to about 5% of the born fish in a month (estimated 400 sturgeons of a few centimeters), then underwent another drastic cut due to a bacteriosis that developed in the breeding trough, treated with the available disinfectants, but which reduced the young Huso to about fifty specimens.
The experience of giving birth and weaning this fish, despite the poor results in numerical terms, is believed to have been fundamental to understand the ethology of the species in these conditions and in these stages of development, and has allowed to acquire a unique experience, leaving to think about various future possibilities to mitigate the problems and to put different breeding strategies in place. Huso huso proved completely different from Acipenser naccarii, despite the common belonging to the Acipenseridae family.