Action C2: breeding and restocking of Acipenser naccarii and other species of Community Interest in the Rete Natura 2000 Sites included in the project area.
The activities carried out in recent years as part of this project have enabled the preparation and consolidation of artificial reproduction protocols for a number of target species: Adriatic sturgeon, Italian nase, South European nase, Pigo and Italian barbel.
Over the years, a series of agreements have been made with companies outside the Ticino Park, making it easier to pursue the project objectives. Worthy of note are the collaborations with the regional fish hatchery of Abbiategrasso (Milan), that of FIPSAS in Somma Lombardo (Varese) and, in part, that of Tinella (Varese).
Adriatic sturgeon: Activities related to the artificial reproduction of this species have continued in accordance with the consolidated protocol implemented by the Park several years ago.
In recent years, in order to make the activity more efficient, a selection was made in the large pool of broodfish present at the Park's facilities, selecting the specimens based on size, sex, age and genetic profile. Discarded specimens were used for biotelemetry activities.
One of the most critical phases of the entire artificial reproduction cycle is the weaning of young larvae. The greatest number of deaths occurs at this time, due to the natural mortality rate, but also to the difficulty faced by young sturgeons in getting used to artificial foods. In order to improve the results achieved during this phase, over the last two years the Park has been collaborating with the Department of Veterinary Sciences of the University of Bologna, where experiments have been carried out on the weaning of young sturgeons. This has brought about significant improvements.
As regards the artificial reproduction phase conducted in 2017, a considerable number of eggs were taken (it is estimated, about 500,000), from as many as 8 females. Having a considerable number of fertilized eggs available, therefore, incubation was split among the above facilities, both for reasons of space and to prevent any possible unforeseen events that could have led to the loss of the entire batch if it had been held in one facility alone. As many as 75% of the eggs are estimated to have hatched, releasing more than 200,000 yolk-sac larvae into the natural environment. The rest were held at the Fagiana hatchery to continue the growth and weaning phase. To date, the incubator holds about 5,000 young growing sturgeons that are to be transferred to the semi-natural tanks of Cassolnovo, where they will begin to adapt before being released into the wild.
In recent years, the stocking of sturgeons has resulted in the release of a total of 4,317 Pit-Tagged sturgeons aged 2+ and 4+, in addition to a total of 100 adults marked with an ultrasound transmitter; all have been released in the Ticino River and in the Po River, in the provinces of Rovigo and Piacenza. Added to these are 300,000 fry (recently hatched fish that have reached the stage where the yolk-sac has almost disappeared) and 40,000 specimens measuring between 0+ and 2 cm.
In addition to these subjects released in the Ticino River and the Po River, other specimens have also been released in three areas south of the Po Delta by the University of Bologna, which has been cooperating with the Park for the last three years. A total of 790 specimens measuring 0+ and 436 measuring 1+ and 2+ were released. These derive from fertilized eggs taken at the Parco Ticino throughout the project.
Freshwater cyprinids (South European nase, Pigo, Italian nase and Italian barbel): Activities related to these species have had two basic purposes: to determine an effective artificial reproduction protocol specific to each species, and to produce stocking material. The two objectives are naturally interrelated, and over the years successful results have been achieved in both cases. Particularly worthy of note are the excellent results achieved with the South European nase, regarding which there was very little information on how to carry out artificial reproduction. The project led to the definition of the necessary protocols, which are being used by the Park and may be used by anyone else who should need them.
From the point of view of stocking juvenile fish, the objectives set at the start of the project were met, and in some cases even exceeded. Compared to the initial goals, greater emphasis was placed on releasing specimens of around six months rather than fry. This was done in order to release larger animals with a higher chance of survival. In all, more than 1,800,000 specimens were released (485,000 fry and 1,400,000 weaned fish of a few months of age).
An important contribution to the reproduction of these species was the availability of an artificial pond in the regional hatchery of Abbiategrasso (Milan), where these species were weaned and their first growth phase was completed with success. This is because the pond environment creates extremely favourable conditions for young cyprinids, which can count on large resources of natural food in the early stages of life and optimal heat conditions.
As regards the South European nase, a rather effective artificial reproduction protocol was developed, allowing the production of a considerable number of specimens. To date, two pools of broodfish are being used by the Park: a smaller one at the Fagiana hatchery, and a larger one, housed in the FIPSAS hatchery in Varese.
As for the Pigo, whose reproduction remains linked with capturing wild subjects during the reproduction phase, over the years a drastic fall in broodfish has been recorded in the historic reproduction areas of Somma Lombardo (Varese). Through the collaboration with the FIPSAS fishermen of Novara, during the last year of the project a new area was identified for sourcing broodfish.
Also during the last year of the project, we experienced difficulties with the artificial reproduction of the Italian nase. Due to unidentified factors and despite having adult broodfish to hand, the process of hormonal induction did not, as in previous years, yield eggs from the induced females.
Finally, as regards the Italian barbel, eggs were taken from just one female, which, as a result of hormone induction, released about 120 ml of eggs which were then fertilized by 4 males, producing about 10,000 juvenile fish.
Action D2: Check the effectiveness of the Acipenser naccarii and other species repopulation.
The purpose of this action is to verify directly the effectiveness of the restocking of Adriatic sturgeon and 4 species of Cyprinids reofili that have been released in the river, after the activities envisaged by Action C2. To these data are added those of the monitoring, mediated cameras, conducted under Action D1.
The partners involved are the Lombardy Region in general, Ticino Park, Emilia Romagna, Province of Piacenza and Province of Rovigo, which are each responsible for their sector.
- Adriatic sturgeon (Acipenser naccarii):
The project foresees, as of 2015, the activation of the monitoring on the individuals that are released during the Action C2 in the areas of the Natura 2000 Network of the River Po and Ticino.
The activities already completed are those of the Ticino park and relate to monitoring the Lanca Bernate through electrofishing:
- 09/02/2014, prior to the release of 10,000 fingerlings of Adriatic sturgeon, with yolk sac resorbed.
Results: have not been detected individuals of this species
- 17/07/2015, prior to the release of 30,000 fingerlings of Adriatic sturgeon, with yolk sac resorbed.
Results: have not been detected individuals of this species.
The other partner will start the activities from 2016. The delay in the completion of the fish ladder in Isola Serafini has led currently the non-activation of the monitoring point with ultrasonic receiver.
2. Cyprinids reofili:
For the four target species (Pigo, South European nase , Common Barbel and Italian Nase) the project foresees the activation of the monitoring campaigns through electrofishing from 2015, because the breeding activities began in 2013 on the individuals that are released during the C2 action in areas of the Natura 2000 Network of the River Ticino.
Due to the reduced growth of the Cyprinidae in 2014, it has been revised methodology tracking, that still proved to be effective. It is not practicable to mark it with elastomers fingerlings at the age of one year.
So 10,000 fingerlings have been bred up to 6 months-1 year. 8,000 specimens were then released in the lateral environments of the River Ticino and the remaining 2,000 were placed in ponds outside of the hatchery of the Province of Milan, managed by the Park, and left to grow until they reach a size suitable to be marked (10 / 12 cm), before releasing them.
Lacking the individuals marked, for monitoring has been verified with electrofishing the presence of the target species, prior to the release of the reared specimens, with the idea of observing through time an increase in species subject of the releases:
- 06/05/2014 - In the branch of the river Delizia, previous to the release of 50,000 Common Barbel and of 60,000 Italian Nase, both yolk sac resorbed.
Results: has been detected only the Common Barbel, but with a population not well structured.
- 14.10.2014 - In the branch of the river Delizia and in the Calderara irrigation ditch, prior to release on each of the two places of 4,000 individuals Pigo of Common Barbel and Italian Nase .
Results: in the Calderara irrigation ditch has not been found the presence of the four target species, in the branch of the river Delight has been found to contain a population of Common Barbel well structured.
- 28.05.2015 In the branch of the river Delizia and in the Calderara irrigation ditch, prior to release of fry of Pigo, Common Barbel and Italian Nase
Results: In the branch of the river Delizia has confirmed the presence of Common Barbel, but has made its appearance also Italian Nase, missing prior releases; in the Calderara irrigation ditch, was found the common barbel, that was missing.