Description
On 23 October 2024, the first crayfish translocation operation took place in Valsugana. The EMF research team, foresters from the Grigno and Borgo Valsugana district offices, an official from the Protected Areas Service and the coordinator of the Brenta River Reserve Network were involved.
The operation starts with a feasibility study commissioned by the Network of Reserves to the Edmund Mach Foundation, which analysed the possible risk factors associated with reintroduction and identified possible measures to contain these risks.
Translocation is an effective tool for the conservation of endangered species: it consists in moving part of a population to a suitable place to colonise.
The feasibility study ascertained
- the health suitability of the source population, which was therefore not affected by the pathogens responsible for an infectious disease known as 'crayfish plague
- the genetic variability of the populations, with a clear genetic distinction between the right and left orographic sides of the Adige River
- suitable environmental-ecological parameters of the reintroduction sites (oxygenation and temperature of the water, environmental heterogeneity of the micro fauna and vegetation of the watercourses that can guarantee sources of sustenance and refuge for the crayfish).
The donor population was identified as the one present in the Rio Laguna di Grigno and in the adjacent artificial pond. The place chosen for the translocation was the biotope Palude di Roncegno, a place very rich in interconnected watercourses and ponds that make it particularly suitable for the reintroduction project.
The intervention took place in the evening hours, as crayfish are nocturnal animals.
The researchers, equipped with nets, buckets and head torches, began the meticulous search and capture work on the stream bed. The crayfish were then measured, weighed and observed closely to assess their state of health, to check for the presence of any parasites or other diseases. They were then classified according to sex and age class.
For the purpose of translocation, the aim was to capture about twenty adult male and about 40 female individuals, possibly already fertilised by the males. The total number of individuals captured was not to exceed 10% of the donor population.
This resulted in the selection of 24 males and 36 females, a total of 60 individuals, which were placed in special plastic containers with wet rags to keep the environment moist and protected.
For release in the Roncegno marsh biotope, the crayfish - after spending a few minutes acclimatising with the temperature of the new body of water immersed in their containers - were released in a quiet area of water that would allow their natural dispersion.
The new population will be constantly monitored and strengthened over the next two years with two more translocations. the actual success of the project can be ascertained next year if yearlings are found, confirming that the crayfish have managed to complete their life cycle in their new environment.
