Based on previous habitat surveys and literature reviews, the REVIVO Institute implemented fishing surveys in hope to find sterlet in two Slovenian rivers – the Mura and in the lover part of the Sava. About our habitat survey you can read more in our previous news story, here.
Due to the lack of data, we focused on wintering and feeding habitats. We focused on using other methods which are or were used in the past by fishermen in the Danube and its tributaries where sterlet fishing was more common than in Slovenia.
On potential feeding habitats we tested longlines and net drifting (read more here) and on potential wintering habitats we tested the visual census method (read more here) and fixed trammel nets, which proved to be more successful (read more here).
We caught three migratory fish species such as Nase (Chondrostoma nasus), Cactus Roach (Rutilus virgo) and Barbel (Barbus barbus). Our project partners from Croatia – VUKA, tested the same method on the Sava River just few kilometers below Zagreb and caught 20 sterlets.
However, we confirmed that sterlets are rare in our rivers so additional modern methods should be used in the future. We recommend using eDNA and telemetry to first confirm in which sections of the river we can still find sterlets. Then using telemetry, habitats for feeding, wintering and spawning can be found and monitored. In order to establish a stable sterlet population in our rivers, restocking end habitat restoration efforts are also necessary.
You can read more about our findings in the articles below, published in the Slovenian fishing magazine Ribič.