Blog.

30.10.2024

Thymallus Aeliani the real Adriatic grayling?

About 4 million years ago the Adriatic lineage of grayling has been split from the other lineages, and has been evolving separately ever since. This makes that genetically seen the difference between Adriatic grayling and Danubian grayling, is even bigger than the difference between marble trout and brown trout. For a long time, everyone saw European grayling as just one species, but maybe we should see Adriatic as a separate species. The story of Thymallus Aeliani starts in 1848 when this species was described from Lake Maggiore, a lake in the north Adriatic basin. Even though this species was connected to the Adriatic grayling (from the Po in the west until the Soca in de east). Research into the mitochondrial haplotypes between the neotypes from Lake Maggiore and the Adriatic grayling where never done. But in 2020 a research team has tried to do this since the neotype fish can not be found they used 4 fish from Lake Maggiore caught in 1880 and 1881 these fish were compared to fish from the Adige and Adda rivers in Italy. The conclusion of this research was that these fish are from the same lineage and there are no objections to give the name Thymallus Aeliani to the Adriatic grayling (Research link). Since this research concludes we could see Adriatic grayling as a separate species I’ll make a separate description for the Adriatic grayling.

sadly this also comes with bad news. During my visit to Slovenia, I heard, that research into the grayling in the Soča river concluded, that no pure Adriatic grayling was found in the Soča river basin. This made me decide that I’ll not yet include Adriatic grayling into the Slovenian Native Slam as a species to catch. Luckily the good news is that in the parts of the Po basin pure Adriatic grayling where found, and the ZZRS is trying to get the species back to Slovenia. In the fish farm I visited the breeder talked about the options they have at the moment. And the most likely thing is that they will try and cryogenically preserve sperm from these populations to fertilize the eggs from wild females in the Soča. This means that the species will gain a good amount of Adriatic genetics but will not yet be pure. For the species to come close to a pure Adriatic grayling this will take a few generations of fertilizing eggs with pure Adriatic sperm.

Since this plan will take time to realize with training for the used methods and import regulations, currently wild fish from the Soča are bred to maintain a grayling population in the basin.