Two lakes, seven whitefish species
Species-rich Bernese Oberland lakesAmong the lakes which were originally particularly species-rich, those less affected by eutrophication were Lake Lucerne and the lakes of the Bernese Oberland. Harbouring respectively six and seven known species, these are still among the lakes with the highest whitefish diversity worldwide.
At least six of the Bernese Oberland species arose after the end of the last ice age, around 12,000 years ago. The origins of the seventh species are more complex, as its history involves hybridisation with whitefish from Lake Constance, introduced to Lakes Thun and Brienz by stocking in the 20th century. All seven species have now been scientifically described – four for the first time – by Oliver Selz and a group of evolutionary and fish biologists led by Ole Seehausen at Eawag and the Bern University Institute of Ecology & Evolution.
Four newly described speciesScientific descriptions already existed for the “Brienzlig” (Coregonus albellus), the “Balchen” (Coregonus alpinus) and the “Felchen” (Coregonus fatioi). The first two – the smallest and the largest species – had already been described by the Genevan zoologist Victor Fatio in 1885. All three species are found both in Lake Thun and in Lake Brienz.
The “Kropfer”, a Lake Thun deep-water whitefish, has been known for the past 20 years as Coregonus alpinus, in accordance with Kottelat’s “European freshwater fishes”. However, Kottelat’s handbook clearly referred to a specimen, held at the Natural History Museum of Geneva, which had been designated as “Balchen” by Fatio in 1885. For this reason, the authors of the study have now restored the name C. alpinus to the “Balchen”. The “Kropfer” has been newly described and named Coregonus profundus. In 2018, the scientists discovered a species which, on account of its similarity to the “Balchen”, was provisionally designated as “Balchen2”. This species, in Lake Thun, has now been named Coregonus steinmanni – in honour of the whitefish researcher Paul Steinmann. Further investigations revealed that the Lake Brienz whitefish initially also designated as “Balchen2” is in fact a separate species. As the only species endemic to Lake Brienz, it has been named Coregonus brienzii.
Old name, new fish
Also scientifically described for the first time in this study is the “Albock” (Coregonus acrinasus). The common name “Albock” has been in use since medieval times. In old documents, invoices and fisheries laws, it is used to refer to the larger whitefish from Lake Thun, many of which regularly migrated to the Aare river, where large numbers were caught. According to first author Oliver Selz, “It’s not quite clear what became of this species.” Morphologically, specimens of the migratory “Albock” preserved from the 19th century most closely resemble today’s “Felchen” (C. fatioi).
“Today’s pointy-snouted ‘Alböcke’, which have only been observed in increasing numbers in the catches of Oberland fishermen since the late 20th century, have a recent history of hybridisation: genetically, they are closely related both to whitefish introduced to the Oberland lakes from Lake Constance in the 20th century, and to the other Lake Thun whitefish.” Why the traces of stocking are only apparent in Lake Thun, and not in Lake Brienz, and what species the original “Albock” should be assigned to, are questions to be investigated in future research projects. The biologists conclude that further surprises emerging from the depths of the Oberland lakes cannot be ruled out.
Paul Steinmann (1885–1953)
Paul Steinmann (1885–1953): researcher, teacher, expert, fishing society president Paul Steinmann, having studied in Basel and Munich, completed his doctoral thesis on “The fauna of mountain streams” under the zoologist Friedrich Zschokke in 1907. Following study visits to Naples and Trieste, and a brief period as a privatdozent at Basel University, Steinmann was appointed to teach natural history at the Kantonsschule Aarau in 1911 – a position he held until his retirement in 1953. As co-founder and Director of the Aarau Natural History and Heritage Museum, he served as President of the Aargau Naturforschende Gesellschaft from 1923 to 1928. As President of the Swiss Fishing Society (now the Swiss Fishing Federation/SFV) and Editor of the Schweizerische Fischerei-Zeitung – and an internationally recognised expert in hydrobiology – Steinmann was an early advocate of the protection of natural waters and fish habitats. His extensive fish collection, originally donated to Eawag and still a valuable resource for researchers, is now curated by the Natural History Museum of Bern and forms the subject of a new exhibition. His monograph on Swiss coregonids, published in 1950, remains a vital reference for the study of whitefish diversity in prealpine lakes several generations later. Following this week’s publication of the taxonomic revision in ZooKeys, the Bernese Oberland whitefish species discovered in 2018 now bears Paul Steinmann’s name – Coregonus steinmanni. Literature: Entry for Paul Steinmann in Historisches Lexikon der Schweiz and Obituary in Mitteilungen der aargauischen Naturforschenden Gesellschaft Vol. 25 (1958), pp. 224–228.