Arctic Charr

Salvelinus alpinus

Arctic Charr

The Arctic Charr in Loch Rannoch have been the subject of much study not least by the acknowledged local expert Ron Greer who has coauthored scientific papers on the subject.

I will attempt to summarise the situation -

There appear to be three distinct morphs of the fish -

1) a benthivorous morph - feeds on the bottom of the loch and is long living

2) a planktivorous morph - feeds at the surface and does not get as big or live as long as the benthivorous morph

3) a piscivorous morph - eats fish

When the world was young, very young, in the late 1970s and early 1980s I took over a project at Rannoch School (Dall school if you prefer), which was started by André Zaluski. It looked at the morphology of the Charr in Loch Rannoch. It was funded by the Royal Society and pupils examined the body ratios of the fish as well as dissecting out the otoliths to age the fish and using electrophoresis to help determine the presence of chemical evidence of different morphs. The research into the Charr in Loch Rannoch was later carried on by Glasgow University and Faskally Fisheries Research Laboratory.

The school project was just that, a school project, but it was highly educational and at least one participant has gone on to forge a career in aquatic reasearch - Demetri Ponirakis now researches Cetacean Acoustics at Cornel University - well done Demetri :-)

The Charr in Loch Rannoch have been trapped in the loch since the last ice age (10,000 years) and this has given them time to evolve. It is interesting that even when creatures occupy the same geographical space (are sympatric) they can begin to separate genetically by evolving to occupy separate niches. Thus one morph is specialised for bottom living and one for the surface niche. The piscivorous morph has specialised in catching and consuming fish and this requires a difference in morphology. The Ferrox trout is an example of a similar effect in the trout population in Loch Rannoch.

Needless to say the Charr in Loch Rannoch do not migrate to the sea but in Scandinavian countries there are populations that do in a way that is similar to sea trout. The technical term for such behaviour is anadromous i.e. the populations the move between freshwater and the sea, returning to freshwater to spawn.

A group of people from Rannoch, including Richard Legate and Ron Greer attended a conference in Sweden to link the conservation efforts for safeguarding Arctic Charr in Ireland, Scotland and Scandinavia.

Arctic Charr are circumpolar in distribution with populations found in Iceland, Svalbard, Scandinavia and Siberia.

Creative Commons - credit Xepheid