Riverwoods, SBP's feature-length film narrated by Peter Capaldi, was screened in November on 5Select and is now available to watch for free on My5, the on-demand streaming service from Channel 5.

The TV broadcast was watched by thousands and follows a tour of screenings across Scotland earlier this year, which culminated in a successful screening at the British Film Institute in London.

Riverwoods reveals the link between Scotland's declining salmon and the deforestation of Scotland's hills, making explicit the link between the future of Scotland's most iconic fish and the health of the catchments through which Scotland's rivers flow.

But this is not just a story about salmon, or just trees. It is a clarion call to understand nature holistically, to appreciate how the influence of the salmon extends beyond the river bank, while the fate of the river's fish, invertebrates and other inhabitants depends on the health of the system as a whole.

And while the contrast between Scotland's bare hills and the forested catchments of Alaska and Norway is made starkly obvious, the film also contains a message of hope – recording how the complex inter-relationships that sustain healthy ecosystems can be restored through the work and passion of disparate stakeholders united by a shared vision.

Salmon need trees, for shade, shelter and to support them through their life cycle. Equally, riverwoods need salmon to bring nutrients upriver into the poor soils of the upland headwaters. The film shows how each supports the other, and reminds us that we need them both.