Community figures have warned that rising property prices in the Hebrides, Western Isles and Skye are preventing locals from buying a home.
In an open letter they described the situation as akin to an “economic clearance” that was threatening the sustainability of the islands.
They said young islanders could not compete with offers made by buyers from elsewhere in the UK.
It follows claims parts of Scotland are seeing a post-lockdown property boom.
The uptick in interest has been put down to previously office-based staff being able to work from home and perceived lower rates of Covid-19.
The letter’s signatories – which includes crofters, development officers and Gaelic campaigners – said 40% of housing stock on both Tiree in the Inner Hebrides and West Harris in the Western Isles were holiday homes.
They said the availability of affordable properties for young islanders had been a long-running problem, but was expected to worsen post-lockdown.
They pointed to reports of people across the UK looking to relocate to the Highlands and Islands, and having the means to make higher offers than local buyers.
The letter said: “Part-time residencies do not sustain our communities and we should therefore ensure that houses are bought with the intention of being a primary residency.
“Inaction will allow this economic clearance to be consolidated in history.”
The use of the term “clearance” echoes back to the Highland clearances when tenants were evicted from land in the 18th and 19th Centuries so landlords could increase their income.
The letter suggests Uist in the Western Isles be used as a trial location where properties are advertised locally in the first instance prior to being listed on the national market.
The letter said: “A recent example of a house in Uist becoming available for rental shows the scope for positive action.
“The owner agreed that the house should first be advertised to young locals, and a number of applications were received.
“They seized this opportunity to invest in the community by offering the house to a returning young couple with three children.”
The letter comes after concerns were raised that Gaelic speakers among the islands’ communities could vanish within 10 years.
Researchers said daily use of Gaelic was currently too low to sustain it as a community language in the future.
The letter’s signatories include Pàdruig Morrison, a Uist crofter, researcher and musician and architect and Gaelic campaigner Martin Baillie, from Skye.
Uist businesswoman Emma Axelsson and crofter Fiona NicÌosaig have also signed it.