The population of Stroma continued to rise until it reached a peak in 1901, after that the population began to dwindle as people found new lives elsewhere.

Population Statistics-. 'Stroma' edited by D. Young
(second source)

After the second world war the population kept decreasing until the last family were forced to leave in 1962.

There were numerous reasons for the depopulation of Stroma; and a number of myths also. Many Stroma men who served in the first world war returned to find very little work because of overfishing by seine net boats. They had also seen more of the world, where previously they may never have left the island, they often found they could not settle back into their old wets of life and searched for a better life elsewhere. These men either left for the mainland or emigrated to Canada and the United States.

Large families were common at that time, with little work going the children had to go elsewhere to find employment. The fishing catches and prices suffered a sharp drop, resulting in families being forced to leave.

One Stroma man said:

"The politicians emptied it."

The Third Statistical Account of Scotland 1983
The Parish of Canisbay, by Mrs Margaret C. Gunn 
(primary source)

he was referring to the Act which made it compulsory for all children over twelve to go to Wick High School and board there.

Accommodation was difficult to find and expensive, families with children of that age had to leave. This in turn meant that there were fewer able bodied men left to crew, launch and haul the boats; continuing with the demise of the fishing industry.

Jessie Crowe wrote:

'The two mile stretch of unfriendly and dangerous water between Stroma and the mainland was the main reason for the total depopulation of our island'.

from'Stroma', edited by D. Young primary source


Conclusion.

From the statistics concerning population it is apparent that the inhabitants of Stroma were dwindling. This was greatly different to everywhere else in the parish, as population continued to increase in all other areas.

I would say that the main reason for families leaving Stroma was so they could afford to educate their children, after the education act made it compulsory for all children over 14 to attend secondary school.