6 McGonagle, 3 McLoughlin and 1 Loughry households on Inishtrahull, according to Griffiths in 1857.
http://www.askaboutireland.ie/griffith-valuation/index.xml?a...RC parish is Clonca but parish records only seem to start in 1870.
Here’s the occupants of the island in the 1901 census:
http://www.census.nationalarchives.ie/pages/1901/Donegal/Ard...