James Isbister married Mary Parker 29 Jun 1806 at Sunderland, Durham and to my knowledge they had the following childen all born Sunderland, Durham Mary b 30 Jan 1817, Sarah b 21 Nov 1819 and Christina b 30 Jan 1822. In the 1851 Census James is listed as a Mariner (and something with this which I cannot read) and his age is 68 and Mary is 66, Mary was born at Sunderland, Durham. In the 1841 Census their age is to the nearest 5 below.
I could not find a christening for James Isbister around 1783 but some records were destroyed around that time in a Church fire. Unfortunately, the census records only say Orkney as his birth place. I hope this is helpful to you