Scottish Secretary Alistair Carmichael has claimed concerns over the future of oil, fishing and agriculture resulted in people across the north and north-east decisively rejecting independence.
The Liberal Democrat MP for Orkney and Shetland said people connected to the industries did not believe Scottish Government assertions that the country would be able to join the European Union in 18 months.
Mr Carmichael said: “These issues were enormously important in the north-east and throughout the Highlands and islands.
“In many ways the debate on oil was not one of the better aspects as we had all these conspiracy theories about massive reserves that were somehow being concealed and frankly that did not help anybody.
“But the reasons why you saw the emphatic No votes coming from these areas is because people know about the oil industry and the EU.
“So when the Nationalists came forward and said ‘of course we can get into the EU and we will do it in 18 months’, farmers and fishermen raised their eyebrows because they know how glacial the pace of change in Europe is.”
Conservative MEP Ian Duncan agreed the issues were at the heart of why people in the north overwhelmingly rejected separation.
“I was speaking to fishermen last week and they said they needed the security and certainty that the UK and the EU provided, and farmers said the same thing,” he added.
“They rely on subsidies from Brussels to make ends meet and they were fearful this vote could seriously undermine their prospects and ultimately end their relationship with the EU.
“They will breathe a sigh of relief and have recognition that things will never be the same again and change will come.”
Mr Duncan said all political parties must now “pull in the same direction” to ensure Scots get the reforms they want.