The total amount of renewable energy produced from wind and hydro power schemes in Scotland fell last year.
Low rainfall meant hydro production fell by a third.
And despite a sharp increase in the number of wind turbines installed, there was only a 6% increase in the amount of power they produced.
UK government figures also showed a decline in oil and gas production earlier this year, which industry leaders described as “worrying”.
The statistics from Whitehall’s Department of Energy and Climate Change showed the second quarter of this year saw some of the sharpest falls on record of oil and gas production from under UK waters.
Oil production was down 16% and gas by 25% compared with the second quarter of 2010.
This was attributed to planned maintenance as well as emptying oil reservoirs.
The amount of renewable energy produced in Scotland has increased sharply since 2003, before dropping back last year.
Richard Yemm, founder of the wave energy firm Pelamis Wave Power, said: “Renewable energy sources depend on weather conditions year to year and it is well understood that the best way to stabilise and guarantee renewable energy supply is to diversify the mix of technologies installed.
“That’s why these figures emphasise the need for Scotland to push forward with the commercialisation of marine energy, which is inherently more predictable, and mixes well with other sources.”
He added: “The sooner we can include wave power as a significant proportion of the UK’s energy mix, the more secure our renewable energy supplies will become.”
Niall Stuart, chief executive of Scottish Renewables, said despite the drop in output the figures still emphasised the importance of renewable energy.
He added: “The figures show that even in an exceptionally dry and calm year, renewables provided over 30% of all electricity consumed in Scotland.
“This reinforces that the sector is now a major part of our energy mix, and a significant part of our economy.
“Our hydro sector met more than 10% of sales to consumers.”
The Scottish government said the only drop in renewable output last year had been in the hydro sector and it pointed to more recent figures showing an increase in renewable energy generation.
A spokesman said: “Just this week, more up-to-date figures showed that renewables generation has increased significantly in 2011, with UK onshore wind energy generation up 111% on the same period last year and hydro up by 74%.
“This comes at the end of a week when Nobel Laureate Al Gore lauded Scotland for its leadership and we see yet more jobs and investments in our fast growing clean green energy sector.”
“We have ambitious renewables targets and we are making progress.”
Scottish Labour leader Iain Gray MSP called for the Scottish government to set interim annual targets on renewable energy production.
He said: “Alex Salmond’s overblown rhetoric on energy needs to match reality.
“This week he hailed Scotland’s renewables revolution as a ‘paradigm shift’, the greatest in 10,000 years, equivalent to the ‘change from hunter gathering to agriculture’ but he is failing to come up with the goods or even outline milestones towards 2020.”
Mr Gray said Scotland had “colossal” renewable energy potential which must be seized.
He added: “It is not good enough for the SNP government to simply cross its fingers and hope it is breezy in 2020.”