The trade body said the decline was due to a tough comparison with 2013 when a record capacity was installed offshore. "The industry has seen exponential growth in the early part of this decade and this is a natural stabilising of that progress," said Justin Wilkes, EWEA deputy chief executive officer.
Total cumulative offshore capacity now stands at 8.05GW spread across 74 wind projects.
Last year, 408 turbines were installed offshore. The UK accounted for over half of all new installations, with Germany installing 35.7% of the total, and Belgium making up the rest with 9.5%.
But in 2015 Germany is expected to install more offshore capacity than the UK, which has dominated installations in Europe for the past three years.
"Germany is set to buck the trend this year. The UK has more installed offshore capacity than the rest of the world combined, but this year shows that other countries in the EU are making serious investments in the sector," said Wilkes.
The biggest project expected to come fully online next year is RWE's 576MW Gwynt y Mor in UK waters, followed by the 400MW Global Tech 1.