There certainly were, but on a much smaller scale than we would currently consider a fleet An example that springs to mind is in 875 when according to the Anglo-Saxon Chronicle, "King Alfred went out to sea with a naval force, and fought against the crews of seven [Viking] ships and captured one ship and put the rest to flight."

Fleet actions by the West Saxon navy proved quite effective at keeping the Vikings at bay, but boats were predominantly considered transport rather than warships, usually used to ferry soldiers along rivers and the coast. The Chronicle records several incidents where militia levies responding to Viking attacks first try to destroy their ships in order to prevent them escaping before tracking them down.

There were several large fleet actions in Viking times.

In the Battle of Nisa, in 1062, the forces of Norwegian King Harald Hardradea with 150 ships fought the fleet of Sweyn Estirdsson, King of Denmark with 300 ships. The Battle was won by the outnumbered Norwegians.

The Battle of the Helgea, in 1026, pitted the 600 ship Danish and English fleet of Cnut the Great against 480 Norwegian and Swedish ships. It was a hard fought battle but Cnut won.

The semi legendary Battle of Hjorungavagr, circa 986, was fought between the 180 ships of Haakon Sigurdsson of Norway and the Jomsvikings with 60 ships. The Norwegians won.

The sagas do not relate the number of ships in the battle of Nesjar in the Oslo fjord in 1016 between Olaf Haraldsson (later St. Olaf) fighting to become King of Norway, and the allies of Sveinn Hakonarson. It is thought to have been a fierce battle, with Olaf prevailing.

In 999 or 1000 the Battle of Svolder was fought between King Olaf Tryggvason of Norway and a number of his enemies. Olaf had only 11 ships, while the coalition of Swedish, Danish, and other Norwegian allies had more than 70. Olaf was defeated and died in this battle.

Source:

http://en.wikipedia.org/wiki/Category:Naval_battles_involving_the_Vikings