Planning and operation

General info

The wetland
At the west coast of Thermaikos gulf extends one of the most important wetlands in Greece. Starting from Thessaloniki and heading west to find Kalohori Lagoon, the estuary of Gallikos river, Axios delta, the estuary of Loudias, the delta of Aliakmonas river and the salt pans of Alyki Kitros. It is a large complex wetland system with a total surface area of around 33000 ha. The high biological diversity, coupled with the existence of rare and protected species of flora and fauna, support the site’s internationally recognition. The wetland is one of the 10 Greek Ramsar Wetlands; parts of the wetland area are included in the Natura 2000 Network (SPA GR 1220010 and SCI GR 1220002) protected by international conventions, EU Directives and National Legislation.
Aliakmonas and Axios Rivers
The main rivers are Aliakmonas and Axios. Aliakmonas is the largest Greek river with a length of 350 km. The river’s headwaters are located in the mountains of Grammos and Voio, while its estuary is in the southern part of the Thermaikos Gulf, where it forms an extensive delta. In mythology Aliakmonas river was a riverine deity and according to Hesiod was the son of Ocean and Tithys. An artificial lake created by a regulatory barrier that receives water from three hydropower dams regulates the flow of the river.
Axios is the second longest river in Greece with a total length of 320 km, of which 76 km belong to Greece. The river headwaters are located in F.Y.R.O.M, and discharges into Thermaikos Gulf. Around 95% of the river basin belongs to F.Y.R.O.M. There are 13 dams along the riverbed, of which twelve are on his tributaries in F.Y.R.O.M. In 1934, a river diversion took place, in order to avoid the blockage of Thessaloniki port due to extreme sedimentation process. New fertile areas were formed for cultivation and a new delta established in the today’s position. River discharge
Management Authority of the National Park
The Axios Management Authority is responsible for an area of 33.000 ha. The area includes the lower reaches of four rivers and their estuaries (Gallikos, Axios, Loudias, Aliakmonas), the Kalohori lagoon and the salt marshes of Alyki Kitros. A Visitor Information Center is in operation since 1997, in the town of Chalastra.


The spawning of the mussels takes place during late autumn till early spring. The farmers put the spat collectors during middle winter.


Spat collectorThe mussel larvae live as meroplankton for one-two months and after metamorphosis are settled on spat collectors.





Spat growth

The spat after its settlement grows up to a length of 2-3 cm on the collectors for 3-5 months, depending on the environmental conditions of each year. At the time that spat reaches this length (2-3 cm), the operator uses it to prepare new socks. This is the first thinning procedure.


thinningThe mussels grow for the next three months in the same socks until late summer (August) where a new (second) thinning procedure takes place. Depending on the environmental conditions/toxic algae/microbial load, a new one (third) thinning procedure may occur. Aeration (poles) or sinking (longlines) process is needed, when the epibionts have to be removed.


harvestingThe harvest takes place when the mussels overreach the length of 5 cm after a total average period at least of 8 months since reproduction. The mussels are transported as socks or as 20 kg bags to the appropriate vehicles for the markets.