page_title: Lake Ohrid
section_title: Human influence
hierarchical_section_title: Lake Ohrid / Human influence
caption_attribution_description: Ohrid Lake and Galichitsa Mountain near St. Naum Monastery, Republic of Macedonia
context_page_description: Lake Ohrid is a lake which straddles the mountainous border between the southwestern part of North Macedonia and eastern Albania. It is one of Europe's deepest and oldest lakes, with a unique aquatic ecosystem of worldwide importance, with more than 200 endemic species.
  North Macedonia's side of Lake Ohrid was declared a World Heritage Site by UNESCO in 1979, with the site being extended to also include the cultural and historic area of Ohrid in 1980. In 2010, NASA named one of Titan's lakes after it. In 2014, the Ohrid-Prespa Transboundary Reserve between Albania and North Macedonia was added to UNESCO's World Network of Biosphere Reserves. Albania’s side of Lake Ohrid was also designated UNESCO world heritage status in 2019.
  In Albania, the coastal portion of the lake holds Managed Nature Reserve status. In North Macedonia, a portion of the lakeside is part of the Galičica National Park.
  The towns situated at the lakeside are Ohrid and Struga in North Macedonia along with Pogradec in Albania. The lake is otherwise densely surrounded by settlements in the form of villages and resorts in both basin countries.
context_section_description: Shore habitats are under particular pressure from human activities. Particular threats are the building of tourist facilities directly at the shore, destroying of reed belts to gain agricultural land and intense pollution close to the mouth of tributaries. Although the effects of these human impacts have not been evaluated in detail they are of great concern, as the shallow water sites are particularly rich in endemic bottom fauna and form important spawning grounds for several endemic fish species. Moreover, reed belts have great importance for water birds.
  Commercial fish yield, i.e. the two endemic trout species, has dropped significantly over the past decades, both in North Macedonia and in Albania. The most probable reason is overfishing and possibly destruction of spawning grounds. Pollution may also be a factor. Although there are regulations regarding fishing practice (e.g. minimal mesh size) and only a limited number of licensed fishermen, these rules are always not obeyed as a result of the high market value of the endemic trout. As a reaction to the situation, a seven-year moratorium on fishing Ohrid trout was imposed from 2004 to help the population recover and to allow scientists collect further data. Nonetheless, even though thorough assessment of fish stocks has not been conducted since the 1990s and trout populations are still believed to be in decline, fishing with quotas was restarted in 2012 under the auspices of a concessionaire. More data is required to determine whether these current fishing levels are sustainable and illegal fishing, particularly on the Albanian side of the lake, remains a problem.
  While most of the endemic fish species are non-migratory, the European eel spawns in the distant Sargasso Sea while its offspring return to the lake. Unfortunately, as in many European lakes, it is very unlikely today that eels can reach Lake Ohrid naturally and return to the Sargasso Sea, as a result of several hydropower dams on the Black Drin and the Drin River, both in North Macedonia and Albania. As a result, eel found in Lake Ohrid are stocked populations.
  Given the population growth over the past 50 years, a particular concern is the potential eutrophication of currently oligotrophic Lake Ohrid from increased pollution. Indeed, sediment cores show a ~3.5 fold increase in phosphorus concentration over the past century. On the one hand, shifts from endemic to common European species, which are better adapted to higher nutrient conditions, have already been observed close to polluted inflows. On the other hand, higher nutrient levels have reduced the water transparency, as well as the oxygen availability in the deep water and at the lake bottom, two properties which are requisite for the endemic flora and fauna. Still, the lake is in a comparably good state at the moment. However it may take more than a decade to see the effects of today's pollution level in the lake, because of its long water residence time. Moreover, it was shown that the negative effects from eutrophication would be significantly amplified by global warming. Although there is time to react, computer simulations indicate that at least a 50% reduction in phosphorus input must be reached to keep the deep water oxygenated for the next 50 years at predicted atmospheric warming. This aim could be reached by controlling household wastewater, which is by far the biggest phosphorus source at the moment. First steps in that direction have been taken by extending and improving the existing sewage system in North Macedonia in the framework of a GEF (Global Environment Facility) program. The most important next task would be a solution for three remaining, severely polluted tributaries, one in North Macedonia and two in Albania.
caption: The lake coast at St. Naum Monastery, with Galičica Mountain in the background.
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