The taxonomy of roaches inhabiting northern Italy, the Western Balkans and southern Greece has not been definitively resolved.

At the generic level, they were included in the genus Rutilus prior to the mid-2010s, before being transferred to the resurrected genus Leucos based on a series of molecular and morphological characters (Bianco and Ketmaier 2014).

However, a number of authors have opted against support of this split, and there is a further lack of consensus regarding the validity of nominal taxa inhabiting the Western Balkans. Subpopulations occurring in this region are either treated as distinct, locally-endemic Rutilus species, i.e., R. basak from the Neretva River system, R. albus from the Lake Skadar basin, R. ohridanus from Lake Ohrid and R. prepsensis from the Prespa Lakes basin (Marić 2010, 2019, Perea et al. 2010, Milošević et al. 2011, Tsoumani et al. 2014, Barbieri et al. 2015, Tutman et al. 2018, Ćaleta et al. 2015, 2019, Freyhof et al. 2020), or lumped together under Leucos basak (Bianco and Ketmaier 2014, Pietrock et al. 2022).

In addition, molecular analyses have demonstrated a close relationship between the Skadar, Ohrid and Prespa subpopulations, with this subgroup divergent from the Neretva River subpopulation (Geiger et al. 2014, Petrosino et al. 2022).

Global and European regional assessment: Least Concern (LC)
EU 27 regional assessment: Near Threatened (NT)

The Dalmatian Roach has a relatively restricted range (extent of occurrence (EOO) c. 28,297 km²), which approaches the threshold for the Vulnerable category under Criterion B1 (EOO < 20,000 km²). In the EU 27 member states, the EOO is 15,721 km² and meets the threshold for Vulnerable. The extent and quality of habitat are estimated to be declining, but it is not understood to be severely-fragmented, the number of locations is unknown, and there is no evidence that it demonstrates extreme fluctuations.

Therefore, this European endemic species is assessed as Least Concern at the global scale.

It is assessed as Near Threatened for the EU 27 member states, because it is close to qualifying for Vulnerable under Criterion B (B2b(iii)).

This species inhabits river and lake systems in the western Balkans region, where its range extends from the Neretva River in Bosnia and Herzegovina and Croatia to the Bojana (sq. Bunë) River in Montenegro and Albania, including the Skadar (sq. Liqeni i Shkodrës; cnr. Skadarsko jezero), Ohrid (sq. Liqeni i Ohrit; mk. Охридско Езеро) and Prespa (sq. Liqeni i Prespës; mk. Преспанско Езеро; el. λίμνη Πρέσπα) lake basins.

In the Neretva River, it is present in the Buna, Bregava, Trebižat, Norin and Matica tributary rivers and associated wetlands, including Hutovo Blato in Bosnia and Herzegovina, and Prološko Blato and the Baćina Lakes in Croatia. An isolated subpopulation inhabits the Trebišnjica River system in Bosnia and Herzegovina, which partially drains to the Neretva via subterranean karstic conduits. It does not occur upstream of Mostar in Bosnia and Herzegovina.

In the Lake Skadar basin, it is present in the lake itself, the lower reaches of its tributaries including the Morača River, and the outflowing Bojana River. It has not been reported from the Drin (sq. Drini; mk. Дрим) River system, which connects lakes Ohrid and Skadar, but does enter some affluent streams in the Ohrid basin.

It occurs in both lakes comprising the Prespa basin (see 'Habitats and Ecology'), where field observations suggest that it rarely enters tributaries. There also exist a handful of recent records from the Devoll River, an upper tributary of the Seman River in Albania. However, it remains unclear whether these represent a natural subpopulation or are the result of artificial colonisation after the river was connected to the Prespa Lakes during the late 20^th century.

Its extent of occurrence is 28,297 km², and in the EU 27 region it is 15,721 km².

This species' population size is unknown, but is understood to exceed the minimum threshold for Red List criteria (< 10,000 mature individuals). The current population trend has not been quantified, and the number of subpopulations is unclear.

It reportedly remains abundant throughout much of its range, with the most recent (2017) appraisals of the Ohrid and Skadar stocks describing both to be in "good condition". Monitoring data indicate that it may be increasing in Lesser Prespa.

However, it is considered to be threatened in all countries for which a national Red List (or equivalent) assessment has been carried out (see 'Conservation'), and there is clear evidence that its global abundance has reduced since the mid-20^th century (see 'Threats').

This gergarious species inhabits shallow, slow-moving reaches of karstic streams and rivers, oligotrophic lakes, backwaters and artificial water bodies with abundant vegetation.

Some of its habitats in the Neretva River system, e.g., Hutovo Blato, experience seasonal flooding driven by natural increases in discharge.

The Drin River system is a major biodiversity hotspot, within which the oligotrophic and oligomictic lakes Ohrid and Skadar hold the largest stocks and are particularly significant in terms of endemic aquatic fauna.

Lake Ohrid is of tectonic origin, and with an age of c. 2-3 million years is considered to be the oldest extant lake in Europe. Its surface area is c. 358 km² and it has a maximum depth of c. 289 metres (average depth c. 164 metres). The lake receives almost 50% of its water from two main surface springs located at its southern end and numerous sub-lacustrine (underwater) springs along its eastern shoreline, all of which are fed by subterranean karstic conduits draining the adjacent Lake Prespa basin. There are a number of additional sub-lacustrine springs along the western side. There are also four perennial tributary rivers which drive small fluctuations of the lake’s surface level in late spring or following heavy rainfall. The lake drains towards the Adriatic Sea via the Black Drin (sq. Drini i Zi; mk. Црн Дрим) River, which originates at its northern tip, and it loses significant volumes of water (c. 40%) via evaporation. Ohrid is considered to be among the most diverse ancient lakes in the world in terms of endemic species richness.

Lake Skadar is the most extensive freshwater wetland in the Balkan region, with a surface area that seasonally fluctuates between c. 370 km² and c.530 km². It is situated in a tectonic karstic cryptodepression and is rather shallow, with an average depth of c. 5 metres and a maximum depth of c. 60 metres. The lake is fed by numerous sub-lacustrine karstic springs which are distributed around its periphery, and a series of affluent rivers of which the largest is the Morača. It drains to the Adriatic Sea via the short Bojana River, which also receives water from the Drin River and thus connects the system to Lake Ohrid. The precise origin of the lake remains unclear to an extent, but it is understood to have comprised a much larger wetland until c. 1,200 years ago. It is considerably more productive than Lake Ohrid in terms of fish biomass.

During the winter, this species aggregates in areas of these lakes influenced by sub-lacustrine springs, where the water temperature remains relatively constant throughout the year.

The Prespa Lakes basin lies at 850 metres AMSL and is a hotspot for endemic freshwater fishes and migratory birds. It comprises the relatively shallow Greater Prespa and Lesser Prespa lakes, which are separated by a narrow strip of alluvial land. The basin is fed solely by precipitation through runoff and snowmelt, but is connected to adjacent Lake Ohrid via subterranean karstic flows.

The Dalmatian Roach is a generalist omnivore and feeds on a range of algae, plankton and small invertebrates.

The maximum recorded lifespan is c. 10 years and sexual maturity is attained at age 2-3+.

This species is relatively sedentary and does not undertake extensive spawning migrations during the annual reproductive period, which in the Neretva River system extends from February to April with a peak in March, and in the Prespa Lakes from May to June.

It is a fractional, polygamous spawner. Individual females can produce up to 100,000 eggs per year, which are adhesive and deposited onto submerged vegetation and hard surfaces in littoral areas.

Some lacustrine subpopulations are important components in the diet of piscivorous birds including Dalmatian Pelican (Pelecanus crispus) and Pygmy Cormorant (Microcarbo pygmaeus).

This species is plausibly threatened by water abstraction, pollution from agricultural, domestic and industrial sources, altered hydrological regimes driven by barrier construction and introduction of non-native fish species.

For example, the Hutovo Blato wetland naturally floods on an annual basis, but the extent to which it does so has decreased significantly due to reduced flow caused by hydropower development on the affluent Čapljina spring and elsewhere in the Neretva River system. This has led to some areas becoming dewatered and an expansion of reedbeds, with a reduction in the extent and quality of foraging, spawning and nursery sites. A plan (ongoing as of late 2019) to divert significant volumes of water from Hutovo Blato for human use is also likely to have serious detrimental consequences for native fish populations.

Most rivers entering lakes Ohrid and Skadar flow through areas undergoing rapid urbanisation with insufficient water treatment systems. The lake ecosystems are thus threatened by discharge of anthropogenic nutrients, chemicals and sediment loads from a variety of sources, including untreated domestic sewage, industry and agriculture, which are driving increased rates of eutrophication and sedimentation with an array of proven negative impacts on the composition of plant and animal communities. The development of tourist facilities, increased boat traffic, and ongoing capture and pollution of karstic springs in the two basins are also of concern. Plastics and other solid wastes are regularly washed into the lakes because effective landfill sites are limited or do not meet modern standards.

In Lake Ohrid, excessive water abstraction and eutrophication in the neighbouring Prespa basin is believed to be partially responsible for increasing nutrient levels. Moreover, the Sateska River was in 1962 diverted from its former confluence with the Drin River into Lake Ohrid in order to improve the water balance of the lake and enhance its potential for hydropower generation, but has since become a major driver of biochemical oxygen demand and sedimentation.

Construction of hydropower dams on the adjacent Drin River have interfered with natural fluctuations in the water level of Lake Skadar. Proposals to construct a series of additional dams on the Morača River, which provides more than 60% of the lake's water, represent a plausible future threat. Native fish declines in the lake have been ongoing since the mid-20^th century. The lower portion of the Morača River system is polluted due to long-term discharge of agricultural and industrial contaminants, plus insufficiently-treated municipal wastewater from the city of Podgorica and other urban centres. As a result, the formerly oligotrophic lake has become increasingly eutrophic since the 1970s, leading to structural changes in the resident planktonic and zoobenthic communities. Overharvesting may constitute an additional threat, but this has not been extensively-studied.

The Prespa Lakes have been partially modified. They are connected by a man-made channel excavated through the alluvial isthmus which separates them, on which a controllable man-made sluice is installed and was reconstructed in 2004. In addition, a minor natural outflow from the Agios Germanos River delta to Lesser Prespa was blocked during the 1930s and has not been re-established, reducing the volume of water that flows into the lake. In Albania, Lesser Prespa was for a number of years artificially connected to the Devoll River via the so-called Prespa Canal Scheme in order to abstract water for irrigation purposes, but the project was abandoned and the canal filled in during the early 2000s after it failed to function as planned. During the period that the canal was open, sedimentation in the southern portion of Lesser Prespa increased drastically, leading to a pronounced reduction in water depth and expansion of reedbeds. Water abstraction for agricultural and domestic usage continues to take place throughout the basin, and has been cited as the central cause for the continued diminishing water level in Greater Prespa, which has receded by at least eight metres since the mid-20^th century. Climate change is also a primary driver, with a significant decrease in tributary discharge, winter precipitation and snowfall observed since the 1960s. The situation is so drastic that the sluice gate between the lakes has to be kept closed at all times in order to maintain the water level in Lesser Prespa, which is now located at a higher altitude than Greater Prespa and would otherwise drain into it. The reduction in water volume, coupled with an increase in nutrients, toxic substances and solid materials (including plastics) entering the lakes from surrounding farmland, industry (small-scale food processing, poultry farming, textiles, metal and wood processing, civil construction, ceramics and chemical production), illegal landfills, fly-tipping and untreated domestic wastewater has resulted in escalating eutrophication. This is particularly evident in Lesser Prespa, where blooms of toxic cyanobacteria now occur on a regular basis during the months of summer and autumn.

Non-native fish species established within the Dalmatian Roach's range include the Goldfish (Carassius auratus), Prussian Carp (Carassius gibelio), Common Carp (Cyprinus domestic strain), Eurasian Perch (Perca fluviatilis), Eurasian Pikeperch (Sander lucioperca), Pumpkinseed (Lepomis gibbosus), Brown Bullhead (Ameiurus nebulosus), Rainbow Trout (Oncorhynchus mykiss), Topmouth Gudgeon (Pseudorasbora parva) and European Bitterling (Rhodeus amarus), all of which are considered invasive and can exert detrimental pressures on native freshwater fauna through increased competition, predation, habitat degradation or transmission of pathogens.

In Bosnia and Herzegovina, this species is harvested as bycatch by artisanal fishers in the Hutovo Blato wetland, and is consumed raw or smoked by local communities.

It is a minor component of the Skadar and Ohrid commercial fisheries, which are dominated by native Skadar Bleak (Alburnus scoranza) and introduced Common Carp (Cyprinus domestic strain).

In the Prespa Lakes, it is harvested on a more intensive basis and sold to local restaurants or exported to regional wholesalers.

The total number of fishers in the Prespa basin has declined considerably since the late 20^th century, and most traditional landing methods were abandoned during the early 2000s. Models of fishing sustainability suggest that offtake has historically been reasonable, and does not currently constitute a threat.

This species is included (as Rutilus rubilio) in Appendix III of the Bern Convention and Annex II of the European Union Habitats Directive.

At the National Red List (or equivalent) scale, the Dalmatian Roach has most recently been assessed as Near Threatened in Croatia, Endangered in Bosnia and Herzegovina, Near Threatened in Montenegro and Vulnerable (as Rutilus prespensis) in Greece.

It is nationally-protected in Croatia (Law of Nature Protection No. 70/05 and 139/08), and regionally-protected in the Federation of Bosnia and Herzegovina.

It occurs within the boundaries of several protected areas of which some are included in the European Union's Natura 2000 network, e.g., Delta Neretve (site HR1000031), or Ramsar Convention on Wetlands of International Importance (e.g., Hutovo Blato, Neretva River Delta, Lake Skadar and the Buna River, Lake Ohrid and the Prespa Lakes). In addition, Hutovo Blato was in 1995 designated as an official Nature Park. The Montenegrin part of Lake Skadar was declared a National Park in 1983, while the Albanian portion has been officially protected since 2005.

The North Macedonian portion of Lake Ohrid has been included in UNESCO's list of World Heritage sites since 1979, while a bilateral agreement between Albania and North Macedonia resulted in establishment of the Ohrid Watershed Management Committee in 2004 and the Ohrid-Prespa Transboundary Biosphere Reserve in 2014. At the national level a number of additional protected sites have been created around the lake, including the Pogradec Aquatic and Terrestrial Protected Landscape and Drilon National Monument in Albania, and the Lake Ohrid Monument of Nature and Galicica National Park in North Macedonia.

The entire Prespa Lakes basin falls within the limits of the Prespa Park, the first transboundary protected area in the Balkan Peninsula, and the lakes are also surrounded by four National Parks.

There is a minimum-size limit for commercial fishers in the Albanian portions of lakes Ohrid and Skadar, and a weight-based limit throughout the the Prespa Lakes. Closed fishing seasons are established in both the Montenegrin and Albanian parts of Lake Skadar. No other species-specific conservation actions are in place, but it may have benefitted from broad-scale management activities in some areas.

For example in the Prespa Lakes, the Prespa Park Management Body controls the volume of water exiting Lesser Prespa to Greater Prespa by regulating the outflow discharge on the artificial channel connecting the two lakes. The environmental organisation 'Society for the Protection of Prespa' currently coordinates a transboundary environmental monitoring system within the Prespa basin, which includes tri-annual fish surveys.

The European Union co-funded LIFE project 'Prespa Waterbirds' (LIFE15 NAT/GR/000936) ran from 2016-2021 and aimed to contribute to waterbird conservation in Lesser Prespa via a series of actions, including a specific plan to improve "spawning grounds and access for fish species". Specific actions included the clearing of sediment and reedbeds from around the mouths of tributary streams to facilitate the passage of migratory fishes. An earlier LIFE project (LIFE2002 NAT/GR/8494) also targeting bird conservation took place from 2002-2007 and aimed to "increase fish spawning grounds", while the Global Environment Facility project 'Integrated Ecosystem Management in the Prespa Basin in Albania, FYROM and Greece' ran from 2006-2011.

Furthermore, a LIFE+ Information and Communication Project entitled 'Fish, Fisheries & European Policy' in the Prespa Basin (LIFE09 INF/GR/000319) was funded from 2010-2013 with the objective to "promote the conservation of the threatened endemic and rare fish fauna of the area and the implementation of sustainable fishery practices".

The introduction of non-native species to the Prespa Lakes has been outlawed, and strict annual catch limits are in place for the native fishes of commercial interest. Fishing of any kind is also forbidden during mid-to-late spring, when native fish species spawn. Fly-tipping, disposal or processing of any kind of waste, discharge of untreated waste water, shoreline construction, excavation of sand or gravel, unlicensed use of lake water, uncontrolled cutting of trees and forests, and inappropriate utilisation and burning of pastures have all been prohibited.

It is strongly recommended that clarification of this species' taxonomic status is treated as a research priority. For example, the Prespa Lakes subpopulation would probably qualify for a threatened category should it be recognised as a distinct taxon (see 'Taxonomic Notes).

Given that it is treated as nationally-threatened in at least four countries (see above), a re-evaluation of its population trend and response to the identified threats may also prove appropriate.