Molecular evidence suggests that this species is very closely-related to the Italian congeners Scardinius hesperidicus and S. scardafa, and additional systematic research is recommended (Geiger et al. 2014).

Global and European regional assessment: Near Threatened (NT)
EU 27 regional assessment: Vulnerable (VU°)

The Neretva Rudd is endemic to the Neretva River system in the Dinaric Karst region of southern Croatia and Bosnia and Herzegovina. It has a restricted range (extent of occurrence (EOO) c. 3504 km²), which meets the threshold for the Endangered category under Criterion B1 (EOO < 5,000 km²). The extent and quality of habitat are estimated to be declining due to river regulation and anthropogenic degradation, 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 species is assessed as Near Threatened at the global and European regional scales, because it is close to qualifying for Endangered under Criterion B.

In the EU 27 member states, the EOO is c. 1,254 km² and it is present at five threat-defined locations where the quality of habitat is estimated to be declining. However, these sites are linked to a transboundary river system which is understood to be inhabited by the largest extant stock, therefore its assessment is downlisted by one category from Endangered to Vulnerable under Criterion B (B1ab(iii)).

This species is endemic to the Neretva River system in the Dinaric Karst region of southern Croatia and Bosnia and Herzegovina.

It is present in the Neretva main stem and tributaries from the river's delta upstream to the affluent Buna River, including the Baćina and Kuti lake basins, Vrgorsko polje (Vrgorska Matica River), the Crna Rijeka, Norin, Trebižat, Bregava and Krupa rivers, and Hutovo Blato wetland. Some areas within this range, e.g., Imotsko polje in the upper catchment of the sinking Trebižat River, Vrgorsko polje, and the Baćina Lakes, have no surface connection to the Neretva, but are linked by subterranean karstic conduits.

It may have formerly occurred further upstream in the Neretva, prior to damming of the river's middle reaches (see 'Threats').

This species' current population size and trend have not been quantified, and the number of subpopulations is unknown. It is locally abundant in some areas, e.g., in Hutovo Blato it is estimated to comprise c. 3.5% of total fish abundance.

This benthopelagic species naturally inhabits spring-fed karstic river systems, lakes and associated temporal wetlands characterised by complex surface-groundwater hydrological interactions and seasonal fluctuations in discharge. It demonstrates a preference for lentic conditions, and often occurs in areas with dense aquatic vegetation, with adults tending to inhabit deeper and more open water. Field observations indicate that it is somewhat eurytopic and able to withstand a relatively wide range of water temperatures, oxygen concentrations and salinities, although it may be sensitive to increasing nutrient loads. It inhabits some channelised river stretches and drainage canals, and enters brackish water in the lower Neretva River.

A number of its habitats naturally flood on an annual basis, providing spawning and nursery zones for resident fishes. In the Hutovo Blato wetland, Bosnia and Herzegovina, it tends to be most abundant in smaller lakes such as Drijen Vrelo which are not dominated by non-native fish species (see 'Threats'), while smaller individuals are often observed in the cold karstic springs which feed the system.

It is omnivorous and feeds primarily on benthic invertebrates and plant material.

The maximum recorded age is 10 years, and adult individuals reportedly mature at age 3-4+. The annual reproductive period extends from spring to early summer, e.g., from March to June in Hutovo Blato. It is a fractional, polygamous spawner, and the eggs are deposited among submerged vegetation.

This species is plausibly threatened by river regulation and other forms of anthropogenic habitat degradation.

In particular, construction of four large hydroelectric dams along the middle section of the Neretva River main stem since the 1950s has altered natural flow and sedimentation regimes, blocked possible migration routes and markedly reduced the extent and quality of habitat for all life stages. The scale of annual flooding in the Hutovo Blato wetland has declined significantly due to reduced discharge of the Neretva and some affluent springs such as Čapljina, which is also exploited for hydropower generation. The southern part of the wetland was partially impounded in 1979, and a proposed plan to divert water from Hutovo Blato for domestic use may further reduce habitat quality. The Dalmatian Nase now regularly fails to spawn in the majority of springs around Hutovo Blato, but is observed to return in years when spring flooding conditions resemble the former natural situation.

Hydroelectric dams also create unnatural fluctuations in discharge and water temperature (hydropeaking and thermopeaking) which bring about artificial dewatering of downstream river stretches and loss of stable nursery habitat for juveniles. Furthermore, the combined effect of hydropeaking, dam flushing operations and changes in land use is likely to have increased accumulation of fine sediments and negatively impacted foraging and reproductive success at some locations. The proposed construction of around 70 additional hydroelectric projects in the upper reaches of the river, plus an ongoing expansion scheme in the adjacent Trebišnjica River catchment (see below) together represent a plausible future threat to the entire Neretva ecosystem.

The extent and quality of habitat in the Neretva catchment has been further diminished by bank stabilisation, channelisation and other efforts to enhance flood protection or exploit water resources for irrigated agriculture. In the river's delta, only three of its original twelve branches remain and most former marshes and lakes have been reclaimed for agriculture since the 1960s.

Diffuse and point source agricultural, domestic and industrial pollution has resulted in eutrophication or discharge of toxic substances at some locations. For example, a number of springs in the Hutovo Blato basin are typically clogged with macrophytes due to increased nutrient loads caused by runoff from surrounding agricultural land. This has not only reduced the flow required for successful spawning, but decreased dissolved oxygen as plant material decomposes. Elsewhere, Vrgorsko polje is almost entirely turned over to agriculture, and the Vrgorska Matica River is heavily impacted by eutrophication and water abstraction. The extent of natural flooding has been markedly reduced by agricultural activities in Imotsko and Ljubuško poljes (Trebižat River catchment) and the Neretva delta, which in the latter has also led to saltwater intrusion.

The industrial extraction of riverine gravel and other sediments for urban development has taken place in the Neretva main stem since the 1970s, and has led to the artificial deepening of some stretches while hampering the transport of heavy sediments.

A number of non-native fish species that are documented to exert negative effects on native ichthyofauna through predation, resource competition, habitat degradation or transmission of pathogens are established within this species' range, including Eurasian Pikeperch (Sander lucioperca), Pumpkinseed (Lepomis gibbosus), Largemouth Bass (Micropterus salmoides), Eurasian Ruffe (Gymnocephalus cernua), Prussian Carp (Carassius gibelio), Common Carp (Cyprinus domestic strain), Topmouth Gudgeon (Pseudorasbora parva), Brown Bullhead (Ameiurus nebulosus) and Rainbow Trout (Oncorhynchus mykiss).

Future threats involve the channelling and pumping of water from isolated poljes (karstic plateaus) draining to the Buna and Bregava rivers in the lower Neretva catchment to an accumulation reservoir in the Trebišnjica River, within the framework of the ongoing (2023) "Upper Horizons" hydropower strategy. Once complete, the scheme is projected to significantly reduce discharge in the lower Neretva, with a range of negative impacts on Hutovo Blato and the river's delta region.

This species is not generally used or traded, although larger individuals are sometimes harvested for food by local fishers.

This species is present within the boundaries of several protected areas, some of which are included in the European Union's Natura 2000 network. The Neretva Delta and Hutovo Blato are included in the Ramsar Convention on Wetlands (sites 585 and 1105, respectively). A new, ostensibly more sustainable, management policy was implemented in the Hutovo Blato basin following a European Union co-funded LIFE project which ran from 2000-2002.

The proposed hydropower developments in the Neretva and Trebišnjica rivers have been opposed by local communities and several NGOs, leading to the publication of various news articles, reports, research projects and dissemination events, e.g., Neretva Science Week (July 2022).

A deeper understanding of this species' population trend, abundance, distribution and life history would likely prove useful in the establishment of future management efforts.