Research Article |
Corresponding author: András Attila Nagy ( nagyandrasattila@yahoo.com ) Academic editor: Maria Elina Bichuette
© 2023 András Attila Nagy, Nándor Erős, István Imecs, Gábor Bóné, Attila Fülöp, Péter László Pap.
This is an open access article distributed under the terms of the Creative Commons Attribution License (CC BY 4.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.
Citation:
Nagy AA, Erős N, Imecs I, Bóné G, Fülöp A, Pap PL (2023) Distribution and diversity of fishes and lampreys in Transylvania (Romania): a complete survey and suggestions for new protected areas. ZooKeys 1166: 351-373. https://doi.org/10.3897/zookeys.1166.102854
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Freshwater fishes are in a serious state of decline across the world, making them one of the most threatened groups of vertebrates. The Danube River catchment area in Europe holds the richest freshwater fish community, but our knowledge of the current distribution of these species is limited. Transylvania, the largest region of Romania, is one of the important tributaries of the Danube, from where 77 fish and two lamprey species were recorded until now. Despite this large diversity of freshwater fishes, there is a lack of systematic survey of the fish fauna in this region for the past 50 years. In this study, we present data on the occurrence and distribution of fishes and lampreys collected in Transylvania from 2007 to 2022. This data covers 43% of Romania’s surface and includes all major rivers from Transylvania. 65 species of fish and three species of lampreys are recorded, and an additional nine fish species are also reported based on information from competent people. Of the 77 fish and lamprey species recorded 19 (24.7%) are non-native, although their relative abundance was low (5.1%) compared to other similar regions in Europe. The first records of Eudontomyzon mariae, Neogobius melanostomus, Piaractus brachypomus, Pygocentrus nattereri, and Salvelinus alpinus in Transylvanian rivers are presented, as well as the first record of Cobitis elongata outside the Nera River basin (from the Caraș River) and the detection of three new populations of the vulnerable Umbra krameri. Data on changes in distribution that have occurred since the last comprehensive survey 50 years ago are also provided and the importance of our results in conservation planning are discussed, including the designation of new protected areas for freshwater bodies and the compilation of the Romanian Red List of fishes.
Conservation, fish distribution, freshwater ichthyofauna, Natura 2000, non-native species
Freshwater fishes make up 50% of all fish species (
Identification of biodiversity hotspots, areas with high concentrations of individuals, such as those used for reproduction, as well as of endemic species and the invasive species threatening native communities, is critical for actions aiming to reduce biodiversity loss (
The last comprehensive survey of the fish fauna of freshwater habitats in Romania, including Transylvania, dates back to 1964 (
Transylvania is the largest region of Romania, covering an area of 102,226 km2 (43% of Romania). It is bordered by the Carpathian Mountains in the north, east, and south, and by the Pannonian Plain in the west (see Fig.
In the past two centuries, river regulations have affected Transylvanian rivers, especially floodplains and marshes. The largest marsh, the Ecsed Moor, situated on the boundary between Romania and Hungary, was drained in the 19th century. Another important lowland floodplain, the Ier River valley, was also drained. Most of this land has been converted into agricultural land. After accession to the European Union in 2007, agriculture intensified significantly, with monocultures taking priority over small parcels of land, which probably have an effect on the fish communities of the rivers. Although there are relatively few large cities in the region, the numerous villages may pose an important source of pollution. The five largest cities in Transylvania are Cluj Napoca (with 286,598 inhabitants), Timișoara (250,849), Brașov (237,589), Oradea (183,105), and Arad (145,078) (2021 population census).
Data were collected between 31 March 2007 and 29 October 2022 from a total of 679 sampling sites, including all rivers and major tributaries in Transylvania (Fig.
We compiled the distribution maps of species using the data from our survey and information provided by anglers, angling associations, fish stocking projects, or the Facebook page “Ichthyology of Romania” (https://www.facebook.com/groups/ichthyologyofromania). From the sources other than our own capture data we only used data that were supported by documentary photographs so that the species could be accurately identified. Information obtained from these sources and additional personal occurrence data for four species (Cottus gobio, Eudontomyzon mariae, Sabanejewia romanica, Umbra krameri) is not included in the raw data of distribution (Suppl. material
The survey data stored in the OpenFishMaps database were exported to the R statistical environment (v. 4.2.2;
Between 2007 and 2022 we have identified 129,212 individuals belonging to a total of 68 species (65 fish and 3 lamprey species) (Table
The complete checklist of freshwater fish and lamprey species of Transylvania (Romania). The taxonomy follows the FishBase online database (
No. | Scientific name | Recorded until 1969 ( |
New species recorded between 1964 and 2022 | Present study | Origin | Natura 2000 protection | Observation |
---|---|---|---|---|---|---|---|
Petromyzontidae | |||||||
1 | Eudontomyzon danfordi Regan, 1911 | x | x | native | yes | ||
2 | Eudontomyzon mariae (Berg, 1931) | x | native | yes | |||
3 | Eudontomyzon vladykovi Oliva & Zanandrea, 1959 | x | x | native | yes | ||
Acipenseridae | |||||||
4 | Acipenser gueldenstaedtii Brandt & Ratzeburg, 1833 | x | native | no | |||
5 | Acipenser ruthenus Linnaeus, 1758 | x | x | native | no | ||
Anguillidae | |||||||
6 | Anguilla anguilla (Linnaeus, 1758) | x | native | no | |||
Cobitidae | |||||||
7 | Cobitis elongata Heckel & Kner, 1858 | x | x | native | yes | ||
8 | Cobitis elongatoides Băcescu & Maier, 1969 | x | x | native | yes | ||
9 | Misgurnus fossilis (Linnaeus, 1758) | x | x | native | yes | ||
10 | Sabanejewia sp. (incuding S. balcanica (Karaman, 1922) and S. bulgarica (Drensky, 1928)) | x |
x | native | yes | ||
11 | Sabanejewia romanica (Băcescu, 1943) | x | x | native | no | ||
Nemacheilidae | |||||||
12 | Barbatula barbatula (Linnaeus, 1758) | x | x | native | no | ||
Cyprinidae | |||||||
13 | Barbus barbus (Linnaeus, 1758) | x | x | native | no | ||
14 | Barbus balcanicus Kotlík, Tsigenopoulos, Ráb & Berrebi, 2002 | x All species were treated together as Barbus meridionalis petenyi by |
x ( |
x | native | yes | |
15 | Barbus biharicus Antal, László & Kotlík, 2016 | x ( |
x | native | yes | ||
16 | Barbus carpathicus Kotlík, Tsigenopoulos, Ráb & Berrebi, 2002 | x ( |
x | native | yes | ||
17 | Barbus petenyi Heckel, 1852 | x | native | yes | |||
18 | Carassius carassius (Linnaeus, 1758) | x | x | native | no | ||
19 | Carassius gibelio (Bloch, 1782) | x | x | non-native | no | ||
20 | Cyprinus carpio Linnaeus, 1758 | x | x | native | no | ||
Xenocyprididae | |||||||
21 | Ctenopharyngodon idella (Valenciennes, 1844) | x ( |
x | non-native | no | ||
22 | Hypophthalmichthys molitrix (Valenciennes, 1844) | x ( |
x | non-native | no | ||
23 | Hypophthalmichthys nobilis (Richardson, 1845) | x ( |
x | non-native | no | ||
Tincidae | |||||||
24 | Tinca tinca (Linnaeus, 1758) | x | x | native | no | ||
Acheilognathidae | |||||||
25 | Rhodeus amarus (Bloch, 1782) | x | x | native | yes | ||
Gobionidae | |||||||
26 | Gobio gobio sensu lato (Linnaeus, 1758) | x | x | native | no | The taxonomic position of stream dwelling gudgeons is still not clearly detailed (see |
|
27 | Gobio obtusirostris Valenciennes, 1842 | The species was treated as a subspecies of Gobio gobio by |
x ( |
x | native | no | |
28 | Pseudorasbora parva (Temminck & Schlegel, 1846) | x ( |
x | non-native | no | ||
29 | Romanogobio kesslerii (Dybowski, 1862) | x | x | native | yes | ||
30 | Romanogobio uranoscopus (Agassiz, 1828) | x | x | native | yes | ||
31 | Romanogobio vladykovi (Fang, 1943) | x | x | native | yes | ||
Leuciscidae | |||||||
32 | Abramis brama (Linnaeus, 1758) | x | x | native | no | ||
33 | Alburnoides bipunctatus (Bloch, 1782) | x | x | native | no | ||
34 | Alburnus alburnus (Linnaeus, 1758) | x | x | native | no | ||
35 | Ballerus ballerus (Linnaeus, 1758) | x | x | native | no | ||
36 | Ballerus sapa (Pallas, 1814) | x | x | native | no | ||
37 | Blicca bjoerkna (Linnaeus, 1758) | x | x | native | no | ||
38 | Chondrostoma nasus (Linnaeus, 1758) | x | x | native | no | ||
39 | Leucaspius delineatus (Heckel, 1843) | x | x | native | no | ||
40 | Leuciscus aspius (Linnaeus, 1758) | x | x | native | yes | ||
41 | Leuciscus idus (Linnaeus, 1758) | x | x | native | no | ||
42 | Leuciscus leuciscus (Linnaeus, 1758) | x | x | native | no | ||
43 | Pelecus cultratus (Linnaeus, 1758) | x | native | yes | |||
44 | Phoxinus phoxinus (Linnaeus, 1758) | x | x | native | no | ||
45 | Rutilus rutilus (Linnaeus, 1758) | x | x | native | no | ||
46 | Rutilus virgo (Heckel, 1852) | x | native | yes | |||
47 | Scardinius erythrophthalmus (Linnaeus, 1758) | x | x | native | no | ||
48 | Squalius cephalus (Linnaeus, 1758) | x | x | native | no | ||
49 | Telestes souffia (Risso, 1827) | x | x | native | yes | ||
50 | Vimba vimba (Linnaeus, 1758) | x | x | native | no | ||
Serrasalmidae | |||||||
51 | Piaractus brachypomus (Cuvier, 1818) | x | non-native | no | |||
52 | Pygocentrus nattereri Kner, 1858 | x | non-native | no | |||
Siluridae | |||||||
53 | Silurus glanis Linnaeus, 1758 | x | x | native | no | ||
Ictaluridae | |||||||
54 | Ameiurus melas (Rafinesque, 1820) | x ( |
x | non-native | no | ||
55 | Ameiurus nebulosus (Leseur, 1819) | x | x | non-native | no | ||
Esocidae | |||||||
56 | Esox lucius Linnaeus, 1758 | x | x | native | no | ||
Umbridae | |||||||
57 | Umbra krameri Walbaum, 1792 | x ( |
x | native | yes | ||
Salmonidae | |||||||
58 | Coregonus albula (Linnaeus, 1758) | x | x Coregonus. sp. | non-native | no | ||
59 | Coregonus lavaretus (Linnaeus, 1758) | x | non-native | no | |||
60 | Hucho hucho (Linnaeus, 1758) | x | x | native | yes | ||
61 | Oncorhynchus mykiss (Walbaum, 1792) | x | x | non-native | no | ||
62 | Salmo trutta Linnaeus, 1758 | x | x | native | no | ||
63 | Salvelinus alpinus (Linnaeus, 1758) | x | non-native | no | |||
64 | Salvelinus fontinalis (Mitchill, 1814) | x | x | non-native | no | ||
65 | Thymallus thymallus (Linnaeus, 1758) | x | x | native | no | ||
Lotidae | |||||||
66 | Lota lota (Linnaeus, 1758) | x | x | native | no | ||
Odontobutidae | |||||||
67 | Perccottus glenii Dybowski, 1877 | x ( |
x | non-native | no | ||
Gobiidae | |||||||
68 | Babka gymnotrachelus (Kessler, 1857) | x ( |
x | non-native | no | ||
69 | Neogobius fluviatilis (Pallas, 1814) | x ( |
x | non-native | no | ||
70 | Neogobius melanostomus (Pallas, 1814) | x | non-native | no | |||
71 | Proterorhinus semilunaris (Heckel, 1837) | x | x | non-native | no | ||
Poeciliidae | |||||||
72 | Gambusia affinis (Baird & Girard, 1853) | x | non-native | no | |||
73 | Poecilia reticulata Peters, 1859 | x ( |
non-native | no | |||
Centrarhidae | |||||||
74 | Lepomis gibbosus (Linnaeus, 1758) | x | x | non-native | no | ||
Percidae | |||||||
75 | Gymnocephalus baloni Holčic & Hensel, 1974 | x ( |
x | native | yes | ||
76 | Gymnocephalus cernua (Linnaeus, 1758) | x | x | native | no | ||
77 | Gymnocephalus schraetser (Linnaeus, 1758) | x | x | native | yes | ||
78 | Perca fluviatilis Linnaeus, 1758 | x | x | native | no | ||
79 | Sander lucioperca (Linnaeus, 1758) | x | x | native | no | ||
80 | Sander volgensis (Gmelin, 1789) | x ( |
x | native | no | ||
81 | Zingel streber (Siebold, 1863) | x | x | native | yes | ||
82 | Zingel zingel (Linnaeus, 1766) | x | x | native | yes | ||
Cottidae | |||||||
83 | Cottus gobio Linnaeus, 1758 | x | x | native | yes | ||
84 | Cottus poecilopus Heckel, 1837 | x | x | native | no |
Species with the highest number of occurrences in our sampling sites were the Squalius cephalus (present in 56.6% of the sampling sites), Alburnoides bipunctatus (51%), Gobio gobio sensu lato (39.3%), Sabanejewia sp. (including S. balcanica and S. bulgarica) (37.8%) and the Rhodeus amarus (37.7%). Species with the highest number of individuals captured were the Alburnoides bipunctatus (16.8% of all individuals), Squalius cephalus (10.5%), Barbus petenyi (9.8%), Rhodeus amarus (7.8%) and the Alburnus alburnus (5.6%). The following species had the lowest occurrence: Ameiurus nebulosus (captured at one site), Eudontomyzon vladykovi (1), Hypophthalmichthys nobilis (1), Babka gymnotrachelus (2), Eudontomyzon mariae (2), Gymnocephalus baloni (2), Hypophthalmichthys molitrix (2), Leuciscus idus (2), Ctenopharyngodon idella (3) and Gymnocephalus cernua (3), while the 10 least abundant species were the Ameiurus nebulosus (one individual), Eudontomyzon mariae (4), Gymnocephalus baloni (4), Perccottus glenii (5), Hypophthalmichthys nobilis (5), Babka gymnotrachelus (7), Leuciscus idus (8), Hucho hucho (10), Gymnocephalus cernua (13) and Lota lota (14).
Four fish species caught by fishermen are reported for the first time from Transylvanian natural waters: Neogobius melanostomus, Pygocentrus nattereri, Salvelinus alpinus (all three species caught in 2022) and Piaractus brachypomus (caught in 2020 and 2021). Eudontomyzon mariae is recorded for the first time from Transylvanian waters, and Cobitis elongata is recorded for the first time in Transylvania (in the Caraș River), out of its exclusive occurence in the Nera River basin. We found three new populations of the vulnerable Umbra krameri.
The number of fish and lamprey species was the highest (33–40 species; Fig.
The highest number of Natura 2000 species (10–12 Natura 2000 species) were located mainly in lowland areas, but not exclusively: E515N255 (in the lower Timiș-Bega River basin, 12 species), E540N275 (in the upper Mureș River basin, 12 spp), E525N280 (in the lower Someș River basin, 12 spp), E530N285 (Tisa River basin, 11 spp), E530N280 (in the lower Someș River basin, 11 spp), E540N270 (in the upper Mureș River basin, 11 spp), E520N265, E525N265 (in the Crișuri River Basin, 10 spp), E535N265 (middle Mureș River basin, 10 spp) and E545N275 (upper Mureș River basin, 10), (Fig.
The highest number of native species was found in lowland areas (E525N280 in the lower Someș River basin, 32 species) and in one grid cell from the hilly-mountainous area (E540N275 upper Mureș River basin, 31 spp) (Fig.
The abundance of non-native species was overall low (5.1%). The grid cell with the highest number of non-native species (7) was found in the lowland, in the lower Timiș-Bega River basins (E515N255), while the least invaded areas were found in mountainous areas (Fig.
Out of our survey, a total of 77 species of fish and 2 species of lampreys have been recorded in Transylvanian rivers until now (Table
Out of the 77 identified species recorded during our survey, 19 (24.7%) are introduced, while 24 (31.2%) species belong to Natura 2000 species. Of the total of 129,212 captures, 6,553 individuals (5.1%) belong to non-native species, and 46,497 individuals (36%) belong to Natura 2000 species. Overall, the abundance of non-native species in our study region can be considered relatively low. For example, in Hungarian waters, 28.8% of identified species and 18.3% of total captures are non-native (
Comparing our data with those collected during the last comprehensive survey by
Carassius carassius was prevalent in most floodplains in the past (i.e., before 1964) but has now vanished from most of its former habitats (Suppl. material
Our data indicates that the distribution range of Zingel zingel has decreased, as the species has disappeared from the Someșul Mare, Someșul Mic, Crișul Repede, Olt Rivers and the middle part of the Mureș River. We found viable populations of the species in the Someș, Crișul Negru, Crișul Alb, Mureș, and Timiș Rivers, and a very fragile population in the Bega River (Suppl. material
We have observed a drastic reduction in the distribution of Gymnocephalus schraetser, as this species was not identified during our surveys, except a few records from other verified sources, although it was found in several rivers (Mureș, Crișul Repede, Crișul Negru, Crișul Alb Rivers) in the 1990s (
Umbra krameri has disappeared from most of its known habitats, particularly from the Ier River valley and from the Carei Plane in north-west Transylvania. In a survey, the species was found only in two out of 13 sites where the species was formerly recorded (
The presence of Romanogobio vladykovi has increased as a result of human activities in the Tisa River basin (
Hucho hucho has returned to the upper Mureș River basin due to stocking (
Although the method used in our study was moderately suitable for assessing Cyprinus carpio populations, our data indicates a massive decline of the species (Suppl. material
Eudontomyzon mariae is reported for the first time in Transylvanian waters and is present in the Olt River basin (Suppl. material
Three species, Babka gymnotrachelus, Neogobius fluviatilis, and Perccottus glenii, have recently appeared in Transylvania (
Pseudorasbora parva, a non-native species, was not present in Transylvania before 1964, but we found it in almost all river basins and at 19.9% of the sampling sites (Suppl. material
Many of the Natura 2000 sites from Transylvania have been designated predominantly in mountainous areas to enhance the protection of Natura 2000 fish species, although only a few of these species occur there (as seen in E530N255 and E535N255). However, important river sectors in hilly and lowland areas, which have a high number of Natura 2000 fish and lamprey species, remain unprotected (such as parts of the Crișul Alb River from E520N265, the Bega and Bega Veche River from E515N255, the lower part of the Niraj River from E540N270, and important sectors of the Someș River and the middle and lower part of the Lăpuș River at E530N280). These hilly and lowland river sectors require protection as they are vulnerable to anthropogenic disturbances, particularly due to river regulation. These areas are home to most of the native and Natura 2000 species (Figs
River sections from Transylvania, Romania, proposed for protection and reasoning for designation. The ROSCI codes define the current Natura 2000 sites.
Proposed SCI | Reasoning for designation | Natura 2000 species for which protection is recommended | Description |
---|---|---|---|
Timișul Mort River | The largest Umbra krameri population from Transylvania, according to our present knowledge | Umbra krameri | From Pădureni to Macedonia (the whole sector of the Timișul Mort River and its floodplain that is not included currently in ROSCI0109 and ROSCI0348) |
Homorodul Vechi River | The last and only known Umbra krameri population from the Crasna River basin | Umbra krameri | The whole Homorodul Vechi River and its floodplain (between Cionchești and confluence with the Crasna River) |
Lăpuș River | One of the best preserved highland river sector with high fish diversity | Romanogobio vladykovi, Romanogobio uranoscopus, Romanogobio kesslerii, Rhodeus amarus, Barbus carpathicus, Cobitis elongatoides, Sabanejewia balcanica | From ROSCI0030 to the confluence with the Săsar River. |
Someș River between Dej and Tămaia | High species diversity | Romanogobio vladykovi, Romanogobio uranoscopus, Romanogobio kesslerii, Rhodeus amarus, Barbus carpathicus, Cobitis elongatoides, Sabanejewia balcanica, Zingel streber | From Dej to Tămaia, excluding the two short sections which are already Natura 2000 SCI (ROSCI0314 and ROSCI0435). |
Upper basin of the Barcău River | High species diversity. The only known Transylvanian population of the Salmo trutta characterized with the phenotype of missing red spots. | Eudontomyzon danfordi, Romanogobio kesslerii, Rhodeus amarus, Sabanejewia balcanica, Cottus gobio | Barcău River and its tributaries (Iaz, Valea Mare, Drighiu) from the ROSCI0322 to Marca locality |
The middle sector of the Timiș River, between Prisaca and Lugoj | High species diversity | Romanogobio uranoscopus, Romanogobio kesslerii, Rhodeus amarus, Barbus petenyi, Sabanejewia balcanica, Cobitis elongatoides | Between Prisaca and Lugoj |
Upper and middle sector of the Bega River | High species diversity. One of the few rivers from Transylvania where Eudontomyzon vladykovi still have stronghold populations | Eudontomyzon vladykovi, Leuciscus aspius, Romanogobio vladykovi, Romanogobio uranoscopus, Romanogobio kesslerii, Rhodeus amarus, Barbus petenyi, Sabanejewia balcanica, Cobitis elongatoides, Misgurnus fossilis, Zingel zingel | Between Luncanii de Jos and Timișoara |
Bega Veche River | Natural lowland river habitat | Misgurnus fossilis, Rhodeus amarus | Between Săcălaz and the Romanian-Serbian national border |
Upper Crișul Negru River | High species diversity | Romanogobio vladykovi, Romanogobio uranoscopus, Romanogobio kesslerii, Rhodeus amarus, Barbus biharicus, Sabanejewia balcanica, Cobitis elongatoides | Between Ștei and Uilacu de Beiuș |
Crișul Alb River | High species diversity | Romanogobio vladykovi, Romanogobio kesslerii, Rhodeus amarus, Leuciscus aspius, Sabanejewia balcanica, Sabanejewia bulgarica, Cobitis elongatoides, Zingel streber, Zingel zingel | Between Ineu and Chișineu Criș. |
Mureș River Between Aiud and Mintia | High species diversity | Romanogobio vladykovi, Romanogobio uranoscopus, Romanogobio kesslerii, Rhodeus amarus, Barbus petenyi, Sabanejewia balcanica, Cobitis elongatoides, Zingel streber | Mureș River between Aiud and Mintia, except ROSCI0419 |
Niraj River | High species diversity | Eudontomyzon danfordi, Romanogobio vladykovi, Romanogobio kesslerii, Rhodeus amarus, Barbus petenyi, Sabanejewia balcanica, Cobitis elongatoides | From Eremitu to the confluence with the Mureș River |
Considering that Romania does not currently have an officially adopted Red List for fish and lamprey species, our results can contribute to the creation of such a list. Some species, although not listed as Natura 2000 species, are of prime conservation concern due to drastic reductions in their distribution (e.g., Carassius carassius, Leucaspius delineatus, Lota lota, Tinca tinca) or diminished abundance (Thymallus thymallus) in recent decades. It is crucial to assess their current conservation status to ensure their long-term survival. Many environmental impact assessments are hindered by a lack of up-to-date data on fish fauna, and often rely on assessments that are not appropriate for studying fish communities. Our data can provide valuable information for these conservation studies.
The species pool and distribution of some species in the study area is likely greater than what our survey shows due to several reasons. Firstly, we mainly sampled rivers and several species that were recorded in the past or are present in neighboring countries are expected to occur in the area, especially in stagnant or enclosed water bodies. Although we did sample a few backwaters to gather data on species that inhabit stagnant waters and are threatened by habitat loss (e.g., Carassius carassius, Leucaspius delineatus, Umbra krameri), a comprehensive survey of these habitats was not conducted. Additionally, the fish fauna of thermal springs and lakes was excluded from the study, despite of some of these habitats are known to host exotic fish populations (
Our study provides the most comprehensive and up-to-date data on the ichthyofauna of Transylvanian rivers in the last 50 years. Compared to the historically recorded 77 species of fish and two species of lampreys, we identified 74 fish and three lamprey species. The discovery of one lamprey and four new fish species for Transylvania (Eudontomyzon mariae, Neogobius melanostomus, Piaractus brachypomus, Pygocentrus nattereri and Salvelinus alpinus) and new populations of several rare species (Cobitis elongata, Sander volgensis, Umbra krameri) highlights the need for further ichthyological research. There is also a need for a similar systematic assessment of the ichthyofauna of standing waters and ponds. Despite the negative impact of human activities on rivers in recent decades, these water bodies still hold a rich fish community that should be protected through designation of new protected areas as part of the Natura 2000 network. Urgent conservation measures are needed to ensure the long-term survival of non-Natura 2000 fish species, particularly those that have suffered significant range reductions. Anthropogenic pressure on fish populations is increasing, making necessary immediate conservation action in order to protect the diverse Transylvanian freshwater fish and lamprey populations.
We are grateful to many colleagues who faithfully helped us during fieldwork: Ferenc Alpár Gothárd, Zsolt Hegyeli, Antal Levente Kapás, Alpár Kelemen, István Sándor Komáromi, Attila Kovács, Zoltán Sallai, Ervin Szegedi, Miklós Zsigmond and many others. Data provided by Andrei Togor greatly complemented our distribution maps. People who contributed with own data are Mihai Caltea, Daniel Cocan, Levente Farkas, Călin Latiu, Adrian Maxim, George Cătălin Muntean, Tudor Papuc, Marius Poenariu, Romeo Stoicescu. Zoltán Benkő greatly helped us in spatial analyses. Vasile Oțel kindly helped us with critical feedback on Table
No conflict of interest was declared.
No ethical statement was reported.
No funding was reported.
The study was designed by AAN and PLP. AAN, II collected data from the field investigations, NE, GB and AF analyzed the data. AAN and PLP wrote the manuscript with critical feedback from all co-authors. All authors gave final approval for publication and agreed to be accountable for the aspects of work that they conducted.
Nándor Erős https://orcid.org/0000-0001-8921-482X
Attila Fülöp https://orcid.org/0000-0001-5337-336X
Péter László Pap https://orcid.org/0000-0002-3659-7684
All of the data that support the findings of this study are available in the main text or Supplementary Information.
Raw data of sampling sites, fish and lamprey species and their numbers
Data type: occurrences (excel file)
Maps S1–S77
Data type: occurrences (pdf file)
Explanation note: Distribution maps of fish and lamprey species in Transylvania, Romania.