THE FISH FAUNA OF THE IZA RIVER, MARAMURES (ROMANIA)

Trav. Mus. natl. Hist. nat. sgrigore Antipas Vol. XXXVII pp. 205-212 1997 THE FISH FAUNA OF THE IZA RIVER, MARAMURES (ROMANIA) PETRE BACALU Les poissons captures dans les 12 stations de prtltvement le long de la rivikre Iza caracthisent des secteurs distincts de 1'Ccosystkme lotique. Leur presence a kt6 corr61ce avec les caractkristiques du lit de la rivikre. Les observations directes, sous-aquatiques, complttent les donnees de biologie. The Iza river represents a zone scarcely investigated as concerning the fish fauna. The first anterior contribution based on collected material is that of Bgngrescu (1953) who is mentioning 7 species from the station Sighetu Marmafiei: Leuciscus cephalus, Barbus barbus, Gobio gobio, Alburnus alburnus, Rhodeus sericeus amarus, Perca fluviatilis, Zingel streber. Bere$ (1990) is giving a list of 31 fish species, not only from Iza, but from all the Maramure~ aquatic ecosystems. During the faunistical captures made in 1995 by a team of researchers of the "Grigore Antipa" National Museum of Natural History in Maramure~, there were also collected some fishes, too. This note representes the first methodical investigation, from the spring till the river mouth, dedicated exclusively to the Iza. The faunistical list which resulted for the year 1995 will be completed by later captures. The presence of some other species we did not capture is certain, especially in the zone of the lower course, where many species of the Tisa river are penetrating. The most notable absence from our samples is that of Leuciscus souffia agasizi, which is surely present at the station Sighetu Marmafiei (Bere~, personally communication). MATERIAL AND METHOD The collected material contains a number of specimens, belonging to the 13 fish species. The captures were made with a net of a 6 m with a height of 1.5 m and with net-eyes of 2 mm, handled by two persons. There

206 PETRE BACALU were also used two hand-nets. The selectivity of the samples may be considered as a mean one, permitting some conclusions regarding the abundance of some species in the various sectors of the river. Simultaneously with the fishing there were made under-water watches regarding the behaviour of some species. The captures were made during the period 3-10 July 1995. There were made 12 stations, in 10 of them the fishing being effective (in the first two stations, near the spring, the fishing had no results). These stations are, from upstream to downstream: (the number of the stations are in accordance with the numbers + general gatherings). 1. #I0 Iza r., Izvorul Albastru a1 Izei (500 downstream), 6.VII.1995. 2. #11 Iza r., 2 km downstream spring, 6.VII.1995. 3. # 1 Iza r., upstream, Sgcel, 3.VII. 1995. 4. # 2 Iza r., downstream Sgcel, 3.VII.1995. 5. # 4 Iza r., 1 km dowstream Silli~tea de Sus, 3.VII.1995. 6. # 5 Iza r., Bogdan Vod5,4.VII.1995. 7. # 6 Iza r., between Rozavlea and StrAmtura, 4.VII.1995. 8. # 7 Iza r., downstream StrAmtura, 5.VII.1995. 9. # 8 Iza r., downstream BArsana, 5.VII.1995. 10. # 9 Iza r., Onceqti, 5.VII.1995. 11. #13 Iza r., downstream Once~ti, 10.VII.1995. 12. #12 Iza r., downstream the confluence with Mara, at the entry in Sighet, 9.VII.1995. The captured specimens were fixed in solution of formaldehyde 7-8% then removed in alcohol 70%. The material is gathered in the scientific collection of the "Grigore Antipa" National Museum of Natural History. RESULTS AND DISCUSSIONS The description of each station is concerning strictly the about 100 m where the captures were made. (1) #lo, 500 m downstream Izvorul Albastru a1 Izei. Maximum breadth 3 m; maximum depth 50 cm; stream extremely fast, very cold water, strong oxygenation and perfect water clarity. The bottom is stony, here and there with great boulders out of water aforested banks. The fishing was not successfull, a normal result having in mind the small distance from the spring (about 500 m). (2) #11,2 km downstream spring.

THE FISH FAUNA OF THE IZA RIVER (ROMANIA) 207 Maximum breadth 4 m, maximum depth 1 m. Very fast stream, cold water, strongly oxygenated, clear water. The bottom stony, many artificial thresh-holds for water oxygenation in favour of the trouts, aforested banks. Although the fishing was not successfull, the presence of the trout (Salrno trutta fario) and of the Cottus poecilopus is certain (information from natives). (3) #I, upstream Siicel. Maximum breadth 5 m, maximum depth 1 m. Stream slower as to the previous station, cold water, oxygenated and clear, gravellous bottom, stony in some place. Banks with groups of trees and free sections. Results of the fishing: 2 specimens Cottus poecilopus, captured with the hand-net. (4) #2,1 km downstream Siicel. Maximum breadth 7 m, maximum depth 1.5 m. Although the stream is fast, there appear the first sections with slow water; cold water, oxygenated, clear. Gravellous bottom. Banks with groups of trees and arbusts or free on extended sections. Results of the fishing: 5 specimens of Phoxinus phoxinus and 2 of Barbus peloponnesius petenyi. While the specimens of Phoxinus were captured in the stream, the Barbus peloponnesius petenyi ones were captures in slow water, where the river made a curb, near the bank, in a zone with gross detritic remains. (5) #4,1 km downstream Sgli~tea de Sus. Maximum breadth 8 m; maximum depth 1.5 m. Uniform stream relatively fast, without sections of slow water; cold, oxygenated and clear water. Gravellous bottom, large zones of gravel non-convered by water if the level of the river is not growing. Banks free or with rare trees and arbusts. Results of the fishing: 3 speicmens Phoxinus phoxinus, 1 of Barbus peloponnesius petenyi, 1 of Alburnoides bipunctatus, 1 of Orthrias barbatulus, 2 of Sabanejewia aurata. All the specimens were captured in the fast stream. (6) #5, Bogdan Vodii. Maximum breadth roughly 15 m, maximum depth 2 m. Mosaic of biotopes; great breadth and small depth of the river, fast stream; small breadth and great depth, fast stream; curb with still water and small depth. Clear and clean water, well oxygenated. Grevellous bottom, grassy banks with isolated trees. Results of the fishing: 53 specimens of Phoxinus phoxinus, 21 of Alburnoides bipunctatus, 1 of Alburnus alburnus.

208 PETRE BACALU All specimens were captured in fast stream. Beginning with this station and till the last one (#12), Alburnoides will be present in great number. (7) #6, between Rozavlea and Strimtura. Maximum breadth roughly 15 m, maximum depth 1.5 m. The fast stream is dominant, the water clear, oxygenated. Grevellous bottom, large zones of gravel non-covered by water. Grassy banks. Results of the fishing: 34 specimens of Phoxinus phoxinus, 2 of Barbus peloponnesius petenyi, 30 of Alburnoides bipuncta tus, 9 of Sabanejewia aurata, 1 of Leuciscus cephalus, 2 of Gobio gobio, 1 of Barbus barbus. All speimens were captured in fast stream. Although the river is conserving its aspect of mountain river till the mouth, this station is the last one where Phoxinus was captured in great number. At the same time it is the first station where Barbus barbus appears, being less rheophyl then Barbus peloponnesius petenyi. (8) #7, downstream Striimtura. Maximum breadth 15 m, maximum depth 2 m. Very fast stream, cold and muddy water (after a rain). Gravellous bottom, large zones of gravel non-covered by water, grassy banks with arbusts. Results of the fishing: 1 specimen Barbus peloponnesius petenyi, 26 of Alburnoides bipunctatus, 3 of Sabanejewia aurata, 3 of Gobio uranoscop us. The capture of Gobio unaroscopus was made possible by high and muddy water after a rain. Although Gobio uranoscopus is the most rheophyl species of Gobio and is surely present also upstream of this station, it was captured here only due to favorable conditions. (9) #8, downstream Biirsana. Maximum breadth 20 m, maximum depth 2 m. Fast stream, cold and muddy water (after a rain), roughly gravellous bottom. Zones of gravel non-covered by water, bank with groups of trees. Results of the fishing: 1 specimen of Barbus peloponnesius petenyi, 10 of Alburnoides bipunctatus, 5 of Sabanejewia aurata, 17 of Alburnus alburnus, 2 of Gobio uranoscopus. (10) #9, Once~ti. Maximum breadth 15 m, maximum depth 2 m. Fast stream, cold and muddy water (after a rain). In a deep zone near the bank, very slow water. Gravellous bottom, there appear the first sandy sections. One of the banks with rare trees, the other one more dyked. Results of the fishing: 50 specimens of Alburnoides bipunctatus, 1 of Sabanejewia aurata balcanica, 2 of Alburn us alburnus, 2 of Leuciscus cephalus, 1 of Barbus barbus, 7 of Gobio uranoscopus, 1 of Cobitis taenia.

THE FISH FAUNA OF THE IZA RIVER (ROMANIA) 209 From the fishes, only Barbus and Leuciscus were captured in the deep zone near the bank, all the other species being captured in the fast stream. (11) #13, downstream Once~ti. Maximum breadth 25 m, maximum depth 1 m. Temperate stream, water appreciably warmer than to the other stations (large sections with smaller depth made easy the warming up of the water). Bottom with fine gravel, little sandy zones. Uncovered banks, with very rare arbusts. Results of the fishing: 1 specimen of Phoxinus phoxinus, 11 of Alburnoides bipunctatus, 4 of Alburn us alburn us, 1 of Gobio uranoswpus. (12) #12 downstream the confluence with Mara, at the entry in Sighet. Maximum breadth 40 m, maximum depth 1.5 m, temperate stream, limited zones with fast stream, water temperature like in the precedent station, clear water. Gravellous bottom, sandy zones, other ones with mud. Uncovered banks with isolated trees. Results of the fishing: 1 specimen Phoxinus phoxinus, 15 of Alburnoides bipunctatus, 1 of Sabanejewia aurata, 2 of Alburnus alburnus, 2 of Barbus barbus, 1 of Rhodeus sericeus amarus. The river has here, near its mouth, a distinct aspect, with the riverbed much wider here and there and greater depth, alternating with extended zones with a fast stream and small depth (10-15 cm). Precisely at the fishing point there is a dead river branch, with very warm water and muddy bottom. The presence of Phoxinus phoxinus at this floor (including the precedent station) is remarkable, this fact prooving the mountainous and submountainous character retained by the Iza till its mouth. At the same time there appear also some of the species which characterize the lower course of the rivers: Rhodeus sericeus amarus, Barbus barbus, Alburnus alburnus. The collecting data for all stations are cumulated in table 1. Any fishing, even an experimental one, is subject to the influence of aleatory factors. The maximum abundance in the case of species with larger populations: Phoxinus phoxinus and Alburnoides bipunctatus, correspond to the floors of the rivers where the characteristic biotopes of the concerned species are dominant. In this case the selectivity of the samples may be considered as acceptable. The general trend of the last decades is the moving towards upstream of the fishes populations. It seems that Iza is not an exception (there is information from the natives regarding the presence of Silurusglanis till the station #7). However, the image we received was a different one. As much from the fish fauna diversity, as from the relative abundance of the fish populations there results the pronounced mountain character of this river, a character that keeps till its mouth. The species we collected where almost entirely species with a high degree of rheophily.

210 PETRE BACALU Cottus poecilopus poecilopus deserves a special attention, because it is present in Romania only in the Maramureq rivers, in the mountain tributaries of the rivers Siret, Moldova and Bistrifa moldoveneascii. The distribution area of this subspecies includes Central and Oriental Europe, Siberia, the Amur Basin. The western limit of this vast area is situated in Romania. Although its presence in Iza was supposed, it was not certified yet. Bereq (op. cit.,) is mentioning it in the Maramureq waters, without specifying if it is - or not - present in Iza. The differences, if compared to Cottus gobio, consist in the lateral line - which is incomplete - and the internal radia of the ventral finns which is shorter than the half of the neighbouring radia. Behaviour observations The size of the Phoxinus phoxinus observed schools is estimated at some hundreds specimens. For the schools of Alburnoides bipunctatus the number of specimens is comparable. We mention that during the reproduction period the school may be much greater especially in the case of Phoxin us phoxin us. The Gobio gobio specimens are forming smaller schools of 20-50 individuals. These schools are formed from specimens of different ages and dimensions, but less in the case of class (O+) of age, which are forming greater schools of young fishes. The schools of adults have usually 2-3 great specimens, in all probability belonging to the extrem classes of age (4+, 5+). Frequently, together with these schools of Gobio there are juveniles of Barbus peloponnesius or of Barbus barbus, very similar in aspect and dimensions with the specimens 4+, 5+ of Gobio, seeming to assume their role. This observation was made on many occasions. The specimens of Sabajenewia aurata were never watched in schools,but only isolated. The individuals are advancing upstream "jumping"; after swimming a few meters they stop in full stream, but using the shelter of a stone, or lightly burried in the bottom sand. Usually the big specimens of Leuciscus cephalus are searching for zones with deep, slow running water. At the station 13 there were observed for a long time 5 big specimens (over 20 cm) still-huting in a very fast stream, being protected only by a trunk on the bottom (the depth was there of about 1.5 m).

THE FISH FAUNA OF THE IZA RIVER (ROMANIA) 211 CONCLUSIONS The faunistical list resulted from our collecting actions on the Iza river includes 13 fish species(tab. 1). Later collectings will complete it. In this stage of the research there appears the contour of a river which is keeping its mountainous and submountainous character till the mouth, being populated especially by strongly rheophil fish specific. The anthropic impact is almost absent. The fish populations have considerable dimensions and constitute significant elements in stable lotic ecosystems. IHTIOFAUNA RAULUI IZA, MARAMURES ( ROM~IA) REZUMAT Ihtiofauna Izei a fost investigatg din punct de vedere calitativ ~i colectatg cu saci de pescuit qi cu volocul din 12 puncte de colectare situate pe tot cursul raului. Lista faunistic5 cuprinde 13 specii in conditiile in care r5ul nu este atins de vreo presiune antropicg vizibil2, iar populatiile de peqti prezente reprezint2 un element de stabilitate a1 ecosistemului. Datele de colectare au fost completate cu observatii etologice.

212 PETRE BACALU REFERENCES BANARESCU (P.), 1953 - Contributiuni la studiul faunei ihtiologice dulcicole a R.P. Romlne. Studii pi Cerceta'ri $tiin{. (Cluj), 4 (314): 153-187. BERE$ (I.), 1990 - Influenla zonelor umede in repartilia $i conservarea vertebratelor din Maramurev. Rev. Muz., 27 (5): 65-72. Received: June 10,1996 Accepted: July I, 1996 Muzeul National de Istorie Natural2,,Grigore Antipa" Sos. Kisselef nr. 1 79744 - Bucure~ti 2, Rornsnia