Conclusion
Detection efficiencies
PIT tag systems are a well-established method for studying fish
migration and movement (Schmidt et al., 2016; Lucas & Baras, 2000;
O’Donnell et al., 2010; Sloat et al., 2011; Hodge et al., 2015). When
analysing migration patterns based on antenna detections, it’s important
to account that detection efficiencies can vary due to changing abiotic
factors, such as flow velocity and water depth at the antenna site.
Aymes & Rives, (2009) showed that upstream movements were better
detected than downstream movements. Nase, which have been tagged in the
Danube downstream of the HPP Ottensheim and migrated upstream into the
fish pass, showed a higher detection efficiency (approximately 60 %)
(Reckendorfer, personal communication) than fish migrating downstream
(24-45%, Table 1). The lower detection efficiency of fish moving
downstream is probably due to the faster downstream movement of fish
with the current, using the entire water column, compared to the slower,
more bottom- oriented upstream movement against the current.
Fish size & detection rates
In this study, we found that detection rates increased with fish size:
12% of juvenile nase (<20 cm) were detected in the fish pass,
compared to 59% of adult nase (>20 cm). Additionally, larger
individuals tended to enter the fish pass earlier than juveniles. This
aligns with documented behaviour of potamodromous species like nase,
where larger adults typically move to spawning grounds earlier. For
example, Kamler & Keckeis (2000) observed in the Austrian Fischa River
that male nase (size 30-48 cm) often arrive at spawning sites before
females (size 40-52 cm), occupying deep pools near the spawning area,
with females arriving later and positioning upstream or downstream of
the males, whereas small-sized fish were less numerous or even absent.
Similarly, Penaz (1996) reported comparable behaviour. Epple et al.
(2020) noted that adults were detected earlier in the year (March to
April) and at lower water temperatures, while juvenile abundance peaked
in August in fish bypass channels in the River Iller, Bavaria. Benitez
et al. (2022) also found that juvenile nase used fish passes later in
the year, from late June to early November. Apparently, juveniles use
the fish pass for feeding during the growing season and enter the bypass
system later in the year.
In addition to spawning migrations, nase use the fish pass at HPP
Ottensheim throughout the year, depending on their size class.
Meulenbroek et al. (2008) observed that nase in the 200 to 350 mm length
class were underrepresented in a newly constructed fish bypass on the
Danube in Vienna, while juveniles were found throughout the bypass,
particularly in stagnant side arms and the pool pass. Larger individuals
(>350 mm) were almost exclusively found in the meandering and
straightened sections.
In our study, we found that fish repeatedly using the bypass and passing
downstream were significantly larger than the average of all 190 tagged
fish (p = 0.005). Previous research by Sanz-Ronda et al. (2021) showed
that over 40% of tagged barbel in headwaters successfully found the
exit of a slot bypass, with larger or more experienced fish showing an
even higher success rate (>50%). Fish rely on spatial
perception, using all senses and memory for orientation (Salena et al.,
2021; Healy & Patton, 2022). This enables older and larger fish to
learn and repeatedly find bypass entries (Reckendorfer et al. 2023).
Kieffer & Colgan (1992) noted that fish can adapt to environmental
changes and that homing behaviour is influenced by both brain
development and experience. Similarly, Odling-Smee & Braithwaite (2003)
suggested that fish may be predisposed to learn specific associations
relevant to their navigational and migrational challenges.
During our 4-year study, larger fish (>250 mm at tagging in
2020) were detected twice as often (average 2.2 years) as smaller fish
(average 1.1 years). This supports the hypothesis that larger,
potentially more experienced fish may learn to use the bypass repeatedly
over time. Especially considering that the upstream inlet structure,
where the fish enter the fish pass from the Danube, is relatively small
(2 x 5 m wide and 3.4 m high) compared to the Danube’s width (around 320
meters) and is located within a monotonous rip- rap bank at the upper
end of the impoundment with a reduced flow velocity.
The total number of fish entering and leaving the bypass system has
steadily decreased over the years, from 78 nase in 2021 to 31 in 2023,
and just 15 fish recorded entering the system by mid-June 2024. This
decline is likely caused by natural mortality. Spindler (1993) reported
an average annual mortality rate of 42% for nase in the Austrian Danube
and its backwaters below Vienna. Therefore, it is not surprising to see
a reduction in detections four years after tagging in 2020, especially
given that only a few younger nase have been detected during the study
period.
The use of fish pass for downstream migration
Most research on fish passes focuses on their role in upstream
migration, with many studies suggesting that fish passes are either
unsuitable for downstream migration or play a minimal role in this
regard (Pelicice et al., 2015, Knott et al., 2023, Larinier & Travade,
2002, Agostino et al., 2011, Pelicice & Agostinho, 2012; Bravo-Cordoba
et al., 2018; Birnie-Gauvin et al., 2019; Geist, 2021, Eberstaller et
al., 2001). However, recent research has begun to recognize the
importance of fish passes also for downstream migration of potamodromous
fishes (Reckendorfer et al., 2023, Bravo-Cordoba et al., 2023,
Sanz-Ronda et al., 2021, Celestino et al., 2019, Unfer & Rauch, 2019,
Petz-Glechner, 2009, Telhado et al., 2015). Especially on the Austrian
Danube, with 10 large HHPs on a river length of only 350 km, the
installation of fish passes allowing bi-directional movement and ideally
providing habitat, is essential to benefit fish populations. In
particular nase, which suffer significant habitat loss in dammed
stretches, require restored migration routes alongside improved habitat
conditions in the main river and its tributaries (Panchan et al., 2022).
The fish bypass system at Ottensheim-Wilhering resembles a natural
river, allowing fish to swim freely in both directions. This is shown by
numerous fish entering the fish pass from upstream and hundreds of
detections across the five antenna arrays throughout the year. The final
annual detections of some nase at the lowest antenna (#5) indicate a
complete downstream migration into the Danube below the HPP.
Nevertheless, nase are likely to display strong homing behaviour, also
regarding their wintering habitats (Ovidio & Nzau Matondo, 2024,
Panchan et al., 2022). This drives them to migrate from the bypass
system back upstream into the Danube during autumn and winter, as
reflected by many last annual detections at Antenna #1, situated at the
upper entrance of the bypass.
Our findings demonstrate that nase, though in relatively low numbers,
successfully used the fish pass for a downstream passage into the Danube
below the dam. These results align with other studies conducted on the
Austrian Danube by Eberstaller et al. (2001) and Meulenbroek et al.
(2018).
The (repeated) use of the fish pass as a suitable habitat
During our 4-year study, 51 % of nase, tagged in the Danube above the
HPP, were detected within the fish pass. By analysing the detection
patterns across the 5 antenna arrays and tracking individual fish over
time, we observed that while some nase used the fish pass to overcome
the HPP dam within a few days, the majority spent several weeks within
the bypass system (average stay >86 days per year, with a
maximum of 358 days in 2022).
This 14 km long, near-natural fish bypass, with its integrated
tributaries, provides suitable habitats for spawning, as shown by
elevated detection rates in spring. Spawning activities in the bypass
have also been reported by Zauner et al (2017), the extremely high
numbers of 0+ fish and feeding traces of juvenile nase within the fish
pass reported by these authors indicates the use of the bypass as fish
nursery. The high “traffic” at Antenna #3, located in the Aschach
River, accounted for 48% of all detections in the system, highlighting
the importance of a connection to natural tributaries.
Detection data also show that after entering the fish pass in spring
from the Danube above the HPP, nase utilize the various habitats within
the bypass system during summer before leaving the fish pass again via
the upstream end to spend winter in the Danube. Thus, near-natural
bypass rivers offer much more than just longitudinal connectivity; they
provide valuable habitats for numerous fish species and life stages
throughout the year. These habitats are very rare in degraded large
rivers like the Austrian Danube and near natural fish passes which
include natural tributaries, such as at the one at HPP Ottensheim,
significantly support the potamodromous fish fauna of the main river and
its tributaries.
In contrast to our study, investigations of nase migration through
fish-bypass channels in the Iller River, Germany, revealed that most
nase entered the bypass solely for spawning and left immediately
afterward to migrate downstream (Epple et al., 2020). A telemetry study
by Panchan et al. (2022) on the Austrian Danube found that 100% of nase
exhibited distinct homing behaviour during the spawning season,
returning to specific tributaries to spawn and migrating afterwards
along the entire river stretch between two hydropower plants.
In our study, 47 of 80 nase (59%) were detected in the bypass system
for more than one year, suggesting repeated use and homing behaviour.
This aligns with Panchan et al. (2022), who observed nase returning,
sometimes multiple times, to specific sites in the river and its
tributaries after months of absence. The study also highlighted that
Danube nase populations have a much larger home range compared to
populations in smaller waters outside the reproductive period (Baras,
1997; Huber & Kirchhofer, 1998; Benitez et al., 2018; Ovidio et al.,
2016).
Results of telemetry studies on the Austrian Danube by Wagner (2010) and
Eschelmüller (2009) showed that nase exhibited an average total
migration of 23.11 and 33.3 km respectively and a home range of 12.1 and
14.1 km. Migration behaviour varied seasonally: Winter showed the
shortest migrations (4.9 km and 7.8 km), while prespawning (1st week in
February to mid of April) recorded the longest distances (up to 10.8
km). Moderate migration activities were observed in summer and autumn.
Individual nase have been observed to migrate distances up to 110 km,
although this is less common. Historical data show that in the 1930s,
when the Danube still had richly structured river sections, the
migration distances of nase were significantly shorter than in recent
years (Steinmann et al., 1937).
Meulenbroek et al. (2018) observed that the migration behaviour of nase
and barbel, along with their multiple spawning activities within a
nature-like fish pass at the HPP Freudenau on the Austrian Danube, is
comparable to behaviour observed in natural streams and tributaries of
the Danube (Keckeis et al., 1997, Ovidio & Philippart 2008; Melcher &
Schmutz 2010). While artificially constructed systems can provide
functional spawning grounds (Pander & Geist, 2016; Meulenbroek et al.,
2018), large river-like bypasses that incorporate natural tributaries
offer particularly suitable habitats for the rheophilic fish fauna of
the Danube.
Our data showed that nase remained within the fish pass system for
extended periods, averaging about three months each year, rather than
simply passing through. Given the poor quality and limited availability
of habitats in both the upstream and downstream areas of the Danube, it
raises an important question: why would fish migrate along the
monotonous main channel of the Danube when suitable habitats are
available within the bypass system? This study indicates that bypasses
serve a greater purpose than just passageways, offering significant
potential to support potamodromous fish species in large rivers, as
supported by other research (Quigley & Harper 2006; Calles & Greenberg
2007,2009, Tamario et al. 2018, Meulenbroek et al. 2018, Panchan et al.,
2022).
References
Agostinho, C.S.; Pelicice, F.M.; Marques, E.E.; Soares, A.B.; de
Almeida, D.A.A. (2011): All that goes up must come down? Absence of
downstream passage through a fish ladder in a large Amazonian river.
Hydrobiologia 2011, 675, 1–12.
Aymes, J. C., Rives, J. (2009): Detection efficiency of multiplexed
Passive Integrated Transponder antennas is influenced by environmental
conditions and fish swimming behaviour. Ecology of freshwater fish,
Volume 18, Issue 4, Pages 507-513
https://doi.org/10.1111/j.1600-0633.2009.00373.x
Baras E (1997) Environment determinants of residence area selection by
Barbus barbus in the River Outhe. Aquat Living Resour 10:195–206.
https:// doi. org/ 10. 1051/ alr: 19970 21
Baras, E., Lucas, M. C. (2001): Impacts of man’s modifications of river
hydrology on the migration of freshwater fishes: a mechanistic
perspective. International Journal of Ecohydrology & Hydrobiology,
1(3), 291-304.
Benitez, J. P., Dierckxa, A., Nzau Matondoa, B., Rollinb, X., Ovidioa,
M. (2018): Movement behaviours of potamodromous fish within a large
anthropized river after the reestablishment of the longitudinal
connectivity. Fisheries Research 207 (2018) 140–149
Benitez, J.-P.; Dierckx, A.; Rimbaud, G.; Nzau Matondo, B.; Renardy, S.;
Rollin, X.; Gillet, A.; Dumonceau, F.; Poncin, P.; Philippart, J.-C.; et
al. (2022): Assessment. of Fish Abundance, Biodiversity and Movement
Periodicity Changes in a Large River over a 20-Year Period. Environments
2022, 9, 22.
Birnie-Gauvin, K., Franklin, P., Wilkes, M. & Aarestrup, K. (2019):
Moving beyond fitting fish into equations: progressing the fish passage
debate in the Anthropocene. Aquatic Conservation: Marine and Freshwater
Ecosystems, 29(7), 1095–1105.
Bravo-Cordoba, F.J., Sanz-Ronda, F.J., Ruiz-Legazpi, J., Fernandes
Celestino, L. & Makrakis, S. (2018): Fishway with two entrance
branches: understanding its performance for potamodromous Mediterranean
barbels. Fisheries Management and Ecology, 25(1), 12–21.
Bravo-Córdoba, F. J. García-Vega, A., Fuentes-Pérez, J. F., Fernandes
Celestino, L., Makrakis, S., Sanz-Ronda, F.S. (2023): Bidirectional
connectivity in fishways: A mitigation for impacts on fish migration of
small hydropower facilities. Aquatic Conservation: Marine and Freshwater
Ecosystems. 2023;33:549–565.
Castro-Santos, T., & Haro, A. (2010): Fish guidance and passage at
barriers. In P. Domenci & B. G. Kapoor (Eds.), Fish locomotion: An
eco-ethological perspective (pp 62–89). Enfield, NH: Science
Publishers. https://doi. org/10.1201/b10190
Celestino, L. F.; Sanz-Ronda, F. J.; Miranda, L. E.; Makrakis, M. C.;
Dias, J. H. P. et al. (2019): Bidirectional connectivity via fish
ladders in a large Neotropical river. In: River Res. Appl. 35, S.
236-246.
Connolly, P.J. Jezorek, I.G., Martens, K.Ds., Prentice, E.F. (2008):
Measuring the Performance of Two Stationary Interrogation Systems for
Detecting Downstream and Upstream Movement of PIT-Tagged Salmonids.
North American Journal of Fisheries Management 28:402–417, DOI:
10.1577/M07-008.1
Calles, E.O., Greenberg, L.A. (2007): The use of two nature-like
fishways by some fish species in the Swedish River Emån. Ecology of
Freshwater Fish, 16(2), 183–190.
https://doi.org/10.1111/j.1600-0633.2006.00210.x
Calles, E.O., Greenberg, L.A. (2009): Connectivity is a two-way street.
The need for a holistic aprroach to fish passage problems in regulated
rivers. River Research and Applications, 25(10), 1268–1286.
https://doi. org/10.1002/rra
Eberstaller, J., Pinka, P., and Honsowitz, H. (2001).
Fischaufstiegshilfe Donaukraftwerk Freudenau Forschung im Verbund,
Schriftenreihe 72, 177–196.
Epple, T., Friedmann, A., Wetzel, K.F., Born, O. (2020): The life cycle
of nase (Chondrostoma nasus) before and after the construction of
hydropower plants in the river Iller (Bavaria, Germany) and its
migration behaviour through fish-bypass channels. Danube News - June
2020 - No. 41 - Volume 22, https://www.danube-iad.eu Page
Eschelmüller, M. (2009): Fischökologisches Monitoring mit Hilfe der
Radiotelemetrie im Rahmen des EU-LIFE-Projekts ”Vernetzung - Donau -
Ybbs” : spezielle Betrachtung der saisonalen Migration von Chondrostoma
nasus, Hucho hucho und Silurus glanis. Diplomarbeit BOKU Wien, 230pp.
Geist, J. (2021). Challenges for fish and freshwater biodiversity
conservation related to hydropower. Aquatic Conservation: Marine and
Freshwater Ecosystems, 31(7), 1551–1558.
Greenberg, L. A., Giller, P. S. (2000). The potential of flat bed
passive integrated transponder antennae for studying habitat use by
stream fishes. Ecology of Freshwater Fish 9:74–80.
Hauer, C., Gunther, U., Schmutz, S., Habersack, H. (2007): The
importance of morphodynamic processes at riffles used as spawning
grounds during the incubation time of nase (Chondrostoma nasus).
Hydrobiologia 2007, 579, 15–27.
Healy, S. D.; Patton, B. W. (2022): It began in ponds and rivers:
charting the beginnings of the ecology of fish cognition. In: Frontiers
in Veterinary Science 9 (2022).
Hodge, B. W., R. Henderson, K. Rogers, B., and K. D. Battige. (2015):
Efficacy of portable PIT detectors for tracking long-term movement of
Colorado River Cutthroat Trout in a small montane stream. North American
Journal of Fisheries Management 35:605–610
Hohensinner S, Herrnegger M, Blaschke AP, Habereder C, Haidvogl G, Hein
T, Jungwirth M, Weiß M (2008): Type-specific reference conditions of
fluvial landscapes: a search in the past by 3D-reconstruction. Catena
75:200–215
Hohensinner S, Jungwirth M (2009): Hydromorphological characteristics of
the Danube River—the historical perspective. Z Österr Ing-Archit-Ver
154(1–6):33–38
Hohensinner S, Jungwirth M, Muhar S, Schmutz S (2011): Spatio-temporal
habitat dynamics in a changing Danube River landscape 1812–2006. River
Res Appl 27:939–955
Huber, M., Kirchhofer, A. (1998): Radio telemetry as a tool to study
habitat use of nase (Chondrostoma nasus L.) in medium sized rivers.
Hydrobiologia 372, 309–319.
Hudson, A.G.; Vonlanthen, P.; Seehausen, O. (2014): Population
structure, inbreeding and local adaptation within an endangered riverine
specialist: The nase (Chondrostoma nasus). Conserv. Genet. 2014, 15,
933–951.
Jungwirth, M., Schmutz, S., Weiss, S., Wootton, R. J (1998): Fish
Migration and Fish passes. In: Ecology of Teleost Fishes. Fish and
Fisheries Series 24. 2 Ed., 87–106, 141–143, and 259–283 (Kluwer
AcademicPublishers, 1998).
Kamler, E., Keckeis, H. (2000): Reproduction and early life history of
Chondrostoma nasus: implications for recruitment [a review]. Polskie
Archiwum Hydrobiologii 47.1.
Keckeis, H., Winkler, G., Flore, L., Reckendorfer, W. & F. Schiemer
(1997): Spatial and seasonal charakteristics of 0+ fish nursery habitats
of nase, Chondrostoma nasus in the river Danube, Austria. Folia
Zoologica 46 (Suppl. 1): 133–150.
Kieffer, J. D. & Colgan, P. W. (1992): The role of learning in fish
behaviour. Reviews in Fish Biology and Fisheries Volume 2, pages
125–143.
Knott, J., Mueller M, Pander, J., Geist, J. (2023): Downstream fish
passage at small-scale hydropower plants: Turbine or bypass? Front.
Environ. Sci. 11:1168473. doi: 10.3389/fenvs.2023.1168473
Koller-Kreimel, V. (2017): Fischaufstiegsanlagen in Österreich –
Vorgaben der WRRL, Stand der Umsetzung und Ausblick. In:
WasserWirtschaft 107 (2017), Heft 2-3, S. 14-19.
Kowal, J. L., Funk, A., Unfer, G., Baldan, D., Haidvogl, G., Hauer, C.,
Ferreira, M.T., Branco, P., Schinegger, R., Hein, T. (2024): River
continuum disruptions in a highly altered system: The perspective of
potamodromous fish. Ecological Indicators, 164, 112130.
Larinier, M., Travade, F. (2002): Downstream migration: problems and
facilities. Bulletin Français de la Pêche et de la Pisciculture, (364),
181-207.
Lucas, M., Baras, E. (2000): Methods for studying spatial behaviour of
freshwater fishes in the natural environment. Fish and Fisheries
1:283–316
McKenzie, J., Parsons, B., Seitz, A., Keller Kopf, R., Mesa, M., Phelps,
Q. (2012) Advances in Fish Tagging and Marking Technology. 560 pages,
hardcover, Symposium 76 Published by the American Fisheries Society
ISBN: 978-1-934874-27-1 doi: https://doi.org/10.47886/9781934874271
Melcher, A.H., Schmutz, S. (2010): The importance of structural features
for spawning habitat of nase Chondrostoma nasus (L.) and barbel Barbus
barbus (L.) in a pre-Alpine river. River Systems Volume 19 Issue 1
(2010), p. 33 – 42 DOI: 10.1127/1868-5749/2010/019-0033
Meulenbroek P, Drexler S, Nagel C, Geistler M, Waidbacher H (2018) The
importance of a constructed near-nature-like Danube fish by-pass as a
lifecycle fish habitat for spawning, nurseries, growing and feeding: a
long-term view with remarks on management. Mar Freshw Res 69:1857–1869.
https:// doi. org/ 10. 1071/ MF181 21
Nagel, C., Droll, J., Kroemer, K., Pander, J., Geist, J. (2023). Testing
the effects of passive integrated transponder (PIT) tags on survival,
growth, and tag retention of common nase (Chondrostoma nasus L .)
and European barbel (Barbus barbus L.). Anim Biotelemetry 11, 33
(2023). https://doi.org/10.1186/s40317-023-00344-z
Northcote, T. G. (1984): Mechanisms of fish migration in rivers.
Mechanisms of migration in fishes, 317-355.
Odling-Smee, L., Braithwaite, V. A. (2003): The role of learning in fish
orientation. Fish and Fisheries Volume4, Issue3 Pages 235-246.
Ovidio, M., Hanzen, C., Gennotte, V., Michaux, J.R.,Benitez J.P. (2016):
Is adult translocation a credible way to accelerate the recolonization
process of Chondrostoma nasus in a rehabilitated river? Cybium:
International Journal of Ichthyology 40(1):43-49
Ovidio, M., Nzau Matondo, B. (2024): Ecology and Sustainable
Conservation of the Nase, Chondrostoma nasus: A Literature Review.
Sustainability 2024, 16, 6007. https://doi.org/10.3390/su16146007
O’Donnell, M. J., Horton, G. E. , Letcher, B. H. (2010): Use of portable
antennas to estimate abundance of PIT-tagged fish in small streams:
factors affecting detection probability. North American Journal of
Fisheries Management 30:323–336.
Panchan, R.,Pinter, K., Schmutz, S., Unfer, G. (2022): Seasonal
migration and habitat use of adult barbel (Barbus barbus) and nase
(Chondrostoma nasus) along a river stretch of the Austrian Danube River.
Environ Biol Fish (2022) 105:1601–1616
Pander, J, Geist, J. (2016) Can fish habitat restoration for rheophilic
species in highly modified rivers be sustainable in the long run?
JournalEcological Engineering, Volume 88: 28-38
Pelicice, F.M.; Agostinho, C.S. (2012): Deficient downstream passage
through fish ladders: The case of Peixe Angical Dam, Tocantins River,
Brazil. Neotrop. Ichthyol. 2012, 10, 705–713.
Pelicice, F. M.; Pompeu, P. S.; Agostinho, A. A. (2020): Fish
conservation must go beyond the concrete: A comment on Celestino et al.
(2019). In: River Res. Appl. 36, S. 1 373-1 376.
Pelicice, F. M.; Pompeu, P. S.; Agostinho, A. A. (2015): Large
reservoirs as ecological barriers to downstream movements of Neotropical
migratory fish. In: Fish, Nr. 16, S. 697-715.
Penaz, M. (1996) Chondrostoma nasus, its reproduction strategy and
possible reasons for a widely observed population decline-a review. In
Conservation of Endangered Freshwater Fish in Europe; Kirchhofer, A.,
Hefti, D., Eds.; Birkhauser Verlag: Basel, Switzerland, pp. 278–285
Pennuto, C. M., Cudney, K. A., Janik, C. E. (2018): Fish invasion alters
ecosystem function in a small heterotrophic stream. Biol. Invasions 20,
1033–1047 (2018)
Petz-Glechner R. (2009): Salzach Kraftwerk Gamp - Funktionskontrolle der
Fischwanderhilfe. Im Auftrag der Salzburg AG für Energie, Verkehr und
Telekommunikation.
Porcher, J.P., Travade, F. (2002): Fishways: Biological basis, limits
and legal considerations. Bull. Français la Pêche la Piscic. 2002, 364,
9–20.
Quigley, J. T., and Harper, D. J. (2006): Effectiveness of fish habitat
compensation in Canada in achieving no net loss. Environmental
Management 37(3), 351–366. doi:10.1007/S00267-004-0263-Y
Reckendorfer, W. (2019): Fischverhalten und Habitatverfügbarkeit:
vernachlässigte Parameter bei der Abschätzung turbinenbedingter
Schädigung. Wasserwirtschaft October 2019, DOI:
10.1007/s35147-019-0265-6
Reckendorfer, W., Keckeis, H., Tiitu, V., Winkler, G., Zornig, H., &
Schiemer, F. (2001). Diet shifts in 0+ nase, Chondrostoma nasus:
size-specific differences and the effect of food. Archiv fuer
Hydrobiologie Supplement, 13512, 425-440.
Reckendorfer, W., Schabuss, M., Petz-Glechner, R. (2023):
Abwärtswanderung durch eine Fischaufstiegsanlage - neue Erkenntnisse
durch Untersuchungen mittels PIT-Tags. WASSERWIRTSCHAFT 113(2-3):31-34.
Roussel, J.-M., Cunjak, R. A., Newbury, R., Caissie, D. Haro, A. (2004):
Movements and habitat use by PIT-tagged Atlantic salmon parr in early
winter: the influence of anchor ice. Freshwater Biology 49:1026–1035.
Salena, M. G.; Turko, A. J.; Singh, A.; Pathak, A.; Hughes, E. et al.
(2021): Understanding fish cognition: a review and appraisal of current
practices. In: Animal cognition 24, Nr. 3, S. 395-406.
Sanz-Ronda, F. J.; Fuentes-Pérez, J. F.; García-Vega, A.; Bravo-Córdoba,
F. J. (2021): Fishways as Downstream Routes in Small Hydropower Plants:
Experiences with a Potamodromous Cyprinid. In: Water 13 (2021), Nr. 8,
S. 1 041.
Schiemer, F., Spindler, T., Wintersperger, H. & A. Chovanec (1991):
Fish fry associations: important indicators for the ecological status of
large rivers. Verh. int. Verein theor. angew. Limnol. 24: 2497–2500.
Schiemer, F., Guti, G., Keckeis, H., Staras, M. (2004): Ecological
status and problems of the Danube and its fish fauna. A review.
https://www.researchgate.net/publication/24189928
Schmidt, T., Löb, C., Schreiber, B., & Schulz, R. (2016): A Pitfall
with PIT Tags: Reduced Detection Efficiency of Half-Duplex Passive
Integrated Transponders in Groups of Marked Fish. North American Journal
of Fisheries Management, 36(4), 951–957.
Schmutz, S. & Jungwirth, M. (2022): Die Fischfauna der Donau Die
historische und aktuelle Fischfauna der Donau Artenbestand – Gefährdung
– Schutz. In: LIFE & The Danube Renaturierungsprojekte an der Donau
ISBN 978-3-903257-05-4
Schmutz, S. (2012): Was bringt die Durchgängigkeit für den guten
Zustand? In: ÖWAV-Tagung „Fischaufstiegshilfen – Neue Anforderungen und
Erfahrungen aus der Praxis“, 25.10.2012, Wien
Silva, A. T., Lucas, M. C., Castro‐Santos, T., Katopodis, C.,
Baumgartner, L. J., Thiem, J. D., … & Cooke, S. J. (2018): The future
of fish passage science, engineering, and practice. Fish and Fisheries,
19(2), 340-362.
Sloat, M. R., Baker, P. F., Ligon, F. K. (2011): Estimating
habitat-specific abundances of PIT-tagged juvenile salmonids using
mobile antennas: a comparison with standard electrofishing techniques in
a small stream. North American Journal of Fisheries Management
31:986–993.
Sommerwerk, N., Baumgartner, C., Blösch, J., Hein, T., Ostojic, A.,
Paunovic, M., Schneider-Jakoby, M., Siber, R. & Tockner, K. (2009): The
Danube River Basin. In: Tockner, K., Uehlinger, U. & Robinson, C.T.
(Hg.), Rivers of Europe. Elsevier Academic Press, Amsterdam, S. 59–112.
Spindler, T. (1995): The influence of high waters on stream fish
populations in regulated rivers. Hydrobiologia 303: 159-161.
Spindler, T. (1993): Populationsdynamische Untersuchungen im
Altarmsystem und in der Donau im Bereich von Regelsbrunn und Haslau. WWF
Forschungsbericht 9/1993. Fischereimangement 3. Eigenverlag
Forschungsgemeinschaft Auenzentrum Petronell. Wien. 80.
Steinmann, P., Koch, W., Scheuring, L. (1937): Die Wanderungen unserer
Süsswasserfische dargestellt auf Grund von Markierungsversuchen. – Z.
f. Fischerei, 35: 369-67.
Tamario, C., Degerman, E., Donadi, S., Spjut, D., and Sandin, L. (2018).
Nature-like fishways as compensatory lotic habitats. River Research and
Applications 34, 253–261. doi:10.1002/RRA.3246
Telhado, A., Ferreira, J., Quadrado, F., Proença, J., Batista, C.,
Quintella, B. R., & Almeida, P. R. D. (2015): Session D2: Coimbra
Fishway: Restoring Connectivity in River Mondego. ln: Fish Passage,
Groningen, 20.-25. Juni 2015.
Thurow, R. (2016): Life Histories of Potamodromous Fishes. In: An
Introduction to Fish Migration DOI: 10.1201/b21321-7
Unfer, G. & Rauch, P. (2019): Bundesministerium für Nachhaltigkeit und
Tourismus (Hrsg.): Fisch-schutz und Fischabstieg in Österreich -
Endbericht. Wien, 2019.
Wagner, C. (2010): Fischökologisches Monitoring im Rahmen des EU-LIFE
Projekt „Vernetzung Donau Ybbs“ mit Hilfe der Radiotelemetrie
Darstellung der Gesamtergebnisse von November 2007 bis Juni 2009 unter
spezieller Berücksichtigung der saisonalen Migrationen und des
Verhaltens im Bereich der FAH am KW Melk. Diplomarbeit an der
Universität für Bodenkultur.
Zauner, G. & F. Schiemer (1992): Auswirkungen der Schifffahrt auf die
Fischfauna – aufgezeigt am Beispiel der österreichischen Donau.
Landschaftswasserbau 14, 133–151
Zauner, G., Jung, M., Mühlbauer, M., Ratschan, C. (2015):
Fischökologische Sanierung von Fließstrecken und Stauhaltungen der
österreichischen Donau gem. WRRL: Immer der Nase (Chondrostoma nasus)
nach. In: Österreichs Fischerei 68 (2015), 7, S. 177-196
Zauner, G., Jung, M., Lauber, W., Mühlbauer, M., Ratschan, C. (2017):
Dynamischer Umgehungsarm Donaukraftwerk Ottensheim-Wilhering
—Durchgängigkeit und Lebensraum. Wasserwirtschaft Ausgabe 12/2017 DOI:
10.1007/s35147-017-0210-5
Zydlewski, G. B., Horton, G., Dubreuil, T., Letcher, B., Casey, S., &
Zydlewski, J. (2006). Remote monitoring of fish in small streams: a
unified approach using PIT tags. Fisheries, 31(10), 492-502.