Reintroduction and stock enhancement of European weatherfish ( Misgurnus fossilis L.) in Rhineland-Palatinate and Hesse, Germany

Abstract

A stocking program for the endangered European weatherfish (Misgurnus fossilis L.) was conducted in the German federal states of Rhineland-Palatinate and Hesse, southwest Germany. An initial monitoring enabled to identify local broodstock and to assess habitats regarding their ecological suitability for reintroduction. In a second step, broodstock were caught for artificial propagation and cultured fry were released in previously selected river sectors. Furthermore, reintroduction sectors were biannually monitored to assess stocking success. Within the study period (2014–2016), a total number of approximately 83,500 juveniles were stocked in three river sectors for reintroduction and approximately 85,000 juveniles were stocked in four other river sectors to strengthen existing populations. During the post-release monitoring, 45 individuals were recaptured in two sectors. The documented short-term reintroduction success (i.e. survival of released individuals) indicates appropriateness of the selected stocking strategy. Furthermore, the provided course of action might be transferred to further states or countries and thereby contribute to weatherfish conservation at larger scales.

Full text

RESEARCH PAPER
Reintroduction and stock enhancement of European weatherfish
(Misgurnus fossilis L.) in Rhineland-Palatinate and Hesse, Germany
Benjamin Schreiber
1,*
, Egbert Korte
2
, Thomas Schmidt
1,3
and Ralf Schulz
1,3
1
Institute for Environmental Sciences, University of Koblenz-Landau, Fortstrasse 7, 76829 Landau, Germany
2
Institut für Gewässer- und Auenökologie GbR, Riedstadt, Germany
3
Eusserthal Ecosystem Research Station, University of Koblenz-Landau, Birkenthalstrasse 13, 76857 Eusserthal, Germany
Abstract –A stocking program for the endangered European weatherfish (Misgurnus fossilis L.) was
conducted in the German federal states of Rhineland-Palatinate and Hesse, southwest Germany. An initial
monitoring enabled to identify local broodstock and to assess habitats regarding their ecological suitability
for reintroduction. In a second step, broodstock were caught for artificial propagation and cultured fry were
released in previously selected river sectors. Furthermore, reintroduction sectors were biannually monitored
to assess stocking success. Within the study period (2014–2016), a total number of approximately 83,500
juveniles were stocked in three river sectors for reintroduction and approximately 85,000 juveniles were
stocked in four other river sectors to strengthen existing populations. During the post-release monitoring, 45
individuals were recaptured in two sectors. The documented short-term reintroduction success (i.e. survival
of released individuals) indicates appropriateness of the selected stocking strategy. Furthermore, the
provided course of action might be transferred to further states or countries and thereby contribute to
weatherfish conservation at larger scales.
Keywords: conservation / artificial propagation / endangered species / stocking / Rhine
Résumé –Réintroduction et soutien de la loche d'étang (Misgurnus fossilis L.) en Rhénanie-Palatinat
et en Hesse, Allemagne. Un programme d'empoissonnement pour la loche d'étang menacée (Misgurnus
fossilis L.) a été mené dans les états fédéraux allemands de Rhénanie-Palatinat et de Hesse, au sud-ouest de
l'Allemagne. Un premier suivi a permis d'identifier les stocks de géniteurs locaux et d'évaluer les habitats en
fonction de leur aptitude écologique à la réintroduction. Dans un deuxième temps, les géniteurs ont été
capturés pour la reproduction artificielle et les alevins d'élevage ont été relâchés dans des secteurs fluviaux
préalablement sélectionnés. De plus, les secteurs de réintroduction ont fait l'objet d'un suivi semestriel pour
évaluer le succès de l'empoissonnement. Au cours de la période étudiée (2014–2016), un nombre total
d'environ 83,500 juvéniles ont été déversés dans trois secteurs fluviaux pour réintroduction et environ
85,000 juvéniles ont été déversés dans quatre autres secteurs fluviaux pour renforcer les populations
existantes. Au cours de la surveillanceaprès déversement, 45 individus ont été recapturés dans deux secteurs.
Le succès documenté de la réintroduction à court terme (c.-à-d. la survie des individus relâchés) indique que
la stratégie d'empoissonnement choisie est appropriée. De plus, les mesures prévues pourraient être
transférées à d'autres états ou pays et contribuer ainsi à la conservation de la loche d'étang à plus grande échelle.
Mots-clés : conservation / propagation artificielle / espèces menacées / empoissonnement / Rhin
1 Introduction
The world’sfish fauna is increasingly threatened by
impacts of the expansion of human populations, including
(i) competition for water, (ii) habitat alteration, (iii) pollution,
(iv) introduction of exotic species and (v) commercial
exploitation (Moyle and Leidy, 1992;Clausen and York,
2008). On the European red list of freshwater fishes (2011),
37% of 531 occurring native species are listed as threatened at
a continental scale and 17% show declining populations
(Freyhof and Brooks, 2011). In contrast to fish species of high
public attention like European sturgeon (Acipenser sturio)or
Atlantic salmon (Salmo salar) that are used as conservation
*Corresponding author: benjaschreiber@gmail.com
Knowl. Manag. Aquat. Ecosyst. 2018, 419, 43
©B. Schreiber et al., Published by EDP Sciences 2018
https://doi.org/10.1051/kmae/2018031
Knowledge &
Management o
f
A
quatic
Ecosystems
www.kmae-journal.org Journal fully supported by Onema
This is an Open Access article distributed under the terms of the Creative Commons Attribution License CC-BY-ND (http://creativecommons.org/licenses/by-nd/4.0/), which permits unrestricted use,
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flagships for European major rivers (Ludwig, 2006;
Monnerjahn, 2011), other endangered species with low
economic value might be overlooked and neglected by
conservation efforts (Kalinkat et al., 2016). This latter category
includes the European weatherfish (Misgurnus fossilis L.).
The European weatherfish belongs to the Cobitidae family
and occurs in densely vegetated river areas with muddy
substratum, including oxbows, flood plains or ditch systems
(Lelek, 1987;Kottelat and Freyhof, 2007). It is a demersal
species native to Europe that can be found north of the Alps,
from the Volga basin to France (Lelek, 1987). Presumably, as a
result of habitat degradation, management practices in
secondary habitats and water pollution, weatherfish popula-
tions declined or even became extinct in many regions across
its original range (Ko
sčoet al., 2008;Drozd et al., 2009;
Hartvich et al., 2010). However, only few of the mentioned
reasons have so far been investigated with specific relation to
the conservation of weatherfish. Investigations by Meyer and
Hinrichs (2000) indicated that weatherfish populations found
in ditch systems are mainly endangered by intensive
mechanical maintenance like dredging or weeding measures.
Studies that were conducted in order to evaluate potential
threats posed by chemical stress indicated that weatherfish
embryos are highly sensitive to contaminants dissolved in
water and contaminants associated with sediments (Schreiber
et al., 2017a,2018). Today, the weatherfish is listed under
Annex II of the Habitats Directive 92/43/EEC and classified as
vulnerable or nearly extinct on Red Lists of numerous
countries, including Austria, Czech Republic, Denmark,
Germany, Hungary, Slovakia, Slovenia and Switzerland
(EU, 1992;Zulka and Wallner, 2006;Haupt et al., 2009;
Hartvich et al., 2010;Sigsgaard et al., 2015).
Restoration of habitats and removal of invasive species are
key strategies to support the viability of existing freshwater fish
populations (Cochran-Biedermann et al., 2015). However, the
increasing number of eradications of fish species from parts of
their historical range led to enhanced use of reintroduction
measures for conservation purposes (Armstrong and Seddon,
2008;Tatáret al., 2017). In the case of weatherfish, (Lelek, 1987)
also recommended the reintroduction of hatchery-reared
individuals to areas with suitable conditions. In general, there
is agreement that every conservational reintroduction practice
should be well documented and that standardization along
guidelines can increase the reintroduction outcome (IUCN,
1987,1998,2013;Lee and Hughes, 2008;Sutherland et al.,
2010).
In order to counteract the ongoing decline of weatherfish
populations,a regional joint conservation program in Rhineland-
Palatinate and Hesse(southwest Germany) was initiatedin 2014.
The program area lies at the southwestern boundary of the
species distribution range and is supposed to play a significant
role for weatherfish conservation on a national level as the Rhine
floodplains provide rare primary habitats for this species (Copp,
1989;Dister et al., 1990). Main objectives of the program were
determined as (i) to support existing weatherfish populations by
stock enhancement and (ii) to reintroduce this species in sectors
with suitable conditions where the specific reasons for its
eradication can be excluded. For both objectives, hatchery-
reared weatherfish fry derived from local broodstock should be
utilized (Lelek, 1987). The aim of the present paper was to
comprehensively document all necessary steps of the mentioned
program, from the planning stage to the implementation, as well
as to critically discuss achieved objectives and remaining
challenges and to identify opportunities for improvement.
2 Methods
2.1 Initial monitoring: identification of broodstock and
reintroduction habitats
As a first step, an initial monitoring within thestudy area was
carried out to identify (i) relic weatherfish populations for
broodstock sampling and (ii) potential areas for reintroduction
measures that meet the species requirements. Selection of the
specific monitoring regions was made on the basis of available
data of past weatherfish detections (unpublished) and on the
identification of potential areas on topographic maps. In total,
144 river sectors, belonging to 10 catchments, were monitored
for weatherfish presence via fish traps (total number of trap
nights =1948) or electro-fishing (total electro-fishing distance =
2700 m) between 2007 and 2016 (Tab. S1 in the supporting
information). The used drum-shaped fish traps were equipped
with baits. During themonitoring, traps were distributed for one
night in the investigated sectors with distances of 5–10 m
between each trap (depending on the width of the respective
sector). In order to allow trap-caught weatherfish to swallow air
from above the water surface, traps were placed in the water
without full immersion. Electro-fishing was only carried out in
water sectors with lower vegetation densities by using battery-
powered devices (EFGI 650 and EFGI 4000; Bretschneider
Spezialelektronik, Chemnitz, Germany).
Concerning the habitat assessments for an identification
of reintroduction sites, special attention was given to good
connectivity and year-round water bearing and none to
moderate maintenance practices (e.g. mowing of the banks),
presence of spawning habitats (i.e. connected flood plains)
and absence of nocturnal predators (in particular, the
European eel Anguilla anguilla L.). Occasional presence
of low numbers of other piscivorous predators (e.g. Esox
lucius) was not defined as a criterion for excluding the site for
a reintroduction.
2.2 Captive breeding and rearing of fish
For the broodstock sampling, weatherfish spawners were
caught with baited fish traps at the beginning of the spawning
season (March to April) as already described. Subsequently,
individuals from different populations origin were maintained
separately. Artificial propagation followed the procedure
reported by Schreiber et al. (2017b). In brief, males and
females were isolated from each other, and water temperature
was gradually increased to 18 °C, before a gonadotropin-
releasing hormone (GnRH) containing preparation (Ovopel,
Unic-trade) was intramuscularly injected in two divided doses.
Stripped eggs of one female were fertilized with sperm of two
males and subsequently transferred to hatching troughs.
Incubation of embryos (18 °C) and rearing of larvae (21 °C)
was carried out in recirculation aquaculture systems. Weath-
erfish fry were fed with Artemia salina nauplii and reared until
they reached a total length (L
T
) of approximately 2–4 cm. This
rearing duration was chosen as it represents a feasible
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B. Schreiber et al.: Knowl. Manag. Aquat. Ecosyst. 2018, 419, 43

compromise to overcome the most sensitive life stage and to
limit the adaptation to artificial conditions.
2.3 Stocking procedure and post-release monitoring
One half of the cultured fry was released in areas where the
broodstock was originated (i.e. endogenous enhancement).
The other half was used for reintroductions in habitats that
were previously assessed as suitable (Tab. 2). The only
exception to this procedure happened at waters of the
Schwarzbach catchment (49°5906.400 N; 8°29042.100 E): here,
endogenous enhancement was not possible so that fry from the
Horloff catchment were used for stock enhancement (i.e.
exogenous enhancement).
Stocking was carried out in several batches per year
and site by evenly distributing weatherfish fry in shallow and
densely vegetated water stretches. Prior to release, fish were
gently acclimated to the on-site water conditions (e.g.
temperature) by placing the fish containing buckets in the
water and gradually adding water from the releasing site to the
buckets. Batches of cultured fish were divided and stocked in
several sectors to limit the risk linked to unpredictable
fluctuations in water level (Meyer and Hinrichs, 2000), which
might negatively influence their survival.
Stocking success was monitored biannually in late summer
from the first year of stocking (2014) by using fish traps. As
stocked individuals could not be distinguished from previously
occurring weatherfish, only sectors selected for reintroduction
could be used for a reliable assessment of the efficiency of the
stocking.
2.4 Documentation and assessment of the program
In order to provide a standardized documentation and
assessment of the conducted program, a questionnaire template
that was originally designed for waterbird re-establishment
programs (Lee and Hughes, 2008) was completed in a slightly
adapted form (Tab. S2 in the supporting information).
Furthermore, the costs per released individual were
estimated, including the following work stages: (i) broodstock
sampling, (ii) captive breeding, (iii) rearing of fish and
(iv) stocking procedure. For the estimation, acquisition costs
were neglected (e.g. fish traps, electro-fishing device,
establishment of an aquacultural system) and staff expenses
were included for two different educational levels (i.e. research
associate and research assistant). Ongoing costs that arise
during the rearing of fish (e.g. electricity, feed, wear of the
aquacultural system) were taken into account by calculating a
fixed amount per day. In total, 151 working hours of a research
associate (40 Euro per h), 257 working hours of a research
assistant (15 Euro per h) and 48 days of ongoing costs (25 Euro
per day) were included, resulting in an aggregate amount of
11,095 Euro per stocking season.
3 Results
3.1 Initial monitoring: identification of broodstock and
reintroduction habitats
In the initial monitoring, weatherfish populations suitable
for broodstock sampling were detected in four catchments
(Horloff: 50°25014.700 N, 8°52044.900 E; Queich: 49°13019.400 N,
8°15013.100 E; Streitgraben: 49°05043.000 N, 8°19003.700 E;
Weschnitz: 49°40025.500 N, 8°34056.100 E). Furthermore, three
catchments were assessed as suitable for weatherfish
reintroduction (Gersprenz: 49°50054.800 N, 8°50046.000 E; Rhein:
49°38045.900 N, 8°24030.700 E; Speyerbach: 49°18049.000 N;
8°17023.100 E) (Tab. 1). A table with all sites investigated during
the initial monitoring can be found in the supporting information
(Tab. S1).
3.2 Stocking of weatherfish
During the study period (2014–2016), approximately
275,000 eggs were produced from 38 females (mean L
T
±
standard deviation (SD) = 202 ± 27 mm; mean wet mass
(M
W
) ± SD = 47 ± 15 g). From these eggs, approximately
168,500 individuals reached the juvenile stage (resulting
mortality rate: 39%) and were released in identified sectors
(Fig. 1;Tab. 2). On the basis of a mean number of 56,167
released individuals per stocking season, the conducted cost
estimation revealed an expenditure of approximately 0.20 Euro
per released individual.
3.3 Post-release monitoring
In the Gersprenz catchment, seven individuals (size class:
7–8 cm) were recaptured in 2015 (40 traps) and one individual
(10 cm) in 2016 (50 traps). In the Rhein catchment, 37
individuals of two size classes (34 individuals of 10–14 cm and
3 individuals of 16–18 cm) were recaptured in 2016 (40 traps)
(Tab. 3).
4 Discussion
The low number of weatherfish populations identified
during the initial monitoring (Tab. 1; Tab. S1) illustrates the
species' critical situation within the study area (i.e. southwest
Germany) and consequently underlines the need for
conservation measures. However, the successful determina-
tion of weatherfish refuges ensured the opportunity of
broodstock sampling from populations that might be
genetically adapted to local conditions a factor considered
crucial for reintroduction success (Weeks et al., 2011;
Cochran-Biederman et al., 2015). A genetic characterization
of the populations selected for broodstock sampling might
further improve the reintroduction strategy with respect to
prioritization possibilities (Attard et al., 2016;Schmidt et al.,
2017). Numerous ditch systems located in the study area
generally met the species requirements but lacked suitable
spawning habitats like floodplains because ditches typically
prevent water from bursting its banks (Dollinger et al., 2015).
This observation might explain the frequently reported
absence of juvenile weatherfish in comparable systems and
leads to the assumption that successful reproduction in
ditches might be limited to years with high water levels in
spring. As the long-term absence of appropriate spawning
habitats can result in a lack of reproduction success, stock
enhancement might be particularly effective in these systems.
Generally, highly artificial water systems that are inhabited by
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B. Schreiber et al.: Knowl. Manag. Aquat. Ecosyst. 2018, 419, 43

Fig. 1. Map of the study area. Overview map on the left shows the location of the federal states of Rhineland-Palatinate and Hesse (dark grey) in
Germany (grey) and Europe (light grey; GADM, 2012), including codes of the countries bordering Germany. The dotted black line indicates the
international Rhine river basin district (European Environment Agency, 2011). Detailed map on the right shows the sectors investigated in the
initial monitoring, catchments used for the different stocking measures (reintroduction, endogenous enhancement, exogenous enhancement) and
the broodstock source used where no enhancement took place (Horloff). Black arrows indicate the broodstock origin used for reintroductions.
White lines show main rivers (GADM, 2012).
Table 1. Catchments investigated in the initial monitoring that were either selected as suitable for broodstock sampling (Horloff, Queich,
Streitgraben, Weschnitz) or for weatherfish reintroduction (Gersprenz, Rhein, Speyerbach). Furthermore, information includes the number of
investigated sectors per catchment, the number of fish traps, the electro-fishing distance and the number of caught weatherfish.
Catchment No. of investigated sectors No. of fish traps Electrofishing distance (m) No. of caught weatherfish
Gersprenz
*
6 262 –0
Horloff
**
17 170 500 49
Queich
**
15 150 –7
Rhein
*
6 131 300 0
Schwarzbach
***
3 373 200 1
Speyerbach
*
7 120 100 0
Streitgraben
**
260–44
Weschnitz
**
13 482 –124
Total 69 1748 1100 225
*
Catchments selected for reintroduction of weatherfish.
**
Catchments selected for broodstock sampling and endogenous enhancement.
***
Catchment selected for exogenous enhancement.
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B. Schreiber et al.: Knowl. Manag. Aquat. Ecosyst. 2018, 419, 43

weatherfish as secondary habitats (e.g. ditch systems) are
difficult to manage from a conservation point of view, as they
are built by humans to drain water from the field. Thus,
management activities that might be conducted to allow for
the development of flood plains might counteract the original
usage of these waters. However, since the weatherfish is listed
under Annex II of the Habitats Directive 92/43/EEC, sites
with weatherfish occurrence must be managed in accordance
with the ecological needs of the species.
The methods used for assisted reproduction and rearing of
juvenile weatherfish can be considered as efficient to address
the objectives considered in the present program as sufficient
stocking material could be provided every year (≥52,000
juveniles per year) (Tab. 2). A good feasibility of weatherfish
production was previously reported in several studies (Kouril
et al., 1996;Demény et al., 2009). However, comprehensive
investigations on the thermal requirements of weatherfish
larvae carried out along with the program helped to increase
their survival and growth rates during the rearing period
(Schreiber et al., 2017b). This illustrates how scientific
guidance of different steps in comparable conservation
programs may improve the prospects and hence is explicitly
recommended.
The total number (45) of individuals recaptured at two
reintroduction sites can be considered as relatively high
because traditional capturing methods (e.g. fish traps or
electro-fishing) were frequently reported as inefficient when
applied for weatherfish (Meyer and Hinrichs, 2000;Sigsgaard
et al., 2015)(Tab. 3). A solution to these problems might be the
implementation of environmental DNA (eDNA) monitoring
(Sigsgaard et al., 2015). Increasing catching efforts and eDNA
sampling are planned for the near future, especially for the
third so far unsuccessfully monitored reintroduction site
(Speyerbach). However, the clear size classification of
recaptured individuals indicates a certain survival of stocked
weatherfish (Tab. 3). Therefore, it can be assumed that the
conducted habitat assessment indicated suitable waters for
reintroduction and that the stocking strategy is generally
appropriate (for reintroduction and stock enhancement). Since
weatherfish reach maturity after 2–3 years (Kottelat and
Freyhof, 2007), a confirmation of successful reproduction and
estimations about the establishment of self-sustainable
reintroduced populations (IUCN, 1998) is still pending.
However, as the presence of appropriate spawning habitats
was considered as crucial, natural reproduction in the stocked
sectors is considered a realistic prospect. In order to assess the
Table 3. Number of recaptured individuals from weatherfish post-release monitoring conducted in areas used for reintroduction, including year
and date of monitoring, name of the monitored catchment, number of fish traps, number of recaptured individuals and size class of recaptured
individuals.
Year Dates Catchment No. of fish traps No. of recaptured individuals Size class (cm)
2015 23 September and 30 October Gersprenz 40 7 7–8
2016 22 September Rhein 40 34 10–14
316–18
2016 27 September and 18 October Gersprenz 50 1 10
Total ––130 45 –
Table 2. Number of weatherfish released into the selected water sections, subdivided by stock enhancement and reintroduction measures.
Information includes year of stocking, stocked catchment and the broodstock origin. For a geographical orientation, the reader is referred to
Figure 1.
Stock enhancement Reintroduction
Year of stocking Stocked
catchment
No. of released
individuals
Stocked catchment No. of released
individuals
Broodstock origin
(catchment)
2014 Streitgraben
*
24,000 Speyerbach 11,000 Streitgraben
2014 Weschnitz
*
12,000 Gersprenz 13,000 Weschnitz
Total for 2014 –36,000 –24,000 –
2015 Streitgraben
*
13,000 Speyerbach 7,500 Streitgraben
2015 Queich
*
10,000 Gersprenz 8,000 Weschnitz
2015 –– Rhein 18,000 Weschnitz
Total for 2015 –23,000 –33,500 –
2016 Streitgraben
*
6,000 Speyerbach 14,000 Streitgraben
2016 Schwarzbach
**
20,000 Gersprenz 5,000 Horloff
2016 –– Rhein 7,000 Horloff
Total for 2016 –26,000 –26,000 –
Total –85,000 –83,500 –
*
Stocking site is equivalent to the site of broodstock origin (i.e. endogenous enhancement).
**
Broodstock originates from the Horloff catchment (i.e. exogenous enhancement).
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B. Schreiber et al.: Knowl. Manag. Aquat. Ecosyst. 2018, 419, 43

success of stock enhancement, the establishment of a chemical
marking protocol for weatherfish fry is possible (e.g. with
oxytetracycline). However, marking success and mortality
during marking are hard to predict as the outcome of both is
driven by various factors (Hundt et al., 2015). Furthermore, a
parental assignment based on microsatellite markers can be a
promising alternative, but the polyploidy of weatherfish might
limit the feasibility of this method (Drozd et al., 2010;Zhao
et al., 2015). The possibility of using passive integrated
transponders (PIT-tags) for tagging of juvenile weatherfish
prior to release was discussed within this project as well.
However, since the small size of the stocked individuals
(L
T
=2–4 cm) prevented a save injection of the smallest
available transponders (12 mm), PIT-tagging of the stock
material would have required an extended rearing duration
prior to release, which might negatively influence the survival
of individuals after release. Furthermore, as the detection
efficiency of PIT-tags negatively correlates with the
density of marked fish in the reading area of the antenna, the
release of tagged individuals in great quantities might
limit the explanatory power of this method (Schmidt et al.,
2016). In order to investigate the fate of released individuals,
as well as to gain more insights into the movement
activity of weatherfish in general, an additional study with
larger PIT-tagged individuals is intended within the project at a
later stage.
A factor that needs more attention within the continuing
implementation of the project is an increased involvement
of socio-economic aspects, since the acceptance and support
of local people can positively influence the outcome of
reintroduction programs (IUCN, 1987,1998,2013;Bajomi
et al., 2013). This particular potential for improvement of the
project could be identified by completing the questionnaire
template drafted by Lee and Hughes (2008) (Tab. S2).
Furthermore, the questionnaire provides the possibility to
document reintroduction programs in a standardized way
(Sutherland et al., 2010). However, as it was originally
designed for waterbird re-establishment programs, the
questionnaire had to be slightly adopted for an application
for fish reintroduction. The revealed expenditure of 0.20 Euro
per released individual constitutes an estimation based on
assumptions only applicable for the circumstances under
which the present program was conducted (e.g. existing
infrastructure). Moreover, as the program is part of a larger
scientific project with additional investigations of other aspects
than stocking activities (Schreiber et al., 2017a,2017b,2018),
only approximations could be provided. Therefore, it has to be
emphasized that additional costs that were excluded from the
presented calculation (e.g. acquisition costs, investments
needed for other work stages) might lead to expenditures
that are much higher or lower than estimated.
As a conclusion, indicators for short-term success of
reintroduction and stock enhancement measures conducted
with hatchery-reared weatherfish fry could be detected (i.e.
survival of released individuals) but indicators for long-term
success (i.e. spawning of reintroduced individuals) are still
pending. Consequently, the present approach might be
effective for further federal states and countries with
critical populations, but for sustainable improvements,
stocking has to be maintained in future and individual steps
can be refined.
Supplementary Material
Supplementary figures and tables.
The Supplementary Material is available at https://www.
kmae-journal.org/10.1051/kmae/2018031/olm.
Acknowledgements. The authors would like to than k for financial
support by Struktur- und Genehmigungsdirektion Süd (Rheinland-
Pfalz), Regierungspräsidium Darmstadt (Hessen), and Hessisches
Landesamt für Naturschutz, Umwelt und Geologie. Furthermore,
as parts of the study were conducted at the Eusserthal Ecosystem
Research Station, University of Koblenz-Landau, we would like to
thank the research station staff.
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Cite this article as: Schreiber B, Korte E, Schmidt T, Schulz R. 2018. Reintroduction and stock enhancement of European weatherfish
(Misgurnus fossilis L.) in Rhineland-Palatinate and Hesse, Germany. Knowl. Manag. Aquat. Ecosyst., 419, 43.
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