Zingel Asper Research Articles

Effect of 12 mm PIT tags on the survival, growth, and ecologically significant behaviours of juvenile critically endangered endemic Zingel asper

Understanding the movement ecology and habitat use of freshwater fish is crucial for their conservation, with telemetry being an essential tool. Current tagging methods are restricted by the minimum body size of fish, as tags should not exceed 2% of the fish's body mass. This limitation hinders the study of juvenile small-bodied endangered species, as the reduced fitness of tagged individuals can negatively impact their populations. This study examines the feasibility of using 12-mm PIT tags on juvenile and subadult individuals (63–90 mm fork length) of the critically endangered Rhône streber, Zingel asper. Results indicate that tagging does not significantly affect survival, growth or behavioural traits, despite the tag weight being between 2.2% and 5.4% of the fish's weight. Tag retention was 100%, with 90% of individuals having the PIT tag fully encapsulated in the body cavity wall after 55 days. The only possible negative effect observed was a tendency, albeit statistically non-significant, for slower escape velocity in the smallest tagged individuals. These findings reduce the known minimum body size limit for 12-mm PIT tags for this species. However, the smallest individuals may be more sensitive to tagging, warranting careful consideration to avoid potential negative impacts on wild populations.

DNA metabarcoding suggests adaptive seasonal variation of individual trophic traits in a critically endangered fish.

Dietary studies are critical for understanding foraging strategies and have important applications in conservation and habitat management. We applied a robust metabarcoding protocol to characterize the diet of the critically endangered freshwater fish Zingel asper (the Rhone streber). We conducted modelling and simulation analyses to identify and characterize some of the drivers of individual trophic trait variation in this species. We found that population density and ontogeny had minor effects on the trophic niche of Z.asper. Instead, our results suggest that the majority of trophic niche variation was driven by seasonal variation in ecological opportunity. The total trophic niche width of Z.asper seasonally expanded to include a broader range of prey. Furthermore, null model simulations revealed that the increase of between-individual variation in autumn indicates that Z.asper become more opportunistic relative to summer and spring, rather than being associated with a seasonal specialization of individuals. Overall, our results suggest an adaptive variation of individual trophic traits in Z.asper: the species mainly consumes a few ephemeropteran taxa (Baetis fuscatus and Ecdyonurus) but seems to be capable of adapting its foraging strategy to maintain its body condition. This study illustrates how metabarcoding data obtained from faeces can be validated and combined with individual-based modelling and simulation approaches to explore inter- and intrapopulational individual trophic traits variation and to test hypotheses in the conventional analytic framework of trophic ecology.

Diet Metabarcoding Reveals Extensive Dietary Overlap between Two Benthic Stream Fishes (Zingel asper and Cottus gobio) and Provides Insights into Their Coexistence

Niche partitioning studies are essential to understand the mechanisms that allow ecologically similar species to coexist. The Rhone streber (Zingel asper) and the European bullhead (Cottus gobio) are both benthic riverine fishes that consume macroinvertebrates. Both species are protected under European legislature. We focused on trophic niche partitioning between these species, as sufficient access to trophic resources is an important requirement for long-term coexistence. We used a combination of faeces metabarcoding dietary data and prey community data to evaluate dietary overlap, trophic niche variation and dietary preferences. Sampling was performed in three sites along the Durance River (France). Both species consumed a wide range of macroinvertebrates but neither C. gobio nor Z. asper selected the most abundant taxa (chironomids and simuliids). Both species selected larger mayfly (Baetis and Ecdyonurus) and caddisfly (Hydropsyche) taxa. Dietary overlap was generally high but declined when large mayflies were rare. Contrasting secondary prey preferences and trophic niche variation may allow these species to exploit the same preferred mayflies in periods of abundance and to avoid competition during resource scarcity. We propose that dietary partitioning may support the coexistence of these two ecologically similar, benthic predators.

Growth variation in the endangered fish Zingel asper: Contribution of substrate quality, hydraulics, prey abundance, and water temperature

Abstract Intraspecific variation in life histories and its environmental correlates can indicate the degree of vulnerability to extinction of endangered taxa and guide conservation actions. Zingel asper (Percidae) is an endangered fish endemic to the Rhône catchment (France and Switzerland), where five populations subsist in separate river systems (Loue, Beaume, Durance, Verdon, and Doubs). Two populations of Z. asper differ in growth and longevity, but the existence of broader intraspecific differentiation in life histories and the environmental origins of this variation (if any) remain unknown. The age structure and growth profile of four populations of Z. asper (Loue, Beaume, Durance, and Verdon) and nine additional sub‐populations within the Durance system were determined by scale‐reading analysis, before evaluating the contribution of measured variation in substrate quality, hydraulics, prey availability, and water temperature to growth differentiation among and within populations. A trade‐off between early growth and longevity largely differentiated the populations of Z. asper along a slow (i.e. slower growth, smaller adult size, longevity of >5 years) to fast (i.e. faster growth, larger adult size, longevity of <4 years) continuum of life histories. This continuum differentiated populations from different river catchments along a south (Durance, Verdon) to north (Beaume, Loue) latitudinal gradient, and mapped onto an upstream–downstream gradient of sub‐populations within the Durance system. Differences in prey availability, hydraulics, and water temperature explained most of the growth variation among populations from different catchments, whereas local variation in prey availability, substrate quality, and water temperature mostly contributed to within‐river growth differentiation. These results indicate that short life cycles strongly expose all populations of Z. asper to extirpation and should motivate additional conservation actions. This study illustrates how quantifying intraspecific variation in life histories and its sensitivity to ecological context can reliably assess extinction risk and guide conservation actions by identifying endangered populations requiring priority management.

Bayesian hierarchical model used to analyze regression between fish body size and scale size: application to rare fish speciesZingel asper

Key-words: hierarchical Bayes model, backcalculation, fish, scales, Zingel asper Back-calculation allows to increase available data on fish growth. The accuracy of back-calculation models is of paramount importance for growth analysis. Frequentist and Bayesian hierarchical approaches were used for regression between fish body size and scale size for the rare fish species Zingel asper. The Bayesian approach permits more reliable estimation of back-calculated size, taking into account biological information and cohort variability. This method greatly improves estimation of backcalculated length when sampling is uneven and/or small.

Reproductive biology of the endangered percid <i>Zingel asper</i> in captivity: a histological description of the male reproductive cycle

The endemic Rhodanian percid Zingel asper (Linnaeus, 1758), is usually found throughout the Rhône basin, but this fish is now in sharp decline. Understanding its reproductive physiology is important so as to be able to artificially control its reproduction with a view to re-introducing it. This study was carried out on a population obtained by artificial fertilization and bred in external tanks. Fishes were observed from the juvenile stages through to adulthood. Patterns of testicular development were defined from histological observations. Testes of Z. asper were paired, elongated and fusiform dorsocaudal organs. The two lobes of each gonad joined together to form a duct that extended to the urogenital papillae. They showed a lobular structure. The testicular lobules were of the unrestricted spermatogonial type. Up to 10 months-old, most of the males were immature: their testes showed only type A spermatogonia. The appearance of type B spermatogonia in the lobules of a testis indicated the beginning of spermatogenesis in 10 months-old fish. Spermiogenesis occurred 24 months after the fertilization and, in 26 months-old fish, the cyst opened and released spermatozoa into the lumen of lobules. The spermiation belonged to a cystic type. During the third year, histological observations pointed to the same evolution of adult gonads as during the second year. Sexual maturity was reached in captive Z. asper after two years. The spawning occurred in May in the breeding conditions.

Development of 55 novel polymorphic microsatellite loci for the critically endangered Zingel asper L. (Actinopterygii: Perciformes: Percidae) and cross-species amplification in five other percids

By combining biotin-enrichment protocol and next generation pyrosequencing, through 454 GS-FLX Titanium technology, 55 polymorphic microsatellites loci with perfect motif were isolated from the Rhone streber (Zingel asper), a critically endangered European fish species. Eight multiplex PCR kits were optimised in order to genotype a total of 58 polymorphic loci, including three previously published loci. The level of genetic diversity was assessed for 68 Z. asper, 30 Sander lucioperca, 33 Perca fluviatilis and four Gymnocephalus schraetzer individuals. Amplification success was also assessed on Romanichthys valsanicola and Zingel streber using single individuals. These markers will be useful to investigate the population structure of the highly fragmented Rhone streber. They represent a powerful tool for conservation issues and evolutionary approaches of this endemic species. Moreover, part of our markers demonstrated applicability to other percid species, allowing for potential applications to fisheries and aquaculture management.

Twenty‐four hours in the life of Zingel asper

For the first time, radio-tracking observations were made over 24 h cycles during the growing season to quantify the habitat use and home range of Zingel asper, a critically endangered fish species, endemic to the Rhône River with a high risk of extinction (IUCN). New advances in radio telemetry with regard to the size of tags provided an opportunity to collect behavioural and habitat use information while remaining non-lethal. Zingel asper was characterized by small ranges of habitat use and, contrary to previous assumptions, the species was diurnal as illustrated by a smaller home range during the night than during daytime.

Microsatellite analysis of relatedness structure in young of the year of the endangered Zingel asper (Percidae) and implications for conservation

Summary1. Zingel asper is one of the most endangered freshwater fish of Western Europe. Because of critical habitat loss and fragmentation, stocking or reintroduction protocols are sometimes considered even though few data are available about the behaviour and biology of the species.2. The present study is the first attempt to explore the population genetic structure of juveniles (young of the year, YOY) of this endangered species using genetic markers (microsatellite loci). In the Beaume River (ardeche, France), Z. asper exhibits very low densities (10–80 fish per hectare), and it was expected that annual recruitment would comprise only few clutches (full‐ or half‐sibs groups).3. However, sibship reconstruction in one YOY cohort showed that more than 60% of the adult population reproduced. Dispersal rate in early YOY was high: relatedness estimates showed that only few months after hatching, YOY sibs were mixed among study sites. A large number of breeders together with high dispersal rates explain the high genetic variability observed in small populations of Z. asper.4. Conservation strategies for the species are discussed based on these results, emphasizing the importance of conserving population genetic variability and preserving habitat connectivity for juveniles.

Scale measurements as a conservation tool in endangered Zingel asper (Linnaeus, 1758)

Abstract Zingel asper (a percid) is a highly endangered endemic fish of the Rhone catchment (France). Scale reading was used to estimate age and growth rates in one of the two last remaining populations that are still present in relatively high densities (River Beaume). Scale reading was validated for the first time in Z. asper by comparing back‐calculated lengths from scale annual increment to actual lengths obtained by individual mark–recapture monitoring. The impacts of age or sampling site on individual growth rates were explored using generalized linear models. No major discrepancy was observed between actual and back‐calculated lengths. Longevity of Z. asper was inferred from the age data and did not exceed 3 years. Results showed variation in growth rates among ages (20 times higher for 1+ fish than for 2+ or 3+ fish) and also among sampling sites. The present work provided the first estimates of annual growth rates in the Beaume population. This study also showed that scale reading allowed a valuable trade‐off between accuracy and conservation imperatives that often imply avoiding invasive techniques such as the implantation of passive integrative transponders. Scale reading will be a valuable tool for future ecological studies in Z. asper and will help in developing conservation strategies for this species as longevity and growth patterns are two life‐history traits of major importance for the management of endangered populations. Copyright © 2007 John Wiley & Sons, Ltd.

Modelling population viability in fragmented environments: contribution to the conservation of an endangered percid (Zingel asper)

Zingel asper is an endemic percid of the Rhône catchment. The demography and habitat use of this endangered benthic species have been studied in previous works. The species exhibits natural low densities and clumped distribution related to habitat distribution. Based on these results, the authors build a stochastic equations network model, integrating spatial structure at intrapopulation level and vague density dependence. Calculation of density, growth rates, and local extinction rates globally match the field results. The numerical sensitivity analysis on extinction probabilities shows that adult and juvenile survival rates and spawning success (due to random events) are the key parameters of intrapatch dynamics. Low negative variations in these parameters increase extinction probabilities. The number of available connected patches and the dispersal rate drive the population persistence at the interpatch scale. Population extinction probability over 100 years is at least 0.4 for dispersal rate below 0.2, or when the number of connected patches is below 15. These results enlighten the role of dispersal in nonmigratory fish populations and should be useful in assessing the impact of riverine habitat fragmentation through river-damming and habitat loss.

Exploring Population Dynamics Patterns in a Rare Fish, Zingel asper, through Capture‐Mark‐Recapture Methods

Abstract: We performed a capture‐mark‐recapture study on one of the last populations of Zingel asper, an endemic percid species of the Rhône River basin in France. The distribution of Z. asper has decreased dramatically during the last century. We sampled three sites in suitable habitats in the Beaume River. No impact of individual tagging on survival was found. The demography of the population was analyzed using capture‐recapture methods that allow the estimation of survival, recruitment, and demographic growth rates. Annual survival rates were low (0.35–0.50). The level of transience was high (5% to 25%), suggesting that a significant number of individuals were highly mobile or shifted to suboptimal habitats. Seniority rates suggested random highly variable recruitment between years. The three sites had similar variation patterns in all demographic parameters, indicating broad spatial covariation in population dynamics. We found some local differences in demographic parameters, which could be linked to local habitat quality. Individual tagging allowed for the estimation of demographic parameters that improved our understanding of Z. asper population dynamics and revealed mechanisms that may affect population persistence, such as stochastic recruitment, low survival, and frequent dispersal. The fragmentation of habitat through river damming inhibits dispersal and represents a threat to the persistence of Z. asper in the Rhône basin. Our results offer evidence of the importance of dispersal in nonmigratory fishes and confirm the usefulness of individual tagging methods in rare fish demography.

Capture–recapture estimates of space used in streams (CRESUS) at the population scale: case study onZingel asper(percid), a threatened species of the Rhône catchment

In this study, capture–mark–recapture statistics were applied to spatial recapture histories to assess the intensity of fish restricted movements along the longitudinal axis of a river using a previously described model for survival and recruitment analysis. Adapting the stopover estimation method to spatial data, movement probabilities were then used to estimate space used at the population scale. This capture–recapture estimates of space used in streams (CRESUS) method may thus be seen as a complementary tool of classic home range methods and should be used to explore the consequence of behavioural strategies on population mechanisms. We propose a methodological example where movements and space use strategies of a Zingel asper (percid) population in the Beaume River (Ardèche, France) were directly estimated at the population scale taking account of the effects of different biotic or abiotic factors. Results showed differences in Z. asper space use patterns among sexes, periods of biological cycle (growing and spawning period), and types of mesohabitat. Downstream movements were more important during the spawning period and by the way the riffle was more intensively used.

Genetic structure of fragmented populations of a threatened endemic percid of the Rhône river: Zingel asper.

Zingel asper is an endemic percid of the Rhône basin considered to be critically endangered. This species was continuously distributed throughout the Rhône in 1900, but today only occupies 17% of its initial area. In the present study, five microsatellite loci were used to assess the level of genetic variability within and among populations localized in different sub-basins. Contrasting results were obtained for the three main populations from the Rhône. A reduced allelic diversity was observed for the two populations displaying the lowest patch sizes (length of the river system occupied); of these, a recent genetic bottleneck was detected for the population showing a particularly low density. However, the third population was characterized by a relatively large spatial extent, high local fish concentrations and an allelic diversity that was twice as high and associated with an equilibrium between mutation and drift. Thus, this population shows an apparently better evolutionary potential for long-term survival. Since 1930, a marked fragmentation of the whole Rhône system has appeared, related to the development of dams, and we assume that the significant genetic differentiation detected between the populations could mainly reflect the impact of this fragmentation. The high turnover of the Z. asper populations, and the major role of dispersal in population persistence (highlighted in a recent population dynamics study), indeed suggest that the differentiation observed could mainly have arisen from habitat fragmentation in recent history.

Diet and growth of the endangered Zingel asper in the Durance River

Annual monitoring of the apron Zingel asper in the Durance River, a tributary of the Rhône in which the fish is endemic, indicated its narrow diet range. Three types of prey made up the basic diet: Diptera (Simulidae and Chironomidae), mainly in winter, and Ephemeroptera (Baetidae) and Trichoptera (Hydropsychidae), during the rest of the year. Although some potential prey (Coleoptera and Gammaridae) were present in the substratum, they were not found in the stomach contents of the apron. In spring specific food items (Heptageneidae) appeared to be actively searched for as indicated by stomach contents. This period coincided with the renewal of growth. More than 80% of the annual occurred before the beginning of autumn.

Use of a generalised linear model to test habitat preferences: the example of Zingel asper, an endemic endangered percid of the River Rhône

SUMMARY 1. A study of microhabitat preferences was conducted on Zingel asper, an endangered endemic species from the Rhône catchment. A generalised linear model allowed us to test statistically the non‐random habitat selection and the effect of season and site on this habitat selection.2. The analysis detected significant preferences for the three physical variables considered: water depth, water velocity and substratum size.3. A seasonal shift in the substratum size preference was found: preference for stones increasing during the spawning season. Depth preference varied between sites, suggesting a possible plasticity in habitat selection.4. These results suggest that the availability of suitable physical habitat plays a significant role in determining fish distribution in the River Beaume.

Current status of the riverine fishes of the French Mediterranean basin

We have undertaken a study of current knowledge on the distribution and abundance of 10 freshwater fish species with a restricted geographical range, recorded since 1950 from French rivers flowing into the Mediterranean, including those in Corsica. In order of decreasing abundance these are: Leuciscus (Telestes) souffia, Chondrostoma toxostoma, Barbus meridionalis, Zingel asper, Blennius fluviatilis, Aphanius fasciatus, Alosa fallax rhodanensis, Aphanius iberus, Valencia hispanica and Cottus petiti. Distribution maps for the first seven taxa have been produced on the basis of 3124 fisheries surveys included within Fisheries Orientation Schemes carried out in French départements. These taxa are distributed in three different zoogeographical regions: a northern mainland region, a southern mainland region and the island of Corsica. The distribution of these taxa in the major rivers is shown on maps by means of lines of varying thickness and for the minor river courses by shading. The detailed habitat preferences of the first three species have been determined, showing a succession of Barbus meridionalis, Leuciscus (Telestes) souffia and Chondrostoma toxostoma going downstream within the southern mainland region. Following a discussion of the requirements of each of these species and of the threats that they face within the study area, their status is defined according to the International Union for the Conservation of Nature definitions.