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Invasive predators pose a critical threat to native taxa. Body size plays an important role in mediating the interactions of predator and prey. For piscivorous fishes, increased predator body size can be accompanied by the selection of increasingly larger prey or may reflect a mix of small and large prey. Knowledge of such interactions helps determine how predation affects population vital rates. Here, we assessed the predatory effects of invasive Brown Trout (Salmo trutta) on populations of native Rio Grande Sucker (Catostomus plebeius) and Rio Grande Chub (Gila pandora) in streams of the Jemez River watershed (New Mexico, USA). Trout diets were sampled every two weeks during the 2020 growing season. Predator and prey body lengths were measured to examine relationships to better understand patterns of piscivory and quantify the threat Brown Trout pose to populations of Rio Grande Chub and Rio Grande Sucker. Across all streams and sampling dates, 7% of Brown Trout diets contained fish. Predator–prey length relationships reflected a ‘wedge’ pattern, indicating that Brown Trout consumed an increasing range of prey body sizes as they grew larger. Rio Grande Sucker and Rio Grande Chub comprised 46% of consumed fishes. The findings demonstrated that Rio Grande Sucker and Rio Grande Chub experience constant predation over the growing season by Brown Trout. Moreover, our study provides evidence that these invasive predators pose a threat to the viability of Rio Grande Chub and Rio Grande Sucker populations. Conservation efforts to protect these chub and sucker populations must account for and directly address predation by invasive Brown Trout.

Stream restorations are increasingly critical for managing and recovering freshwater biodiversity in human-dominated landscapes. However, few studies have quantifiedhow rehabilitative actions promulgate through aquatic communities over decades. Here, a long-term dataset is analyzed for fish assemblage change, incorporating data pre- and post-restoration periods, and testing the extent to which native assemblage stability increased over time. In the late 1950s, a large capacity dam was installed on Putah Creek (Solano County, CA, USA) which altered the natural flow regime, channel structure, geomorphic processes, and overall ecological function. Notably, downstream flows were reduced (especially during summer months) resulting in an aquatic assemblage dominated by warmwater nonnative species, while endemic native species subsisted at low levels as subordinates. A court-mediated Accord was ratified in 2000 providing a more natural flow regime, specifically for native and anadromous fishes in the stream. Richness of nonnative species decreased at every site following the Accord, while richness of native species increased or stayed constant. At the three most upstream sites, native species richness increased over time and ultimately exceeded nonnative richness. Native assemblage recovery was strongest upriver, closer to flow releases and habitat restoration activities, and decreased longitudinally downstream. Rank-abundance curves through time revealed that while species evenness was low throughout the study, dominance shifted from nonnative to native species in the upstream sites coincident with rehabilitation efforts. Mean rank shifts decreased following flow rehabilitation; thus the assemblage became increasingly stable over time following flow rehabilitation. Putah Creek’s rehabilitation may represent a model for others interested in improving endemic freshwater communities in degraded ecosystems.

Producción Científica, 1.Most freshwater fish need to move freely through rivers to complete their lifecycles. Thus, river barriers (e.g. dams, culverts and gauging stations) may delay,hinder or even block their longitudinal movements, affecting fish conservation.The most widespread solution to allow upstream fish migration are fishways,whereas downstream migration is basically facilitated through spillways, turbinesor specific solutions such as bypass systems.2. So far, studies and scientific discussions concerning bidirectional movementsthrough fishways are scarce and focused on large dams and reservoirs, mainlywith large migratory species such as salmonids, rather than smaller facilities andlesser known species.3. This study investigated bidirectional movements through a small run-of-the-riverhydropower plant with a pool-and-orifice type fishway, using the Iberian barbel(Luciobarbus bocagei), a potamodromous cyprinid, as the target species. Passiveintegrated transponder and radio tracking data were collected over 4 years andcombined to characterize upstream and downstream movements. The studyfocused primarily on fish movements through the fishway, but also estimated themultiple associated routes of passage.4. The results show diverse fish movements with inter- and intra-annual variability,with several individuals performing bidirectional movements and even some fishreturning over the years.5. The documented movements and observations indicate that fishways can serveas an effective bidirectional migration corridor for fish, potentially enhancing theconservation efforts for potamodromous species. This study supports thedecision to use fishways as an overall mitigation tool to reduce the impact ofsmall hydropower facilities on fish., European Union’s Horizon 2020 research and innovation program. grant agreement no.727830, European Union’s Horizon 2020 research and innovation programme under the Marie Skłodowska-Curie grant agreement no.101032024

Dam impoundment can cause many adverse impacts on fish assemblages upstream of dams. Here, we investigated fish diversity in one plateau riverine reservoir (Wanfeng Reservoir) using environmental DNA (eDNA) metabarcoding technology. The following conclusions were drawn: (1) 39 species of fish were monitored belonging to 9 orders and 13 families in the Wanfeng Reservoir, most of which were Cypriniformes and included a variety of common farmed fish belonging to Culter, Oreochromis, Acipenser, and Clarias; (2) the fish assemblage structures in the Up (upstream section), Mid (midstream section), and RA (reservoir area section) of this reservoir was significantly different (p-value < 0.01); (3) among the 7 environmental variables that were measured (Tem, TDS, Sal, pH, DO, NH4+, and Tra), DO (p-value < 0.01) and pH (p-value < 0.05) were the main environmental stressors causing differences in fish assemblages in different sites of the Wanfeng Reservoir. This study concluded that dam construction in the karst region provided habitats for the establishment and dispersal of exotic fish.

The spatial–temporal patterns of fish assemblages in lotic systems can provide useful information in developing effective conservation measures. This study aimed to explore the spatial and seasonal changes in fish assemblages and their association with environmental factors in mountain streams of the Ren River, southwest China. Field investigations were conducted at 18 sites during the rainy and dry seasons in 2017. A total of 1,330 individuals, belonging to three orders, eight families, 19 genera, and 21 species, were collected. Analysis of similarities (ANOSIM) showed that the structure of fish assemblages varied significantly at the spatial scale, but not at the seasonal scale. In low‐order sites, fish assemblages were mainly dominated by cold‐water and rheophilic species (e.g., Rhynchocypris oxycephalus, Scaphesthes macrolepis, Metahomaloptera omeiensis, and Gnathopogon herzensteini), while those in high‐order sites were predominated by warm‐water and eurytopic or stagnophilic species (e.g., Squalidus argentatus, Hemiculter leucisculus, and Zacco platypus). Canonical correspondence analysis (CCA) showed that the fish assemblages were structured by a combination of large‐scale landscape factors (e.g., altitude and C‐link) and small‐scale habitat features (e.g., channel width, water temperature, and depth). Among these factors, landscape had the greatest influence on fish assemblages, while local habitat variables were less important or were only significant in certain seasons., This study demonstrated how fish assemblages changed at different spatial and temporal scales in this mountain river. Furthermore, environmental factors that contributed most to the observed spatial–temporal patterns of fish assemblage structure were identified. These results provide useful information in understanding the mechanisms structuring fish assemblages and making effective protection measures.

The study described the length–weight relationships (LWRs) and diversity status of fishes in the midstream of the Jialing River, which is the largest tributary of the upper Yangtze River, China. A total of 4592 specimens from 53 fish species belonging to three orders and eight families were collected from December 2021 to November 2022. The results showed that Culter oxycephaloides, Xenocypris davidi, Hemibarbus labeo, Hemiculter tchangi were dominant fish species in the study region. Twenty-five fish species (IRI ≥ 10) were subjected to LWR analysis, and the regression parameters a and b for fish species varied from 0.006 to 0.333 and 2.129 to 3.391. Eleven fish species were determined to have isometric growth, and 14 fish species were determined to have allometric growth. The diversity analyses suggested that the diversity status of fishes were kept relatively stable during the sampling period and that the fishes suffered moderate disturbance in the midstream of the Jialing River. The present study provided basic biology data for fish conservation and management after the fishing ban in the Jialing River.

Capacity to cope with warming temperatures is a key determining factor of species' persistence under global climate change. Many successful invasive species have heightened thermal tolerance relative to their native counterparts, which may provide competitive advantages for habitat utilization and resource acquisition under warming scenarios, ultimately contributing to radically altered community composition. Enhanced transcriptional plasticity may be an important factor conferring superior abilities to cope with environmental stress, but the molecular mechanisms driving key differences of organismal traits in invasive versus native species are not well known. Although it is predicted that established invaders will evolve canalized phenotypes well‐adapted to new environments, it is not clear whether the same expectations are true for invaders of variable thermal environments or under climate warming scenarios where abilities to cope with fluctuating and increasing temperatures may provide fitness advantages. Here, we compare a highly successful invasive fish and a sympatric endangered native fish living in a dynamic estuarine environment that is projected to warm under climate change. We linked organismal physiological limits with global transcriptional responses at multiple common relative and absolute temperature thresholds and determined that heightened thermal tolerance of invasive Inland Silversides (Menidia beryllina) is associated with transcriptional changes that are greater both in the number of genes and the magnitude of response relative to native Delta Smelt (Hypomesus transpacificus). Modulated genes contributed to the enrichment of biological processes that differed between species and generally increased with temperature. These results are in concordance with the hypothesis that transcriptional plasticity may play a key role in determining population persistence, species interactions, and shaping community assemblages under climate change. Future studies encompassing a wider range of species and taxa are needed to determine whether this is a general pattern found between native and invasive species more broadly.

The Beibu Gulf is considered as one of China’s four major fishing grounds, although the substantial overexploitation of fisheries has led to the collapse of many fish stocks, and to changes to spawning grounds in recent decades. Classifying fish eggs is an important way to monitor the recruitment process and identify the spawning sites of fish. However, the lack of a basis for morphological identification and difficulties in correctly identifying fish eggs based on morphological characteristics has limited scientific studies. In the present study, we identified fish eggs using molecular detection of cytochrome c oxidase subunit I and cytochrome b fragments. Ichthyoplankton surveys were conducted in the spring and late autumn–winter of 2020 in the eastern Beibu Gulf. Among the DNA extracted from the 873 chosen fish eggs, we successfully obtained 541 high-quality cytochrome c oxidase subunit I sequences and 41 high-quality cytochrome b sequences. We successfully identified 212 fish eggs (36.4%) from 32 species; 291 eggs (50.0%) showed ambiguous species delimitation, and 79 eggs (13.6%) could not be identified. Among the identified species, we found 25 species in spring and 25 species in late autumn–winter, out of which 18 species occurred in both seasons. We also obtained high resolution photographs of fish eggs at the species level for further morphological analysis and identification. The present study confirms the efficacy of using molecular methods to identify fish species from eggs and provides valuable information for protecting the spawning ground of economically valuable fish and for managing fishery resources.

Anthropogenic introgressive hybridization is increasingly common in many ecosystems, with inland waters being particularly sensitive to bioinvasions of interfertile non-native taxa. Salmonid native populations are detrimentally affected by such human-induced secondary contacts in several countries promoting sport and commercial salmonid fisheries. In northern Italy, the Critically Endangered marble trout Salmo marmoratus Cuvier, 1829, is a species with exceptional cultural, economic, and conservation value. Supporting breeding programs based on phenotypic selection of wild-caught and captive broodstock is a widespread management practice to supplement local marble populations with both declared conservation and exploitation goals. Using mtDNA and nDNA markers (D-loop; 15 microsatellites) we compare a hatchery-bred sample of marble trout used as broodstock for support breeding with a smaller sample of wild-caught phenotypically selected individuals collected in the Toce River, a large glacial river within the Lake Maggiore basin (northern Italy and southern Switzerland). We measured genetic integrity and introgression levels with non-native Atlantic S. trutta, a non-native species massively introduced in the last two centuries. Consistent levels of introgression were found in these two samples, but asymmetrical introgression with higher mtDNA introgression levels was observed in hatchery-bred individuals. The detected genetic structure of wild-caught and domesticated stocks suggest that in synergy with potential domestication effects, inbreeding and genetic drift, caused by small number of founders and closed reproductive cycle, this practice can have negative effects on the genetic diversity and integrity of the wild population. On the other hand, our preliminary analysis of the Toce River sample suggests that this population may contain genetically pure individuals, thus acting as a key repository of genetic diversity for the long-term conservation of this species. The lack of correspondence between a set of coded coloration traits and genetic traits in both samples highlights the limits of using phenotypic selection during artificial breeding, as also supported by previous studies on this species. Our results strongly suggest to revise current supportive breeding programmes of the marble trout in this system. We finally propose possible future directions for the restoration and sustainable management of the genetic diversity of the Toce River marble trout population.

The objective of this study was to develop a successful freezing protocol for cryopreservation of Danube barbel sperm, and to identify the presence of different spermatozoa subpopulations. By testing different concentrations of different cryoprotectants, we determined that the use of 5% dimethyl sulfoxide (DMSO) yielded the highest total motility of ~25%. Cooling rates influenced by frame height and cooling time in liquid nitrogen vapor showed that a frame height of 3 cm and cooling time of 2 min yielded the highest post-thaw motility. Supplementation of cryomedia with 0.1 M of sugars led to an increase in the total post-thaw motility by ~50%, while protein supplementation lowered post-thaw motility. Motile spermatozoa hierarchically clustered according to their motility parameters, displaying a four-subpopulation (SP1-SP4) structure. SP1 was defined by low values of velocity but high overall linearity; SP2 was comprised of fast non-linear spermatozoa, that had high velocity values but low linearity; SP3 was characterized by fast linear spermatozoa, and SP4 by slow non-linear spermatozoa. Protocols developed in this study will lead to the creation of new and enhanced conservation strategies for this species.

Atlantic salmon are facing population declines and loss of productivity within populations due to anthropogenic impact factors and reduced survival at sea. Biobanking is an increasingly used tool to conserve the genetic integrity and diversity of populations threatened by extirpation. The aim of the current article is to discuss the opportunities and challenges that increased use of cryopreservation brings to biobanking activities, using the Norwegian Gene Bank (NGB) for Atlantic salmon as a model system. The NGB was established in 1985 and involves a traditional living gene bank, as well as “frozen gene bank” where paternal germplasm is stored as cryopreserved sperm. Cryopreservation is a method where cells or tissues are frozen in liquid nitrogen to temperatures where all biological processes are paused, thus allowing the cells to remain viable after later warming/thawing to temperatures above 0°C. Cryopreservation is therefore used in long‐term preservation of genetic diversity and characteristics of wild populations. Until recently, implementation of large scale use of cryopreserved sperm in the live gene bank has been limited by a lack of protocols/capacity to preserve larger portions of sperms. More recent developments in cryopreservation methodologies, now enables preservation of samples sufficient for mass fertilization. Mass fertilization by cryopreserved sperm opens new opportunities to gene bank operations, including increased capacity to restore lost populations, mitigation of genetic changes in broodstock fish, as well as increased capacity at live gene bank facilities through the replacement of older males with frozen sperm. Knowledge demands regarding potential genetic damage to cryopreserved milt and potential epigenetic effects caused by the cryopreservation procedure should, however, be addressed.

The Amazon River Basin, one of the world’s most threatened ecosystems, has an enormous diversity of fish species, a result of temporally and spatially complex habitat containing biogeochemically different river systems. The annual hydrologic cycle results in floodplain lakes during low water and inundates forests during high water, exposing fish to different resources and environmental conditions. The two principal river systems in the central Brazilian Amazon are blackwater, with nutrient-poor acidic water, and nutrient-rich whitewater. Although species-rich, the Amazon Basin is data-poor in terms of comparative studies on a regional scale. We analyzed data sets from independent sampling studies of pelagic fish in 16 floodplain lakes, nine whitewater (Rio Solimões) and seven blackwater (Rio Negro), in the central Amazon Basin of Brazil. Our findings suggest striking similarities in pelagic fish diversity patterns. Species richness was virtually equal (165 in whitewater and 168 in blackwater). Both species richness, and number of migratory species, per lake increased toward the confluence of the rivers in both systems in our study. The proportion of unique species was also similar in whitewater lakes and blackwater (41 and 43%, respectively), boosting total regional richness to 237 species. However, species composition in whitewater lakes was more homogenous (lower β diversity), and species composition was associated with conductivity and pH in whitewater, but with dissolved oxygen and transparency in blackwater. Therefore, regional fish diversity cannot be represented by sampling one lake or even one drainage system, but must include multiple lakes from both systems. These two systems may differ in sensitivity to anthropogenic stressors such as damming and deforestation.

Simple Summary This study aims to understand if the threats to freshwater-dependent species identified by The International Union for Conservation of Nature Red List of Threatened Species are correctly supported by valid literature. The results show that 99% of threats are not supported by validated published scientific knowledge. This may lead to ineffective conservation and management plans. Funding to study and fill baseline knowledge gaps about threats should be a priority. Abstract Freshwater ecosystems are disproportionally important for biodiversity conservation, as they support more than 9% of known animal species while representing less than 1% of the Earth’s surface. However, the vast majority of the threats (99%, or 826 out of 837) identified by the International Union for Conservation of Nature Red List of Threatened Species known to affect the 434 known freshwater-dependent fish and lampreys of Europe are not supported by validated published scientific knowledge. This general lack of information about freshwater-dependent fish and lamprey species may have deleterious effects on species conservation, and additional funding is required to fill baseline knowledge gaps.

The Yarlung Zangbo River is the largest river on the Tibetan Plateau, which is considered a hotspot of biodiversity conservation efforts. In this study, the fish fauna of the middle and lower Yarlung Zangbo River was investigated, to explore the species composition and spatial patterns of fish assemblages as well as the associated environmental factors. Thirty-four sites across an elevation of 589 to 3410 m were sampled in 2015 and 2016. A total of 35 species—28 native and seven exotic—was collected. Of these species, four were described for the first time, 14 were endemic to the Yarlung Zangbo-Brahmaputra River drainage and five are considered endangered. Cluster analysis revealed significant spatial changes in fish assemblages along the longitudinal gradient. Two site-groups separated by the Yarlung Zangbo Grand Canyon were identified, corresponding to midstream and downstream. In the midstream, fish assemblages were characterized by typical plateau fish species (e.g., Schizopygopsis younghusbandi, Schizothorax oconnori, Triplophysa stenura, Triplophysa brevicauda, Schizothorax macropogon, Triplophysa tibetana and Ptychobarbus dipogon), while in the downstream fish assemblages were characterized jointly by plateau species (e.g., Schizothorax curilabiatus and Schizothorax molesworthi) and oriental species (e.g., Garra tibetana, Psilorhynchus homaloptera, Pseudecheneis sulcata, Exostoma tenuicaudata, Parachiloglanis hodgarti, Neolissochilus hexagonolepis and Garra yajiangensis). Canonical correspondence analysis (CCA) showed that altitude, channel width and the density of macroinvertebrates were the main environmental factors determining the spatial distribution of fish assemblages. This study is an important step towards understanding fish assemblages in the middle and lower Yarlung Zangbo River and will help with future efforts to protect aquatic communities and their habitats.

Fish passes facilitate fish movement in fragmented river systems, yet they can also provide important habitat functions. This study investigated the fish community composition of different constructed habitat types (fluvial habitats, floodplain ponds) within fish passes in relation to habitat characteristics in order to deduce recommendations for fish-friendly designs of such structures. Fish community structures within passes differed significantly from those in the main river, comprising a high number of rheophilic species in fluvial habitats (Thymallus thymallus, Hucho hucho, Salmo trutta, Cottus gobio, Chondrostoma nasus, and Barbus barbus), and of stagnophilic species in floodplain ponds (Rhodeus amarus, Scardinius erythrophthalmus, Misgurnus bipartitus, and Tinca tinca). During summer, floodplain ponds also provided important juvenile habitats for the target species C. nasus and B. barbus. Differences between the two habitat types in fish abundance were mostly explained by differences in macrophyte coverage, gravel, boulders, temperature, and current speed. The findings of this study stress the important habitat functions of fish passes. They also suggest that integration of diverse habitat structures, especially of currently hardly considered constructed floodplain ponds into fish passes, can greatly enhance their fish communities and contribute to the restoration of several declining target species of conservation.

Delimiting ichthyoplankton is fundamental work for monitoring the recruitment process and identifying the spawning and nursing grounds of fishes. Nevertheless, it is extremely difficult to identify the fish during the early stages at the species level based on morphological characters because of the paucity of diagnostic features. In this study, we investigated the fish larval community through large-scale ecosystemic sampling in South China Sea (SCS) during 2013 and 2017 using DNA barcodes. To maintain the morphologies of fish larvae, we preserved the larvae in formalin and developed a technique to recover their DNA. Among the 3,500 chosen larvae, we successfully extracted DNA from 2,787 larval samples and obtained 1,006 high-quality sequences. Blast searches showed that 408 larvae (i.e., 40.5%) could be unambiguously identified to species, 413 larvae (i.e., 41.1%) were ambiguously species delimitation, and 185 larvae (i.e., 18.4%) showed a low match similarity with target sequences. A total of 101 species were identified, among which 38 and 33 species corresponded to demersal and reef-associated species, whereas the remaining 30 species corresponded to benthopelagic, pelagic-oceanic, bathypelagic, and pelagic-neritic species. High-quality larval photographs of the 101 diagnosed species showed intact morphological characters and thus provided a reference for identifying fish species during the early stages based on morphological characters. Our study highlighted the possibility of recovering and amplifying DNA from formalin-fixed samples and provided new insight into the fish larval community in the SCS.

We report here the complete mitochondrial (mt) genomes of six individuals of Cheilinus undulatus (Napoleon Wrasse), an endangered marine fish species. The six mt DNA sequences had an average size of 17,000 kb and encoded 22 tRNA, two sRNA, 13 highly conserved protein coding genes and a control region. The polymorphic variation (control region) in these six individuals suggests their potential use as a specific marker for phylogeographic conservation. Moreover, the sequence polymorphism within the control region (D-loop) suggests that this locus can be applied for phylogenetic studies.

Protected areas are frequently established as a management tool to conserve terrestrial and aquatic habitats and species. Monitoring and evaluation are a necessary part of adaptive management to determine whether such protected areas are effectively meeting their objectives. While numerous initiatives have developed methods to evaluate terrestrial and marine protected areas (MPAs), similar efforts and resources are lacking for freshwater protected areas (FPAs), which have become widespread as a community-based fisheries management approach in the Lower Mekong Basin (LMB). This review summarizes published literature on the evaluation of marine and freshwater protected areas to provide guidance on the evaluation of community-managed FPAs in the LMB. Specifically, the review examines several indicators related to common objectives of aquatic protected areas and provides considerations for measuring these indicators in the context of community-managed freshwater protected areas in the LMB. Key conclusions include that first, FPAs should be established with clearly defined objectives, and these objectives should inform the selection of indicators for evaluation. Second, indicators identified for MPAs are highly relevant to FPAs, although methods may require adaptation to a freshwater environment. Finally, socioeconomic and governance indicators are overlooked in both MPA and FPA evaluations compared to biophysical indicators, and interdisciplinary assessment teams could ensure these indicators receive adequate consideration.

Fish behavior measurements are important for river and fishery scientists to protect fish resources and for ecological engineers to guide ecosystem conservation but they can pose a practical challenge. In this study, an acoustic camera was used to observe the migration patterns of fish species downstream of an under-construction hydroelectric dam, the Lianghekou dam in the middle Yalong River, China. The fixed-point method was employed to continuously measure fish migration using a dual-frequency identification sonar (DIDSON) during the spawning periods from April to August. The fish number and length measured by sonar were in fairly good agreement with the results of manual counting and field fishing, respectively. The results showed that the number of fish individuals migrating upstream (NFU) and fish length varied monthly and diurnally, and the NFU measured at dark twilight were 2–3 times greater than those measured during the daytime. The analysis showed that the upstream migratory behavior is dominated by the combined actions of river discharge, water temperature, and time of day. Based on the results, we suggest that the suitable operation time for future fish passage facilities could be when the river discharge ranges from 500 m3/s to 1500 m3/s and the water temperature ranges from 13 °C to 16 °C when the fishes in the study area mostly migrated upstream. The optimal operation time could be at night when the river discharge and water temperature are approximately 1000 m3/s and 15 °C, respectively. Although the indirect evidence of fish migration was recorded at a single location, this study reveals the great potential of acoustic cameras for measuring fish migration behavior downstream from hydropower stations which could be helpful for fish passage studies and fish resource conservation in China.

Knowledge on the extent and mechanisms of fish damage caused by hydropower facilities is important for the conservation of fish populations. Herein, we assessed the effects of hydropower turbine passage on internal fish injuries using X-ray technology. A total of 902 specimens from seven native European fish species were screened for 36 types of internal injuries and 86 external injuries evaluated with a previously published protocol. The applied systematic visual evaluation of X-ray images successfully detected skeletal injuries, swim bladder anomalies, emphysema, free intraperitoneal gas and hemorrhages. Injuries related to handling and to impacts of different parts of the hydropower structure could be clearly distinguished applying multivariate statistics and the data often explained delayed mortality within 96 h after turbine passage. The internal injuries could clearly be assigned to specific physical impacts resulting from turbine passage such as swim bladder rupture due to abrupt pressure change or fractures of skeletal parts due to blade-strike, fluid shear or severe turbulence. Generally, internal injuries were rarely depicted by external evaluation. For example, 29% of individuals with vertebral fractures did not present externally visible signs of severe injury. A combination of the external and internal injury evaluation allows quantifying and comparing fish injuries across sites, and can help to identify the technologies and operational procedures which minimize harm to fish in the context of assessing hydropower-related fish injuries as well as in assessing fish welfare.

In the autumn 2010 ichthyofauna was investigated in ROSCI0103 Buzau meadow Natura 2000 site (from Siriu dam to near Vișani locality, in main riverbed). The status of fish species of community interest (An. II / H.D.) inside of ichthyocenoses, as abundance, biomass and anthropogenic impact were assessed. In this sites it was recorded 4 species of Community Interest: or , but in comparison with Standard Sheet of Natura 2000 ROSCI0103 which contain also 4 species but missing, in addition is . Between abundance and biomass of fish species is different from submountain to plain area: and in submountain area to from hill area to in plain area were dominating species as abundance and biomass. A main anthropogenic pressure consists in the building of dams in investigated water bodies (like Siriu dam), which stop the fish movement at the normal water levels (every define time the dam is open disturbing the water transparency affecting fish populations), also the ballast exploitation from riverbed and pollution by locals and tourist increase negative impact on fish community.

Pomacentridae is a common family in the aquarium fish trade. Most species are harvested from nature. Here we evaluate the following water parameters in the pomacentrid sergeant major,Abudefdufsaxatilis(Linnaeus, 1758), to assess their stress level during a 24, 48, and 72 hours transport: dissolved oxygen (DO), total ammonia, and pH. In addition, we evaluated the following physiological parameters: plasma osmolality, muscle water content, blood glucose, and the enzyme activities of the branchial carbonic anhydrase (CA), the hepatic glutathione S-transferase (GST), catalase (CAT), and superoxide dismutase (SOD). The mortality of fish measuring >6 cm total length was 22%, while no mortality was observed for fish measuring

A wealth of data exists on the ecophysiological constraints of many fishes, but much of this information is underutilized in recovery plans due to a lack of synthesis. We used the imperiled green sturgeon as an example of how a quantitative synthesis of physiological data can inform conservation plans., Reversing global declines in the abundance and diversity of fishes is dependent on science-based conservation solutions. A wealth of data exist on the ecophysiological constraints of many fishes, but much of this information is underutilized in recovery plans due to a lack of synthesis. Here, we used the imperiled green sturgeon (Acipenser medirostris) as an example of how a quantitative synthesis of physiological data can inform conservation plans, identify knowledge gaps and direct future research actions. We reviewed and extracted metadata from peer-reviewed papers on green sturgeon. A total of 105 publications were identified, spanning multiple disciplines, with the primary focus being conservation physiology (23.8%). A meta-analytical approach was chosen to summarize the mean effects of prominent stressors (elevated temperatures, salinity, low food availability and contaminants) on several physiological traits (growth, thermal tolerance, swimming performance and heat shock protein expression). All examined stressors significantly impaired green sturgeon growth, and additional stressor-specific costs were documented. These findings were then used to suggest several management actions, such as mitigating salt intrusion in nursery habitats and maintaining water temperatures within optimal ranges during peak spawning periods. Key data gaps were also identified; research efforts have been biased towards juvenile (38.1%) and adult (35.2%) life-history stages, and less data are available for early life-history stages (embryonic, 11.4%; yolk-sac larvae, 12.4%; and post yolk-sac larvae, 16.2%). Similarly, most data were collected from single-stressor studies (91.4%) and there is an urgent need to understand interactions among stressors as anthropogenic change is multi-variate and dynamic. Collectively, these findings provide an example of how meta-analytic reviews are a powerful tool to inform management actions, with the end goal of maximizing conservation gains from research efforts.

Human modification of floodplain ecosystems is widespread and a major threat to fish populations, particularly in the tropics where fish diversity and rates of floodplain degradation are high. Identifying measures to minimize the susceptibility of floodplain fishes to habitat modification requires understanding dry-season lake habitat selection for species of conservation concern. This study examined the effects of environmental factors on dry-season floodplain lake habitat selection by arapaima (Arapaima spp.) and determined the extent to which they differed across three size classes. In floodplain lakes of the lower Amazon River, variables were measured at locations representing habitat availability and compared with measurements taken where arapaima were observed during surface breathing. Regression models were used to account for between-lake variation in the presence of arapaima owing to nearby fishing communities. The probability of arapaima presence at each sample location was modelled based on the variables measured. The results indicated that arapaima expressed distinct habitat selection patterns, which differed significantly across size classes. The general pattern observed was that all arapaima were more likely to be found in deeper, more turbid, and higher conductivity locations, whereas smaller arapaima were more likely to remain near dense beds of floating macrophytes. The probability of arapaima presence differed among fishing community territories, reflecting differences in management schemes. Deeper, macrophyte-rich sections of floodplain lakes appear to provide key habitats for arapaima and deserve consideration for becoming priority targets for conservation of the rich diversity of fish species in these systems. US Geological Survey, Virginia Tech, Virginia Department of Game and Inland Fisheries; Wildlife Management Institute Ronei, C.C. Arantes and Poly provided valuable assistance in the field. D. Orth gave valuable input to research design, data analysis and the main text. The Virginia Cooperative Fish and Wildlife Research Unit is jointly sponsored by US Geological Survey, Virginia Tech, Virginia Department of Game and Inland Fisheries, and the Wildlife Management Institute. Any use of trade, firm, or product names is for descriptive purposes only and does not imply endorsement by the U.S. Government. The authors declare no conflict of interest. Public domain – authored by a U.S. government employee

AGOSTINHO, Carlos Sérgio; AGOSTINHO, Angelo Antonio; PELICICE, Fernando Mayer; ALMEIDA, Deusimar Augusto de; MARQUES, Elineide Eugênio. Selectivity of fish ladders: a bottleneck in Neotropical fish movement. Neotropical Ichthyology, Porto Alegre, v.5, no.2, p.205-213, 2007. Although dozens of fish ladders have been constructed at dams of Brazilian reservoirs, there are few studies evaluating their efficiency as a tool for the conservation of Neotropical ichthyofauna, especially for migratory species. Therefore, the present study evaluated the selectivity of the species that entered and ascended the fish ladder located next to Lajeado Dam (Luis Eduardo Magalhães Hydroelectric Power Plant) on the Tocantins River. Samples were taken monthly from November, 2002 through October, 2003, in the resting pools of the ladder, using cast nets, and in the downstream stretch, using gillnets. The selectivity of the ladder in attracting fish was evaluated by comparing the occurrence, relative abundance, dominance and the congruence of abundance ranks of migratory and non-migratory species in the ladder and in the stretch of river immediately downstream. Species richness and fish abundance in the resting pools were used to evaluate selectivity along the ladder. The effects on selectivity by temporal variations in water level downriver and maximum flow velocity in the fish ladder were also analyzed. Out of the 130 species recorded downriver, 62.3% were caught in the ladder, and migratory species were clearly favored. However, more than 2/3 of the catch belonged to only three species (Rhaphiodon vulpinus, Psectrogaster amazonica and Oxydoras niger). Although the majority of the species that entered the ladder were able to reach its top, there was a sharp reduction in abundance of individuals towards the top. Temporal variations in the water level below the dam influenced richness and abundance of fish concentrated downstream and in the ladder, with lower values during periods of low water. In the ladder, a maximum flow velocity of 2.3 m/s, although also selective, proved to be more appropriate for fish ascension than a velocity of 2.8 m/s. It was concluded that the entry and ascension of the fish in the ladder were not congruent with their proportions in the downriver stretch: fish samples in the ladder were clearly dominated by a few species, including some that do not need to be translocated. Thus, selectivity constitutes an important bottleneck to initiatives for translocating fish aimed at conserving their stocks or biodiversity. It is urgent to review the decision-making process for the construction of fish passages and to evaluate the functioning of those already operating. Resumo: Dezenas de escadas de peixes foram construídas em barragens de reservatórios brasileiros, mas são raros os estudos acerca de suas eficiências como instrumentos de conservação da ictiofauna Neotropical, em especial de espécies migradoras. Neste contexto, o presente estudo teve como objetivo avaliar a seletividade específica no ingresso e ascensão de peixes na escada localizada junto à barragem de Lajeado (UHE Luis Eduardo Magalhães, rio Tocantins). Amostragens foram realizadas mensalmente de novembro de 2002 a outubro de 2003 nos tanques de descanso da escada, utilizando tarrafas, e no trecho a jusante, utilizando redes de espera. A avaliação da seletividade no ingresso da escada foi realizada através da comparação da ocorrência, abundância relativa, dominância e congruência dos ranks de abundância de espécies migradoras e não migradoras na escada e no trecho imediatamente a jusante. A riqueza e abundância específica nos diferentes tanques de descanso foram utilizadas para avaliar a seletividade ao longo da escada. Os efeitos das variações temporais do nível hidrométrico de jusante e da velocidade de fluxo na seletividade foram também analisados. Das 130 espécies registradas a jusante, 63,2% foram capturadas na escada, com claro favorecimento das espécies migradoras. Entretanto, mais de 2/3 das capturas pertenceram a apenas três espécies (Rhaphiodon vulpinus, Psectrogaster amazonica e Oxydoras niger). Embora a maioria das espécies que ingressa na escada possa alcançar seu topo, constatou-se uma redução pronunciada na abundância. Variações temporais no nível da água a jusante da barragem influenciaram a riqueza e a abundância de peixes que se concentram na entrada e dentro da escada, com redução nos valores durante períodos de níveis baixos. Já na escada, a velocidade de fluxo de 2,3 m.s-1, embora também seletiva, mostrou-se mais adequada à ascensão de peixes em relação a de 2,8 m.s-1. Conclui-se, portanto, que o ingresso e a ascensão de peixes na escada não são congruentes com a composição e relações de abundância das espécies no trecho a jusante. O conjunto de espécies que efetivamente ascende a escada é dominado por poucas espécies, podendo incluir entre as dominantes aquelas que não necessitam ser transpostas. Dessa maneira, a seletividade se constitui num importante gargalo nas iniciativas de transposição de peixes visando a conservação dos estoques ou da biodiversidade, sendo urgente a revisão do processo decisório sobre a construção destes dispositivos e a avaliação acerca do funcionamento daquelas já construídas. Dezenas de escadas de peixes foram construídas em barragens de reservatórios brasileiros, mas são raros os estudos acerca de suas eficiências como instrumentos de conservação da ictiofauna Neotropical, em especial de espécies migradoras. Neste contexto, o presente estudo teve como objetivo avaliar a seletividade específica no ingresso e ascensão de peixes na escada localizada junto à barragem de Lajeado (UHE Luis Eduardo Magalhães, rio Tocantins). Amostragens foram realizadas mensalmente de novembro de 2002 a outubro de 2003 nos tanques de descanso da escada, utilizando tarrafas, e no trecho a jusante, utilizando redes de espera. A avaliação da seletividade no ingresso da escada foi realizada através da comparação da ocorrência, abundância relativa, dominância e congruência dos ranks de abundância de espécies migradoras e não migradoras na escada e no trecho imediatamente a jusante. A riqueza e abundância específica nos diferentes tanques de descanso foram utilizadas para avaliar a seletividade ao longo da escada. Os efeitos das variações temporais do nível hidrométrico de jusante e da velocidade de fluxo na seletividade foram também analisados. Das 130 espécies registradas a jusante, 63,2% foram capturadas na escada, com claro favorecimento das espécies migradoras. Entretanto, mais de 2/3 das capturas pertenceram a apenas três espécies (Rhaphiodon vulpinus, Psectrogaster amazonica e Oxydoras niger). Embora a maioria das espécies que ingressa na escada possa alcançar seu topo, constatou-se uma redução pronunciada na abundância. Variações temporais no nível da água a jusante da barragem influenciaram a riqueza e a abundância de peixes que se concentram na entrada e dentro da escada, com redução nos valores durante períodos de níveis baixos. Já na escada, a velocidade de fluxo de 2,3 m.s-1, embora também seletiva, mostrou-se mais adequada à ascensão de peixes em relação a de 2,8 m.s-1. Conclui-se, portanto, que o ingresso e a ascensão de peixes na escada não são congruentes com a composição e relações de abundância das espécies no trecho a jusante. O conjunto de espécies que efetivamente ascende a escada é dominado por poucas espécies, podendo incluir entre as dominantes aquelas que não necessitam ser transpostas. Dessa maneira, a seletividade se constitui num importante gargalo nas iniciativas de transposição de peixes visando a conservação dos estoques ou da biodiversidade, sendo urgente a revisão do processo decisório sobre a construção destes dispositivos e a avaliação acerca do funcionamento daquelas já construídas.

The process of supplying water to the new anthropogenic wetland is achieved gravitationally, and the excess water in the wetland will be directed towards the Hârtibaciu River in a similar natural way. The fish and fauna of the Hârtibaciu River have a disrupted lateral connectivity due to its banks embanking including in the proximity of the Alţâna locality. The newly proposed anthropogenic wetland would improve habitat quality for the fish species of conservation interest, Rhodeus amarus (Bloch, 1782), and increase its population numbers. A new fish species, Chondrostoma nasus, was identified for the first time in the Hârtibaciu River.

Background. Some studies in the Neotropical ecozone evaluated the correlation between the ichthyofauna and the physical and chemical characteristics of streams. This study aimed to estimate the environmental quality of Neotropical streams through quality protocols and diversity indexes. The hypothesis is that it is possible to identify fish species indicators of variables and streams quality associated to environmental conservation and degradation. Materials and methods. Sampling occurred quarterly from October 2012 to July 2013, totalling four phases of field surveys in three sample units on each stream (Água dos Anjos Stream, Monjolinho Stream, and Ubá Stream, upper Paraná River basin) in southern Brazil. The Indicator Value Method (IndVal) was used to relate the ichthyofauna (abundance and relative frequency of fish species) to physical and chemical variables and streams and their respective environmental characteristics. Results. A total of 33 species were analysed as possible indicators by the IndVal method, and 21 species showed a significant relation (P < 0.05) to one or more environmental variables. The exotic Poecilia reticulata Peters, 1859 was best linked to low-oxygen water. Bryconamericus iheringii (Boulenger, 1887) was an indicator of the stream with the worst environmental quality among the analysed streams, and also indicated significantly lower extent of riparian vegetation (18 m) and high water oxygenation. Conclusion. The fish species: P. reticulata, B. iheringii, and G. brasiliensis were indicators of inferior environmental quality, and T. diabolus was an indicator of superior quality, and its abundance can characterize as important bio-indicators of environmental characteristics of Neotropical streams.

The introduction of exotic species is a key global threat to biodiversity. Beyond an increased risk of native species extinction, there exists a loss of biodiversity distinctiveness. Nevertheless, quantitative information on biotic homogenization at the taxonomic level in relation to basin features is rare. We used freshwater fish distribution data in Spain at three different time periods (1952, 1995, and 2007) to assess the species introduction process and the temporal dynamics of taxonomic homogenization among river basins in relation to basin size, native species richness and dam construction variables. The degree of alteration of original faunas by species introduction has increased through time, especially in native richer species, which suggest that the number of non-native and native species covariate with environmental heterogeneity. On the other hand, neither basin size nor habitat modification by dam construction seems to explain the number of introduced species. Our results indicate that the taxonomic homogenization of Spanish fish fauna is a temporally and spatially dynamic process; initial local increases in β-diversity through species introduction could be blurred because of scaling to regional and national levels or by the continuous expansion of a reduced number of exotic species.

Background. The goliath grouper, Epinephelus itajara (Lichtenstein, 1822), is the largest Atlantic grouper. It has been the first marine fish subjected to a fishing moratorium in Brazil (since 2002). The aim of this study was to investigate basic biological aspects, particularly the diet and reproduction of this endangered species. We believe that our results, together with information already available in the literature, may be a foundation for new management and conservation strategies for this grouper in Brazil. Materials and methods. Specimens were obtained from an artisanal fish landings collaborative monitoring program in the cities of Caravelas and Alcobaça, Abrolhos Bank, eastern Brazil. Because of the fishing moratorium, we relied on sporadic incidental captures from fishermen or donation from the law enforcement agencies. Diet and reproduction of the goliath grouper was evaluated based on 34 specimens obtained between May 2005 and September 2010. Results. Body size of 32 females ranged from 27.4 to 150.0 cm total length (TL) (mean 87.4 ± SD 34.8), while size of 2 males were 97.0 and 115.0 cm TL. Of these, 16 specimens (47%) were juveniles. Sex ratio was estimated as 1 : 16 (males to females). Two developing females were recorded, one obtained in February 2006 and another in January 2007. The length of first maturation (L50) for females was estimated at 105.64 cm and the length where 100% of individuals are mature (L100) at 126.0 cm TL. A total of 34 stomachs were analyzed, six of them were empty. Teleosts and decapods dominated the diet. The major food items of mangrove-associated fish were decapods Callinectes sp., while the coral reef-associated fish ingested mainly the boxfish Acanthostracion sp. The most important item for juveniles was Callinectes sp., while Acanthostracion sp. was the most important item for adults. Conclusion. We suggest that the goliath grouper moratorium in Brazil should be maintained for a relatively long time frame—more than four decades.

A Thesis for applying for the degree of Doctor of Philosophy in Agricultural Sciences Fishes provide food and livelihood for hundreds of millions of people around the world and currently fish consumption is higher than ever before. As a consequence, the threats of over-exploitation, illegal fishing and fish trade are very high. Because biologically insensible management actions or lack of necessary regulations may lead to population collapse, better understanding of genetic population structure and fisheries-induced changes in life-history traits is essential for conservation of local fish populations. Thus, the main goals of this thesis were to generate novel genomic resources, characterize population genetic structure, and study the consequences of overfishing of Eurasian perch populations and its potential causes to various life-history traits in Estonia. The over-exploitation of Eurasian perch population had strong influence on size- and age-distribution, juvenile growth rate and age of sexual maturation in males. Development of novel low-cost genome complexity reduction protocol enabled to identify large number of single nucleotide polymorphisms and microsatellite markers. Based on observed genetic structuring between two commercially most important perch fishery locations in Estonia (Väinameri Sea region and Lake Peipus), new microsatellite markers successfully revealed the genetic origin of perch, which can be used to fight against illegal fishing and fish trade. The population genetic framework described within this thesis represents a small but important milestone towards developing biologically sound conservation and management strategies for Eurasian perch. Erinevad kalaliigid moodustavad suure osa sadade miljonite inimeste toidu- ja elatusallikast üle maailma ning selle tulemusena on paljud liigid tugevalt ülepüütud. Kalavarude kaitse ja säästliku kasutamise eelduseks on täpne teave liigi populatsioonide geneetilise muutlikkuse ja struktuuri ning kalapüügist põhjustatud elukäiguomaduste muutuste kohta. Neid aspekte arvestamata on väga keeruline kaitsemeetmeid rakendada. Sellest tulenevalt oli doktoritöö põhieesmärgiks uurida ülepüügi ja populatsiooni taastumise mõju populatsioonigeneetilistele näitajatele ja elukäiguomadustele ning välja selgitada ahvenapopulatsioonide geneetiline struktuur Eestis. Lisaeesmärgiks oli ahvena jaoks välja töötada uudseid molekulaarseid markereid (mikrosatelliidid, ühenukleotiidsed polümorfismid), mida saaks rakendada geneetilise populatsioonistruktuuri detailsemaks väljaselgitamiseks ja illegaalse püügi kahtlusega ahvenate päritolu määramiseks. Tulemustest selgus, et ülepüük mõjutas oluliselt ahvenate vanuselist struktuuri, suurust ja noorkalade kasvukiirust ning põhjustas isaste kalade varasema suguküpsuse saabumise. Uue põlvkonna sekveneerimise meetodeid kasutades oli võimalik kiirelt ja odavalt saada uut geneetilist informatsiooni, mida saab tulevikus kasutada usaldusväärseks populatsioonigeneetika näitajate hindamiseks ning illegaalse püügi kahtlusega kalade päritolu määramiseks. See võimaldab tõhusamalt võidelda illegaalse kalapüügi ja kaubandusega. Samuti saadi uut informatsiooni Eesti ahvenapopulatsioonide geneetilise struktuuri kohta nii mage- kui riimvee tingimustes. Doktoritöös kirjeldatud populatsioonigeneetiline teave ahvena kohta on oluline eeldus bioloogiliselt põhjendatud kaitsestrateegiate ning populatsioonide jätkusuutliku majandamise kavade väljatöötamiseks Eestis. The publication of this dissertation is granted by Estonian University of Life Sciences.

The fish diversity and the main environmental factors affecting the spatial distribution of species, life history stages and community structure in the Río de la Plata (RdP) and adjacent waters are reviewed and analysed, with emphasis on the functional guild classification. The functional guild classification indicated that most species in the RdP were marine stragglers, zoobenthivores and oviparous species, although the biomass was dominated by estuarine species. Salinity had a stronger influence than temperature on the spatial pattern for all life stages, shallower and fresher waters are the preferred habitats of neonates and juveniles. During the breeding season (spring-summer), adults showed an intrusion into the inner part of RdP or to its adjacent nearshore waters from the offshore waters for spawning or mating, respectively. Variations in river discharge and wind patterns greatly affected the spatial extent of estuarine water, which ultimately influenced the domain of the main life-history stages (juveniles or adults) for both marine and estuarine fishes, as well as species and fish assemblage composition. The strong environmental gradient restricts some species and life-history stages to a particular section and defines three main fish assemblage areas. The composition of the fish assemblage is indicative of the recruitment of freshwater and marine species to the estuary in opposite ways, determined by the vertical stratification. Seasonal changes in the species composition were related to migration as a result of salinity and temperature variations and reproductive migrations to spawning and mating areas. This overview reveals that the RdP is under environmental variations that are likely to produce modifications to fish distribution and abundance that affect its fisheries. This context plus fish stock declines and changes in exploitation patterns could amplify the magnitude of the variations in the fisheries resources availability and affect the sustainability of fishing communities. Fil: Jaureguizar, Andrés Javier. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Mar del Plata. Instituto de Investigaciones Marinas y Costeras. Subsede Instituto Nacional de Investigación y Desarrollo Pesquero; Argentina. Provincia de Buenos Aires. Gobernación. Comisión de Investigaciones Científicas; Argentina Fil: Solari, Agustín. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Nordeste. Instituto de Biología Subtropical. Instituto de Biología Subtropical - Nodo Posadas | Universidad Nacional de Misiones. Instituto de Biología Subtropical. Instituto de Biología Subtropical - Nodo Posadas; Argentina Fil: Cortés, Federico. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Mar del Plata. Instituto de Investigaciones Marinas y Costeras. Subsede Instituto Nacional de Investigación y Desarrollo Pesquero; Argentina Fil: Milessi Millan, Andres Conrado. Provincia de Buenos Aires. Gobernación. Comisión de Investigaciones Científicas; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Mar del Plata. Instituto de Investigaciones Marinas y Costeras. Subsede Instituto Nacional de Investigación y Desarrollo Pesquero; Argentina Fil: Militelli, Maria Ines. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Mar del Plata. Instituto de Investigaciones Marinas y Costeras. Subsede Instituto Nacional de Investigación y Desarrollo Pesquero; Argentina Fil: Camiolo, Martina Daniela. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Mar del Plata. Instituto de Investigaciones Marinas y Costeras. Subsede Instituto Nacional de Investigación y Desarrollo Pesquero; Argentina Fil: Luz Clara Tejedor, Moira. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Mar del Plata. Instituto de Investigaciones Marinas y Costeras. Subsede Instituto Nacional de Investigación y Desarrollo Pesquero; Argentina Fil: Garcia, Mirta Lidia. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina. Universidad Nacional de la Plata. Facultad de Ciencias Naturales y Museo. Departamento Científico Zoología Vertebrados; Argentina

A better understanding of population dynamics including the identification of reproductive areas and their contribution to the maintenance of fish stocks is essential for population conservation. Dusky grouper, Epinephelus marginatus, is a broadly distributed fish species, usually found in marine rocky bottoms. It is currently listed as “endangered” by the IUCN Red List. The available information on its population in southern Brazil suggests that the neritic habitat of Carpinteiro Bank - CB is the main growth and spawning ground in the region. We investigated if the dusky groupers caught in the rocky-jetties of Rio Grande city (a littoral artificial habitat with no spawning activity) originated from the CB. We sampled 28 individuals from the littoral rocky-jetties aged between 2 and 12 years, and 44 individuals from the neritic CB aged between 2 and 40 years. Individuals from both areas had their otolith sections analyzed with LA-ICPMS (core-to-edge profiles) for 86Sr:43Ca, 138Ba:43Ca ratios. The otolith core (natal origin) and edge (time shortly before capture) from individuals of the same age class showed no difference between the two sites. Individual profiles of 138Ba:43Ca ratios of fish from the littoral zone indicated, for the first time, that some juveniles of dusky grouper enter the Patos lagoon and remain within the estuarine environment between the first and second years of life. This interpretation of otolith chemical data is supported by the marked differences in salinity between the littoral and estuarine sites in these studies areas, and by the marked differences in otolith 138Ba:43Ca of other fish species analyzed along the salinity gradient in the Patos Lagoon estuary. The identification of differential juvenile habitat use patterns is crucial for the establishment and implementation of management and conservation strategies to safeguard this endangered species.

Marine Protected Areas are increasingly becoming a tool of choice for conservation and management of marine resources and ecosystems. Data on biodiversity are necessary to assist in establishing protected areas for conservation objectives to be met. Toward that effect, we investigated reef biodiversity patterns in three large-scale coastal regions of Brazil. The study areas comprised of an upwelling region, an adjacent high impacted region, and a more distant marine park. We surveyed four reef sites in each study region. Fish species and abundance, substrate relief, and water temperature were recorded during the surveys. Biodiversity was estimated using Simpson’s and Shannon’s indices on species richness and abundance. Fish diversity was highest at the upwelling area. No difference in diversity was observed between the high impacted region and the marine park. No substrate relief patterns were found. Temperature readings showed higher frequency of low temperature episodic events at the upwelling region. Our results favor the upwelling region for establishment of a Marine Protected Area. Moreover, the similar diversity between the high impacted region and the marine park showed evidence of spillover effects from the upwelling into the high impacted region, further demonstrating the importance of the upwelling region for conservation.

In the autumn 2008 ichthyofauna was investigated in 3 Natura 2000 sites: Cheile Nera-Beuşniţa (Nera river and Miniş valley), Cheile Semenic –Caraş (Caras valley) and Timiş Meadow (Timiş river). The status of fish species of community interest (An. II / H.D.) inside of ichthyocenoses, as abundance and frequency, anthropogenicimpact, were assessed. In all 3 sites it were recorded 9 species of community interest (Aspius aspius, Barbus balcanicus, Cobitis elongata, Cottus gobio, Gobio kessleri, Gymnocephalus schraetzer, Rhodeus amarus, Sabanejewia balcanica, Zingel streber) in comparison with the reference lists which contain 15 species. Barbus balcanicus was a dominating species (as abundance and biomass) in the investigated area of Nera river, Miniş and Caraş valley. Cobitis elongata was found only in Nera river and probably this is the only place of Romania where it lives nowadays. Gymnocephalus schraetzer were collected by us in Timiş river and has to be added in the reference list of Timiş Meadow site. A main anthropogenic pressureconsists in the building of dams in all investigated water bodies, which stops the fish movement at the normal water levels.

La Mesa Central de México cuenta aproximadamente con 100 especies nativas de peces, el 70% son endémicas de la región. Los ecosistemas de esa área geográfica son sobre los que mayor impacto ha tenido la actividad antropogénica. El grupo de peces más representativo es el de los goodeidos que aparentemente han sobrevivido a grandes cambios de calidad de agua y flujo hídrico. Para entender los cambios en la distribución de esta familia, el presente trabajo documenta las desapariciones y extinciones locales de especies de goodeidos y su relación con las diferentes regiones de la Mesa Central. Para conocer su distribución previa, se realizó una búsqueda bibliográfica y en bases de datos de colecciones. Estos registros se compararon con recolectas realizadas entre junio de 1999 y septiembre del 2004 en 287 localidades en 15 estados de la República Mexicana. Se cubrió el 95% de los sitios de recolecta que presentaban registros previos. La comparación entre distribuciones arrojó que en el 68% de estos sitios se registró la desaparición de alguna especie. En 9 de las 18 regiones, las especies previamente registradas redujeron su distribución a la mitad, han desaparecido 5 en más del 50% de su intervalo de distribución y al menos 2 se señalan como extintas. Las especies se clasificaron según su vulnerabilidad y las localidades fueron categorizadas de acuerdo al promedio de desaparición de poblaciones. Se discute el efecto de las extinciones sobre la viabilidad de las especies a largo plazo, y la pertinencia de establecer áreas de conservación para los goodeidos. Las extinciones locales pueden afectar la viabilidad de las especies, y por lo tanto es urgente generar áreas de conservación para los godeidos.The Mexican central plateau hosts around 100 native freshwater fish species, 70% of which are endemic to the region. Freshwater ecosystems in this area are highly impacted by anthropogenic activities. Goodeids are the most representative fish in lakes and rivers in the central plateau. In recent decades, these fishes have suffered from water quality depletion and modification of hydrological regimes, leading to reduction of their original distributions. To understand changes in the distribution of species of this family, we documented local extinctions of its species and its relation with their sensitivity to environmental changes. Previous distribution records for each species were obtained from bibliographical sources and museum collection data. We compared previous distribution with more recent fieldwork data, which was conducted between 1999 and 2004, in 287 localities in 15 states of the country. Fieldwork covered 95% of the localities sampled in previous records. We found local extinction in 68% of the localities surveyed. In 9 of the 18 regions, species distribution was reduced to half of their reported areas. Five species have disappeared in 50% of their original distributional range, and at least 2 species are already extinct. We classified Goodeid species according to their vulnerability and localities were categorized by the quantity of local extinctions. Local extinctions may affect species viability, and it is therefore urgent to generate areas of conservation for goodeids.

The “Gârla Pasarea” was a former flood plane watercourse in connection with Vedea River discharged in Danube River. The floodplane was embanked for agriculture polder, Vedea River was redirected to discharge direct into Danube River and Gârla Pasarea was cut in several sectors, connected through underground tubes. Fish fauna inventory of Gârla Pasarea was performed in august 2007, using for shallow water backpack electrofisher and deep large water by Nordic gillnets. The species richness includes 15 fish species with a gradient of increasing from upstream to downstream. The most frequent species (very abundant) are two exotic respectively, Pseudorasbora parva and Carassius gibelio that survive in extreme condition. Four species are included in Annexes of Emergency Order of Romanian Govern No.57/2007, concerning regime of natural protected area,conservation of natural habitats and wild flora and fauna, respectively Aspius aspius, Cobitis danubialis (elangoides) and Misgurnus fossilis are included in Annex 3 that need designate of Special Protected Area for conservation (SPA), andProterorhinus marmoratus (semilunaris) is included in Annex 4B, for species of national interest that need strict protection. Recovering and conservation of fish fauna need ecological restoration based on rebuilding of longitudinal connectivity of Gârla Pasarea sectors, reconnect with Vedea River and lateral connectivity of Danube River with it former floodplane.

The Jucar River Basin (Spain) harbours endemic aquatic species that are declining or going extinct at an alarming rate. After evaluating several possible stressors, flow modification is identified as the factor critically threatening one endemic cyprinid fish species Chondrostoma arrigonis. Physical habitat for this species is compared for river reaches with different flow modification histories to understand local extinctions across this species' historical range. Time-series of physical habitat, generated using PHABSIM, indicate a dramatic reduction in habitat area with flow modification. Our findings indicate that efforts to regulate and stabilize flows in the Jucar River Basin may cause the rapid extinction of the remaining populations. Copyright © 2007 John Wiley & Sons, Ltd.

The fish fauna of the Atrai River were studied for a period of two years from January 2011 to December 2012. Sampling was carried out by several fishing nets and traps on fortnight basis. A total of 74 fish species belonging to 27 families and 52 genera were recorded. Cyprinidae was the most dominant family contributing 18 species in 9 genera. Two alien species were found- Hypophthalmichthys molitrix and Hypostomus plecostomus. Thirty locally threatened species (Vulnerable 13.51%, Endangered 18.92% and Critically Endangered 8.11%) were recorded. But, no globally threatened species was found. Relative abundance of majority 36.49% species was rare. Global population trend of 24.32% recorded fish species was Declining. The highest number of species (42) was recorded in the November 2011. Whereas, the lowest the number of fish species (12) recorded in June and August 2011. Very high correlation was found between fish species and physical environmental parameters (air temperature, water temperature, and water transparency). This study concluded that Atrai River could be an excellent place for natural conservation of fish species. Nevertheless, efforts to maintain a sustainable fishing pressure, removal of existing alien species and avoiding further introduction of such species are recommended.

Metadata only record The contributions presented at the European Inland Fisheries Advisory Commission Symposium on The Effects of Fisheries Management Practises on Freshwater Ecosystems in 2002 are reviewed. The principal mechanisms of inland fisheries management concentrate on four categories: fish stock enhancement (stocking and introductions); rehabilitation and habitat manipulation for fisheries purposes, including biomanipulation; fisheries regulations; and conservation and protection of fish and fisheries. The negative and beneficial impacts of these activities are summarised and options for improving the outputs of fisheries management practices to accrue wider benefits to society are discussed. Wider stakeholder participation and a shift from traditional fisheries towards ecosystem-based management approaches are the main mechanism proposed. This calls for new management tools to cater for legitimate human demand for water abstraction, hydropower generation and effluent disposal, as well as alternative commercial use of water bodies such as bathing, boating and tourism, in addition to fisheries exploitation and conservation needs.

International audience; The inclusion of key environmental covariables in habitat quality models is crucial to improve the ability of indicators to predict the response of aquatic organisms to anthropogenic stress. The sensitivity of the freshwater blenny (Salaria fluviatilis) to anthropogenic factors was found to be inconsistent among studies, and this might have been because background environmental heterogeneity was not considered. The goal of this study was to assess whether the inclusion of key environmental variables in habitat models would improve the ability to detect the effects of anthropogenic stress on vulnerable fishes. We used a theoretical–information approach to rank different models intended to predict the relative abundance of freshwater blenny in 10 Corsican rivers based on a combination of environmental and anthropogenic indicators. The results show a clear relationship between water velocity and blenny abundance in the studied streams. When this key variable is taken into account in the model, anthropogenic variables such as Enterococcus spp. and Escherichia coli counts, which are indicators of fecal pollution, and the number of competitor species also explain a significant proportion of the variation in blenny abundance. This study reveals the importance of statistically accounting for natural environmental variability, which may conceal other effects, when modeling anthropogenic impacts on a species

Many factors are known to influence long-term growth potential of primary cell cultures, such as cell culture conditions and culture establishment techniques. This study investigates the relationship between fish cell culture conditions and cell viability as a means of developing cell culture procedures for the conservation of endangered freshwater fish species. The cell culture conditions investigated include: donor age, biopsy size, sampling location, enzymatic dissociation treatments and incubation temperature. Culture quality was assessed for cell viability, oxidative stress, senescence and cell death. The conditions that were most effective for culture quality were 6 mm biopsy punches taken from the proximal area of the caudal fin, digested with collagenase I for 60 minutes, and grown in L-15 medium containing 1x Primocin at 25oC. Viable cell concentrations obtained from fluorescent staining confirmed that cell populations declined to less than half their initial concentration within 7 days in culture. Autophagy and apoptosis may play a role in the resulting cell death inferred by the presence of vacuoles and lysosomal activity observed on advanced cultures. The presence of vacuoles, oxidative stress and senescence among treatment groups are indicative of the inadequacies in the presently evaluated protocols. Further research into the conditions required for culturing healthy cell lines is essential for fish somatic cell banking. Toronto Zoo's Endangered Species Research Fund, the Canadian Association of Zoos and Aquariums marine and freshwater grant, and the Natural Sciences and Engineering Research Council of Canada- Industrial Postgraduate Scholarship.

Riverine environments present specific barriers and challenges to dispersing fish, depending on their dispersal capability. While some barriers are obvious and finite (for example a waterfall), the subtle influences of dendritic river network structure can also affect the dispersal, and therefore the genetic structure, of freshwater fish within river catchments. In addition to these natural barriers, artificial barriers like weirs and dams can have significant effects on the flow of genes between populations in rivers. In order to achieve the effective management and conservation of populations there is a need to understand dispersal and how the movement of individuals impacts populations at a variety of scales. Studies of dispersal are important for the perspective they bring to the movement and migration of individuals and the subsequent flow of genes – both temporally and geographically. It is this spread of genes that largely determines the genetic diversity of populations, which is a quality necessary for the stability and persistence of individuals and populations.

https://doi.org/10.15447/sfews.2011v9iss1art5 This paper is a review of the biology of Sacramento perch (Archoplites interruptus) based mainly on recent studies of their distribution, ecology, physiology, and genetics. The Sacramento perch is the only member of the family Centrarchidae that is endemic to California. It is most closely related to the rock basses (Ambloplites spp.) and is thought to have split from its eastern cousins during the Middle Miocene Period (15.5 to 5.2 million years ago, MYA). Their native range includes the Central Valley, Pajaro and Salinas rivers, tributaries to the San Francisco Estuary (e.g., Alameda Creek), and Clear Lake (Lake County). Today, they are most likely extirpated from all of their native range. They are known to persist in 28 waters outside their native range: 17 in California, nine in Nevada, and one each in Utah and Colorado. Disappearance from their native range coincided with massive changes to aquatic habitats in the Central Valley and with the introduction of alien species, including other centrarchids. Unfortunately, many populations established outside their native range have also disappeared and are continuing to do so.

Aim Increasing threats to freshwater biodiversity are rapidly changing the distinctiveness of regional species pools and local assemblages. Biotic homogenization/differentiation processes are threatening the integrity and persistence of native biodiversity patterns at a range of spatial scales and pose a challenge for effective conservation planning. Here, we evaluate the extent and determinants of fine-scale alteration in native freshwater fish assemblages among stream reaches throughout a large river basin and consider the implications of these changes for the long-term conservation of native fishes. Location Guadiana River basin (South-Western Iberian Peninsula). Methods We quantified the magnitude of change in compositional similarity between observed and reference assemblages and its potential effect on natural patterns of compositional distinctiveness. Reference assemblages were defined as the native species expected to occur naturally (in absence of anthropogenic alterations) and were reconstructed using a multivariate adaptive regression splines predictive model. We also evaluated the role of habitat degradation and introduced species as determinants of biotic homogenization/differentiation. Results We found a significant trend towards homogenization for native fish assemblages. Changes in native fish distributions led to the loss of distinctiveness patterns along natural environmental gradients. Introduced species were the most important factor explaining the homogenization process. Homogenization of native assemblages was stronger in areas close to reservoirs and in lowland reaches where introduced species were more abundant. Main conclusions The implementation of efficient conservation for the maintenance of native fish diversity is seriously threatened by the homogenization processes. The identification of priority areas for conservation is hindered by the fact that the most diverse communities are vanishing, which would require the selection of broader areas to adequately protect all the species. Given the principal role that introduced species play in the homogenization process and their relation with reservoirs, special attention must be paid to mitigating or preventing these threats.

Most studies analyzing patterns in biotic homogenization of fish communities have used large-scale approaches, while the community-level effects of species intro- ductions and local extinctions within river basins have been sparsely analyzed. In this article, we examine patterns in freshwater fish a- and b-diversity in relation to the presence of reservoirs in a Mediterranean river (Guadiana river; Iberian Peninsula). We used fish samples from 182 river localities and 59 reservoir ones to address two main questions: (i) do reservoirs favor the establishment of invasive fish species?; and (ii) do reservoirs bear taxonomically homogenized fish communities? Although total species richness was not different between rivers and reservoirs, the latter had more invasive species and less native ones. Fish species found in reservoirs tended to be larger ones, but invasive species of any size showed higher preferences for reservoirs. Native species that were rare or absent in reservoirs were those that showed higher sensitivity to invasive species in rivers. Reservoir fish communities were taxonomically homogenized in relation to river ones, both when considering all fish species and using only natives or only invasive ones. Our results suggest that invasive species occupying reservoirs constitute an ecological filter excluding most native species from such systems. Invasive species in the study area are often widely introduced elsewhere, while native species found in reservoirs are congeneric and eco- logically similar to those found in other Iberian studies. Thus, we conclude that reservoirs

Aim The level of imperilment of mediterranean freshwater fish is among the highest recorded for any group of organisms evaluated to date. Here, we describe the geographical patterns in the incidence of threats affecting mediterranean freshwater fish and test whether the effects of specific threats are spatially related to the degree of imperilment of fish faunas. Location The Mediterranean Basin Biome. Methods From the IUCN Red List, we recorded the six main threats to 232 endemic freshwater fish species. We used data on fish distributions from IUCN to characterize the spatial patterns in the incidence of threats (as percentage of species affected) through multivariate statistics. We studied the relationships between threat incidence and two estimators of imperilment (proportion of species threatened and an index of extinction risk) at two spatial scales (10 • 10 km and basins) using partial least squares regressions (PLSR) that incorporated the effects of species richness and mean range size. Results The main axis of variation in the incidence of threats to freshwater fish split areas mainly affected by invasive species from those areas where species are threatened by pollution and agriculture. Wherever invasive species and water extraction were predominant threats, fish assemblages consistently tended to be more imperilled. Main conclusions As far as we know, this is the first large-scale analysis on the spatial relationships between the incidence of threats and level of imperilment of any taxonomic group. Our results highlight the primary role of invasive species and water extraction as drivers of native fish declines in the Mediterranean Basin. Large-scale patterns described here should be generated by local-scale impacts of both threats on fish biodiversity, widely reported in Mediterranean areas. Because all the species under concern are endemic, control of invasive species and reducing overexploitation of freshwater resources should be conservation priorities for mediterranean freshwater systems.

Reservoirs have been built in almost all of the hydrographic basins of Brazil. Their purposes include water supply for cities, irrigation and mainly, generation of electricity. There are more than 700 large dams and associated reservoirs in the large rivers of the country. These reservoirs favor local and regional economic development, but they also bring serious and irreversible alterations in the natural hydrologic regime of rivers, affecting habitat quality and the dynamics of the biota. In the impounded area, the main impact is the change from lotic to lentic water, which influences aquatic fauna, including fishes. Impacts of reservoirs present relevant spatiotemporal variations. Immediately after reservoir formation, fish species richness usually increases due to incorporation of surrounding habitats, but richness decreases as reservoirs age. However, impacts downstream of dams appear to be similar or stronger than those that occur within the reservoir. Dams promote discharge control, altering the seasonal cycles of floods. These effects are augmented when dams are constructed in cascades. Therefore, dams profoundly influence composition and structure of fish assemblages. Most affected species are the rheophilics and long distance migratory that require distinct habitats to fulfill their life cycles. Populations of migratory species may collapse or even disappear in intensely regulated stretches. Management actions taken to minimize impacts of dams in Brazil historically considered construction of fish passages, fishery control and stocking. The results of these actions are questionable and/or with clear failures. In this paper, we give emphasis to the Paraná River basin, the most affected by dams in Brazil. We describe some patterns in the alteration and decline in fish diversity in areas influenced by dams. We also discuss negative consequences in the fishery and ecosystems functioning. Finally, we argue the relevance and the success of the management actions taken and present some suggestions to improve conservation of the ichthyofauna in South American basins influenced by dams. No Brasil, reservatórios foram construídos nas principais bacias hidrográficas, para fins de abastecimento humano, irrigação e, principalmente, geração de energia elétrica. Como resultado, praticamente todos os grandes rios estão hoje sob influência de barragens, sendo que mais de 700 grandes reservatórios encontram-se espalhados pelos rios do País. Apesar de importantes para o desenvolvimento econômico, os barramentos promovem alterações graves e irreversíveis no regime hidrológico natural dos rios, alterando também a qualidade dos hábitats e a dinâmica de toda a biota. Na região do reservatório, o principal impacto é decorrente da alteração de ambiente lótico para lêntico, que influencia sobremaneira a fauna aquática, inclusive peixes. Esses impactos apresentam variações temporais e espaciais relevantes. Logo após a formação de um reservatório, há aumento da riqueza de espécies de peixes devido à incorporação de diversos hábitats, que tende a diminuir à medida que o reservatório envelhece. Porém, os impactos a jusante de reservatórios parecem ser tão ou mais importantes que os de montante, devido a alterações no ciclo de cheias sazonais (controle de vazão). Estes efeitos são mais relevantes quando os reservatórios são construídos em cascatas. Barragens, então, causam profundas alterações na composição e estrutura das assembléias de peixes. As espécies mais afetadas são as reofílicas e aquelas que desempenham longas migrações e que precisam de diferentes tipos de hábitats para completar seus ciclos de vida. As populações dessas espécies podem, em certas circunstâncias, entrar em colapso ou mesmo desaparecer. As ações de manejo tomadas para minimizar os impactos das barragens historicamente incluem a construção de mecanismos de transposição e a estocagem, mas com resultados questionáveis e/ou claro insucesso na conservação da ictiofauna. Neste trabalho, será dada ênfase à bacia do alto rio Paraná, a mais afetada por represamentos no Brasil. Serão abordados os padrões de alterações e declínio da diversidade de peixes, em áreas influenciadas por barragens, e discutidas as conseqüências negativas sobre a atividade pesqueira e funcionamento do ecossistema. Por fim, o trabalho discute a relevância e sucesso das medidas de manejo realizadas até o momento e apresenta sugestões para aperfeiçoar a gestão e conservação da ictiofauna sul-americana.

Reservoirs have been built in almost all of the hydrographic basins of Brazil. Their purposes include water supply for cities, irrigation and mainly, generation of electricity. There are more than 700 large dams and associated reservoirs in the large rivers of the country. These reservoirs favor local and regional economic development, but they also bring serious and irreversible alterations in the natural hydrologic regime of rivers, affecting habitat quality and the dynamics of the biota. In the impounded area, the main impact is the change from lotic to lentic water, which influences aquatic fauna, including fishes. Impacts of reservoirs present relevant spatiotemporal variations. Immediately after reservoir formation, fish species richness usually increases due to incorporation of surrounding habitats, but richness decreases as reservoirs age. However, impacts downstream of dams appear to be similar or stronger than those that occur within the reservoir. Dams promote discharge control, altering the seasonal cycles of floods. These effects are augmented when dams are constructed in cascades. Therefore, dams profoundly influence composition and structure of fish assemblages. Most affected species are the rheophilics and long distance migratory that require distinct habitats to fulfill their life cycles. Populations of migratory species may collapse or even disappear in intensely regulated stretches. Management actions taken to minimize impacts of dams in Brazil historically considered construction of fish passages, fishery control and stocking. The results of these actions are questionable and/or with clear failures. In this paper, we give emphasis to the Paraná River basin, the most affected by dams in Brazil. We describe some patterns in the alteration and decline in fish diversity in areas influenced by dams. We also discuss negative consequences in the fishery and ecosystems functioning. Finally, we argue the relevance and the success of the management actions taken and present some suggestions to improve conservation of the ichthyofauna in South American basins influenced by dams.