Native Fish Populations Research Articles

Influence of hydrochemical factors on morphometric variability of Scardinius erythrophthalmus in a freshwater river system

Studying fish growth is a complex task because growth depends on many factors. The process of fish growth is influenced by ecological factors of the water environment. Each species of fish has growth characteristics and characteristic changes in this process as a result of the action of natural and anthropogenic factors. We investigated the morphometric features of Scardinius erythrophthalmus in the hydroecosystem conditions of the Horyn River. Fish were caught by amateur fishing methods during 2018–2021 in the section of the hydrographic system of the Horyn River within the Rivne Plateau, which is the northern part of the Volhynian Upland , namely the Horyn River and its tributaries – the Zamchysko River, the Ustia River, and the Stubelka River. The catches included fish aged from 0+ (one-year-olds) to 5+ (five-year-olds). Growth variability was studied for fish aged 1+ to 4+ because their numbers were sufficient for statistical evaluation. We noticed clear features of the morphometric variability of the fish. According to the coefficient of variation for the general populations of S. erythrophthalmus from different rivers, there was mostly significant variability of such growth characteristics as the largest and smallest fish body height, total length, Smith length and short body length of fish. We also noticed the similarity of the morphometric variability of fish of different ages for the Horyn River and Stubelka River and Zamchisko River and Ustia River. The analysis and evaluation of the surface water quality of these rivers was also similar. Thus, Horyn and Stubla districts had a transitional state from II to III quality class, and the Zamchysko River and Ustya River districts had a transitional state from III to IV quality class. We conducted a multivariate regression and it revealed statistical significance and a close correlation between the coefficients of variation of the growth characteristics of fish with the phosphate content in the water (with an average value of the weighting coefficients of 0.50 ± 0.06), nitrite nitrogen (0.39 ± 0.10) and nitrate nitrogen (0.84 ± 0.34). The calculation of the specific growth of fish by full length revealed that the intensity of growth is the highest between the first and second year of life of fish for small rivers (Zamchysko River, Ustya River, Stubelka River) and between the second and third year for the Horyn River. The results presented in the article are valuable and describe the local variation in the morphometric variability of S. erythrophthalmus. This expanded the understanding of the influence of ecological factors of the aquatic environment on the formation of growth characteristics of this species of fish. In the future, our research will continue and study the linear growth of natural fish populations against the background of changes in the ecological and hydrological conditions of the studied region

Size distribution and length-weight relationship of invasive species flowerhorn (Cichlasoma trimaculatum (Günther, 1867) in Lake Mahalona, South Sulawesi

Lake Mahalona is one of the lakes located in the Malili Complex, South Sulawesi and is included in the Natural Tourism Park Area. Cichlasoma trimaculatum are ornamental fish from the Cichlidae family that become invasive in Lake Mahalona. A total of 29 fish species were recorded in this lake, and most of them are endemic fish. It is estimated that native and endemic fish species and populations will decline due to invasive alien species intentionally or unintentionally in Lake Mahalona. The study to determine the size distribution and length-weight relationship of C. trimaculatum was conducted in Mahalona Lake. The study was conducted at 11 stations in October 2020. Experimental gill nets used to catch Bilih. The total length of C. trimaculatum ranged from 10.0 ± 1.57 cm (Kusapa and Badilla stations) to 18.0 ± 1.57 cm (Benu station), and the weight ranged from 19.0 ± 19.2 g (Kusapa station) to 140.0 ± 19.2 g (Muara station). The correlation coefficient (r) value for this fish ranges from 0.8685 - 0.9691. The growth pattern of C. trimaculatum was a negative allometric characteristic. An exception in Muara dan Tandu Mata stations was positive allometric.

Experimental reductions in subdaily flow fluctuations increased gross primary productivity for 425 river kilometers downstream.

Aquatic primary production is the foundation of many river food webs. Dams change the physical template of rivers, often driving food webs toward greater reliance on aquatic primary production. Nonetheless, the effects of regulated flow regimes on primary production are poorly understood. Load following is a common dam flow management strategy that involves subdaily changes in water releases proportional to fluctuations in electrical power demand. This flow regime causes an artificial tide, wetting and drying channel margins and altering river depth and water clarity, all processes that are likely to affect primary production. In collaboration with dam operators, we designed an experimental flow regime whose goal was to mitigate negative effects of load following on ecosystem processes. The experimental flow contrasted steady-low flows on weekends with load following flows on weekdays. Here, we quantify the effect of this experimental flow on springtime gross primary production (GPP) 90-to-425km downstream of Glen Canyon Dam on the Colorado River, AZ, USA. GPP during steady-low flows was 41% higher than during load following flows, mostly owing to nonlinear reductions in sediment-driven turbidity. The experimental flow increased weekly GPP even after controlling for variation in weekly mean discharge, demonstrating a negative effect of load following on GPP. We estimate that this environmental flow increased springtime carbon fixation by 0.27g C m-2 d-1, which is ecologically meaningful considering median C fixation in 356US rivers of 0.44g C m-2 d-1 and the fact that native fish populations in this river are food-limited.

Temporal segregation in spawning between native Yellowstone cutthroat trout and introduced rainbow trout

AbstractHybridisation with introduced taxa poses a threat to native fish populations. Mechanisms of reproductive isolation can limit or prevent hybridisation between closely related species. Understanding how these mechanisms interact between the same species across geographically distinct occurrences of secondary contact, and how regional factors influence them, can inform our understanding of hybridisation as a threat and management actions to mitigate this threat. We used data collected on adult fish migration timing and approximate emergence timing of subsequent juvenile fish paired with genomic data to assess whether temporal isolation in the timing of spawning exists between Yellowstone cutthroat trout, rainbow trout and hybrids in the North Fork Shoshone River drainage in northwest Wyoming. We found evidence that Yellowstone cutthroat trout spawn, on average, two to four weeks later than rainbow trout and hybrids and two environmental covariates related to water temperature and discharge were associated with differences in spawning migration timing. Despite statistical support for Yellowstone cutthroat trout spawning later, disproportionately high numbers of rainbow trout and hybrids, paired with extended spawning seasons, lead to substantial overlap between all genotypes. Our results provide further evidence of temporal segregation in the timing of spawning as a mechanism of reproductive isolation between closely related species, but substantial spawning overlap suggests temporal segregation alone will not be enough to curtail hybridisation in conservation populations.

Reintroduction as a method of restoring valuable rare fish species in the reservoirs of Kazakhstan: state and prospects

A brief assessment of the current state of the populations of valuable native fish of the reservoirs of Kazakhstan — Siberian sturgeon of the Irtysh basin, Aral thorn and barbel of the Aral-Syrdarya and Balkhash-Alakol basins, sterlet of the Ural-Caspian basin is presented. Populations of these species, as a result of the influence of anthropogenic factors, have come to almost complete degradation and depletion and need to develop and take urgent measures to preserve and restore them through reintroduction, which is a priority and urgent task for the republic’s fisheries. The prospects of preserving the biological diversity of reservoirs are assessed and the necessity and validity of measures for the reintroduction of endangered fish species are shown, its directions in modern environmental conditions, the sequence and content of individual stages are determined. The conducted research allows us to develop a set of measures for the restoration of populations of oppressed and endangered rare fish species, which includes collecting information on the state of populations of valuable rare fish, determining the optimal number of producers in order to remove them from the natural environment for the formation of repair and breeding herds, working out the biotechnology of their artificial breeding, calculating the required volume of young — the recipient. To ensure the positive effect of fish reintroduction, measures to enrich the feed base by acclimatization of highly productive forage organisms are justified. The implementation of the project will preserve and restore species diversity, qualitatively improve the composition of the ichthyofauna of reservoirs, as well as preserve the genetic potential of natural populations of these species.

Assessing the role of supplementation stocking: A perspective

AbstractAlthough it is widely accepted that stocking hatchery‐cultured fish can increase the number of fish, decades of scientific evidence have shown that most often those stocking efforts fail to provide the desired “demographic boost” to a naturally reproducing, self‐sustaining target population. Despite this evidence, fish stocking remains a mainstay of fisheries management programmes, even as the biodiversity of wild fish populations and other aquatic organisms are at serious risk due to habitat loss and/or overexploitation across the globe. In this perspective piece, we summarise the reasons why wild and hatchery‐produced fish are not equivalent and describe the genetic and ecological risks associated with stocking programmes. We then present our perspective on the institutional changes that need to occur to assess these risks and offer ways to transition fisheries management strategies to become more effective in conserving levels of aquatic biodiversity from populations to landscapes. We propose that a critical first step to control ill‐conceived fish stocking programmes is to have each country develop, implement, and enforce a scientifically sound National Fish Stocking Policy. To achieve the long‐term sustainability of native fish populations, it is imperative that ecological and evolutionary principles be better integrated into future conservation strategies and management actions.

Silvofishery: In What Mangrove Coverage Condition Can this System Provide Benefits for the Community?

This article aims to explore and discuss silvofishery pond management and aquaculture by providing space for mangroves in ponds. This study focuses on the management of ponds for milkfish, crab, and shrimp cultivation in Tanjung Rejo Village, Percut Sei Tuan District, Deli Serdang Regency. A field study has been conducted for 6 months, during which data were collected from 21 silvofishery ponds using a non-probability convenience sampling method. Data were analyzed using Partial Least Squares (PLS) with Ordinary Least Squares (OLS) series analysis. Results show that the existence of extensive mangroves in ponds leads to good production in mangrove crab cultivation, which is supported by the natural shrimp and fish populations that enter at high tide in ponds, due to the benefits of mangroves as a habitat for mangrove crabs and brackish water fisheries. A small amount of mangrove area is concentrated on milkfish cultivation, which is supported by the addition of natural fish from outside the pond at high tide. The average income from silvofishery ponds, in Indonesian Rupiahs (IDR), is IDR 13,201,243 per ha. From this, it can be ascertained that the mangrove area is related to the amount of production in silvofishery ponds: the greater the use of mangroves in ponds, the more effective the cultivation and the greater the impact on fishermen's incomes. At an alpha level of 10%, all the direct hypotheses tested have a significant effect.

Environmentally-induced sex reversal in fish with chromosomal vs. polygenic sex determination

Sex ratio depends on sex determination mechanisms and is a key demographic parameter determining population viability and resilience to natural and anthropogenic stressors. There is increasing evidence that the environment can alter sex ratio even in genetically sex-determined species (GSD), as elevated temperature can cause female-to-male sex reversal (neomales). Alarmingly, neomales are being discovered in natural populations of several fish, amphibian and reptile species worldwide. Understanding the basis of neomale development is important for conservation biology. Among GSD species, it is unknown whether those with chromosomal sex determination (CSD), the most common system, will better resist the influence of high temperature than those with polygenic sex determination (PSD). Here, we compared the effects of elevated temperature in two wild zebrafish strains, Nadia (NA) and Ekkwill (EKW), which have CSD with a ZZ/ZW system, against the AB laboratory strain, which has PSD. First, we uncovered novel sex genotypes and the results showed that, at control temperature, the masculinization rate roughly doubled with the addition of each Z chromosome, while some ZW and WW fish of the wild strains became neomales. Surprisingly, we found that at elevated temperatures WW fish were just as likely as ZW fish to become neomales and that all strains were equally susceptible to masculinization. These results demonstrate that the Z chromosome is not essential for male development and that the dose of W buffers masculinization at the control temperature but not at elevated temperature. Furthermore, at the elevated temperature the testes of neomales, but not of normal males, contained more spermatozoa than at the control temperature. Our results show in an unprecedented way that, in a global warming scenario, CSD species may not necessarily be better protected against the masculinizing effect of elevated temperature than PSD species, and reveal genotype-by-temperature interactions in male sex determination and spermatogenesis.

The gap between experts, farmers and non-farmers on perceived environmental vulnerability and the influence of values and beliefs

Science has played a mixed role in guiding conservation and sustainability-oriented decision-making by individuals, policymakers, institutions, and governments. Not all science-based conservation and sustainability initiatives that address issues facing humanity and ecosystems and global problems have gained public support. Conservation decisions and policy prescriptions are and may be based on perceptions about and experiences with the environment, local land use, and ecosystems that may not align with or be grounded in science or evidence from experts in the field. Values, beliefs, and perceptions associated with nature play a critical role in how individuals view biodiversity conservation, sustainability, and natural resource management. This study first examines the gap between experts (scientists and other field experts) and the public (farmers and non-farmers) about the state of water and land resources, wildlife and associated habitats, and aquatic biodiversity in the Smoky Hill River Watershed in western Kansas. Second, the study examines the role that values and beliefs play in shaping environmental perceptions for farmers and non-farmers. Analysis confirms that a gap between experts and farmers/non-farmers does exist, especially with respect to the state of the Ogallala Aquifer, playas, rivers and streams, lakes and reservoirs, native grasslands, wildlife habitats, farmland, native fish populations, and wildlife species. Ordered-logistic regression analyses, meanwhile, indicate that farmer and non-farmer perceptions about the state of the local environment are influenced by traditional and self-interested values, as well as environmental values and beliefs, but less so by religiosity and political ideology. Despite broad takeaways, results exhibited heterogeneity across the farmer and non-farmer subpopulations. If environmental professionals cannot align ecological data, stakeholders’ values/perceptions, and policies, then the existing body of technical research and management on sustainability in natural and social sciences may be of little value.

Using genetic data to advance stream fish reintroduction science: a case study in brook trout

Widespread extirpation of native fish populations has led to a rise in species reintroduction efforts worldwide. Most efforts have relied on demographic data alone to guide project design and evaluate success. However, the genetic characteristics of many imperiled fish populations including low diversity, local adaptation, and hatchery introgression emphasize the importance of genetic data in the design and monitoring of reintroduction efforts. Focusing on a case study of brook trout (Salvelinus fontinalis) in North Carolina, we show how the combined use of genetic and demographic data can support reintroduction efforts by improving source population selection and providing opportunities to evaluate genetic viability and adaptive potential in restored populations. Using this combined approach, we reintroduced brook trout into a restored stream from two source populations and monitored changes in genetic diversity and population size in source and recipient populations. Three years after the initial translocation, the reintroduced population had comparable density, but higher genetic diversity, than either source population. This study demonstrates the utility of genetic and demographic data for reintroduction efforts, particularly when extant populations are genetically depauperate and maintaining adaptive potential is a primary restoration goal. However, we emphasize the value of continued monitoring at longer temporal and spatial scales to determine the effects of stochastic process on the long‐term adaptive capacity and persistence of reintroduced populations. Overall, inclusion of genetic data in reintroduction efforts offers increased ability to meet project goals while simultaneously conserving critical sources of adaptive variation that exist across the landscape.

Using palaeolimnology to guide rehabilitation of a culturally significant lake in New Zealand

Abstract Lakes are becoming degraded at an accelerating rate owing to human activity, and understanding their past ecology is necessary for lake management and rehabilitation. Palaeolimnology provides numerous methods that enable the historical state of lakes to be determined. New Zealand provides an ideal setting in which to do this as human modification of the landscape occurred later here than in most regions of the world (approx. 1300 CE). Lake Oporoa is a shallow lake that is highly significant to the local indigenous Māori community. This study used multiple proxy palaeolimnology to explore how lake ecology shifted following Māori and European settlement in the catchment, and how palaeolimnological data can be used to inform lake rehabilitation and conservation measures, alongside the desires of the indigenous community. Sedimentary pollen, diatoms, bacterial communities, and elemental and hyperspectral imaging scanning were used to infer ecological changes in the lake and catchment from pre‐human times to present. Following Māori settlement (approx. 1620 CE) there was gradual vegetation change and a rapid shift in diatom and bacterial assemblages, but not in phytoplankton pigments or sediment geochemistry. An increasing abundance of diatom taxa Discostella stelligera and Staurosirella cf. ovata indicates early nutrient enrichment. European pastoralism from approximately 1840 CE resulted in further deforestation, and all proxies show evidence for enhanced primary productivity driven by a combination of nutrient enrichment and changing lake levels, particularly since the 1960s. This has caused degradation in water quality and is likely to have contributed to the decline in populations of tuna (eel, Anguilla spp.). Conversations with local Māori, together with the palaeolimnological results, indicate that a culturally acceptable and realistic rehabilitation target for Lake Oporoa aligns with ecological conditions in the 1950s. The palaeoecological data provide information to guide catchment and lake revegetation and other methods of nutrient abatement, with the eventual aim of restoring culturally important tuna and native fish populations.

Delineating the genetic status of wild Cyprinus carpio as influenced by anthropogenic interventions

The ability of populations to persist and adapt to environmental changes is based on genetic diversity. Substantial empirical data shows that the genetic integrity of natural fish population is being compromised by the effect of anthropogenic interventions and robust environmental conditions. Genetic diversity estimates were obtained for 210 individuals of Cyprinus carpio sampled from six sites of Indus river basin, using 14 microsatellite loci as markers. The results showed a moderate level of genetic diversity in terms of number of alleles (Na), effective number of alleles (Nae) and heterozygosity (H). Significant deviation from Hardy Weinberg equilibrium was observed in 17 out of 84 tests. The pairwise FST values showed a moderate level of population differentiation. AMOVA revealed a significant genetic structuring among the wild populations. The UPGMA dendrogram constructed for analysis of genetic relatedness grouped all the populations into two clusters. The understanding of genetic structure of C. carpio in natural systems would be instrumental in genetic enhancement programs, effective management and sustainable conservation of riverine genetic resources.

Identifying Translocation Sites for a Climate Relict Population of Finescale Dace

AbstractTranslocation is a management strategy that seeks to address threats to fish and wildlife populations by establishing new populations in ecologically suitable areas. Populations of Finescale Dace Chrosomus neogaeus in the Great Plains may benefit from translocation, as they exhibit a climate relict natural history that has led to a disjunct distribution and minimal dispersal opportunities. We assessed the translocation suitability of sites for Finescale Dace in the Belle Fourche River basin, Wyoming–South Dakota, using a ranking approach for output from multiple analyses. We used multivariate analysis to evaluate dissimilarity in fish occurrence and habitat between sites with and without Finescale Dace in contemporary surveys (2018–2019; n = 68). We further evaluated the capacity for sites to support Finescale Dace under base case and future climate change scenarios using the predicted probability of occurrence (P) from species distribution models (SDMs) fitted with basinwide fish occurrence data from surveys conducted in 2008–2019 (n = 124) and spatially continuous environmental variables, including forecasted stream temperature scenarios. Sites with Finescale Dace tended to occur close to standing waterbodies, contained emergent vegetation cover, and did not exhibit large overlap in species‐space with either native or nonnative species. Predicted P of Finescale Dace exhibited nonlinear relationships with mean August stream temperature, channel slope, and base flow index. The amount of suitable habitat (i.e., high predicted P) declined with forecasted stream warming scenarios in the SDMs. This study highlights the utility of using field observations, historical data, and forecasted climate change scenarios to assess translocation site suitability and inform management of at‐risk native fish populations, and the results may be transferable to other populations with limited data or restricted distributions.

Exotic fish and decreasing habitats vis-à-vis conservation of freshwater fish biodiversity of Bangladesh

Multiple stressors including biological invasion have long been recognised in conservation of freshwater fish biodiversity. Works in this line have, however, been still scanty in Asia and South America – the continents known for rich biodiversity. In this study, the first of its type in Bangladesh, impacts of exotic fish and declining habitats on native fishes have been investigated. Regression and correlation analyses of 16 years production data of ponds, practically the only habitat where exotic fish are cultured commonly with indigenous ones, reveals that a maximum of 25% of the abundance decrease of native fish could be due to the effects of five commonly cultured exotic fish. Rest of the decline might largely be due to shrinkage, degradation, and destruction of habitats. Inland habitats other than ponds shrink, commonly, by about 80 % during the dry season, and most rivers are heavily polluted except for the brief mid rainy season. Decline in native fish populations may result in reduced genetic diversity. Another potential danger is the probable genetic introgression from the less fit hatchery-originated fish with the wild ones. The study concludes that the native freshwater fishes are endangered by declining habitats, exotic fishes, genetic consequences of hatchery supplementation

Thermal Suitability of the Los Angeles River for Cold Water Resident and Migrating Fish Under Physical Restoration Alternatives

Anthropogenic development has adversely affected river habitat and species diversity in urban rivers, and existing habitats are jeopardized by future uncertainties in water resources management and climate. The Los Angeles River (LAR), for example, is a highly modified system that has been mostly channelized for flood control purposes, has altered hydrologic and hydraulic conditions, and is thermally altered (warmed), which severely limits the habitat suitability for cold water fish species. Efforts are currently underway to provide suitable environmental flows and improve channel hydraulic conditions, such as depth and velocity, for adult fish migration from the Pacific Ocean to upstream spawning areas. However, the thermal responses of restoration alternatives for resident and migrating cold water fish have not been fully investigated. Using a mechanistic model, we simulated the LAR’s water temperature under baseline conditions and future alternative restoration scenarios for migration of the native, anadromous steelhead trout in Southern California and the historically resident Santa Ana sucker. We considered three scenarios: 1) increasing roughness of the low-flow channel, 2) increasing the depth and width of the low-flow channel, and 3) allowing subsurface inflow to the river at a soft bottom reach in the LA downtown area. Our analysis indicates that the maximum weekly average temperature (MaxWAT) in the baseline condition was 28.9°C, suggesting that the current river temperatures would act as a limiting factor during the steelhead migration season and habitat for Santa Ana sucker. The MaxWAT dropped about 3%–28°C after applying all the considered scenarios at the study site, which is 3°C higher than the determined steelhead survival threshold. Our simulations suggest that without consideration of thermal restoration, restoring hydraulic conditions may be insufficient to support cold water fish migration or year-round resident native fish populations, particularly with potential river temperature increases due to climate change.

One Year Monitoring of Ecological Interaction of Silurus glanis in a Novel Invaded Oligotrophic Deep Lake (Lake Maggiore)

The European catfish (Silurus glanis) was introduced in Italy during the last century for aquaculture purposes, and now it is well-established. S. glanis is an invasive species and a top predator that can deplete prey supply in the surrounding habitat, leading to changes in the aquatic food web. Consequently, its presence is considered a threat to native fish populations. Its presence in the Lake Maggiore (Northern Italy) is recent and there is a lack of knowledge about its ability to completely exploit this new ecosystem throughout the year. This study corroborated the ability of European catfish to exploit both pelagic and littoral habitats, promoting trophic interactions in both habitats. Over 2019, multiple sampling approaches have been applied by collecting S. glanis and analysing its stomach contents with the aim of inferring interactions with the freshwater community. Its diet was mainly based on crayfish (Orconectes limosus), followed by six prey fish and the genus Corbicula; two fish species (Padogobius bonelli and Salaria fluviatilis) were added to the list of known prey fish. Notably and alarmingly for the early potential top-down pressure towards all trophic levels, young individuals were proved to also feed on fish and crayfish. S. glanis showed the ability to hunt at deep depths (>60 m) and a high growth rate, despite Lake Maggiore being oligotrophic.

Valuing uncertain environmental outcomes from herpes virus control of the European Carp

ABSTRACT European Carp is a species of freshwater fish that live in Australia's freshwater rivers, wetlands and lakes. It is a dominant pest species in Australia. As part of investigations into the potential release of the Cyprinid Herpes Virus 3 to control Carp numbers, a Choice Modelling (CM) study was undertaken to value the potential non-market environmental benefits of such a program. These potential benefits relate to increases in native fish populations, the area of healthy wetlands and waterbird populations. The CM study explicitly included a probability attribute to reflect the risk that various release options will deliver the identified environmental outcomes. Consequently, the willingness to pay (WTP) estimates derived from the choice models are expressed in terms of the expected values of outcomes: the physical outcomes multiplied by their probabilities of occurring. The preferred model of choice was a Random Parameter Logit model with a non-linear (cubed) transformation of the levels for each probability weighted environmental attribute. Consequently, estimates of WTP derived from the model increase as the level of an expected attribute increases. This non-linear form is consistent with respondents treating risk in a nonlinear fashion.

Details of artificial reproduction of Atlantic salmon (Semga) at the Umba fish hatchery

The world's demand for fish products for food and industrial purposes has already significantly exceeded the reproduction capacity of wild fish. Further increasing exploitation of natural fish populations leads to a sharp reduction in their numbers and degradation of population biodiversity. The only way to solve the problem is to develop artificial reproduction of fish. This applies primarily to salmon, which are the most valuable and popular types of fish. In the Murmansk region, there are three fish hatcheries that carry out artificial reproduction of Atlantic salmon. Factory reproduction at the Umba Fish Hatchery (URZ) is currently an important and necessary process, since the plant is the only fish hatchery for reproductive purposes in the Tersk district. The article reveals the peculiarities of reproduction of Atlantic salmon (salmon) in the URZ. A brief description of the Umba River is given. The main fish-breeding activities are covered: catching and keeping of producers, collection of sexual products and fertilization, incubation of eggs, keeping of larvae and their transfer to external nutrition, factory tagging of juveniles, release of juveniles in the Umba River and its tributaries. The peculiarity of the Umba plant in contrast to the other two fish hatcheries of the Kola Peninsula is shown. The question of the necessity of the existence of the Umba fish hatchery and the prospects for its development is highlighted. The reasons for the decline in the number of salmon in Umba are listed. Recommendations for restoring the abundance and preserving the intraspecific biodiversity of the Umba River salmon are provided.

Assessing the migratory histories, trophic positions, and conditions of lake sturgeon in the St. Croix and Mississippi Rivers using fin ray microchemistry, stable isotopes, and fatty acid profiles

BackgroundReproducing populations of invasive carps (Hypophthalmichthys spp.) could alter aquatic food webs and negatively affect native fishes in the Mississippi National River and Recreation Area (MISS) and the St. Croix National Scenic Riverway (SACN). However, proposed invasive carp barriers may also threaten populations of native migratory fishes by preventing movements of fish between rivers that are necessary for life history requirements. In this study, nonlethal chemical techniques were used to provide baseline data related to the condition, trophic position, and migratory histories of lake sturgeon (Acipenser fulvescens) captured in the Mississippi and St. Croix Rivers.ResultsFish length and weight measurements and age estimates determined from pectoral fin rays demonstrated that lake sturgeon from the Mississippi River had greater lengths-at-age compared to sturgeon from the St. Croix River. However, length–weight relations were similar for sturgeon from the Mississippi and St. Croix Rivers. Lake sturgeon captured from different locations had distinguishable fatty acid signatures, and stable isotope analyses demonstrated that lake sturgeon from the Mississippi River generally feed at a higher trophic level than those in the St. Croix River. Strontium-to-calcium ratios (Sr:Ca) from fin ray cross sections indicated that sturgeon captured from the Mississippi River had higher Sr:Ca values than sturgeon captured from the St. Croix River, and natal origins and capture locations were not significantly different among sturgeon captured within individual rivers. Most sturgeon were captured in water with a similar Sr:Ca signature as their natal waters, indicating that there is some separation between populations of lake sturgeon in the St. Croix and Mississippi Rivers. However, Sr:Ca data indicated substantial variation in movement patterns among individual lake sturgeon, indicating that populations interact through migrations of individual fish between rivers.ConclusionsStudy results provide baseline condition and food web structure index data for assessing changes in lake sturgeon populations should invasive carps become established in these areas of the Mississippi and St. Croix Rivers. Controlled-exposure and telemetry studies would help verify and enhance the relations between Sr:Ca signatures in water and lake sturgeon pectoral fin rays to further assess mixing of sturgeons between rivers.

Lake charr (Salvelinus namaycush) clotting response may act as a plasma biomarker of sea lamprey (Petromyzon marinus) parasitism: Implications for management and wound assessment

Sea lampreys (Petromyzon marinus) have decimated the Great Lakes fisheries over the past century, and their control is central to protecting native fish populations. Wounding data collected from host fish, including classifying wounds as Type A (penetrating the integument) or Type B (superficial), is an integral part of sea lamprey monitoring efforts and helps inform management decisions; however, wound assessment is subjective and error-prone. This study aimed to determine if protein biomarkers of parasitism could be quantified in host fish plasma to serve as a potential objective aide in current wound assessment practices. Male siscowet lake charr (Salvelinus namaycush) were parasitized in a lab setting for four days, after which the sea lamprey was removed, host blood was collected, and the wound Type recorded. A second blood sample was collected from host fish with Type A wounds 7 months later. The plasma proteome was quantified using iTRAQ, and the relative abundances of 169 proteins were compared between parasitized and non-parasitized control fish. Three functional classes of proteins were modified by sea lamprey parasitism: immune response, lipid transport, and blood coagulation. A major finding was evidence of a concerted anticoagulation response in fish with Type A wounds, including changes in protein components and regulators of fibrin clot formation, some of which did not fully recover within 7 months. A modified clotting assay yielded a smaller thrombin-induced fibrin clot from parasitized fish, supporting the proteomic results. Therefore, measuring blood clottability could improve sea lamprey damage estimates by providing a more objective and quantitative index of parasitism than is offered by wounding data alone.