Rare Fish Species Research Articles

Разработка мер по сохранению биологического разнообразия рыб, предложений по организации системы мониторинга состояния популяций редких видов рыб западного региона Республики Казахстан

The purpose of the work is to develop measures to ensure the development of fisheries, the conservation of fish resources and the biological diversity of the ichthyofauna of Western Kazakhstan (Mangystau, Atyrau, Aktobe and West Kazakhstan regions), improving the principles and methods of management and protection of fish stocks. The research was carried out both according to the methods generally accepted in the post-Soviet space, and according to the methods developed by the authors (a temporary method of accounting for the number of fish, withdrawal coefficients for populations of fish with undermined stocks) and methods of foresight research. The monitoring system for rare and endangered fish species should include both in-life research methods and the capture of a minimum necessary number of individuals in order to further domesticate and form breeding herds, artificially reproduce and release the resulting juveniles into those reservoirs. The continued decline in populations of rare and endangered fish species indicates the low effectiveness of the measures taken to preserve them. In order to prevent the loss of the gene pool, it is necessary to select sexual products for cryopreservation during the monitoring process. In addition to monitoring the condition of rare species of fish and other animals conducted by scientific organizations, it is necessary to create a geoinformation system for monitoring rare species, which any resident can replenish by sending experts photos of samples of flora or fauna with observation coordinates. The results of the work are supposed to be used to determine further ways of developing reservoirs in the context of “green growth”.

Towards a comprehensive assessment of ichthyofaunal diversity in the Yangtze River estuary: Leveraging environmental DNA technology and bottom trawl surveys

The fishery resources in the Yangtze River Estuary (YRE) have declined drastically because of overfishing and environmental changes, leading to ecosystem degradation of the YRE, and bringing numerous rare fish species to the brink of extinction. As a new technology with great prospects for popularization and application, environmental DNA (eDNA) technology has been utilized and proven by many studies to have high potential in revealing the various species' biodiversity. In this study, we analyzed the species composition and diversity of the Yangtze River Estuary using a combination of eDNA technology and bottom trawling approaches, and later, the comparison of both methods. The results showed that combining eDNA technology and bottom trawling, 30 fish species from 7 orders and 11 families were identified. Among the 30 fish species, a total of six species of fish could be observed in catches from both methods. Perciformes were the most abundant and Coilia mystus was the dominant species. According to diversity indices, the eDNA technology reveals significant differences in fish community richness and diversity in the Yangtze River Estuary compared to the bottom trawl. In summary, the eDNA technology is feasible for monitoring fishery resources in the waters of the Yangtze River Estuary, thereby serving as a valuable supplementary tool for conducting comprehensive surveys in this region. Moreover, it holds significant implications and promising prospects for conserving the diverse ecosystem of the YRE in future conservation efforts.

Європейський харіус (Thymallus thymallus Linnaeus, 1758). Тематична бібліографія

Purpose. Forming a thematic bibliographic list of English-language and Ukrainian-language publications, which highlight the issues of artificial breeding and cultivation of European grayling in Ukraine and abroad, the results of research into its population, ecological, genetic, physiological, biochemical, immunological and other characteristics. Methods. The complete and selective methods were applied in the process of the systematic search. The bibliographic core have been consisted of scientific publications in Ukrainian and English from the fund of the Institute of Fisheries NAAS Scientific Library, as well as resources available to its users. Results. There was composed the thematic list of publications with a total quantity of 200 sources covering the time interval from 1982 to 2024, and outlining issues regarding the reproduction of a representative of Salmonids — European grayling (Thymallus thymallus L.) as one of the most rare, valuable, and significant species in the ichthyofauna of Ukraine in terms of nature protection, research of its biological, morphological, ecological, genetic, physiological, biochemical and other features at various stages of ontogenesis and different living conditions. The literary sources were arranged in alphabetical order by author or title, and described according to DSTU 8302:2015 “Information and documentation. Bibliographic reference. General principles and rules of composition”, with the amendments (code UKND 01.140.40), as well as in accordance with the requirements of APA style — international standard of references. Practical value. The list may be useful for scientists, specialists, professors, and students whose area of interests includes research of rare and endangered species of fish, biological, population, genetic, ecological and other characteristics of Thymallinae, in particular in the context of their artificial reproduction. Key words: European grayling, endangered species of fish, breeding, pisciculture, genetic research, physiological and biochemical research, ecological research.

Diphyllobothrium sp. and Other Parasites of Migrating and Rare Fish Species in the Southern Baltic Sea and Coastal Waters, Poland.

The present study is the first to analyse the parasite fauna of sole Solea solea, dab Limanda limanda, hake Merluccius merluccius, whiting Merlangius merlangus, and plaice Pleuronectes platessa in the Pomeranian Bay, as well as saithe Pollachius virens from the Szczecin Lagoon (Poland). The aim of this study was to determine the occurrence of parasites in migrating and rare fish in the Pomeranian Bay and the Szczecin Lagoon and to determine the composition of the diet of these fish. The fish for analysis were obtained in the years 2010-2019. The typical marine nematode Capillaria (Procapillaria) gracilis, rarely recorded in Poland, was found, in addition to the following parasites: Ichthyophonus hoferi, Trichodina jadranica, Diphyllobothrium sp., Dichelyne (Cucullanellus) minutus, Raphidascaris acus, Anisakis simplex, Contracaecum osculatum, Hysterothylacium aduncum, Pseudoterranova decipiens, and Echinorhynchus gadi. Because the fish species analysed in the study are not typically present in the Baltic (with the exception of plaice), and because we do not know how long they feed while they are in the Baltic, we cannot be certain which parasites they acquired in the water bodies analysed in the study and which were introduced during the migration of fish. Although these fish are outside of their normal geographic range (except for plaice), in the new environment, there were enough suitable intermediate hosts for the parasites of these fish to complete their life cycle and survive.

Where and when has the rare Fish Species Regalecus glesne been Found in the Mediterranean so far?

The finding of two specimens of oarfish, Regalecus glesne, in the north-western Ionian Sea (central Mediterranean), in the years 2021 and 2022 and at depths of 525 and 350 m respectively, is reported to update the current information on the distribution of this teleost fish in the Mediterranean waters. In fact, to date, that most of the R. glesne findings are distributed in the western part of the Mediterranean basin, between the Ligurian Sea (Italy) and the Gulf of Lion (France), with 22 and 17 findings, respectively. The TL recorded in the Ligurian Sea ranges from 86.5 to 433 cm, and in the Gulf of Lion from 88 to 446 cm. For the two captured specimens during these surveys, the estimated total length were 650 and 2700 mm, respectively. Macroscopic examination of the gonads identified these specimens as an indeterminate and a female in the early stage of gonad maturity.

Numerical Simulation of Habitat Restoration for Floating Fish Eggs in the Upper Yangtze River Tributaries

The upper reaches of the Yangtze River not only serve as a crucial waterway in China’s southwestern region but also function as a conservation area for rare fish species. Recognizing the tendency of current navigation channel improvement projects to overlook the impact on aquatic habitats and the limitations of existing habitat assessment systems, this study specifically focuses on the bifurcation section of the upper Yangtze River. To address these issues, a two-dimensional mathematical model is established to simulate and validate various improvement schemes. An analysis of the flow conditions necessary for fish migration and spawning in this section is conducted, determining optimal flow rates and water levels during spawning and migration periods. A suitability assessment system for spawning and migration is then established, utilizing the four major Chinese carps as representative fish species for evaluation. Through a comprehensive analysis of the results, rational improvement schemes are identified. The findings underscore the importance of considering elevation of dam crest during the construction of sub-dams to regulate the navigation channel, particularly regarding its impact on fish habitats during the dry season. In this plan, the weighted available area of the spawning ground increased by 189,251 m2, 165,860 m2, 89,527 m2, 66,542 m2, and 47,182 m2 under five conditions. Additionally, the evaluation indexes PPA, HFI, and CQI showed increases of 5.011%, 4.176%, and 2.901%, respectively. Moreover, this study refines fish habitats based on their reproductive and living habits, thereby enhancing existing habitat assessment models.

Molecular and biological studies of nonindigenous and extremely rare fish species from the western Baltic reported from the Pomeranian Bay (southwest Baltic Proper)

W ięcaszek B., P anicz R., E ljasik P., Tański A., B ushra A. 2023. Molecular and biological studies of nonindigenous and extremely rare fish species from the western Baltic reported from the Pomeranian Bay (southwest Baltic Proper). Folia Biologica (Kraków) 71: 181-194. Water inflows from the North Sea to the Baltic Sea are recognized as a significant factor influencing the diversity of fish species in the region. In this report, we present findings on three newly discovered fish species (Solea solea, Merluccius merluccius, and Limanda limanda) and the presence of species that were previously seldom observed in the Pomeranian Bay and the associated oligohaline waters of Szczecin Lagoon. These fishes were incidentally captured during monitoring surveys of commercially important fish species. Species identification relied on partial sequences of cytochrome c oxidase subunit I (COI), cytochrome b (cytb), and rhodopsin (rho) genes, as well as morphometric diagnostic characteristics. Upon comparing the obtained sequences with GenBank records, it was revealed that the sequences for Merluccius merluccius (rho, GenBank acc. no. OM737733) and Chelidonichthys lucerna (cytb, GenBank acc. no. OM737734) constitute new DNA barcodes. The majority of sequences obtained in our study matched those available in GenBank for fishes inhabiting the North Sea, suggesting spatial and temporal linkages between the two seas. The remaining sequences exhibited similarity to data from the Cantabrian Sea, the coasts of France, and the Norwegian Sea. The study results, in conjunction with information on the inflows of saline waters and data from previous studies on reported fish occurrences, indicate that the bycatch species could serve as potential bioindicators of environmental changes in the study area.

Environmental DNA Analysis in a River Detected a Possible Distribution of Fish Species Difficult to Capture

Environmental DNA (eDNA) analysis is a biological survey method that has drawn much attention in recent years. However, the results of eDNA analysis and capture surveys often do not completely match, and the validity of the eDNA analysis needs to be verified. Verification of eDNA metabarcoding was conducted in a river in Fukushima Prefecture, Japan, in comparison with capture survey data. Most of the captured species were detected, and 13 uncaptured lineages (two genera and 11 species) were detected in the eDNAs. Some rare species detected in the eDNAs were also identified, including exotic eels and an endangered yet out-of-range bitterling fish. To confirm the validity of the exotic Anguilla spp. detected in eDNAs, mitochondrial Cytb sequencing was performed on captured eel specimens. All eel specimens were sequenced as the native Anguilla japonica, indicating a small biomass of the exotic species difficult to capture. Our results clearly indicated the eDNA analysis as a powerful tool for detecting possible habitats of rare fish species without disturbance to the natural environment.

The usage of probiotic microorganisms in production technology of European grayling fish stock

European grayling is a perspective object of a recreational fishing. In addition, the presence of this species in sufficient quantities in rivers has a positive influence on the formation of the recreational attractiveness of mountain regions, where tourism is one of the main sources of local communities existence. However, grayling stocks in the watercourses of Ukraine are significantly depleted nowadays, and populations are in a condition of lack, what has led to the inclusion of this species into the Red Book of Ukraine. Working out of biotechnologies of artificial reproduction of rare fish species in aquaculture conditions for the further reintroduction of the resulting offspring into natural water bodies takes an important place in the system of environmental protection measures to preserve biodiversity. After all, the reintroduction into nature of artificially obtained fish fry is one of the effective ways to restore the optimal number and structure of rare fish species natural populations, and this, in turn, will allow in the future to restore the limited exploitation of the stock of these fish species. One of the critical artificial fish reproduction technology links is the transfer of larvae to external nutrition. Namely on this stage the highest mortality rates are observed. The usage of live feeds as a starter fodder can significantly improve the situation. Forage organisms, in addition to having high nutritional value, can serve as delivering tools of various targeted products, including probiotics, to a fish larvae organism. The assessment of the usage of probiotic strain Lactobacillus casei IMV B-7280 feasibility is carried, and also the possibility of usage the culture Daphnia magna Straus, 1820 grown in the presence of trehalose lipids, within the technology of early feeding of the European grayling Thymallus thymallus (Linnaeus, 1758). It was shown that the larvae of the European grayling, which received investigated probiotic microorganisms strain, had 15% bigger weight on the final stages of feeding than the larvae of the control group. Introduction to the diet of grown-up grayling larvae of the culture Daphnia magna, previously received of common cultivation with microalgae Desmodesmus armatus (Chodat) E.H.Hegewald 2000 with addition of trehalose lipids, contributed to the reduction of larval mortality and the acceleration of their growth rate. Further improvement of proposed approaches of growing grayling fish planting material can be extrapolated to other fish species and in the future may be applicable in the process of growing rare fish species in conditions of farm aquaculture fish farms, what will allow them to be involved into environmental protection activities by placing appropriate orders. This, in its turn, will contribute to the stable development of communities in rural areas.

Биотехнология воспроизводства и выращивания рыбопосадочного материала балхашской маринки (Schizothrax argentatus) в индустриальных условиях

Artificial reproduction is one of the most popular ways to preserve rare fish species. Researchers of the Balkhash branch of the Research and Production Center for Fisheries of the Republic of Kazakhstan carried out the reproduction and cultivation of Balkhash marinka at their own fish farm using a recirculating water supply system. There have been considered the technological methods of removing the marinka spawners from the natural environment, their pre-spawning maintenance in fish tanks, hormonal stimulation of spawning, intravital methods for selecting reproductive products, artificial insemination, incubation of eggs, growing viable material for stocking a native reservoir. The catch of the required number of spawners was carried out from the river Tokyraun (Northern Balkhash). After adaptation and quarantine, female species were exposed to 2x and 3x hormonal stimulation with acetonated carp pituitary. Males were injected once. Reproductive products were obtained from a female injected 3 times, after 15 hours; from a female 2x injected – after 21 hours. Duration of insemination for marinka was 2 minutes. The degluing process lasted 40 minutes with constant stirring and partial replacement of the solution. The eggs were incubated in Weiss apparatus, completely protected from light. With a high quality of reproductive products, the fertilization of eggs was 90%. The incubation time at a water temperature of 19.5-20.0 °C continued 3-4 days (60-78 degree days). The yield of prelarvae made 19-20%. Under industrial conditions, keeping the larvae lasted 4-5 days. When feeding marinka larvae, in order to increase their survival, it is advisable to use only decapsulated Artemia eggs. The juvenile period of development of Balkhash marinka began on the 30-35th day. Aller Aqua dry food was gradually introduced into the diet of fry. Under optimal abiotic and biotic conditions, the fry growth rate reached 0.075 and 7.32%/day. At the end of September marinka underyearlings with an average weight of 11.0 g were released into Lake Balkhash. The research results will serve as a theoretical and practical basis for the development of adapted technologies for the artificial reproduction of rare and endemic fish species and their introduction at fish farms.

Evaluation of Threatened, Endangered, and Rare Fish Species and Communities of the St. Lawrence River and Its Tributaries in the United States

Biodiversity is responsible for important ecological processes like productivity and ecosystem stability, and rare species are a major component of biodiversity. Rarity increases a species' vulnerability to disturbances and also makes them difficult to study. Globally, species of freshwater systems are some of the most threatened, and evaluation of rare freshwater species and their habitats is needed to help preserve natural flexibility and ecological function. We conducted an analysis of full fish communities of the upper St. Lawrence River and its major US tributaries, with the goals of determining species locations and abundances, associated environmental conditions, the distribution of distinct fish assemblages across the landscape (with emphasis on communities supporting rare species), and potential threats. From 2009 to 2015, the US Geological Survey (USGS) and Saint Regis Mohawk Tribe (SRMT) worked together using standardized methods to collect community samples within 4 different aquatic realms (shallow and deep lentic, and small and large lotic systems) and determine species-specific fish abundances, frequencies of occurrence, and associated habitat signatures and spatial distributions. Distinct fish assemblages and associated habitat conditions were objectively identified by multivariate and hypothesis-testing methods. We used a geographic information system (GIS) to spatially associate habitat, biotic, and landscape attributes within each stream reach throughout the study area, facilitating quantification of distribution patterns. Comparisons with historical data provided estimates of loss or gain of threatened and endangered species (T&E) colonies. We developed a disturbance index to highlight potential threats to aquatic species. More than 140,000 fishes of 87 species were collected from a total of 1140 sample sites, covering 278 stream reaches, including the endangered Notropis anogenus (Pugnose Shiner), and threatened Hiodon tergisus (Mooneye), Etheostoma pellucidum (Eastern Sand Darter), and Acipenser fulvescens (Lake Sturgeon). We identified 50 distinct fish assemblages differing in species composition, abundance, and/or diversity, but only 13 of those assemblages included a T&E species. The rareness, extent, and patchiness of fish assemblages created a mosaic of fish communities across the landscape, from headwaters to the mainstem of the St. Lawrence River. Comparisons with historic surveys (1978–2008) showed a stable number of T&E species colonies or an increase for some species. The geographic distribution of multimetric disturbance index values showed where combinations of disturbances to fish habitats might affect rare fish species and aquatic communities in the region. The species–habitat associations and fish assemblage distributions can be used for evaluation of species, communities, or habitats that may need protection or restoration.

First report of a CMTV-like ranavirus in farmed Percocypris pingi in China

Ranaviruses were recognized as important pathogens from the late 1990s, which are global pathogens that have continued to severely threaten aquaculture and wildlife worldwide. In this study, we report an infection with a CMTV-like ranavirus in cultured Percocypris pingi (P. pingi), a rare fish species that originated in upper Yangtze River system of China. Naturally and experimentally infected fish exhibited body surface ulcers and enlarged spleen and kidney. Histological examination revealed intracytoplasmic inclusions in the liver, spleen and kidney. Meanwhile, hexagonal viral arrays were observed in cytoplasm of infected Epithelioma papulosum cyprini (EPC) cells. Animal experimental trials confirmed that this hexagonal virus, named P. pingi ranavirus (PPRV), was the causative agent. PPRV (Accession no. ON080858) contains a 106.7 kbp genome, with a GC content of 55.03% and 97 ORFs. The results of phylogenetic analysis of the complete genome and dot plot comparisons both confirmed that the virus was classified into the CMTV-like group. Phylogenetic analyses based on MCP, mMMP, DNA polymerase and ribonuclease III genes indicated that PPRV shared the nearest relationship to Triplophysa siluorides ranavirus (Accession no. FYL140220), Chinese giant salamander iridovirus (Accession no. KF512820) and Andrias davidianus ranavirus (Accession no. KF033124), which were from China. Amidst the expanding fish host range of CMTV-like ranaviruses, this is the first report of ranavirus infection in P. pingi.

Using eDNA and SCUBA surveys for detection and monitoring of a threatened marine cryptic fish

Abstract Quantification of species’ spatial distributions and population trends is crucial for successful conservation efforts. Obtaining sufficient population data, however, is often difficult in the marine environment, especially for rare fish and invertebrate species that are small, cryptic and very difficult to detect. This study sought to understand the effort required to search for undiscovered populations of small, cryptic, marine species in shallow vegetated coastal habitats and track population numbers, using the Critically Endangered red handfish (Thymichthys politus) as a representative species. A sampling strategy was designed using a combination of environmental DNA (eDNA) and structured underwater scuba surveys of life‐like 3D‐printed ‘handfish replicas’ to estimate detectability and ultimately determine whether current population monitoring is adequately covering the remaining habitat occupied by the species. Tested over scales of hundreds of metres to kilometres, the eDNA assays performed relatively poorly in situ, detecting red handfish presence in only ~13% of samples collected from the centre of a known, yet low‐density, red handfish site. In contrast, underwater searches for independently placed handfish replicas by scuba divers indicated that mean detection probabilities at finer scales (~100 m) ranged from 57 to 97%. Near certain (95% probability) detection of an adult handfish was achievable with only one to three surveys (300 m2 belt transects), depending on the habitat complexity. While other species will vary in detectability using eDNA and underwater searches, these findings give insight into the general effort required for the detection of small, rare species inhabiting vegetated coastal environments. Such knowledge not only helps to refine monitoring and conservation efforts for known threatened species, but may also assist in identifying other inconspicuous species whose population declines may otherwise go unnoticed.

Fish diversity and assemblage in the Batticaloa lagoon, Sri Lanka.

The Batticaloa Lagoon (Sri Lanka's third-largest brackish waterbody) has suffered habitat degradation and water quality deterioration during the past 30 years due to various anthropogenic activities. Despite Sri Lanka having 40 lagoons, inventories on the lagoon ichthyofauna are rather meagre and data on fish diversity and assemblages are scarce. An assessment of fish diversity is essential to maintain the ecological stability and lagoon fisheries. This study examined the fish fauna of the Batticaloa lagoon considering the northern and southern regions of the lagoon and various depths through a 3-year survey (2017-2019) and documented the dominant and rare fish species. In addition, biodiversity measures, species assemblages and the role of environmental parameters on the distribution of fishes were documented. Various diversity indices (the Margalef richness index, the Shannon-Weiner diversity index, Pielou's evenness index, the dominance index, the taxonomic diversity index, the average taxonomic distinctness index and the total taxonomic distinctness index) were calculated. Analysis of similarities (ANOSIM) was used to examine the seasonal and regional differences in the fish assemblages. The survey showed the occurrence of 96 species belonging to 40 families and 11 orders. Ambassis gymnocephalus was the most abundant fish species (8.7% of the total number of fishes collected) followed by Etroplus suratensis (6.8%), Arius maculatus (6.1%), Gerres filamentosus (5.3%), Oreochromis niloticus (4.6%) and Gerres abbreviates (3.9%). Dasyatis uarnak (0.02%), Acanthurus gahhm (0.03%), Alectis ciliaris (0.04%) and Crossorhombus valderostratus (0.08%) were considered as rare species which constitute less than 0.1% of the total while D. uarnak was considered a doubletons species (represented twice in the whole sample of 16 stations). Two types of species assemblages, one in the northern region and one in the southern region, were evident in a dendrogram (Based on the samples were collected on each region dendrogram were plotted with respect to sites then finally dendrogram of one region pratly connected by other region) based on sample composition similarity estimated with a Bray-Curtis matrix and nonmetric multidimensional scaling plots. The Bray-Curtis dissimilarity was 59.03% between the two regions, indicating statistically significant differences in assemblages (ANOSIM R 0.801; P < 0.01). The northern region of the lagoon had a higher number of species, density, Margalef richness, Pielou's evenness, Shannon-Wiener diversity, taxonomic diversity, taxonomic distinctness and total taxonomic distinctness compared to the southern region. The northern region showed significantly higher levels of salinity and dissolved oxygen (DO) and the southern region higher temperature, turbidity, phosphates and nitrates. The best subset of biota and environmental variables [BEST(BIO-ENV)] test showed a significant relationship between fish assemblage and environmental parameters. Distance-based linear model analysis showed a significant relationship between fish assemblage and the environmental parameters salinity, temperature, pH and DO. The sequential test of this analysis showed the environmental parameters to explain about 74.9% (R2 ) of the total variation. The bioenvironmental model developed was found to be appropriate. Thirteen species were found to be influential as they explained the overall fish distribution pattern with a Spearman rank correlation of 0.951. Ten groups of coherent species were also identified in the study area. In stations having anthropogenic activities, the fish diversity was low. The fish fauna of the Batticaloa lagoon should be monitored periodically to protect the fishery resources here. An understanding of the role that environment plays in structuring the fish assemblage in the Batticaloa lagoon and locations with critical habitats will be of great importance in the conservation and management of fishery resources in this lagoon. However, as monitoring only the dominant species may fail to pick up on important impacts affecting the less common species, it should be done using diversity indices and rare fish species. Monitoring is imperative in view of the livelihood of the fishers this lagoon supports and the health of the local people, as fish is a healthy food. The fishery resources of this lagoon must be protected for posterity with appropriate management measures.

Low-temperature preservation of sterlet reproductive cells (Acipenser ruthenus Linnaeus, 1758) by the acoustic-mechanical influence method

To preserve reproductive cells of rare and endangered species of sturgeon fish using low-temperature cryopreservation methods, acoustic-mechanical impact with the use of piezoactuators was used. As a result of the research, the optimum parameters of signal frequency and time of impact on sturgeon cells were established, at which a high survival rate of sperm after defrosting was observed.Using mathematical modelling, the mechanism of acoustic-mechanical influence was studied, which consists in the wave and mechanical action created by the piezoactuator, which leads to acceleration of the process of diffusion of the cryoprotector inside the cells.For the first time a new methodological approach to low-temperature preservation of fish reproductive cells with the use of acoustic-mechanical impact has been proposed, which makes it possible to preserve genetic material with high survival rate and quality indicators.

Ichthyofaunal diversity of Bhagairia Lake in Bardiya District, Nepal

This study was conducted to assess the ichthyofaunal diversity of Bhagairia Lake located in Bardiya district, Nepal from August 2019 to February 2020. For this research monthly sampling was done to assess ichthyofaunal diversity and water quality parameters i.e. water temperature, water transparency, total dissolved solids, dissolved oxygen, pH, alkalinity, total hardness, ammonia, phosphate and nitrate from six sites around the lake. A total number of 30 species of fish belonging to 8 orders, 13 families and 23 genera were recorded. Among these, Cypriniformes and Cyprinidae were the dominant order and family covering 50% and 44 % of fish species, respectively. Puntius sophore was found to be the dominant fish species with a catch composition of 12%. Maximum fish catch (214 individuals) was recorded in February whereas, minimum fish catch (140 individuals) was recorded in August. The fish catch was found to be positively correlated with dissolved oxygen (r= 0.912), pH (r= 0.876), alkalinity (r= 0.840) and total hardness (r= 0.876). Shannon diversity index was the highest in August (3.14) and lowest in November (2.87). Margalef's richness index was highest in the month of August (5.276) and lowest in February (3.727) whereas, Sheldon evenness index was highest in February (0.925) and lowest in September (0.823). This study revealed that Bhagairia Lake is rich in fish faunal diversity and consists of native, cultivable, ornamental and rare species of fish.

Fish species in need of conservation in Primorsky Krai, Russian Far East (for the regional Red Data Book update)

Based on the results of long-term monitoring of the freshwater and coastal marine ichthyofauna of Primorsky Krai, the list of rare fish species in need of protection for the new version of the regional Red Data Book has been critically revised. The new list includes only two threatened species – Sakhalin sturgeon, Acipenser mikadoi, and Sakhalin taimen, Parahucho perryi, which were also listed in the Federal Red Data Book published in 2021. The other 29 fish species listed in the former Red Data Book of Primorsky Krai (2005) were removed from the list for various reasons, which are discussed in detail in this publication.

New Report of Zu cristatus (Bonelli, 1819) in the Ionian Sea with an In-Depth Morphometrical Comparison with All Mediterranean Records

Monitoring the occurrence and distribution of rare fish species is essential, especially in a semi-closed basin such as the Mediterranean Sea. Biologically interesting species often represent fishing waste (being part of the by-catch) and therefore are not retained, leading to a huge gap in data collection. Here we report about the occurrence in the Ionian Sea of a Zu cristatus (Bonelli, 1819) specimen, a mesopelagic fish from the order Lampriformes considered rare in the whole Mediterranean basin. The sample was captured at a depth of 720 m off the coast of Noto (Sicily, Italy) by deep-sea longline fisheries. The biometrics and meristic data were compared with all the available data on specimens previously reported in the Mediterranean Sea. It is interesting to note that, among the few records in the literature, most reports mention a lower depth range for this species. In fact, it is quite known that juvenile specimens of Z. cristatus were frequently found in shallow waters, while information about the biology of the adult stage is scarce, indicating they would seem to prefer much deeper environments. Considering the difficulty to collect data on this rare fish, this contribution can help to improve the knowledge about its distribution.

Community-based fish sanctuaries: untapped potential for freshwater fish conservation

AbstractRiverine systems and associated fish populations worldwide are threatened by human impacts, especially in tropical countries with emerging economies. In India, community-based fish sanctuaries are a key mechanism for the conservation of freshwater fish populations, but there are few peer-reviewed studies on this subject. Here we integrate over 35 combined years of field experience with a literature synthesis to define and classify community-based fish sanctuaries. We present a novel, critical analysis of fish sanctuaries as social–ecological systems with a functional characterization based on natural capital, ecosystem services, human well-being, and policy and governance. We find that such sanctuaries are shaped by complex social–ecological processes, including coevolution of religious practices and ecological change, feedback processes created by retaliatory conflicts between river users, and diverse and dynamic governance strategies. These sanctuaries hold great potential for the conservation of rare fish species in India, but are subject to myriad threats at local, regional and global scales. Given the complexity of these social–ecological systems, we outline their conservation potential and highlight directions for future research.

Identifying priority aquatic refuges to sustain freshwater biodiversity in intermittent streams in eastern Australia

AbstractThe hydrological variability of intermittent streams means that the spatial distribution of dry‐season aquatic refuges within river networks and the temporal dynamics of hydrological connectivity between them are critical for the persistence of aquatic biodiversity. Here, a new approach is demonstrated to identify surface water bodies as priority refuges for efficient conservation management of freshwater biodiversity in intermittent stream networks.Recently developed models of surface water extent and daily streamflow were used to represent spatio‐temporal variations in hydrological connectivity and surface water persistence within river networks of eastern Australia over a 107‐yr period. Using this information, systematic conservation planning was applied to prioritize aquatic areas for conservation of 25 fish species under two scenarios. One scenario identified priority refuges to complement those already occurring in protected areas, whereas the other did not consider protected area status.The priority networks identified concentrated on the main stems of river catchments where surface water was more likely to be persistent and aquatic refuges were more likely to be connected, but also included headwaters for rare fish species. All three set conservation targets for the 25 fish species can be met in the best solution of priority networks. Although the second scenario achieved the targets with a smaller size of priority network overall, it required more new aquatic refuges and was thus less efficient than the first scenario.The newly developed datasets are useful for freshwater conservation prioritization because they account for hydrological variability of intermittent streams. The systematic prioritization approach applied is transferable to other regions and freshwater taxa to identify aquatic refuges for biodiversity conservation within intermittent stream systems.