Abstract Tenualosa ilisha, commonly called Hilsa, is a highly prized species, which has declined in River Brahmaputra, India. The study was carried out for one year and a total of 1,026 individuals were sampled at monthly intervals. In the study, the following growth parameters were observed: asymptotic length (L∞) = 445 mm, growth coefficient (K) = 0.5 year-1, and age at length zero (t0) = −0.5 year-1. Growth performance index (φ) was estimated to be 2.996. Natural mortality rate, total mortality, and fishing mortality was found to be 0.51 year-1, 1.57 year-1, and 1.06 year-1,respectively. Exploitation ratio (E) was found to be 0.675, which indicates that the species is slightly over-exploited. It was seen that length groups that represented the catch in the Indian part of River Brahmaputra comprised fishes of 0–4+ years age. The present study was carried out to assess the population characteristics of this commercially important species from the Indian part of Brahmaputra River, which will contribute towards sustainable fisheries management.

Abstract India has a vast network of 14 major rivers and their tributaries, covering 83% of the drainage basin and accounting for 85% of the surface flow. Anthropogenic activities like damming, channel modification, water abstraction, sewage and effluent disposal, sand mining, unthoughtful exploitation of biotic resources, etc. are the major threats faced by the rivers in the country. Monitoring protocol of Indian rivers lacks an integrated approach based on judicious use of both abiotic and biotic components as well as a total lack of consideration for ecological health. Index of Biotic Integrity is a flexible multimetric index that can be modified and adapted to the various zoogeographic regions of the world. A fish-based multi-metric IBI was developed by modifying and incorporating metrics that are sensitive to the various ecological stressors faced by Indian rivers, fishes being excellent indicators of river health. The adapted IBI was validated and used to assess ecological health of two rivers—Mahanadi, and its distributary Kathajodi-Devi—flowing through central-eastern India. The study indicated that in River Mahanadi, around 25% of the freshwater river stretch was slightly impaired and the remaining 75% stretch was moderately impaired. In Kathajodi-Devi, most of the river stretches were in a moderately impaired condition, except at Italnga stretch where the river was severely impaired. The Index of Biotic Integrity scores estimated could reflect the ecological health of the rivers. The study shows that use of Index of Biotic Integrity is a useful and reliable approach to assess the health conditions of Indian aquatic resources warranting initiatives to be taken to implement and incorporate it into the country's water resource management.

Abstract The fishery and population dynamics of Otolithoides pama (Hamilton, 1822) were studied from the Hooghly-Matlah estuary of West Bengal from November 2016 to April 2018. The average annual catch of sciaenids for the last five years was estimated at 22 mt and formed 12.66% of the total marine production of the state of West Bengal, India. The peak landings of O. pama were found during March from gill net catches and November–December from bag net catches. The species followed continuous recruitment throughout the year with two distinct peaks during March–August and July–October. The probability of capture was estimated to be 148.35 mm, while the length at recruitment was 104.5 mm. The rate of exploitation (0.73) was found to be higher than Emax (0.58), indicating a higher fishing pressure of the species. The length-based Virtual Population Analysis revealed that the highest fishing mortality occurred from the 140–159 mm length group onwards. Both Beverton and Holt yield per recruit analysis and Thompson and Bell prediction analysis revealed higher fishing effort being employed for the species, which would need to be reduced by 20% for sustainable management of the species at the studied estuarine system.

Abstract The understanding of patterns in fish assemblages is imperative for management and conservation plans. There is a dearth of information on the environmental factors affecting the fish community structure in the reservoirs built on the intermittent rivers of India. We hypothesized that the environmental factors most likely influenced the patterns in the structure of fish diversity at temporal and spatial scales in a sub-tropical reservoir of the Ganga River basin. The data was gathered seasonally from April 2017 to March 2018 from three sites each in the riverine, transitional, and lacustrine zones of the reservoir. About 16,220 fish specimens were captured that belonged to 7 orders, 14 families, 31 genera, and 40 species. The diversity indices showed the highest diversity in the riverine and the lowest in the lacustrine zones of the reservoir. At a temporal scale, the highest diversity was observed in the monsoon season and lowest during the summer season. The cluster analysis spatially separated the fish fauna into three groups, each group formed by sampling sites in the riverine, transitional and lacustrine regions of the reservoir and may have resulted from physico-chemical and anthropogenic influences. Our study suggests the need to consider the possible influence of altered environmental conditions on fish assemblage, and some recommendations were suggested for the improvement of the fisheries impacted by the construction of dams.

Abstract The Ganga is a major riverine system of India providing ecosystem services to millions of households. However, this river is under stress due to various anthropogenic activities. River sediment harbours a variety of microorganisms which has a tremendous influence on river health. In the present study, metagenomic approach for microbial community characterization of three sediment samples collected from River Ganga at Farakka stretch was carried out. The sediment samples were sequenced using a high-throughput Next Generation Sequencing platform. Taxonomical classification study showed that the occurrence of bacteria is higher than other groups of microbes. The bacterial classes, such as Betaproteobacteria, Deltaproteobacteria, Gammaproteobacteria, and archaeal phylum, Thaumarchaeota, and Crenarchaeota were relatively higher than other communities. KEGG pathway analysis of three samples revealed that the number of genes associated with environmental information processing is higher in the Lalbag sample in comparison to Farakka barrage and Dhulian samples. The microbial community was categorized by functional classification using SEED analysis. Both COG and SEED analysis revealed that genes associated with carbohydrate metabolism are higher than other functional categories. The genus-level study confirms the higher occurrence of Pseudomonas, which corresponds to anthropogenic activities like mass bathing. The presence of bacterial genus Nitrospira and archaeal phylum Thaumarchaeota confirms a healthy nitrogen cycle in the environment. Moreover, the generated information would help in understanding the importance of microbial communities and their imperative function in maintaining the riverine ecosystem health.

Abstract Floodplain wetlands located in Ganga-Brahmaputra basin are some of the major inland fisheries resources of India with substantial resource size of 554,213 ha. These resources are amenable to capture fisheries and fisheries enhancement. The Guwahati Regional Centre of Indian Council of Agricultural Research-Central Institute of Fisheries Research Institute, Barrackpore, West Bengal, India has developed protocols for scientific fish stock enhancement (through supplementary stocking) for floodplain wetlands (beels) of Assam. These enhancements aim to increase fish yield based on extensive field studies in the beels of the state during 2007–12. In order to assess the impact of fish stock enhancement following the Institute's guidelines, data on fish production of 183 beels under the administrative control of Assam Fisheries Development Corporation Ltd., Guwahati, India were collected and analysed for the period from 2007–08 to 2016–17. The data were analysed for two periods of 5 years each (2007–08 to 2011–12: period-I and 2012–13 to 2016–17: period-II) for unstocked beels (that are not subjected to supplementary stocking, thereby representing capture fisheries) and stocked beels (where supplementary stocking with Indian major and minor carps for fish stock enhancement is practised) in reference to different agro-climatic zones of Assam. The average fish yield from unstocked beels (96 no.) was 156.6kg ha-1yr-1 during period-I, which increased to 206.4kg ha-1yr-1 during period-II, showing an increase of 31.8% over the five-year period. As much as 47.5% of the beels (87 no.) of the state are now subjected to supplementary stocking for fish stock enhancement. The average fish yield rate of stocked beels was 258.5kg ha-1yr-1 during period-I, which increased to 455.2kg ha-1yr-1 during period-II. Thus, average fish yield rates increased as much as 76.1% over the five year periods in stocked beels showing that supplementary stocking resulted in significant enhancement of fish production from the beels of Assam after the Institute's intervention.

Abstract Deepor Beel is a prominent floodplain wetland and a Ramsar site of northeastern (NE) India (Ramsar site no. 1207) covering a 40.14 km2 area and connected to River Brahmaputra. It provides numerous economic (e.g., livelihood and nutritional security) and ecological benefits (e.g. moderation of floods, groundwater recharge, repository of biodiversity) to the locality and its people. Deepor Beel was declared a Wildlife Sanctuary in 1989 and the area covered by the perennial water spread (10.1 km2) was subsequently designated as a Bird Sanctuary by the Government of Assam in 2009. The present paper provides an overview of the rich floral and faunal diversity of the wetland, including aquatic macrophytes (58 species), diatoms (65), zooplankton (171), bryozoans (5), molluscs (15), aquatic insects (55), prawns (3), crabs (2), finfish (68), amphibians (11), reptiles (33), birds (234) and mammals (24), in addition to the beel's limno-chemistry as well its conservation threats and suggested strategies. The wetland supports 18 globally threatened vertebrate species. Eleven bird species occurring in the wetland (Aythya baeri, A. nyroca, Leptoptilos dubius, L. javanicus, Ephippiorhynchus asiaticus, Gyps bengalensis, G. tenuirostris, Haliaeetus leucogaster, Pelecanus philippensis, Sarcogyps calvus, Threskiornis melanocephalus) have been included in the IUCN Red List of Threatened Species. Finfishes reported from the wetland declined from 67 species in 1999 to 64 between 2016 and 2018, which is a matter of concern. According to available information on limno-chemistry, the waters of the wetland have remained within the favorable range of water quality for fish production. Major threats faced by the wetland (e.g. pollution, encroachment, natural processes, etc.) and possible conservation strategies (e.g. control of aquatic pollution, prevention/ control of siltation, enacting and enforcing appropriate legislation, and other strategies) are outlined.

Abstract Climatic variability threatens inland ecosystems, fisheries, societies and economies globally. The impacts are evident in India as manifested by altered geographic distribution, loss of species, change in breeding period, life cycle and physiological behaviour of inland fishes. In India, several inland fisheries research advancements have been made including development of innovative environmental, climatological and biological thresholds associated with successful spawning of fish species in the Ganges River basin, which is a landmark in predicting reproductive adaptation and minimum fitness required for natural breeding. The innovative concept of determining a threshold condition factor of the female fish population to indicate readiness for spawning, expressed as pre-spawning fitness (Kspawn50), has been used to map and benchmark several freshwater fish species and thereby identify potential climate resilient species. A flow chart showing the impact of climatic variability in inland fisheries and climate resilient fisheries have been conceptualized. Moreover, research pertaining to climate change and its impact on aquatic ecology and fisheries, heat wave studies, climate resilient adaptation techniques, carbon sequestration potential of wetlands, and vulnerability assessment framework at various levels has also been reported. In the present compilation we synthesize, report, and discuss the status of scientific advancements on the impact of the climate change, and associated impacts on inland ecosystems and fisheries at various levels, which would help in developing mitigation and adaptation strategies.

Abstract India is endowed with vast floodplain wetland resources (0.5 million ha), which provide both livelihood and nutritional security to much of the rural populace. These biologically sensitive ecosystems are threatened by a range of anthropogenic and climatic factors. Assessment of their ecological vulnerability, and of the environmental threats that they face, is essential both in evaluating the health of these ecosystems and in developing sustainable management strategies for conservation and fisheries enhancement. In this context, eight wetlands in the Ganga basin were studied for two consecutive years across the seasons and were characterized ecologically based on chlorophyll a, primary productivity, and trophic state index. A warming temperature (+0.20 – +0.47 °C) and a decreasing total annual rainfall (257–580 mm) have been observed along the Ganga basin in the last three decades. The chlorophyll a (mean ± S.E.) content of the water varied from 4.08 ± 1.04 to 38.0 ± 14.11 µg l-1. The high primary productivity, gross primary productivity/plankton respiration ratio and trophic state index correlated positively with the high fish yield in the wetlands. Analysis of data based on Carlson's method revealed five wetlands in the eutrophic category, whereas based on Lamparelli's method, two wetlands fall into the eutrophic category. The Lamparelli TSI value ranged from 54.1 in Majharia to 65.8 in Kararia among the wetlands. The Bishnupur wetland in West Bengal and Kararia wetland in Bihar were found to be eutrophic due to cascading sewage incursion from nearby towns. These altered ecosystems with high TSI values were prudently exploited by selecting suitable fish species for high fish production, and a fish yield of 1200 kg ha-1 yr-1 was achieved in Bishnupur. The study revealed that eutrophic wetlands can be strategically managed for maintaining both ecosystem services and fish production. Careful selection of suitable fish species and stocking rate is crucial. The planned disposal and treatment of sewage is recommended to maintain the ecological health of floodplain wetlands for sustainable fisheries management in the context of a changing climate.

Abstract Shrimp aquaculture in India is synonymous with coastal aquaculture. Like other agricultural activities, it appropriates a wide range of environmental goods and services, and is vulnerable to impacts of climate change as the cultured animals are sensitive to various kinds of biotic and abiotic stressors. Climate change affects the shrimp aquaculture directly by extreme weather events and seasonal variations, and indirectly alter the primary and secondary productivity, structure and composition of the ecosystems or by influencing the availability of fishmeal, fish oil and other goods and services required for aquaculture farmers. The perceptions of farmers on the impacts of climate change on shrimp aquaculture in inland and coastal areas of Krishna District, Andhra Pradesh are discussed. Cyclone and flood were perceived by all the farmers, whereas irregular season, high temperature, heavy rain and drought were perceived by 79, 89, 91 and 5 % of farmers, respectively. Environmental, biological, and economic impacts of climate change drivers on aquaculture indicated 20 to 30 % loss due to seasonal variations and 50 to 100% loss due to extremely heavy rainfall, flood and cyclones. The economic risk rating was high with flood followed by the cyclone and the magnitude was more in coastal areas compared to inland areas. There is no universally applicable list of adaptation measures and need to be evaluated for individual aquaculture systems. Autonomous and planned adaptation measures to be implemented by farmers, researchers and policymakers are discussed for climate-resilient aquaculture. Planned adaptive measures are either at the primary level or non-existence, hence policy initiatives are required to formulate planned adaptive measures to enhance the adaptive capacity of the farmers.

Abstract The climate of Brahmaputra valley (located in the North-eastern Indian state of Assam) witnesses considerable changes with sub-tropical rain-storm atmosphere and has four well-defined seasons (monsoon, post-monsoon, winter and pre-monsoon) in a year. The state is experiencing extreme climatic events like erratic rainfall patterns (causing abnormally high floods) and drought-like situations in recent years, which adversely affects fish seed production thereby affecting pond aquaculture and fisheries enhancements in open-waters of the region. The present paper describes the major constraints faced by fish seed producers of the region because of extreme climatic events (abnormally high floods and prolonged dry spells) based on field studies in 27 fish seed production farms (randomly selected) located in three districts of Lower Brahmaputra Valley Zone of Assam, India. Primary data on different aspects of constraints faced by the fish seed producers because of extreme climatic events were collected and analysed. Rank Based Quotient values were calculated, based on ranks given by the fish seed producers for each constraint to prioritize them. Dominant constraint related to abnormally high floods faced by the fish seed producers was ‘loss of brood stock’ (Rank based quotient = 99.1) whereas the least important constraint was ‘entry of weeds/macrophytes’ during floods (Rank Based Quotient = 25.5). Constraints related to drought-like situations ranged from the least important ones like ‘low milt production of male brood fishes’ that had the lowest value (12.5) to the over-arching constraint of ‘inadequate water depth in fish ponds’ during pre-monsoon and prolonged dry spells (Rank Based Quotient = 100.0). Adaptive strategies developed by fish seed producers of the study region to overcome the major constraints have been outlined in the paper. The need for developing improved risk management at macro-level through appropriate policy support to fish seed producers in the fish-deficit region and suggested policy support measures for ensuring sustainability are discussed.

Abstract Biological invasions are a worldwide threat to the aquatic systems and have the potential to homogenize entire foodwebs and shift species abundance distributions to more skewed ones. Invasion impacts include effects on the foodweb structure and ecosystem functioning leading to a loss in native fish biodiversity and commercially important fisheries in many open water systems. The impacts of invasives are generally devastating as they spread in the foodweb with each species potentially interacting with multiple species. The foodweb modeling studies conducted in different inland aquatic ecosystems show that not all exotics cause a detrimental effect on the resilience of an ecosystem. Information on the foodweb structure and ecosystem properties is a prerequisite for formulating management protocols for conserving biodiversity, enhancement programmes and sustaining fisheries. The present paper reviews the impacts of invasive fishes in Indian aquatic ecosystems in the context of a changing foodweb scenario due to exotic fish species invasions. The information generated here could be applied for future research on similar ecosystems for deducing management actions.

Abstract The present article is aimed at understanding current policies and implementation strategies for the management of aquatic invasive species in India and identifying opportunities for improvement. Existing management approaches and policies have briefly been put into place concerning fish introductions and aquatic invasive species, but looking at their effectiveness, it is argued that mitigating the negative impacts caused by invasive species should be at the core for their successful management. International institutions have explicitly recognized the need to contain and eradicate biological invasions and have set of relevant guidelines and enforcements. In India, risk assessment, risk management, quarantine, biosecurity and regulatory mechanisms have been developed and implemented to filter fish introductions and consequently check aquatic invasions. Nevertheless, invasive species introduced into the inland waters are emerging as ‘chronic risks’ to the aquatic biodiversity and ecosystem services. It is imperative that these emerging issues are put on the National Agenda and Action Plan to regulate fish invasions and minimise their adverse impacts. A National Policy on prevention and control of aquatic invasive species is urgently needed to deal with nuisance and harmful impacts. Some future needs have also been suggested to tackle this issue.

AbstractOften regarded as a potential threat to the native fish fauna worldwide, the Brown Trout (Salmo trutta), has successfully established its population in the majority of the Himalayan rivers post its introduction dating back to the eighteenth century. Over the years, the species has gained infamy as a sport fish and is considered a profitable source of income to the locals ensuing a heightened propagule pressure due to lack of appropriate management actions. No comprehensive study has been conducted to date in order to understand the mechanism by which the Brown Trout poses threat to the native fish populations. Through the present study, we could assess its competition with the native Snow Trout (Schizothorax richardsonii) to understand the spatial assemblage of both the species across space in Tirthan, a pristine high-altitude river of the western Himalaya. River Tirthan is one of the major tributaries of River Beas traversing for most of its stretch within the protected boundaries of the Great Himalayan National Park Conservation Area. A total of 108 sampling points were chosen from confluence to origin of rivers/streams, ranging from 989 to 3677msl. A total of 28 explanatory variables were recorded at each point. Overall, the Brown Trout adults were found to be greater in relative abundance (66.1%) than the Snow Trout adults (33.9%). The fingerlings of Snow Trout on the other hand, were distinctively high in relative abundance (61.9%) than those of the invasive Brown Trout (38.1%). Non-native trout showed higher abundance in the higher stream orders i.e. in the main streams while natives mostly restricted themselves to the lower order streams. Redundancy analysis (RDA) for species and environmental covariates resulted in 40.75% of constrained variance with higher eigen values for Redundancy analysis1 and Redundancy analysis2. Ward’s minimum variance clustering of Hellinger transformed data revealed sites agglomerating into six reasonable distinct subgroups with respect to species abundances. Immature individuals of non-native and native trout used similar habitat conditions, but they differed in using habitats at adult stage. Our results show a competitive dominance of Brown Trout in terms of higher abundance and maximum space utilization that highlight an urgent action for preventing its introductions to new areas. We recommend a national policy of ‘The Indian Invasive Species Act’ and management level interventions to control overstocking in the areas of established population.

Abstract India, a megadiverse tropical country is grappling with the rising trend of aquatic invasions. Out of 532 introduced non-native fish, 16 species of freshwater aquaculture and aquarium were assessed invasive by using a risk assessment protocol, ‘Fish Invasiveness Screening Test’. Six major identified invasion pathways of the aquatic invasive species were inadvertent or deliberate releases, escapes, contaminants from hatcheries, river corridors, stowaways and unaided introductions. Invasion mechanism further elucidated the factors promoting successful invasion in freshwater ecosystems. For predictive future performance of invasive fish, the concrete and predictive values based on mean abundance by weight was calculated. Over 28.67% and 29.02 % persistent increased yield of the invasive Tilapia and Common Carp respectively was predicted in the Ganga river in the coming decades. Single species Tilapia invasion facilitated multiple species fish invasion, manifesting in invasion meltdown. The trophic changes due to fish invasion exhibited biotic homogenization with trophic downgrading. Aquatic invasive species were found highly competitive interacting with native species causing serious biodiversity loss, health hazards, and economic damage consequently affecting the ecosystem services. In spite of available regulatory approaches and guidelines to manage aquatic invasive species, fish invasion has been on the rise. This paper suggests modifications and stringent implementation of the existing regulatory mechanisms besides adopting linkages, cutting-edge research on invasion science and modern molecular containment tools for effective management.

Abstract In order to assess the distribution pattern and understand the prevailing factors for predicting further expansion of an exotic fish Oreochromis niloticus, this study was undertaken in the Ganga river flowing through the state of Uttar Pradesh using MaxEnt model. The authors report the distribution pattern of O. niloticus and prevailing causative factors mounting the expansion of O. niloticus in the Ganges based on MaxEnt modeling technique. The presence only occurrence data-set for this invasive species was prepared from the field data and also from data collated from the authenticated publications of different fisheries researchers. The data-set was analyzed with environmental and topographical variables typically incorporating seasonal and temporal variability using MaxEnt, a maximum entropy algorithm which showed that the area under curve was much closer to 1 ( 0.999). The model predicted elevation as the most influential predictor variable with permutation importance of 69.2% followed by slope_steepness (10.1%), Tmax_1 (7.3%) and Srad_5 (6.8%). The findings from the results suggest that invasive O. niloticus tend to spread in rivers where elevation is lower as well as slope_steepness of the river is higher and thus indicated that invasion might be higher in the downstream of the river. The model suggests that topography and its derived variable are the most significant predictors for distribution of invasive O. niloticus. The results of this study also confirm that the water qualities of the Ganga river are suitable for O. niloticus and if the model is supplemented with water quality variables data, the influential predictor variable in water quality can be well investigated with permutation importance.

Abstract This article examines the non-native fishes in the freshwater bodies of Andaman and Nicobar Islands with a focus on understanding the perception of stakeholders towards providing management solutions. A total of 56 freshwater fish species were reported from Andaman and Nicobar Islands of which 23 species were non-native to the Islands introduced either accidentally or deliberately. Among the 23 fishes introduced, 13 species were found to be transplanted from Indian waters into the Islands and 10 species were non-native to Indian waters. Mosquito Fish (Gambusia affinis), Mozambique Tilapia (Oreochromis mossambicus), Silver Barb (Barbonymus gonionotus), Red Bellied Pacu (Piaractus brachypomus), and Common Carp (Cyprinus carpio) are some of the important invasive species found here. Stakeholder perception studies were undertaken through semi-structured questionnaire and five point likert scale questions. The respondents (N=133) were classified into two groups as a) Fish farmers and b) Research/development personnel. Multinomial logistic regression analysis revealed that the profession of the respondents significantly influenced the awareness about the non-native fishes (p<0.001). Fish farmers (4.04±0.04) and Research/development (4.47±0.21) respondents mutually agreed on the need for awareness and education on the issue of non-native fishes (p<0.01). A management framework is suggested to address the issue of non-native fishes towards effective planning, conservation and management of the fragile Island ecosystems.

Abstract We present results of the first major attempt to record the distribution of aquatic alien species in the Western Ghats Biodiversity Hotspot using Geographical Information System. A total of 32 alien species, including four macrophytes (Salvinia molesta, Pistia stratiotes, Eichhornia crassipes and Cabomba furcata) and 28 fish were recorded from the southern part of the Western Ghats. Seven of these have established natural populations and are invasive, which includes Oreochromis mossambicus, O. niloticus (Cichlidae), Poecilia reticulata, Gambusia affinis (Poeciliidae), Pterygoplichthys pardalis (Loricariidae), Cyprinus carpio (Cyprinidae) and Clarias gariepinus (Clariidae). Oreochromis mossambicus is the most extensively distributed invasive fish in the region. Major reservoirs serve as a spawning hub for species such as C. gariepinus and C. carpio. Significant pathways for the establishment of most alien species in Western Ghats were aquarium trade and aquaculture. Given the increasing records of alien species and proliferation of invasive species in the southern region of the Western Ghats, urgent research and policy interventions are suggested, including the development of a comprehensive database on distribution, trade, invasion biology, as well as determining both short-term and longterm impacts on endemic fauna.

The present study envisages the importance of monitoring and management of freshwater springs of Kashmir Himalaya due to role they play in meeting ever-increasing drinking water demands and maintaining various ecosystem services. Therefore, some of the most pressing issues fundamental to the existence of springs is their monitoring and management because of their geological, ecological, scientific, cultural, religious and societal importance. Despite the key role that they play, springs are today continuously facing various types of threats. Springs have attained recently an extraordinary importance as they play role in providing drinking water, irrigation, sustaining habitats for fisheries, aquatic biodiversity, endemism, spiritual enrichment, recreation, aesthetics etc. especially in scenario of climate change threat predicted for Himalayas. In this backdrop a study directed to assess water quality status and potential of springs to offer the solution to ever-increasing water shortages was carried out. Identification of main threats to spring ecosystems and their subsequent monitoring and management in Kashmir Himalaya has been pleaded in this article. Major research highlights of the work revealed very well to excellent water quality class and Piper trilinear diagram of spring water depicted Ca–Mg–HCO3 water type. ANOVA (Analysis of Variance) revealed significant variations whilst Principal Component Analysis (PCA) generated four principal components (PC1, PC2, PC3 and PC4) with higher Eigen values of 1.0 or more (1.4-9.5) accounting for 34.34, 30.03, 18.50 and 12.4% of the total variance respectively. Consequently, majority of the physico-chemical parameters (95.28%) loaded under PC1 and PC2 were having strong positive loading (>0.60) and are mainly responsible for regulating the hydrochemistry of spring waters. Cluster analysis revealed that springs like Kokernag, Achabal, Sherebagh, and Cheshmashahi and Dobinag fall in same cluster having 47-78% similarity while Verinag, Indraznag and Dobinag fall almost in same cluster showing similarity range of 61-80%.

Growth parameters, mortality, growth performance index and exploitation ratio of Oreochromis niloticus were assessed based on the length-frequency data collected fortnightly from the Allahabad stretch of the Yamuna, India, during September 2011 to August 2013. The size of the catch ranged between 70 and 495 mm total length. The data was analyzed using the Electronic Length Frequency Analysis module in FiSAT software. Asymptotic length and growth coefficient were estimated as 562 mm total length and 0.58 year−1, respectively. Total mortality, natural mortality and fishing mortality coefficients were 3.74, 1.015 and 2.725 yr−1, respectively. The growth coefficient index was calculated as 3.26. The exploitation ratio worked out as 0.667, indicated that the stock was slightly overexploited. Estimated growth at the end of I, II and III years was 247, 386 and 463 mm total length, respectively. The observed multi-year survivorship based on the length frequency data from the river Yamuna in O. niloticus suggested that it has successfully established in the non-native environment and is rapidly spreading in other tributaries of the river Ganga. The recruitment pattern was observed to be continuous throughout the year, with several micro-cohorts and two overlapping peaks of unequal pulse strengths. Estimated maximum sustainable yield for this species in the Allahabad stretch of the river Yamuna was 27.13 t. This study can form an important base for future research work in the management of this invasive species in the Gangetic river system in India.

This study was conducted to assess the recruitment rate of coral spats and other invertebrates near to the coral reef ecosystem of Gulf of Mannar. The reef region examined was at Kurusadai Reef Complex (Gulf of Mannar) for this assessment. There were two sets of invertebrate settlement tripods deployed and exposed at a depth of 2m. Seventy two settlement tiles measuring 20x20 cm in two different angles were fixed in these tripods in the benthic reef ecosystem. In order to assess the impact of Sea surface temperature on the invertebrate settlement, Onset Hobo Pendant® Temperature logger was also attached with the tripods. The sediment traps in duplicate were also erected in the study site to assess the sedimentation rate of the reef ecosystem. About 80% of recruited coral spats were observed on the tiles which were exposed at 60° angle. Principal component analysis also supported that the most influencing species were coral spats followed by barnacles and bivalves in the 60° angle exposed settlement tiles. It was also observed that the most influencing place of coral spats’ recruitment was on the inner tiles. The mean sedimentation rate observed was 14.6 ± 4.8 mg.cm−2.d−1. The lower density of coral spats observed on 90° and 60° angle exposed outer tiles might be due to the observed sedimentation rate and it is believed that coral spats preferred the shaded environment initially for further perpetuation in the environment. Moreover, Bray-Curtis cluster analysis supported that the coral spats found on the inner tiles having 80% similarity in this assessment. The coral spats found in this assessment were species from Pocilloporidae and Poritidae.

The Damodar and Subarnarekha Rivers are the first and second largest running waters of Jharkhand, having variable river bed morphology with naturally hard substrates. The riverine biodiversity is outstanding, as it includes endemic taxa on species and subspecies levels. Aquatic habitats are mostly colonized by native species. Macrozoobenthic animals are important bioindicators of the habitat quality of the river and are used for rapid assessment of river quality globally. In order to have preliminary information on the biodiversity of macrobenthos, the first survey was undertaken to find the impact of domestic pollution, mining, and thermal power plants on the aquatic life of the Damodar in May 2004. On the basis of our observations and species records, systematic field sampling for macro-benthic invertebrates in the Damodar and Subarnarekha Rivers was conducted from 2007 to 2012 during different hydrological conditions to cover the seasonal variation. Synoptic sampling was done to allow comparison between the two rivers. Aquatic invertebrate fauna has been inventoried with 124 identified taxa. The highest proportion of functional feeding groups recorded were detritivores, followed by carnivores and herbivores, respectively. This present study demonstrates the seasonal disappearance of macrozoobenthic invertebrates caused by urban and industrial pollution and that the fauna of the two main rivers of Jharkhand are similar in species inventory. This reflects the ecological conditions of the shared ecoregion known as Chota Nagpur Dry Forests. The results of the present research provide an essential database to evaluate the future environmental impact of restoration and changes in water quality.

The major tributaries of the river Ganges basin are currently threatened by various anthropogenic activities which are hampering the ecosystem stability and fish biodiversity of the basin. Multiple indicators were used to prioritize the fish assemblages in the tributaries and to develop an index that is responsive to human-induced environmental changes. A high percentage of invasive species was described with the orgin index at the most disturbed sites of rivers Gomti and Betwa which also represented a substantial amount of biological disturbance. The Fisheries Assessment Integrity Index based on ecological integrity of different segments of the rivers was used to prioritize different sampling sites of the tributaries. Some of the sampling sites in Gomti and Betwa rivers are reflecting disturbed fish assemblages, a very low Fisheries Assessment Integrity Index score, few threatened species, and a high proportion of invasive species. Principal components analysis of the sampling sites, along with fish assemblage, reflected the influence of the habitat parameters on structuring the assemblage pattern. This study identified depth, flow, water quality and land uses in shaping fish assemblages. The combination of various indices in this study should provide more accurate measures in identifying sites of high conservation value.

Northeast India has rich freshwater fish diversity which is attributed to past geological history and the Himalayan orogeny which played an important role in the speciation and evolution of groups inhabiting mountain streams. The region is criss-crossed by numerous rivers belonging to the three major drainage systems: the Barak–Brahmaputra, the Kaladan and the Chindwin. About 100 species of fish have been described from the region by workers from India, as well as from other countries. Fish survey tours have been organized in the past 30 years in the different river systems of the region. Our survey resulted in the description of more than 50 new species of fish. As many as 40 species of fish are endemic to the Chindwin drainage and 22 to the Brahmaputra basin. The fish fauna of the Kaladan is poorly explored. Of the fish species in the Brahmaputra basin, 34% have not been evaluated for IUCN red list criteria, while in the Kaladan, 48.2% have not been evaluated.