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.

Cyprinus carpio, Oreochromis niloticus and Clarias gariepinus are the most abundantly captured invasive fish species in the mid-stretch of the Ganga river. Fish yield and biomass data based on mean abundance by weight was calculated using algorithms and spatio-temporal population dynamics model for future prediction of these invasive fish species. Temporal biomass forecast based on mean abundance by wieght for the period from 2020 to 2029 was determined. The findings of this study predicted fish yield of 176 ±16.33 kg km^-1 day^-1 C. carpio and 55.43 ± 6.4 kg km^-1 day^-1 O. niloticus during 2029 which might result into 117.87% and 116.9% rise in temporal biomass of Common Carp and Tilapia respectively in a decade's time while 139.2% rise in temporal biomass was predicted for the invasive African catfish. The yield of invasive Common Carp, Tilapia and African Catfish was correlated with rainfall and temperature data using ANOVA and we found that variance was F=1.36; p=0.263 for C. carpio; F=1.60; p=0.326 for O. niloticus and F=1.63; p=0.101 for C. gariepinus, indicating that variance was very close for Tilapia and African Catfish. The observed values of variance indicated that climatic changes had more impact to these two species than to the Common Carp. The concrete and forecast values were calculated considering 95% lower and upper level of confidence, which was significant (p<0.05) and the annual regression was found to be p<0.464, p<0.419 and p<0.499 for C. carpio, O. niloticus and C. gariepinus, respectively. Further, interactive performance of invaded C. carpio, O. niloticus and C. gariepinus was also assessed for understanding invasion meltdown. The results of mean abundance by weight based yield forecast of invaded Tilapia, Common Carp and African Catfish for the period of 2020 to 2029 suggest a stable production in the Ganga River in years to come. It also manifests a positive pattern of invasion in the times of climate change displaying invasion meltdown. This suggests increased pressures of fish invasions on temporal and spatial scales, and imposing new management challenges for freshwater ecosystems.

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.

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.

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.

This study assessed the vulnerability of 16 floodplain wetlands (beels) of the Lower Brahmaputra Valley, Assam, India, in relation to a range of natural and anthropogenic factors including climate change. The total water-spread area of the selected beels varied widely (8–50 ha), with 68.75% of the beels showing a reduction in water-spread area over the past 30 years. High levels of siltation and encroachment and detachment of marginal areas through the construction of roads were the major factors responsible for the reduction in the water-spread area of the beels. The reduction was observed to be in the range of over 33% in three beels (Raghunath Sora, Chulkani, and Dudua beel) to 83% in Bhoishpuri beel. In addition, one beel (Chulkani) experienced reduction in its deep pool area, which is an important wetland area that provides shelter to brood fishes during the dry season. Only 12.5% of the beels studied practiced enclosure (pen) culture for rearing fish. None practiced cage culture. Our study showed that only two beels (Bhoishpuri and Tariachora) were free from exotic fishes; the remaining surveyed beels reported exotic species such as, Cyprinus carpio (Common Carp), Ctenopharyngodon idella (Grass Carp), Hypophthalmichthys molitrix (Silver Carp), H. nobilis (Bighead Carp) and Piaractus brachypomus (Pacu). The prevalence of exotic fishes in the majority of the beels (due both to escape from nearby aquaculture ponds during floods and intentional stocking in certain beels) would have adversely affected the diversity of indigenous fishes in those wetlands. From discussion with the fishers, 50% of the beels surveyed experienced a reduction in the number of fish species from that recorded 10–20 years ago. In addition to climate change-related factors (e.g. abnormal rains, floods, or drought-like situations), other factors – both natural (e.g. hyper-nutrification) and anthropogenic (e.g. construction of roads, houses, and other structures) – also adversely affected the studied wetlands. To help cope with these factors and increase the adaptive capacity of fishers, four measures aimed at mitigation are suggested. These are: the practice of enclosure aquaculture in beels; the construction of floating macrophyte refuges (katal); deep pool refuges; and stock enhancement programmes with climate-resilient indigenous fishes.

Wetlands play an important ecological role by providing shelter and habitat for diverse fish species, migratory birds, macrophytes and other aquatic organisms. Hydrological connectivity with the main river channel has a critical role in fish diversity and production in floodplain wetland. The present study showed the seasonal hydrological alteration on fish species distribution in Ansupa wetland, connected with tropical river Mahanadi, India. The river discharge showed a variation from 4549 cusec during lean season (April) to 204716 cusec during monsoon (August). It has been recorded that water flows/discharge above 200000 cusec only, inundate the wetland resulting in exchange of free flows of fish species and nutrients. The study period for the fish species diversity was undertaken during 2017-18. A total of 46 fish species were observed under the orders Cypriniformes (18), Perciformes (12), Siluriformes (7), Synbranchiformes (2), Cyprinodontiformes (1), Clupeiformes (1), Beloniformes (1), Osteoglossiformes (1), Mugiliformes (1), Anguilliformes (1) and Tetraodontiformes (1). According to the conservation status of the International Union for Conservation of Nature, four species Parambassis lala, Ompok bimaculatus, and Anguilla bengalensis are in the category of Near Threatened. Analysis showed that taxonomic distinctness is more during winter than the monsoon and pre-monsoon, indicating monsoon could play a significant role in the fish species recruitment through river connectivity. Climatic data was analysed for a period of 34 years and indicated that an increment of 0.2⁰C in water temperature and average increase of 129mm rainfall at the study site. This slight increase in rainfall over the years could be one of the factors responsible for the fish recruitment in the Ansupa wetland, through river connectivity underlining the importance of flood for wetland fisheries recruitment and sustainability.

Wetlands are among the most productive of all aquatic ecosystems. In developing countries, millions of marginal fishers rely solely on wetlands for security of both nutrition and livelihood. The decline in wetland fisheries owing to anthropogenic and climatic changes has made fishers increasingly vulnerable. Pen culture can be an effective climate-resilient technology for enhancing fish production in shallow, macrophyte-choked, and multi-stake floodplain wetlands, especially in eastern and north-eastern India. In this context, pen culture was implemented as an adaptive measure in a tropical Gangetic wetland (Mathura) to enhance fish production and increase the adaptive capacity of fishers. Indian Major Carps, Gibelion catla, Labeo rohita, and Cirrhinus mrigala of initial size 10.4±.21g, 8.2±0.48g, and 6.5±0.23g respectively, were stocked at the ratio of 4:4:2 and at the rate of 30 fish m^-2 each in pens of 100 m² in duplicate. For purposes of conservation, Labeo bata and Gudusia chapra, 4.3±0.18g and 3.8±.34g initial size, respectively, were stocked at the rate of 20 Nos.m^-2 each at the ratio of 1:1. The fish were fed with commercial feed at the rate of 4% of body weight. A net survival of 82%, 87%, and 75% was recorded in Indian Major Carps, L. bata and G. chapra. A production of 380 kg IMC was achieved during 120 days of the culture period. L. bata achieved an average weight of 21.40±0.34g during the 90-day culture period, with a survival rate of 87%. G. chapra attained an average weight of 16.5±0.42g during the culture period, with a recorded survival rate of 75%. G. chapra was observed to spawn in the pen. The water quality inside pens and reference sites did not differ significantly (p>0.05). The produced fish were released in the wetland for fisheries enhancement. The present communication discusses the technological suitability and economic feasibility of adopting climate-resilient pen culture as an adaptation measure for enhancing the adaptive capacity of wetland fishers in the face of a changing climate.

India's North Eastern Region comprises eight land-locked states and has a total population approaching 46 million, made up of approximately 220 ethnic communities. A high demand for fish prevails in the region as 90–100% of the population prefers fish in their daily diet. The region faces climate change-related issues at various levels and with a range of impacts on the inland fisheries sector. The period 1951 to 2010 saw a significant increase in annual mean temperature in several states of the region (Arunachal Pradesh, Assam, Manipur, Sikkim, Mizoram, and Tripura). The highest increase in annual mean temperature was recorded in Sikkim (+0.05 °C yr^-1) followed by Manipur (+0.03 °C yr^-1). Significant changes in annual rainfall pattern were also recorded during the same time period in the region: four of the eight states (Assam, Arunachal Pradesh, Sikkim, and Nagaland) experienced a decreasing trend, and the remaining four (Meghalaya, Manipur, Tripura, and Mizoram) an increasing trend. The highest increase in annual rainfall was recorded in Meghalaya (+14.68 mm yr^-1) during this period. The change in seasonal trend of mean temperature and the erratic rainfall pattern in the region have had profound impacts on the traditional fisheries of the region. This study outlines these impacts and suggests potential adaptation actions that may be implemented to cope with climate change.

The frequency of extreme wave events is increasing with climate change. The temporal and spatial variations of extreme wave height affect both human livelihood and the usage of ocean resources. The South China Sea and northern Indian Ocean both support coastal communities of high population density, with varied terrain structures and extreme wind and wave systems. This study focuses on the temporal and spatial variations of the extreme significant wave height in the South China Sea and northern Indian Ocean. Using nonstationary generalized extreme value analysis, trends for a 100-year return period of significant wave height were obtained for both. The most rapid increase in the 100-year return was found to be 0.015 m yr^-1 in the northern South China Sea and in the Arabian Sea; however, the 100-year return significant wave height fell in the mouth of the Bay of Bengal. After analyzing the possible causes and influence factors, we found that the increase in significant wave height in the northern South China Sea was dominated by local wind-waves and similarly, the Arabian Sea was affected by swell. The NINO3.4 index shows good correlation with the significant wave height in the northern South China Sea because typhoons are related to NINO3.4 in this area. The trends of the extreme wave height in the Arabian Sea and southern Bay of Bengal have good correlations with the South Asian summer monsoon index.

Reservoirs are aquatic resources with the potential to increase India's fish production through inland fisheries. Thippagondanahalli is a medium-size reservoir on Arkavathy River, a tributary of the Cauvery. It is located in Bangalore rural district of Karnataka (12°58′24″ to 12°96'49" N 77°20′33″ to 77°35′63″ E) and has a water surface area of 1162 ha at full reservoir level and 784.55 m at full supply level. Fish diversity studies were conducted to examine the spatial and temporal variations in fish diversity in relation to habitat parameters. A taxonomic abundance of 25 fish species (80% of them native) belonging to 14 families and 4 orders was recorded. A range of statistical estimators such as Chao 1, Jack 1, and Bootstrap were used to assess the expected species richness. The Jack 1 method showed the highest abundance with 28 species. The littoral zone, dominated by small indigenous species, was found to have relatively higher fish diversity (Shannon index-1.86) compared to the limnetic zone of the reservoir. Shannon diversity was higher in the monsoon season (1.76) compared to other seasons. Physico-chemical parameters revealed that this waterbody is highly eutrophic. Canonical correspondence analysis between seasonal habitat characteristics and seasonal species abundance showed the abundance of the small indigenous fish Amblypharyngodon mola during the post-monsoon season, the bottom feeder Cirrhinus mrigala and the surface feeder Rasbora daniconius during the monsoon season, and the carnivores Mystus malabaricus and Channa orientalis as well as the planktivore Puntius sarana during the pre-monsoon season. This study suggests the use of fisheries management and conservation measures such as fish-aggregating devices, stocking of certified seed, and impact assessment of exotic species.