Development of E-Atlas on freshwater fish hatcheries in India
The hatchery survey data over time scale of 20 years were collected from the major fish breeding states of Assam, West Bengal, Odisha, Bihar, Andhra Pradesh, Madhya Pradesh and Uttar Pradesh. A standalone software in the form of E-atlas has been developed. The atlas integrates data on hatchery location,fish species cultivated, onset and period of breeding, spawn output of inland fish over the years. The spatial differentiation visualised in the e-atlas will help planners in developing adaptation strategies for inland fisheries to climate related changes.
Influence of water temperature on maturity and spawning of Tenualosa ilisha
T. ilisha recorded conducive spawning (gonadal maturity (VII- stage) and peak GSI at a water temperature range of 29°C - 32°C. Earlier studies reported an optimal temperature range of 26°C to 30°C for conducive spawning.
Impact of climate variation on fish recruitment, fish assemblage pattern in river Ganga
- A decline in spawn availability of IMCs in Ganga river system is evident.
- Spawn prospecting studies near Allahabad indicated low seed availability with a significant decline of the Indian Major Carps compared to the eighties.
- Considerable mortality (43%) of spawn was recorded under nursery rearing.
Fish species diversity (Taxonomic richness) with climatic variables
- Fish species diversity (taxonomic richness, simpson's index, shannon weaver index) in relation to climatic variables (water temperature and rainfall) was assessed using multiple regression. It indicated a significant (p<0.05) positive correlation between fish biodiversity indices (taxa richness, simpson's index, shannon weaver index) and water temperature.
- There is positive influence of rainfall on fish species biodiversity but it is found to be statistically insignificant.
- Data on the region specific multi parameter regression equations of biodiversity indices (dependent variable) and climatic factors viz.- water temperature and rainfall (independent variables) was generated to quantify the changes to be expected in fish biodiversity at that particular stretch of river under projected temperature and precipitation regimes.
Variations in chlorophyll concentration in relation to temperature change in river Hooghly
Assessment of the effect of climate variables on algal biomass (chlorophyll-a) in selected stretch of river Hooghly at Triveni and Godakhali revealed through PCA that three main components explained 80% variability of ecosystem defined by Chlorophyll-a and physico-chemical parameters. Water temperature, air temperature are strongly correlated with chlorophyll-a, however, positive correlation also exists with TDS, specific conductivity.
Assessment of carbon sequestration in wetlands
Experiments were conducted in selected wetlands to find out potential of primary C capture and ultimate C accumulation in the sediments. The study revealed that more C was accumulated in Khalsi than in Akaipur and Jhagrasisa wetland in spite of higher primary production due to phytoplankton in Jhagrasisa and Akaipur. This might possibly be due to more primary production by aquatic macrophytes in Khalsi wetland as there was more population and diversity of macrophytes in Khalsi than in other two wetlands
Biochemical changes in selected fish species of wetlands due to climate variation.
Fishes from Hooghly estuary and Borti wetland were selected for generating data on upper thermal tolerances limit (CTmax) and to predict thermal survival of fishes from different aquatic ecosystems under future global warming scenario. Upper thermal limits (CTmax) of estuarine fishes were 41.86± 0.54 °C and 43.54 ±0.24°C (p<0.01) for Rhinomugil corsula and Apocryptes bato while that were 42.45±0.29°C and 41.2 ±0.5°C (p<0.05) for wetland fishes Channa punctata and Channa orientalis respectively. A. bato is most tolerant fish followed by C. punctata indicating their better survival potential than other two species.
Identified climate change resilient fisheries and aquaculture strategies in floodplain wetlands.
- Deep pool refuge based fishery:
Decreasing water levels can be overcome during winter season by creating deep pools by digging in the beel or by demarcating the naturally existing deep pools.These pools will provide shelter to fishes for survival and growth during the dry season (December-March).
- Net pen enclosures:
Additionally net pens of varying sizes can be installed in the deeper portions of the beels to stock and rear the fishes during dry months. This practice sustain the livelihoods of beel fishers.
- Temporary pre-summer enclosure:
The pre-summer water level recession often encountered by beel fishers can be overcome by erecting enclosure/pen around the deepest part of the beel. The commercially important fishes can be deliberately restocked within the enclosure after catching them from the surrounding waters with the help of cast and drag nets. The fishes are harvested from the enclosures intermittently based on size during January-March.
- Weed refuge based fishery:
After post monsoon water level stabilization for optimum harvesting of fishes weed refuge fishery practice can be adopted by fishers. It is a controlled refuge for fishes created in the wetland during September-October by gathering floating weed masses within a bamboo frame made of tied bamboo poles. During February-March, harvesting is targeted. Net walls are raised all around the weed refuge to surround and trap all the assemblages of fishes. Then weed masses are gradually removed and fishing is done simultaneously.
- Submerged branch pile refuge (periphyton based fishery):
Dried and dead tree branches are plinthed randomly in the deepest parts of the water body during summer months to create locally eutrophic food rich micro-habitat for fishes (shaola) sequestering carbon. These zones serve as a good fish shelter with availability of food.
- Chalonee mara fishing technique:
In thickly weed infested areas of beel, fishermen catch fishes by using large sized circular bamboo seive, which locally called chalonee. It is placed in the bottom of the weeds and raised the weeds hence the fishes attached with the weeds are caught easily by shorting out them from weeds.
- Catching mud eel using prongs:
Discussion with beel fishers and local people indicated that the selected beels have become shallower over the years, because of which indigenous fishing methods used in flooded catchments are now being practiced in the beel proper.
- Database on hatchery spawning of IMC of under different agro-climatic zones (created with Microsoft Access 2007).
- Selection of adaptive fish species and fish breeding practices:
In Assam, since 1990s there has been a shift from breeding of IMC towards fish species like L. calbasu, L. gonius, Ompok pabda, Ctenopharyngodon idella, Hypophthalmichthys molitrix, H. nobilis, Puntius javanicus, Pangasius sutchi.
During drought period in 2009-10, 93.3% of the fish hatcheries breeding IMC in West Bengal adapted to breeding of alternate fish species like Pangasius sp., and Puntius javonicus, which were comparatively more tolerant of water stress condition.and were economically profitable.