Journal of Fisheries

Farm to policy: Socioeconomic dynamics and occupational challenges of freshwater fish farmers in the Cauvery Delta region, Tamil Nadu

S. Dawood Ibrahim — 2026-02-20

Freshwater aquaculture is vital for global food security and rural livelihoods. This study examined 120 fish farmers across Thanjavur, Thiruvarur, and Nagapattinam districts in Tamil Nadu's Cauvery Delta to understand socioeconomic dynamics and constraint hierarchies shaping aquaculture development. Using structured interviews and Garrett ranking, the research revealed critical structural vulnerabilities: the farming population is predominantly male (93.3%), aging (average 45 years; 79.2% middle-aged or older), and faces future labour succession challenges despite relatively high literacy (85% educated). Low organizational participation (54.2% non-members) undermines collective bargaining capacity. Most farmers (80.8%) combine aquaculture with other occupations, reflecting income insufficiency rather than strategic diversification. With 65% representing first-generation farmers averaging eleven years' experience, aquaculture emerges as recent livelihood diversification rather than traditional practice. Landholding patterns showed 75% farm ownership averaging 3.5 acres, though 53.3% operate small farms below three acres, limiting economies of scale. Caste composition revealed predominance of marginalized communities—61.7% Other Backward Class and 27.5% Scheduled Caste—facing systematic barriers to credit, technology, and market access. Constraint analysis identified high feed costs as the primary short-term barrier across all districts, followed by insufficient credit access and inadequate extension services, while low farm gate prices emerged as the dominant long-term constraint. Findings demonstrate that effective aquaculture policies must address structural inequities rooted in caste-based exclusion, land fragmentation, organizational deficits, and market asymmetries through targeted interventions including collateral-free credit, farmer producer organizations, district-level feed cooperatives, and differentiated extension programming to transform aquaculture into dignified, profitable livelihoods.

Modelling of 2,4-dichlorophenol, an emerging pollutant removal from water by adsorption onto sugarcane bagasse biochar using response surface methodology

Tapas Paul — 2026-02-18

This study evaluated the potential of sugarcane bagasse biochar as a low-cost adsorbent for removing 2, 4-dichlorophenol (2, 4-DCP), an emerging pollutant from water using adsorption modelling and response surface methodology. It aimed to determine optimal combinations of concentration, contact time, pH and dose for maximizing contaminant uptake in batch and column systems. Batch adsorption experiments were planned using a Box–Behnken response surface experimental design with initial 2, 4-DCP concentration (25, 50, and 75 mg L^–¹), contact time (20, 40, and 60 min), solution pH (5, 7, and 9), and biochar dosage (6.25, 12.5, and 25 mg). Fixed-bed column studies were conducted under continuous flow to assess dynamic performance and breakthrough behaviour. Adsorption equilibrium, kinetics and column behaviour were analysed using standard isotherm and kinetic models, supported by surface and functional-group characterization. The optimized batch conditions produced removal efficiencies of about 95% with high monolayer adsorption capacity on a homogeneous biochar surface. The equilibrium data followed a monolayer adsorption model, while kinetic analysis indicated rapid uptake controlled primarily by surface-site availability. Column studies showed high dynamic capacity and well-defined breakthrough characteristics under the tested flow conditions. Sugarcane bagasse biochar proved to be an efficient and technically suitable material for removing phenolic contaminants such as 2, 4-DCP from water. The findings demonstrate a productive use of agro-industrial waste for water purification and support its application in practical treatment units for removing emerging pollutants in aquatic environments.

An annotated checklist of ichthyofauna and associated estuarine biota of the Manakudy Estuary, southern Tamil Nadu, India

Adyasha Sahu — 2026-02-11

This study assessed the ichthyofaunal and associated floral diversity of the Manakudy Estuary, southwest coast of India, over a two-year period involving monthly surveys from August 2023 to July 2025. Sampling efforts were stratified across three distinct ecological zones i.e., freshwater influx region (Station 1), mid-mangrove area (Station 2), and estuarine mouth region (Station 3), utilizing traditional fishing crafts and standardized visual census methods to capture spatial heterogeneity. A total of 120 species were recorded, representing 37 orders, 62 families, and 89 genera. The order Eupercaria incertae sedis showed the highest species richness (15.83%), followed by Carangiformes (12.50%) and Clupeiformes (8.33%). Among families, Carangidae was the most dominant with 13 species. Conservation assessment revealed the occurrence of threatened species, including the Endangered honeycomb stingray (Himantura uarnak) and the Vulnerable Coromandel whipray (Brevitrygon imbricata), along with two near threatened species. These findings provide baseline information essential for long-term biodiversity monitoring, sustainable fisheries management, and conservation planning in the Manakudy Estuary.

Unveiling the identity of three Parapsilorhynchus species from the Eastern Ghats: an integrative taxonomic approach

Rajat Kumar Patel — 2026-02-06

The identities of Parapsilorhynchus odishaensis, Mahanadhi minnow P. swaini, and P. alluriensis have been elucidated through a comprehensive integration of morphological and molecular data, specifically utilizing mitochondrial cytochrome oxidase subunit 1 (COI) sequences. Specimens collected from the type localities of P. swaini and P. odishaensis, closely resembling their initial descriptions, underwent molecular analysis and were compared to the holotype sequence of P. alluriensis. The genetic distances (K2P) observed among these three species ranged from 0.0% to 2.1%. Notably, the K2P distance between P. swaini and P. odishaensis ranged from 0.2% to 0.3%, while between P. odishaensis and P. alluriensis (holotype) is 1%, and between P. swaini and P. alluriensis (holotype), there was a 0.7% difference. The intraspecific variations among the P. alluriensis sequences, uploaded from the nearby area of the type locality are 0.0 to 0.8%. Despite minor variations in morphological traits such as snout tubercles, anal fin black bar, and inter-orbital space, molecular analysis revealed no significant genetic differentiation among these species. These morphological variations are likely a result of habitat influences. Considering the overlapping morphological features supported by ML tree and ASAP analysis, P. odishaensis, P. alluriensis, and P. swaini (described from the Eastern Ghats) are suggested to be synonymous. As P. odishaensis was the first species described, the other two should be regarded as junior synonyms of P. odishaensis.

Unveiling hydro-edaphic dynamics of the Manakudy Estuary: implications for ecosystem health

Adyasha Sahu — 2026-01-27

The present study investigated the seasonal variations of physicochemical and sediment parameters in the Manakudy Estuary, a critical tropical estuarine ecosystem in India. Key water quality variables encompassing basic physicochemical properties, oxygen dynamics, inorganic carbon, major ions, primary productivity, and nutrient regimes were analysed, as these collectively regulate estuarine biogeochemical processes and biological functioning. These parameters are essential as they collectively influence the chemical and biological environment of the estuary. Seasonal samples were collected from three selected sites across the estuary over a one-year period from March 2024 to February 2025, covering four seasons with triplicate sampling at each site. Descriptive statistics i.e., mean ± standard error (SE) were calculated based on replicate samples at each site and season to evaluate spatial and temporal variability. Two-way ANOVA revealed significant effects of season and site on several physicochemical and soil parameters (p<0.001), indicating pronounced spatio-temporal heterogeneity in the ecological conditions of the Manakudy Estuary. Such variability reflects shifts in nutrient availability, oxygen balance, and productivity patterns, providing clear insights into the ecological condition and ecosystem health of the Manakudy Estuary and its vulnerability to environmental stressors.