Journal of Fisheries

Occurrence of Gavialis gangeticus in the Lower Ganges of Bangladesh: urgent need for conservation initiatives

2026-05-14T08:01:19+00:00

The gharial, Gavialis gangeticus, a Critically Endangered fish-eating crocodilian native to the Indian subcontinent, has long been considered nearly extirpated from Bangladesh, with records largely limited to incidental captures in fishing gear. This study documents recent occurrences of G. gangeticus along a 100-km stretch of the Lower Ganges (Padma River) in northwest Bangladesh based on local ecological knowledge collected through a participatory monitoring approach conducted between 2018 and 2025. Eight individuals, including six yearlings, one hatchling and one adult, were recorded as accidental captures. An additional four individuals, including two yearlings, one hatchling and one adult, were directly observed on riverine chars. Occurrence records were spatially clustered around sandbar-associated habitats in the Godagari region, suggesting the presence of suitable microhabitats. The repeated detection of individuals indicates the possible persistence of the species in the region, either through localised recruitment or dispersal from upstream populations. However, the absence of systematic monitoring and the prevalence of fisheries interactions highlight significant threats and knowledge gaps.

Diversity, distribution and conservation significance of freshwater fishes in the Veeyapuram stretch of the Pamba River of Kuttanad, Kerala, India

2026-05-14T08:01:19+00:00

The present study investigated the species composition, distribution patterns, and conservation significance of freshwater fishes in the Veeyapuram stretch of the Pamba River, a major river system within the Kuttanad wetland of Kerala, India, focusing on a previously unstudied river segment. Fish sampling conducted between June and December 2025 yielded 7909 specimens comprising 33 species belonging to 13 orders and 17 families. The assemblage was dominated by Cypriniformes (47.40%), followed by Anabantiformes (20.63%), while Perciformes (12.27%) and Cichliformes (12.24%) also contributed substantially to the total abundance. Several species such as Channa striata, Pseudetroplus maculatus, and Puntius sophore were numerically dominant, whereas a few species were represented by low abundance, indicating heterogeneity in species distribution within the study area. The occurrence of ecologically and economically important species, along with species of conservation concern such as Wallago attu and Horabagrus brachysoma, indicates the ecological importance of the study area. In addition, the documentation of species not explicitly reported in earlier regional studies suggests spatial variation in species composition within the Pamba River system. The findings provide baseline information on fish diversity in this river segment and underscore the need for habitat conservation, regulated fishing practices, and long-term monitoring to ensure the sustainability of fish populations.

Length-weight relationship and relative condition factor of Indian river shad Gudusia chapra (Hamilton, 1822) in oxbow lakes of Bangladesh

2026-05-13T08:01:02+00:00

Length–weight relationships (LWRs) and the relative condition factor are crucial parameters in fisheries stock assessment studies. In this study, LWRs and the condition factor of the Indian river shad Gudusia chapra (Hamilton, 1822) were examined from three oxbow lakes (locally known as baor; 42–166 mm, 0.76–24.93 g) in Bangladesh. A total of 924 specimens were collected from Baluhar (n = 316), Purapara (n = 287) and Khushna (n = 321) oxbow lakes across three seasons (pre-monsoon, monsoon and post-monsoon) during March–December 2022 using standardized fishing nets. In Baluhar Baor, the lowest (2.588) and highest (3.017) b values were recorded in the post-monsoon and monsoon seasons, respectively. In Purapara and Khushna oxbow lakes, these values ranged from 2.893 (post-monsoon) to 2.972 (monsoon) and from 2.748 (post-monsoon) to 2.883 (monsoon), respectively. The coefficient of correlation (r) exhibited a consistent trend across all length categories as well as between seasons (all r² > 0.96). The present study will contribute to the development of future strategies for the sustainable management of G. chapra in the oxbow lakes of Bangladesh and similar aquatic ecosystems.

First account on feeding and reproductive biology of Aluterus scriptus (Osbeck, 1765) from the southern coast of India

2026-05-11T07:59:17+00:00

Aluterus scriptus (Osbeck, 1765) is a reef-associated fish from the Monacanthidae family. The data on its reproductive and feeding biology are currently scarce. Exploring these aspects is crucial for gaining insights that help in developing effective conservation strategies. A total of 900 specimens of A. scriptus were studied from February 2022 to January 2023. The samples were investigated for length-weight relationship, food and feeding habits, sex ratio, length at first maturity, spawning seasonality and fecundity. The observed mean length and weight were 50.2±14.7 cm and 1094±374.4 g, respectively. Growth was negatively allometric, with no significant differences observed between sexes in the length–weight relationship. The mean sex ratio (M:F) of 1:1.53 indicates a female-biased population, with a month-to-month variation in sex ratio. The estimated length at first maturity was 53.33 cm for females and 54.21 cm for males. Reproductive activity is observed throughout the year, with the peak occurring in December. A strong positive correlation was observed between the fecundity and total length (Pearson’s r = 0.986, p < 0.001). Seasonal variation in stomach fullness suggested fluctuations in feeding intensity. Diet analysis revealed a strong preference for coral, followed by small crustaceans, fish, jellyfish, and squid. These findings provide baseline data for the responsible management of A. scriptus fishery.

Apparent digestibility coefficients of selected feed ingredients for Asian seabass, Lates calcarifer reared in recirculatory aquaculture system

2026-05-11T07:59:30+00:00

Digestible nutrient-based feed formulations have become more prevalent in aquaculture, especially in intensive recirculatory aquaculture systems (RAS). In order to maximize growth performance and feed efficiency in Asian seabass (Lates calcarifer) raised in RAS while minimizing waste output, it is imperative to assess the apparent digestibility of nutrients from different feed ingredients used in the feed formulations. Accordingly, an eight-week study was conducted to analyse the apparent digestibility coefficients of nutrients in selected protein sources for Asian seabass, Lates calcarifer, reared in RAS. The reference diet consisted of commercial seabass feed with 47% crude protein. The test diets were formulated based on a 70:30 ratio approach for ingredient digestibility evaluation using fishmeal (FM), squid meal (SQM), soybean meal (SBM), corn gluten meal (CGM), wheat flour (WF), and broken rice (BR). The reference and test diets were finely ground for homogeneity, mixed with 0.5% commercial binder for stability, digestibility indicator (0.5% chromic oxide), and 2 mm pellets were produced. Growth of fish fed different diets was significantly affected owing to large variations in the inclusion levels of each ingredient. ADC of protein, lipid and energy varied from 81 to 93%, 62.8 to 90.1% and 81 to 90.3% respectively. FM and SQM exhibited significantly higher nutrient digestibility values, as fish are carnivorous. The higher nutrient digestibility of major plant-based protein ingredients suggests a higher quality of source materials. Overall, the present study provides information on the bioavailability of nutrients in animal and plant feedstuffs for Asian seabass reared in RAS.