Journal of Fisheries

Impact of environmental factors on the dietary preferences of Salmophasia bacaila in the Dhepa River, Bangladesh

2025-05-08T05:06:40+00:00

This study investigates the environmental variability and gut contents of an indigenous fish chela (Salmophasia bacaila) in the Dhepa River, Bangladesh. We conducted fish sampling and measured water quality across three sites from September 2017 to February 2018. The results revealed significant fluctuations in water temperature, dissolved oxygen, and pH (PERMANOVA: p = 0.001). There was spatio-temporal variation in water transparency (PERMANOVA: p = 0.001). The prey analysis identified 13 prey groups in the diet of fish, predominantly consisting of phytoplankton (92.9%), while zooplankton contributed only 7.1%. Twenty phytoplankton and seven zooplankton genera were recorded in the guts, with significant temporal variations in prey diversity (PERMANOVA: p = 0.010). These findings highlight that S. bacaila are primarily plankton feeders, with shifts in prey diversity driven by environmental factors in the Dhepa River. This research enhances our understanding of ecological dynamics and the relationship between S. bacaila and their prey in riverine ecosystems.

Effects of Streptococcus agalactiae infection and oral florfenicol administration on the hemato-biochemistry, erythrocyte morphology and histopathology of Oreochromis niloticus

2025-05-06T05:06:43+00:00

Streptococcosis is considered one of the most important diseases affecting farmed tilapia, causing severe economic losses. Antimicrobial therapy is the principal control measure applied during outbreaks. This research assessed the efficacy of florfenicol (FFC) when fed at 15 mg kg biomass^–1 day^–1 for 10 days against Streptococcus agalactiae infection in Oreochromis niloticus in terms of survival, changes in hemato-biochemistry, erythro-morphology, and histoarchitecture of the vital organs. Streptococcus agalactiae was moderately virulent to O. niloticus with a lethal dose (LD₅₀) of 1.26×10⁸ cells fish^–1 and sensitive to FFC with a minimal inhibitory concentration of 0.78 μg mL^–1. It caused systemic infection in tilapia. FFC therapy reduced bacterium-induced mortality and physiological stress. The histopathological findings indicated significant improvement in the kidney and liver tissues of fish. The erythrocyte morphological alterations noted in the challenged fish were irregularly shaped, elongated, crenated, and teardrop cells, hypochromic erythrocytes, ragged cytoplasmic membranes, hypertrophied nuclei, eccentric nuclei, and vacuolation, all of which were mitigated with FFC therapy. Eventually, FFC therapy improved wound healing, normalized plasma biochemistry, and aided recovery from bacterial infection. This study revealed that the therapeutic dose of FFC was effective against S. agalactiae infection in O. niloticus and lessened the physiological stress.

Stock assessment of Crossocheilus diplochilus (Heckel, 1838) in Dal Lake of Kashmir Himalayas

2025-05-06T05:06:57+00:00

The intricate dynamics governing population parameters stand as pivotal pillars in the realm of fish management and conservation. Accordingly, the various parameters of population dynamics of Crossocheilus diplochilus (Heckel, 1838) from the Dal Lake of Kashmir valley were investigated. The study reported that the fish exhibits a length range of 5.4 to 14.8 cm and a weight range of 1.24 to 17.19 g. The b value was reported to be 2.9 depicting negative allometric growth. The Fulton and relative condition factors were reported to be 0.86 and 0.99 respectively. The growth constant, asymptotic length, age at zero length and growth performance index were reported to be 0.33 year^–1, 17.40 cm, –0.62 years and 2.0 respectively. Fishing mortality was found to be higher than the natural mortality. The exploitation ratio was reported to be 0.52 which was found to be lower than the exploitation rate producing maximum yield (0.81). This is suggestive of an underexploited state of fishery of C. diplochilus from this lake.

The role of integrated prawn farming in climate change adaptation in Bangladesh: ecosystem services, economic viability and barriers

2025-05-06T05:07:10+00:00

The integrated rice-prawn-vegetable culture (RPVC) is an effective farming method that ensures the efficient utilization of water and land. This study aims to evaluate the role of RPVC in climate change adaptation, its ecosystem services, and economic sustainability in Bangladesh. Integrated RPVC provides farmers with ecosystem services, including reducing use of the fertilizers and insecticides and lowering financial instability. The vegetable platform shades prawn ponds naturally, while prawns consume insects in rice fields. After rice plants are harvested, their roots can serve as food for prawns. Majority of the respondents (85%) reported that adopting RPVC increased the overall productivity. Farmers faced a variety of climatic hazards; ranked as: drought (86.3%) > erratic and sudden heavy rainfall (81.5%) > temperature fluctuation (69.6%) > salinity intrusion (67.2%) > storm (28.5%). The ecosystem services provided by RPVC helped farmers to mitigate the adverse impacts of these climate-induced challenges through ecosystem-based adaptation. Integrated RPVC has also enabled farmers to maintain a consistent cash flow throughout the year. By promoting the production of multiple commodities—rice, prawns, and vegetables—the system reduces the risk of financial destitution. Despite benefits, farmers also encountered several challenges in implementing RPVC including water shortage (85.2%), disease (73.5%), theft (60.4%), increased feed costs (70.7%), lack of information (65%), increased labor cost (58.8%), and not getting expected market value of farming products (63.2%). However, if these barriers are addressed, the integrated RPVC system holds significant potential to foster long-term socio-economic growth in the southwest region of Bangladesh.

Social values of angling tourism in the Garo Hills of Meghalaya, North East India: fish farmers’ perspectives

2025-05-06T05:07:23+00:00

Angling tourism is gaining popularity and offers an alternative livelihood opportunity for the fish farmers of the Garo Hills region of Meghalaya, India. This research aims to provide insights into the social value of angling tourism among the fish farmers involved in angling tourism in the area and to identify its determinants. A sample of one hundred fish farmers was selected using snowball sampling from five districts of the Garo Hills, and data were collected using a semi-structured interview schedule. Most farmers considered fisheries a secondary occupation and were sceptical of angling tourism. The multiple stepwise regression analyses revealed that entry fees for daily angling besides competition and secondary occupation negatively impacted social value scores. In contrast, the educational status of fish farmers, annual investment in angling tourism, fish farming experience, total registered anglers annually, and family type positively impacted social value scores. The study confirmed that angling tourism fosters sustainable development within rural communities by nurturing social values and augmenting biodiversity conservation, and economic benefits. Overall, the study provides valuable information on the scope and prospects of angling tourism in leveraging social values and its potential to uplift rural people's social and financial status.