Journal of Fisheries (University of Rajshahi)
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Identification, isolation and pathogenicity of Aeromonas salmonicida and his-topathology of infected Oncorhynchus mykiss in Punjab and northern areas of Pakistan
Full text linkAeromonas salmonicida causes furunculosis in the Oncorhynchus mykiss (rainbow trout) and the effective control over this infection requires knowledge of the genetic variability and epidemiology of A. salmonicida. Pathogenic strains were isolated from kidneys, muscles, liver and spleen of rainbow trout from the provinces, Punjab, Khyber Pakhtunkhwa and Gilgit Baltistan, Pakistan. On the base of 16S rRNA sequencing, physiological and biochemical characterization, isolated bacterial strains were identified as A. salmonicida (NCBI Ref. ArS-Pak-19 [MW307221], ArS-Pak- GB1-19 [MW720959], ArS-Pak-MRE-19 [MW720960], ArS-Pak-SW2-19 [MW720961], ArS-SW1-Pak-19 [MW720962]). Isolated strains were resistant to antibiotics like sulfamethoxazole, penicillin, vanomycine, rifampicin and bacitracin but were extremely sensitive to spectinomycin, ciprofloxacin, ofloxacin, levofloxacin and nalidixic acid. To check out the pathogenicity, rainbow trout were experimentally infected with isolated strains. Experimental fishes showed the same symptoms as were recorded in naturally infected fish including jaw bleeding, intra-abdominal fluid, intestinal bleeding and gill filament anemia. After ten days of post-challenge study, histopathological analysis revealed that there were severe alterations in the spleen, liver and kidney of the infected fish. The present study provides further research foundation and for upcoming research on A. salmonicida disease, its control and epidemiology
Application of machine learning to growth model in fisheries
Full text linkTraditional growth models, such as length-weight relationships (LWRs) and the von Bertalanffy (VB) growth function, have been widely used in fishery science. Their limitations in capturing nonlinear patterns necessitate alternative approaches. Machine learning (ML) techniques have recently gained attention as a powerful tool for enhancing predictive accuracy in biological studies. In this study, the growth parameter of Eastern mosquitofish, Gambusia holbrooki (135 females: 21–58.78 mm and 0.152–3.424 g; 59 males: 19.25–43.20 mm; 0.108–1.075 g), was determined with traditional LWRs, VB, and machine learning algorithms. The LWRs growth equations of female and male individuals were W=0.00002102 L2.8849 and W=0.00003064 L2.8212, respectively. The VB equations were determined Lt=80.990 [1–e–0.990(t+0.208)] for female and Lt=64.172 [1-e–0.610(t+0.271)] for male. In general, the performance of both methods (VB model and ML algorithms) in predicting lengths, as measured by Mean Absolute Percentage Error (MAPE), was satisfactory, with the VB model demonstrating slightly superior performance (2.734). In addition, the ML algorithm gives better results in length data prediction with multilayer perceptron and in weight data prediction with Sequential Minimum Optimization (SMO) algorithm when ML algorithms are examined. The diverse ML algorithms positively impacted the investigations addressing growth-related issues in fisheries
Checklist of Ichthyofaunal diversity of Nagaland, India
Full text linkThe present review presents a checklist with an aim to review and summarize the results of the systematic researches on the freshwater resources including various rivers and aquatic resources of the north eastern state of Nagaland, India. The need of such a review is of utmost importance as systematic status of many of the species has changed, and reorganization and updating of the published information has become essential for future ichthyofaunal studies in the state. The total confirmed fish species of the state of Nagaland comprise of 219 species belonging to 31 families. The most diverse family is Cyprinidae with 90 species (41.09%), followed by Sisoridae with 22 species (10.04%), Nemacheilidae with 16 species (7.3%), Bagridae with 11 species (5.02%) while the remaining 26 families account for rest of the species in the list. This paper will certainly help in making appropriate conservation and management planning for fisheries in all the rivers of Nagaland and would also be helpful in looking at the various degenerative reasons for population decline of fishes
Fecundity of giant freshwater prawn (Macrobrachium rosenbergii) varies with the trophic status and size of the inhabitant perennial reservoirs in Sri Lanka
Full text linkGiant freshwater prawn (GFP, Macrobrachium rosenbergii) is an important commodity in the inland fisheries of Sri Lanka, where fecundity plays a crucial role in estimating the reproductive potential of the species. The fecundity of ovigerous GFP in relation to the trophic status and area of the reservoirs was empirically determined from the GFP collected from twenty-five dry-zone perennial reservoirs across Sri Lanka. Morphometric parameters, total and relative fecundity, and egg characteristics of ovigerous females were calculated. The total fecundity of GFP, which ranged between 5277±2069 – 29366±2371, differed significantly (p<0.05) with the trophic status and size of the reservoirs. The highest total fecundity was observed in the 24–25 cm and 185–210 g length and weight classes of GFP. The GFP inhabiting eutrophic medium perennial reservoirs exhibited the highest fecundity. Fecundity correlates with total length (r=0.75) and weight (r=0.71) of GFP. The total length of GFP was significantly associated with egg mass weight (r=0.74) in mesotrophic reservoirs compared to eutrophic reservoirs. Correlations between fecundity and body weight (r=0.70), fecundity and egg mass weight (r=0.76), egg mass weight and total length (r=0.69), and weight (r=0.72) were stronger in minor perennial reservoirs than in major and medium reservoirs. The present findings confirm that fecundity depends on the length, weight, and egg mass weight of ovigerous GFP, but not on the egg volume. The results align with the postulated hypothesis that the fecundity of ovigerous GFP varies with the trophic status and size of the reservoir
Optimising feed management for green tiger shrimp (Penaeus semisulcatus) in a biofloc system: impacts on growth performance, body composition and antioxidant activities
Full text linkThis study conducted over a 45-day period examined how different feeding strategies affect green tiger shrimp (Penaeus semisulcatus) development in biofloc aquaculture systems. The investigation focused on juvenile shrimp with an initial mean weight 2.85 ± 0.22 g, distributed across various experimental conditions. Five distinct treatment groups were considered, each consisting of tanks with a volume of 150 L of filtered seawater. Each tank was stocked with 53 shrimp, maintaining a stocking density of ~1 g L–1. Four groups utilised biofloc technology (BFT) with varying feeding levels: 0% (BFT0), 2% (BFT2), 4% (BFT4) and 6% (BFT6) of body weight per day. One additional group served as control, using a clear water system with feeding level of 6% (CW6) body weight daily. The BFT systems successfully maintained optimal water parameters despite minimal water exchange requirements. Performance metrics indicated that shrimp in the BFT4 and BFT6 groups achieved higher biomass production and survival rates. Biochemical analyses demonstrated enhanced nutritional profiles (protein, lipid and ash) in BFT-treated specimens. Antioxidant enzyme activity was significantly elevated in BFT systems, indicating improved overall health status. Superoxide dismutase (SOD), catalase (CAT) and glutathione peroxidase (GPx) activities were significantly higher in BFT groups than control. These findings suggest that feeding juvenile green tiger shrimp at 4% body weight within a BFT system represents an optimal strategy, achieving balanced growth performance while maintaining superior water quality and enhanced animal health indicators without compromising survival rates or body composition
Vietnam’s capture fisheries labor shortage explored: difficulties and responses
Full text linkThe fishing industry plays an essential role in Vietnam’s socioeconomic development, providing jobs to millions of workers. In recent years, fishing labor shortages have occurred on many fishing vessels in all capture fisheries, including small-scale and larger-scale fisheries in Vietnam. However, information pertaining to Vietnam’s fishing laborers has been limited for many years. In this study, a combination of secondary data methods and analysis of survey interviews with fishers who are fishing vessels’ owners and fisheries authorities in some key coastal provinces was used to answer the following questions: i) what are the difficulties in recruiting fishing labor in Vietnam’s capture fisheries? ii) How do fishing vessel owners respond to fishing labor’s shortages? Study results show many difficulties in crew labor issues in Vietnam in terms of finding crew members and maintaining minimum conditions for the number of workers on fishing vessels. Many reasons are found that cause the shortage of fishing laborers working on vessels. The owners of the fishing vessel have various ways to address this situation, including forcing fishing vessels to lie ashore or even go fishing in the case of labor shortage, switching to alternatives that require fewer human resources, actively seeking labor in other areas such as remote and mountainous areas, and increasing the share rate and deposit for fishing vessels fishing mates. Several solutions are proposed according to the results to overcome the labor shortage in Vietnam's capture fisheries
Assessment of reproductive biology of Garra langlungensis (Teleostei: Cyprinidae) from the Langlung River, Nagaland, India
Full text linkThe stone sucker, Garra langlungensis Ezung, Shaingningam & Pankaj, 2021, is confined to the Langlung River, near Zutovi village in Dimapur district of Nagaland, India. This endemic fish is a common food item among the local people. There is scarce information available on this species. Despite its rising exploitation, the lack of data could contribute to its decline and potential loss. The present study involved analysis of 213 specimens from the Langlung River, collected monthly over a period of one year, to determine the sex ratio, gonadosomatic Index (GSI), and fecundity. The sex ratio of males to females was 1:0.43 (deviation from the expected 1:1 ratio), showing a male-dominated population. The monthly assessment of GSI indicated that G. langlungensis breed once a year, with maximum GSI values of 8.1 (male) and 11.5 (female) in April and a short breeding season extending from February to May. Fecundity, based on data from 16 mature fish specimens, was the highest (844 eggs) in 77.9 mm TL (0.56 g) and the lowest (319 eggs) in 55.2 mm TL specimen (0.23 g). A significant correlation between fecundity and ovary weight (r = 0.915) was recorded. This study provides insights into the sex ratio, GSI, and fecundity of G. langlungensis, which facilitate the identification of fish stocks in their natural habitats and the development of appropriate conservation measures
Exploring shellfish diversity, utilisation and conservation threats in the Chalan Beel, Bangladesh
Full text linkShellfish are important components of aquatic ecosystems, including freshwater wetlands. In this study, we examined shellfish species diversity and their utilisation by humans in the largest wetland of Bangladesh, the Chalan Beel. Through systematic, standardised field surveys, we recorded 19 shellfish species, including 14 molluscs and five arthropods. The global conservation status of the recorded species was retrieved from the IUCN Red List database, and all were classified as Least Concern. Among the 19 recorded species, the majority—11 species—are used for human consumption, followed by use as animal feed (e.g. for fish, shrimp and poultry) (eight species), as fish bait (eight species), in traditional medicine (eight species), as ornamental species in aquariums (two species) and in freshwater pearl culture (one species). Six threats to shellfish populations have been identified: (i) harvesting for commercial trade, (ii) use of illegal fishing gear, (iii) construction of irrigation canals, (iv) destructive ‘katha’ fishing methods, (v) changes in land use and (vi) duck farming in the wetland. The findings of this study will serve as baseline data for future research. To ensure a sustainable supply of shellfish for human consumption and animal feed, we recommend focusing on shellfish aquaculture rather than harvesting from the wild. This approach may be particularly beneficial for mollusc populations. We also advocate for the formulation of conservation regulations for shellfishes in the country
Comparative efficacy of different doses of inducing agent on breeding performance of a near threatened catfish pabda (Ompok bimaculatus Bloch, 1794) in West Bengal, India
Full text linkIn India, diversification in shrimp culture area is required due to climate changes, fluctuation in resources, and its marginal profit. Near Threatened pabda (Ompok bimaculatus) may be an alternative aquaculture species which can fulfil all the demands for the shrimp farmers. In this study, healthy, disease-free, 12-month reared brood fishes were collected and stocked in eight tanks (8×4×2 feet) sex wise (130 pairs) with shower facilities. Synthetic hormone was used to induce both male and female fishes at 0.3 and 0.6 ml (T1); 0.5 and 0.7 ml (T2) and 0.7 and 0.8 ml (T3) kg-1 body weight (bw) respectively, having 3 replicates for each treatment. Ovulation period (7 to 11 hours), relative fecundity (105.20±39.93 eggs g–1 bw of female), fertilization rates (67.37±20.73 to 75.88±24.84%), hatching rates (62.57±18.46 to 79.67±26.68%) and survival rates (55.01±14.93 to 65.62±19.91%) were observed. Among treatments, T2 exhibited better breeding performance but no significant differences with other treatments were observed. Important water quality parameters like temperature (28.27±1.68°C), pH (7.10±0.44), dissolved oxygen (4.25±0.37 mg L–1), hardness (210.96±9.31 mg L–1) and alkalinity (202.78±8.00 mg L–1) were also recorded during this experiment. After 48 hours of hatching, hatchlings were reared in aerated tanks for another four days with close observation and fries were harvested 24 days of rearing. From the present experiment, T2 exhibited best effective dose for successful induced breeding of pabda
First data on big-scale sand smelt Atherina boyeri Risso, 1810 (Pisces: Atherinidae) from Kılıçkaya Dam Lake, Turkey
Full text linkThis research presents primary evidence regarding the occurrence of Atherina boyeri in Kılıçkaya Dam lake. A total of 345 specimens were obtained from local fishermen during May to June 2023. The sampled fish displayed a length range between 50.30 and 94.24 mm and weight between 0.76 and 4.30 g. The study established the length-weight relationship (LWR) based on total length (TL) as W = 0.00002285 L2.7018 for females, W = 0.00003297 L2.6033 for males and W = 0.00002501 L2.6746 for the pooled individuals. The exponential value b of TL-W ratio was determined as 2.6746, indicating negative allometric growth in the species. The average condition factor (CF) was computed as 0.641 ± 0.067. This investigation not only provides initial and valuable insights into the presence of A. boyeri in Kılıçkaya Dam lake but also enhances the understanding of the diversity of aquatic ecosystem. The findings of this study offer practical guidance to local fishery management authorities and decision-makers aiding in the implementation of suitable fishery management strategies to ensure the sustainability of fishery resources