Journal of Fisheries (University of Rajshahi)
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Development of a model for predicting mussel weight: a comparison of traditional and artificial intelligent methods
Get PDFThe relationship between length and weight is non-linear. Predictive modelling using linear regression methods subjects these variables to transformation which results in models of poor predictive value. Hence, a comparative study on developing a predictive model using traditional (length-weight relationship, LWR; multiple linear regression, MLR) and artificial intelligent (artificial neural networks, ANN) methods was conducted. Specimens (n = 320) of the horse mussel Modiolus modulaides were randomly collected from October 2018 to March 2019 at the coastal area of Dumangas, Iloilo, Philippines. Shell length, shell width and shell height were used as predictor variables for total weight. A multi-layer perceptron architecture model was used and the values were determined by the ANNs model using the actual data. In addition, LWR and MLR models were generated from the same data after log-transformation. The results indicated superiority of the ANN model to predict mussel weight to traditional LWR and MLR models. The ANNs model had the highest correlation coefficient and lowest errors among the predictive models. The ANNs model generated from this study can be a good alternative to existing models and may be useful in sustainable fisheries management
Size at maturity, maturity stages, and sex ratio of Micropterus salmoides (Lacepède, 1802) in Zimbabwe’s largest inland reservoir, Tugwi Mukosi: a baseline study
Get PDFSize at maturity, sex ratio and maturity stages are key population parameters that are important in fisheries management of exploited stocks as they influence survival of fish populations. The introduced largemouth bass Micropterus salmoides has successfully colonised freshwater bodies in southern Africa. In Tugwi Mukosi Dam, Zimbabwe’s largest reservoir, largemouth bass is a fish of importance as it provides tourism, food and income for the local communities. This study investigated population parameters of M. salmoides in Tugwi Mukosi Dam. The study revealed that the size at 50% sexual maturity (L50) value for male and female was 204 mm and 261 mm respectively. The logistic equation for female largemouth bass was M(L) = 1 / [1 + exp (–0.256L + 6.402)]. For male largemouth bass the logistic equation was M(L) = 1 / [1 + exp (–0.1375L + 4.129)]. The results showed that reproductive activity peaked in October. The male to female ratio was 1:1.04 which is typical of healthy populations. More research and monitoring of the population parameters of largemouth bass is needed so as to be able to predict long term effects of overexploitation and enable responsible authorities to protect the fish stock from collapsing
Food aid programme during restricted hilsa fishing period: effectiveness and management perspective
Get PDFHilsa (Tenualosa ilisha) is geographically and economically important species in Bangladesh. To conserve hilsa, the government of Bangladesh has introduced fishing ban for certain periods of the year and also provides food assistance to hilsa fishers during the restriction period. Inadequate management often pushes real fishers out of the assistance programme and therefore, this study focused on assessing the effectiveness of the programme with a view to proposing a better management practice. A total of 202 randomly selected fishermen, living in the villages adjacent to Andharmanik River of Patuakhali district of Bangladesh, were interviewed. The Andharmanik River is famous for the natural breeding of hilsa. Results suggest that the amount of food provided and its distribution pattern were not that effective for the fishermen. Effectiveness was significantly related to the number of earning able family member, income difference between peak and restricted season and loan facility during the restriction period. This study also explained income difference trajectories of the fishermen community. Community-based management with facilitation by the state fisheries department and local government entity may enhance the programme effectiveness. More awareness programme and research are needed in this regard
Does fish price depend solely on weight? A market survey analysis from four districts of West Bengal, India
Get PDFFish is an important food item that contains perfect combination of essential nutrients. The main consumable fishes in West Bengal, India are various carps and other small indigenous fishes. The objective of the study was to find out whether fish weight was a crucial factor to decide pricing and what kind of fish was beneficial for consumer from economic perspective. Thirteen markets in four districts (Kolkata, North and South 24 Parganas, Howrah) of West Bengal were surveyed to collect information about price, weight and number of vendors selling a particular fish considering 22 fish species. Subsequent statistical analyses were performed to conclude about the relationship between fish weight and price. The study indicates that pricing of every fish species does not depend solely on their weight. Weight plays important role to determine the price of few fish species such as Liza persia, Lates calcarifer, Wallago attu, Ompok pabo and Mystus tengara. But, the price of small indigenous fishes like Chanda nama, Colisa fasciata, Harpadon nehereus, Monopterus cuchia, Rhingomugil corsula, Sperata aor and Puntius puntio does not depend on the weight of individual fish. Seasonal availability, taste, consumer’s personal preference have important role to determine fish price
Drivers of fisheries and their management in the lakes of Pokhara Valley, Nepal
Get PDFInland fisheries provide food security, livelihood and well-being to community. Fisheries management of lakes is a complex process, influenced by many drivers. In this study the driver of fisheries of lakes of Pokhara Valley were determined through interview of Jalari fishers, key informants and field visits from July 2016 to June 2017. Key drivers were illegal fishing, siltation, loss of fish habitat, water pollution and accelerated eutrophication, intensification of agriculture, biological invasion and developmental works. These drivers have played a key role in changing lake characteristics including lake size, water quality, water depth and natural food availability which subsequently affected the cage aquaculture and capture fisheries of the lake. This paper included an insight of these drivers along with strategy to mitigate them to ensure sustainable fisheries
Effects of dietary glutamate and succinate on growth performance and mitochondrial respiration in heart and liver of Atlantic salmon (Salmo salar) smolts
Get PDFThe smolt stage of salmon has challenges in reaching adequate growth rates due to the changing environmental conditions at sea. Therefore, it is necessary to provide adequate diets to achieve sufficient growth. This study determined the impacts of glutamate and succinate (1% each) supplemented diet on the growth of Atlantic salmon smolts along with characterization of mitochondrial respiration using high-resolution respirometry technique. Results indicated that there was no significant difference in growth response between the treatment and control groups. Maximum oxidative phosphorylation (OXPHOS) was reached after addition of succinate. Analysis of heart homogenates revealed a significant difference in LEAK respiration state (P = 0.005). No significant difference was recorded between the diet groups for liver homogenates. Differences between heart and liver respiration revealed that mitochondrial activity is organ dependent
Prevalence of diseases caused by Flavobacterium spp. and other opportunistic bacteria in carps of sewage-fed farms in West Bengal, India
Get PDFIndia is the second largest fish producing nation after China, contributing about 5.68% of the global fish production. The state West Bengal is occupying the second position in freshwater fish production after Andhra Pradesh. Although a number of constraints have been put forth, diseases and poor farm management are some of the most noticeable reasons for the reduced fish production in West Bengal. This study reports the prevalence of diseases caused by Flavobacterium spp. and other opportunistic bacteria in carps of sewage-fed farms in West Bengal. The bacteriological examination of the diseased carps revealed infections with different bacterial species and most of them were opportunistic pathogens. Flavobacteriosis, aeromoniasis, pseudomoniasis and other mixed bacterial infections, as confirmed by conventional biochemical tests and by VITEK 2 Compact system, were noted frequently. Antibiotic sensitivity of the opportunistic bacterial pathogens from the diseased carps indicated that some of these bacterial strains are resistant to potential human medicines like erythromycin, cotrimoxazole, oxytetracycline, nitrofurantoin, etc., which is a serious cause for concern. These results further present the fact that sewage-fed fish farms and the food fish from such systems may pose a serious public health risk from the antibiotic-resistant bacteria, if not handled properly
Threatened fishes of the world: Anoxypristis cuspidata (Latham, 1794) (Pristidae)
Get PDFThe knifetooth sawfish Anoxypristis cuspidata (Latham, 1794) is a species of sawfish belonging to the family Pristidae. It is an Indo-West Pacific species occurring from the northern Persian Gulf to Australia and north to Japan. The species is assessed as Endangered in the IUCN Red List of Threatened Species. Main threats to the species are fishing, coastal development and habitat degradation. This sawfish species has considerable ecological importance for the regions, but there are little data of its populations. Hence, a detailed study of population status, ecological and biological characteristics of A. cuspidata is required. This study will provide basic information on distribution, biological characteristics and conservation of this species
Alternative growth models in fisheries: Artificial Neural Networks
Get PDFIn this study growth of Atherina boyeri, collected from Süreyyabey Dam Lake, was determination by Artificial Neural Networks (ANNs) along with study of length weight relationships (LWRs). A total of 394 individuals including 32.5% female and 67.5% male specimens were studied collected during the fishing season between May 2015 and May 2016 from the local fisherman. The total length and weight of the specimens were 32–90 mm and 0.225–4.062 g respectively. The relationships were W = 0.01285708 L2.67 (R2 = 0.983) for females, W = 0.00678019 L2.95 (R2 = 0.969) for males and W = 0.00641527 L2.87 (R2 = 0.970) for pooled individuals. Mean Absolute Percentage Error (MAPE) of ANNs (0.182) for all specimens was lower than MAPE value of LWR (1.763). The results of study show that ANNs are superior tool to LWRs for fishes of Süreyyabey Dam Lake
Fecundity of the blotched picarel, Spicara maena (Linnaeus, 1758) from Oran Bay (Western Mediterranean Sea)
Get PDFThe fecundity of the blotched picarel Spicara maena from the western Mediterranean (Oran Bay) was assessed by the volumetric method. Total length (TL) of studied females varied between 91 and 140 mm (mean ± SD: 111.9 ± 10.6 mm). Estimates of total potential annual fecundity varied from 16750 to 28125 oocytes per individual (mean ± SD: 21404.7 ± 2698.8). Relationships between total potential fecundity (F) and TL, total weight, gonad weight were established using the multiplicative regression model and a high significant correlation was found in all the cases