Mass Fish Deaths Research Articles

Implementation of Naïve Bayes Method Diagnosing Diseases Nile Tilapia

The Nile tilapia, also known as Oreochromis niloticus, was a freshwater fish species first produced in East Africa in 1969. It became a popular aquaculture fish in freshwater ponds across Indonesia. Besides its delicious taste, the Nile tilapia is rich in nutrients essential for human health. However, cultivating Nile tilapia was challenging due to frequent bacterial diseases. These diseases often led to mass fish deaths, causing financial losses, especially for new fish farmers. The rapid spread of diseases emphasized the need for prompt intervention to prevent further losses. Farmers needed adequate knowledge about Nile tilapia diseases, but often struggled to absorb information provided by the government. Hence, the presence of experts or veterinarians was crucial in assisting farmers to address these issues. Farmers of Nile tilapia sought assistance from experts or veterinarians, but this was not easy. It involved substantial costs and time, while quick intervention was necessary to mitigate losses. The solution proposed was the development of an expert system for diagnosing and treating Nile tilapia diseases. Thus, an expert system was built to assist fish farmers in identifying fish diseases and their treatments by implementing the naïve Bayes method. The expert system transferred human knowledge to computers, enabling them to solve problems like experts, thereby making expert knowledge accessible to non-experts. Naïve Bayes was implemented to determine the highest probability based on input symptoms. This research used five test data samples to apply the naïve Bayes method to diagnose Nile tilapia diseases, resulting in an accuracy rate of 80%. Therefore, the implementation of naïve Bayes in diagnosing Nile tilapia diseases is considered reasonably effective.

Sediment capping technology for eutrophication control and its potential for application in Indonesian lakes: a review

Eutrophication occurs when the lakes become enriched with nutrients. Some nitrogen and phosphorus fractions will settle in sediment, and others will be released back into the overlying water column. Excess nutrients in water bodies resulting in hypoxic to anoxic conditions that can cause a mass fish death. Hence, we need a sediment management strategy to minimize resuspension and transport of sediment back into the water column. Sediment capping is a containment technology to reduce the release of nutrients from sediment as a strategy for eutrophication control. This study aims to provide insight into sediment capping technology, including several considerations in capping design, as well as information on several active materials that have been applied as capping materials and their efficiencies. Capping materials such as calcite, zeolite, bentonite, activated carbon, sludge, biochar, and gypsum from previous studies showed the efficiency of 54–99 % nutrient reduction with capping duration of 10–300 days in some eutrophic lakes. Sediment capping technology has successfully promoted lake ecosystem restoration in other countries, and this technology has the potential to be applied in Indonesian eutrophic lakes as a strategy for eutrophication control and sustainable management of lake ecosystems by considering the selection of the most effective, efficient, easy, inexpensive, and eco-friendly capping materials.

Ecological Interdependence of Pollution, Fish Parasites, and Fish in Freshwater Ecosystems of Turkey

Records of mass fish deaths were found in different data sources for this study. A map of mass fish deaths in Turkey was also realized for the first time. We aimed to present a review of the distribution of mass fish deaths in the freshwater ecosystems of Turkey, mostly present in the Marmara Region and Aegean Sea Region, where there are intensive industrial and agricultural activities. Fish parasites generally occur in equilibrium with their hosts in natural environments. In the freshwater ecosystems of Turkey, which are highly affected by human activities and have extremely rich natural ichthyofauna, the negative effects of pollution on environmental parameters, which can directly affect the fish, and the emergence and overextension of fish parasites can cause a supplementary synergic direct negative effect transposition in mass fish deaths due to the deterioration of host immunity and to the wounds induced in fish where bacterial, viral, and fungal pathogens can be effective. Finally, these factors can influence the fish rate of survival and skew the structure of fish populations. Mass fish deaths have been frequently reported in Turkey, but are usually only explained by pollution as a single accepted anthropogenic stressor. Together with pollution, a supplementary induced bioecological stressor, the qualitative and quantitative characteristics of the fish parasites’ association variations should be assessed and monitored as potential complex precursor indicators of fish communities’ structural degradation and freshwater ecosystems’ dreadful conditions. Fish parasites as biomonitor species should be used to identify the effects of pollution in Turkish ecosystems, and not only in freshwater ecosystems, in the future. An optimum management plan for freshwater ecosystems should include all the physico-chemical factors, fish parasites, and fish elements involved in permanent assessment and monitoring activities.

“I choose fish”: Understanding informal civil society in Vietnam through environmental grievances and actions

This paper focuses on informal civil society in an authoritarian context, particularly the unprecedented nation-wide protests and civic action in Vietnam, triggered by the industrial pollution and the resulting mass fish death on the central coast in 2016. We explore civil society actors' motivations and tactics to take action under political restrictions. Data was collected from semi-structured interviews with civil society actors. The findings illustrate how informal civil society in Vietnam is built on independent or partly NGO-affiliated individuals working together to promote non-violent change, although the process of doing so might involve challenging the government apparatus. The activists were motivated to take action by the dead fish’ symbolism of endangered livelihood, environmental protection, and to demand transparency from the government. Critical factors further contributing to the mobilisation of citizens included the combination of food symbolism and anti-China nationalism, the tactical use of Facebook by urban activists, and religious leadership in the rural areas. The protests resulting from the coastal pollution can be seen as boundary-spanning events through which Vietnamese civil society actors ‘invent’ spaces of (political) participation amidst limited ‘invited’ space.

Activism and non-activism: The politics of claiming environmental justice in Vietnam

This paper aims to explore how under authoritarian regimes, undergoing reform processes, divergent forms of environmental activism may emerge. Two severe cases of environmental degradation serve as our starting points: the marine disaster in the central coast of Vietnam in 2016 and the Mekong Delta's ongoing environmental degradation. While the former offers a case of rural grievances over mass fish death in Central Vietnam triggering protests on a national scale, the latter presents a continuum of environmental changes leading to serious impacts on deltaic livelihoods, albeit with no observable efforts of activism compared to the situation in other countries along the Mekong Delta. Drawing from in-depth interviews and participant observation with NGO workers in Vietnam who focus on environment and community development, we unravel the conditions, methods and rationalities behind their engagement (or lack thereof) with environmental activism in each case. We argue that the difference between the cases can be explained by tracing the process of politicising environmental grievances, taking into consideration culinary nationalism, anti-China nationalism and political opportunities under authoritarianism. Moving beyond current literature on activism under authoritarian regimes which relies mainly on institutional and/or social network approaches, our analysis helps further shed light on how contemporary environmental activism is mobilised in Vietnam from a geographically and politically grounded as well as culturally embedded position.

Wise Management or Mismatch? Lessons from Japan

As a precious resource, wetlands support human life in various profound ways, either explicitly or implicitly. However, the values of wetlands have not been sufficiently recognized and greatly appreciated. Their management approaches are often sectoral, and wise use of wetlands is still more of a catchphrase than a well-used management practice. This paper presents a cross-sectoral case study for the evaluation of the primary management practices in a Ramsar-registered wetland in Japan. It employed a literature review, field and laboratory experiments, and a questionnaire survey as well for assessing the wetland conditions and identifying management problems. It revealed that the management of the wetland is still flood regulation–oriented, without sufficient consideration of bird habitats, and the water level drawdown operation for Lake Yanaka inside the wetland may lead to mass fish deaths. Furthermore, the reed burning practice is effective in maintaining the plant structure in the wetland but controversial from different perspectives. Moreover, the questionnaire survey results indicated that the public were not well informed of the wetland conditions and not convinced of the appropriateness of reed burning. Based on these findings, it was concluded that the registration under the Ramsar Convention did not lead to new strategies for the conservation and wise use of the wetland.

The Resilience of Small-Scale Fishing Households to the Anthropogenic Environmental Shocks

The marine environmental incident causing mass fish death in Central Vietnam by Formosa Ha Tinh Steel Plant in 2016 severely impacted people's livelihoods in four provinces. Several previous studies have indicated that diversifying livelihoods is one of the best solutions to increase the resilience of households to overcome such incidents. This study investigated the relationship between livelihood diversification and the stability of small-scale fishing households. Our findings showed that impact levels and resilience capacity under family perception are important aspects for impact assessment in the context of the environmental shock. Local families can diversify their livelihoods based on their resources as well as through government-supporting policies. The livelihood diversification of impacted households is significantly valuable in increasing the resilience process after the Formosa incident. Families with more livelihood activities related to income sources have better resilience than families with less livelihood activities. By the effort of households and government support policies, impacted households have gradually improved their livelihood resilience.

The Fish Health Risk Indicator: linking water quality and river flow data with fish health to improve our predictive capacity around fish death events

Severe drought conditions contributed to three mass fish mortality events in the Darling River near Menindee, part of the Murray–Darling Basin, Australia, during the summer of 2018–19. An independent assessment recommended the need for improved modelling approaches to identify when sections of rivers may be more susceptible to fish kill events. We present a geographic information system (GIS)-based tool that combines meteorological forecasts with river flow and algal biomass datasets to identify river reaches where additional stresses on fish health may produce an increased risk of mass fish deaths. At present the tool is still in development and will require the addition of extra datasets and testing using historical datasets to further validate its accuracy. Despite the tool being in its development stage, the decision support tool has been widely accepted and provides natural resource managers with a rapid way to understand and communicate risks to fish health, supporting improved water management options across the Murray–Darling Basin that may ultimately help reduce the frequency and severity of large-scale fish mortality events.

MULTITEMPORAL ANALYSIS FOR TROPHIC STATE MAPPING IN BATUR LAKE AT BALI PROVINCE BASED ON HIGH-RESOLUTION PLANETSCOPE IMAGERY

Remote sensing data for analyzing and evaluating trophic state ecosystem problems seen in Batur Lake isan approach that is suitable for water parameters that cannot be observed terrestrially. As the multitemporal spatial data used in this study were extensive, it was necessary to consider the effectiveness and efficiency of the processing and analysis, therefore R Studio was used as a data processing tool. Theresearch aims to(1) map the trophic state of Batur Lake multitemporally usingPlanetScope Imagery;(2) assess the accuracy of the trophic state model and applyitto anothertemporal data as a SpatialBigData;and (3) understand the trophic state impacton the water quality of Batur Lake based on physical factors andthelake’s chemical concentration (sulfur concentration). Theresearch showsthatthetrophic state of Batur Lake isin good condition,with an ultraoligotrophic state as the majority class,based on the mean Trophic State Index (TSI) value of9.49. The standard errorsof each trophic state parameter were0.010 for total phosphor, 0.609 for chlorophyll-a, and 0.225 for Secchi Disk Transparency (SDT). The multitemporal model demonstratesthat the correlation between the increase oftrophic state and mass fish death cases in Batur Lake is existent.

Environmental justice and the politics of pollution: The case of the Formosa Ha Tinh Steel pollution incident in Vietnam

Research on environmental justice in authoritarian regimes, and in particular on how transnational networks support problem framing and claims-making in the absence of state-led democratic participation instances, is limited. This article uses the case of untreated wastewater from a steel mill owned by Taiwanese conglomerate Formosa Plastics Group, which caused mass fish deaths along coastal provinces in Vietnam in 2016, to explore how civic groups and local communities problematize official accounts of events and engage with transnational networks to make claims to environmental injustice. The paper highlights local narratives about the adverse impacts of the disaster on residents’ livelihoods and wellbeing, controversies over the causes of and responsibility for the disaster, and the role of transnational alliances with Taiwan in sustaining and magnifying claims to injustice. We argue that viewing issues such as the Formosa steel incident through a transnational environmental justice lens illuminates the effect of global and national processes of economic reform in shaping uneven environmental and social impacts from new infrastructure developments. We also argue that thinking in terms of transnational networks can make sense of the spaces which can emerge for claims-making in authoritarian contexts, where democratic participation instances and access to knowledge may be restricted.

Cryopreservation of testicular tissue from Murray River Rainbowfish, Melanotaenia fluviatilis

Globally, fish populations are in decline from overfishing, habitat destruction and poor water quality. Recent mass fish deaths in Australia’s Murray–Darling Basin highlight the need for improved conservation methods for endangered fish species. Cryopreservation of testicular tissue allows storage of early sperm precursor cells for use in generating new individuals via surrogacy. We describe successful isolation and cryopreservation of spermatogonia in an Australian rainbowfish. Testis histology showed rainbowfish spermatogonia are large (> 10 μm) and stain positive for Vasa, an early germ line-specific protein. Using size-based flow cytometry, testis cell suspensions were sorted through “A” (> 9 μm) and “B” gates (2–5 μm); the A gate produced significantly more Vasa-positive cells (45.0% ± 15.2%) than the “B” gate (0.0% ± 0.0%) and an unsorted control (22.9% ± 9.5%, p < 0.0001). The most successful cryoprotectant for “large cell” (> 9 μm) viability (72.6% ± 10.5%) comprised 1.3 M DMSO, 0.1 M trehalose and 1.5% BSA; cell viability was similar to fresh controls (78.8% ± 10.5%) and significantly better than other cryoprotectants (p < 0.0006). We have developed a protocol to cryopreserve rainbowfish testicular tissue and recover an enriched population of viable spermatogonia. This is the first step in developing a biobank of reproductive tissues for this family, and other Australian fish species, in the Australian Frozen Zoo.

Building and improving the capacity of fish and environmental health management strategy in Indonesia

Fish mortality due to outbreak and to the decrease in the quality of the environment is a latent problem increasingly complex in Indonesia. Extreme weather conditions with high rainfall intensity, reacute actually bring back several opportunistic pathogens of diseases such as Motile Aeromonads Septicemia. Various cases of mass fish deaths re-emerged, especially in public waters such as Maninjau Lake and Cirata reservoir is the sign of the decline in the quality and carrying capacity of the environment and it is suspected to be the main cause of the case. Over the past four years, fish mortality in public water has been regularly recorded and a peak of massive fish mortality occurred in 2016. A total of 4,725 tons of dead fish occurred which is estimated around 0.95 percent of the total production of freshwater net cages cultivation nationally. This amount is estimated to cost economic losses up to IRD 47.25 billion equivalent to 3.3 million US$ (assuming the price of fish is IDR 10,000/0.71US$ per kg). The occurrence of mass mortality of fish from net cages may reduce the aquaculture production originating from public waters up to 23.5 percent. Furthermore, risk of a new cross- border disease such as Acute Hepatopancreatic Necrosis Disease (AHPND); White Fecal Syndrome (WFS); Enterozytozoon hepatopenaei (EHP) and Tilapia Lake Virus (TiLV) heavily threaten aquaculture businesses. There is a need for cross-sectoral and even cross-country collaborative efforts, especially in anticipating the spread of cross-border fish diseases. This condition requires commitment and awareness from all stakeholders involved. Therefore, in order to promote sustainable aquaculture production, a national aquatic animal health (NAAH) strategy was formulated and will assist Indonesia government to: improve the national fish health services skills, make aware fish farmers undertaking responsible fish health management and to improve their capacity on emergency responses and contingency planning against diseases, reduce of important fish diseases and the use of chemicals in aquaculture, and prevent introduction of exotic disease. The implementation of the NAAH strategy needs guidance, support and full commitment from the government. The Ministry of Marine Affairs and Fisheries through Directorate General of Aquaculture is the competent authorities who will share responsibilities in the implementation of NAAH strategy.

Hydrometeorological conditions and water regime of the lake Krasilovskoye (Altai krai) in 2013-2017

The paper presents the analysis of the data on monitoring the hydrological state of the basinal freshwater lake Krasilovskoye (Altai Krai) and hydrometeorological conditions in its catchment in 2013-2017. The data from the automated measuring complex developed at the Institute of monitoring of climatic and ecological systems of SB RAS as well as the data on snow surveys carried out by researchers from IWEP SB RAS in the catchment and water area of the lake are used. Observations of water regime in the basin lake in the years with contrasting hydro-climatic conditions made it possible to identify the dominant factor determining its spring filling and to quantify its level dynamics. The magnitude and rate of level rise in spring mainly depend on hydro-climatic conditions of air and soil of the previous cold period, which in turn determine the ratio of surface and underground runoff in spring.&#x0D; It was found that in the winter of 2014 and 2016, hydro-climatic conditions of the cold period contributed to the freezing of soil and the formation of a "locking" ice layer, which prevented vertical infiltration of melt water. Intensive surface runoff induced a drastic level rise up to 1-1.5 m. In 2015 and 2017, at the absence of soil freezing, the water rise was much lower, despite large snow reserves and intensive snowmelt. In the spring of 2017, the driven out to the water surface diluted near-bottom layer enriched with hydrogen sulfide caused mass fish death after insignificant water inflow to the lake.

Socio-Economic Assessment of Grouper Fishermen and Their Perceptions on Mariculture Development in Buleleng District, Bali, Indonesia

Various activities in the coastal area of Buleleng-Bali for many years affected to the sustainability of mariculture activities. This research aimed to 1) identify the problems of groupers farming in fish cages, 2) analyze the cost-benefit of grouper farming and 3) analyze fish farmer perceptions on mariculture development. Primary and secondary data were collected and analyzed by using descriptive, financial and Likert-type analyzes. The results show that the average production of grouper farming was 450 – 7500 kg per harvest. The main problems in groupers farming are related to uncertainty market demand in recent years, financial capital limitation, high price of fish feeding, and low productivity. Benefit-cost analysis revealed that the benefit-cost ratio is 1.92 (B/C ratio &gt; 1) and the payback period (PP) is 2.3 years (project life assumption: 10 years) and the internal rate return (IRR) is 12%. It means that grouper farming is economically visible to develop in Buleleng District. Fish farmers as well as local stakeholders have positive perception and active participation in grouper farming using floating-fish cages. Fish farmers also needs special trainings related to disease management, seed selection, marketing, and good aquaculture practices. The main obstacles of price and capacity faced by farmers for using various sensors to reduce the risk of mass fish death and other climate change effects should be of special concern to local and central government to install a set of equipment to control and reduce the impact of environmental changes on all grouper floating cages.

Mass fish deaths in Australia set to continue

Drought conditions and poor water management have contributed to the events. Drought conditions and poor water management have contributed to the events.

MATHEMATICAL MODEL FOR DISSOLVED OXYGEN PREDICTION IN CIRATA RESERVOIR, WEST JAVA BY USING ARTIFICIAL NEURAL NETWORK

Cirata reservoir is one of the reservoirs which suffer eutrophication with an indication of rapid growth of water hyacinth and mass fish deaths as a result of lack of oxygen. This paper presents the implementation and performance of mathematical model to predict the concentration of dissolved oxygen in Cirata Reservoir, West Java by using Artificial Neural Network (ANN). The simulation program was created using Visual Studio 2012 C# software with ANN model implemented in it. Prediction process was carried out by training process followed by a testing process using weights that have been obtained from training process. ANN model for predicting dissolved oxygen in Cirata reservoir shows the best performance with correlation coefficient value of 77.44%, Root Mean Square Error (RMSE) = 0.12 and Willmott’s Index of Agreement (WIA) = 0.72.

Using numerical modelling in the simulation of mass fish death phenomenon along the Central Coast of Vietnam

A two-dimensional model was used to reconstruct scenarios related to the mass fish death phenomenon that occurred along the Central Coast of Vietnam. First, a Weather Research Forecasting model was used to simulate the wind field during April 2016, and was then used as an input to the two-dimensional (2D) model. Second, the calibration of the 2D model showed high conformity in both the phases and amplitude between the simulated and observed water levels. The simulation results of two scenarios, S1 and S2, were highly recommended for explaining the mass fish death phenomenon that occurred along the coast from Ha Tinh Province to Thua Thien-Hue Province. The calculated results of water quality data combined with the toxic concentration measured in fish will ultimately enable the simulation of the delimiting pollution zones and will facilitate response solutions when a similar phenomenon occurs in the future.

Analysis of causes of emergency fish death in kharkov region

Recently, the cases of mass fish death assumed dangerous proportions that causes great economic losses to the state and demonstrates the unfavorable ecological condition of surface waters of the country. The article analyzes the causes of fish death in order to anticipate and prevent the emergencies on water. The article shows that the main causes of mass fish death are the increase of average temperature and water pollution. The analysis of the temperature dynamics in Kharkiv region showed that the last 60 years saw the tendency of increase of average annual temperatures that affected the hydrochemical and hydrological conditions of reservoirs. The analysis of the condition of the Loppan' river basin based on the identification of potential risk to public health in the period from 1924 to 2010 showed that the river had been in dangerous condition and required immediate implementation of environmental protection measures. To predict the condition of the Loppan' river basin, the method of double exponential smoothing (Holt’s method) was used. The results of the studies are necessary to develop the conservation programs to improve the ecological state of Kharkiv region and to minimize the cases of mass fish deaths

Cold blamed for Bolivia's mass fish deaths

Extreme weather wreaks havoc in the rivers.

Investigation of Cause of Mass Fish Death in October 2007 at Minami-Sotobori in Osaka-Jo Park

Investigation of Cause of Mass Fish Death in October 2007 at Minami-Sotobori in Osaka-Jo Park