Net Damage Research Articles

Socio-economic impacts of the recent bio-invasion of Callinectus sapidus on small-scale artisanal fishing in southern Italy and Portugal

IntroductionThe recent and growing bio-invasion of the Callinectes sapidus (known as blue crab) is causing damages in the European aquatic ecosystems, and affecting the livelihoods of the fishermen. In this context, this study explores the socio-economic impacts of this bio-invasion on small-scale artisanal fishermen in the Apulia (southern Italy) and Algarve (southern Portugal) regions, analyzing their perceptions and highlighting the repercussions of this bio-invasion on their livelihoods.MethodsFor this purpose, we carried out a field survey with representative small-scale artisanal fishermen based on the “Socio-economic Impact Classification of Alien Taxa” (SEICAT) approach by means of an “Exploratory Factor Analysis” (EFA), and a “Hierarchical Analysis and K-means Cluster Analysis”.Results and discussionThe findings reveal that the two study areas, Apulia and Algarve, exhibit markedly different perceptions of the impact of the blue crab invasion on the well-being and activity of fishermen. In Apulia, the invasion has led to extensive damage to fishing nets, physical harm, a decline in other commercial species, reduced catch quantities, increased working hours, higher costs, and lower incomes. Conversely, in the Algarve, while net damage is less severe, the primary concerns are physical harm, increased working hours, higher costs, and reduced income. Consequently, this research provides an empirical basis for the adoption of management measures and interventions to mitigate the socioeconomic impacts of the blue crab on the fishing community and local economy, thereby contributing to the well-being of both individuals and the marine ecosystem.

Hydrodynamic response analysis of the aquaculture net under the combined action of irregular waves and currents

ABSTRACT The hydrodynamic response of fishing nets is crucial in aquaculture. During service, due to severe sea states and collisions with large fish, potentially resulting in net damage. Analyzing this damage is complex due to the large number of net meshes. This study establishes a mathematical model of the net system under wave-current coupling based on the rigid-body kinematics and the lumped-mass method. An analysis was conducted to investigate how various environmental conditions and types of damage affect net deformation and force. Results indicate that maximum force occurs at the connections to the rigid frame and the midpoint of the net. Among various types of net damage, the nodes motion increased exclusively around the periphery of the damaged area, while the netting twine force significantly decreased only in the direction of the damage. Notably, damage to the upper net has the greatest impact on both netting twine force and deformation.

Hiding the elephant: The tragedy of COVID policy and its economist apologists

AbstractIn 2020 and 2021, the world witnessed policies that caused enormous net damage to most countries. We demonstrate the usefulness of the new WELLBY currency in gauging the costs and benefits of COVID policies and review the contributions of Australian economists to the scholarly and public debates about these policies. Our analysis documents the value of what was destroyed, the weak resistance mounted by the Australian economics profession during this period, and the role played by many Australian economists as apologists for what we view as Australia's most catastrophic peacetime economic policy failure. We close with ideas for working towards a better future.

Environmental Damage of Different Waste Treatment Scenarios by Considering Avoided Emissions Based on System Dynamics Modeling

This study aims to develop a comprehensive model for life cycle assessment and environmental damage cost calculations considering avoided emissions in different waste management scenarios using the system dynamics (SD) approach. Our analysis reveals that under the business-as-usual (BAU) scenario for the period 2020–2050, the total net greenhouse gas (GHG) emissions reach 12.5 Mt, with the highest environmental damage cost being USD 689 million. In contrast, an integrated management strategy encompassing recycling, composting, anaerobic digestion, and incineration results in a 195% reduction in net GHG emissions compared to the BAU Scenario. Concurrently, the environmental damage cost drops to USD 277 million, incorporating USD 347 million in savings, leading to a net environmental damage cost of USD −71 million. The findings affirm that accounting for emissions avoided across various treatment methods offers a more accurate estimate of environmental damage costs. Additionally, policies centered on integrated waste management are more likely to achieve sustainability. The study also demonstrates the utility of the SD approach in providing a holistic view of waste management systems and in evaluating the effectiveness of various policy strategies for sustainable waste management.

Does leaf net carbon gain and damage explain the minimum thresholds of light for shade tolerance in seedlings of an emergent rainforest tropical tree?

Does leaf net carbon gain and damage explain the minimum thresholds of light for shade tolerance in seedlings of an emergent rainforest tropical tree?

The Social Cost of Ozone-Related Mortality Impacts From Methane Emissions.

Atmospheric methane directly affects surface temperatures and indirectly affects ozone, impacting human welfare, the economy, and environment. The social cost of methane (SC-CH4) metric estimates the costs associated with an additional marginal metric ton of emissions. Current SC-CH4 estimates do not consider the indirect impacts associated with ozone production from changes in methane. We use global model simulations and a new BenMAP webtool to estimate respiratory-related deaths associated with increases in ozone from a pulse of methane emissions in 2020. By using an approach consistent with the current SC-CH4 framework, we monetize and discount annual damages back to present day values. We estimate that the methane-ozone mechanism is attributable to 760 (95% CI: 330-1200) respiratory-related deaths per million metric tons of methane globally, for a global net present damage of $1800/mT (95% CI: $760-$2800/Mt CH4; 2% Ramsey discount rate); this would double the current SC-CH4 if included. These physical impacts are consistent with recent studies, but comparing direct costs is challenging. Economic damages are sensitive to uncertainties in the exposure and health risks associated with tropospheric ozone, assumptions about future projections of NOx emissions, socioeconomic conditions, and mortality rates, monetization parameters, and other factors. Our estimates are highly sensitive to uncertainties in ozone health risks. We also develop a reduced form model to test sensitivities to other parameters. The reduced form tool runs with a user-supplied emissions pulse, as well as socioeconomic and precursor projections, enabling future integration of the methane-ozone mechanism into the SC-CH4 modeling framework.

Utilizing interview-based data to measure interactions of artisanal fishing communities and cetacean populations in Kuching Bay, Sarawak, East Malaysia

Kuching Bay is a significant area for artisanal fishing activities as well as an Important Marine Mammal Area (IMMA) for coastal cetaceans. A total of 286 fishers from eight fishing communities were interviewed between 2011 and 2019 to determine the nature and extent of cetacean-fishery interactions in the area. The main types of fishing gears recorded were gillnets, trammel nets, trawl nets, longlines, handlines and crab traps, with the use of gears varying by season and target species. Depredation, net damage, and entanglements in fishing gear were the most frequently reported negative interactions with cetaceans. Thirty-six percent of fishers reported having experienced a cetacean entanglement in their fishing gear at least once. More than half (58.1%) of the respondents who experienced bycatch were able to disentangle and release the animals alive. The more conservative calculated bycatch rate of 0.36 cetaceans per fisher over a fishing career indicates that a minimum estimated average of 19 cetaceans are involved in bycatch annually in Kuching Bay, with as many as nine of these incidents likely resulting in mortality. However, a less conservative method yields a bycatch rate of 0.57 per fisher, and estimated an average of 30 bycaught cetaceans per year. Irrawaddy dolphins (Orcaella brevirostris) were reported to be at the highest risk (72.9% of reported incidents), with an estimated minimum of seven individuals caught and killed per year. Despite the negative interactions, 77.2% of respondents reported a generally positive attitude toward cetaceans based on their value for tourism and as indicators of fish presence and a healthy ecosystem. Mutualistic relationships between fishers and cetaceans were documented, with 53% of respondents reporting that they feed discarded fish to cetaceans. The results of this study can be used to guide effective mitigation measures, which should focus on training fishers in safe handling and release of entangled cetaceans, and, more importantly, methods to prevent interactions with gillnets.

Robust automatic net damage detection and tracking on real aquaculture environment using computer vision

Sea cage inspection is a crucial task in marine aquaculture for both controlling the quality in the fish development process and the environmental impact of these facilities. Net damage in sea cages can cause fish to escape from fish farms to the open sea, producing serious economic losses and compromising the surrounding marine ecosystem. Currently, the most sophisticated inspection processes used in the industry rely on human visual inspection of underwater videos captured with tele-operated underwater ROV (Remotely Operated Vehicles). This process is tedious, time consuming, imprecise, highly dependant on the operator level of expertise, and has low verifiability.This article presents a comprehensive algorithm for automatic net damage detection in sea cages for aquaculture oriented to on-ROV processing and real-time processing. The proposed approach takes a video stream from an on-ROV camera, segments the image frames to separate the net of the sea cage from the background, and applies noise reduction tuned for underwater conditions. Then, to perform net damage detection, the mesh net hole areas are analyzed for detecting outliers that represent potential damage. Finally, holes neighboring to the outliers are analyzed to reduce perspective errors, and a spatial-temporal criterion using tracking is applied, to reduce the chance of false positives. The algorithm was first tested using a set of public images for comparison with state-of-the-art approaches and repeatability of the tests, and then using a dataset of real ROV inspection sequences to evaluate its effectiveness in real-world scenarios. Results show that our approach presents high levels of accuracy even for adverse scenarios and is adequate for real-time processing in embedded platforms.

The Role of Oxidative Stress in the Pathogenesis of Eye Diseases

Oxidative stress can be defined as an excess of intracellular concentrations of reactive oxygen species (ROS). The term ROS is used to describe free radicals such as hydrogen peroxide, superoxide anion or singlet oxygen. All these chemical species are, as the term suggests, in a highly reactive state. Molecules with unpaired electrons in their outer orbits, such as free radicals, seek to react with other molecules to pair their unpaired electrons. ROS may occur as a natural by-product of the normal cellular metabolism of oxygen. Net cellular damage is a result of several factors, including the type and amount of free radicals, the rate at which they are produced, the structural integrity of the cell and its compartments, and the extent to which the antioxidative defense systems is active. Fortunately, the healthy human body has a number of ways to neutralize or eliminate ROS. Oxidative stress emerges when the ROS formation exceeds the capability of cells to clear and neutralize them. This is a harmful process that can negatively affect and damage macromolecules such as proteins and nucleic acids. Cells deploy an antioxidant defensive system to protect themselves from and repair ROS-induced cellular damage. If the body's repair mechanisms are also weakened, the resulting damage may lead to disease. In ophthalmology oxidative stress is a risk factor for the induction of several diseases such as glaucoma, Flammer-syndrome, age-related maculopathy or diabetic retinopathy.

어구부표의 표시 방법 개선에 대한 입법론적 고찰 - 어구 손상사고 사례를 중심으로 -

Accidents between small ships and small fishing vessels sailing in the coastal waters of Korea and facilities installed for fishing on the coast occur frequently every year. These accidents are mainly caused by aquaculture farms, fishing nets, and gill nets installed in coastal waters. Common causes of ship accidents include the negligence of the officers of the crew on a sailing vessel, non-compliance with course maintenance, confirmation of ship position, and general navigation. It can be in various ways, such as non-compliance with the principles and regulations on the prevention of collisions at sea. In particular, to examine the cause of the accident related to the fishing net damage accident, it was analyzed through the decision of the Maritime Safety Tribunal, and as a result, the cause of the accident was neglect of the boundary, not securing an appropriate distance from the installed fishing gear, and insufficient establishment of the voyage plan. In order to reduce accidents caused by these human factors, it takes a long time and a lot of money, such as constant safety education for seafarers or changes to systems such as ship safety management system. In this paper, measures to reduce the occurrence of accidents by removing other risk factors other than human factors by intuitively discovering fishing gear a little faster are presented in 「Fisheries Act」, 「Rules on the Management of Fishing Licenses, etc.」, 「Aquaculture and fishing grounds」 We will try to find a way to reduce the damage to fishing nets by identifying and improving problems in the “Installation Standards for Marking Facilities” and “Aquaculture Industry Development Act”.

Digital twin for rapid damage detection of a fixed net panel in the sea

The fishing net is the most important component of aquaculture net cages. Once damaged, it can cause substantial economic losses and ecological problems to the aquaculture industry. To avoid these subsequent issues caused by the damage to the fishing net, seeking a computerized, labor-saving approach and detecting damage in real time becomes the primary task of this paper. Inspired by recent development of the artificial neural networks and machine learning, this study proposes a fast and accurate approach for fishing net damage detection based on digital twin. Firstly, time-domain numerical simulations of the fishing net are conducted in a series of wave and current conditions to develop the artificial neural network-based digital twin. Then, the significant wave height, the spectral peak period, and tensions of vertical and horizontal ropes are used as input variables during the artificial neural network training; the intact and damaged states of the fishing net are considered outputs. Alongside this, the back-propagation learning algorithm is used for training to maximize damage detection performance. The results highlight that the digital twin model can effectively identify the fishing net damage using the sensor data, and the accuracy of the damage detection reaches above 93%. When the damage occurs at different net positions, the prediction accuracies of the artificial neural network model for training and testing sets are 93.97% and 93.00%, respectively. Regarding different wave-current directions, the prediction accuracies of the artificial neural network model are 99.87 % and 99.34 % for training and testing sets. Moreover, the developed digital twin can accurately detect the damage of the net even sea conditions and sensor data are not included in the training. The digital twin model proposed in the present study can potentially be used for damage detection in other aquaculture components and structures.

Dolphin depredation and damage accumulation on different set nets in the northeastern Mediterranean Sea

Small-scale fisheries represent an economically marginalized sector, that struggles to balance operational costs and profit from catches. Economic revenues from catches have declined due to overfishing, and additional costs may jeopardise the sustainability of the sector. In Greece, reported net damage from interaction with marine megafauna, especially the bottlenose dolphin (Tursiops truncatus) is a common occurrence for many coastal areas, where small-scale fisheries operate. A seasonal experimental trial took place during 2016–2017 in the northern Aegean Sea, in an area where large actively swimming marine organisms other than dolphins were lacking. Three gangs of different panels of net (mixed gill nets and trammel nets) were deployed in three different depth zones. For each gang, we recorded the number, size, and position of holes on each net, and assessed overall damage. Multifactor analysis was used to identify possible links between fishing practices and damage intensity. Results showed a correlation between reduced net damage by dolphins with larger mesh sizes and increasing depth. In the case of small mesh sizes, one should seek a combination of solutions, as changes in deployment depths alone, do not seem to be adequate for the depth ranges studied. The adoption of larger than 22 mm mesh size is proposed for all set nets, to increase net selectivity and decrease accumulated damage. Fishers should focus on adjusting, substituting or even ceasing specific fishing tactics to have the lowest possible economic loss, whereas fisheries scientists, managers and policy makers must monitor and offer guidance for this transition.

Misleading estimates of economic impacts of biological invasions: Including the costs but not the benefits.

The economic costs of non-indigenous species (NIS) are a key factor for the allocation of efforts and resources to eradicate or control baneful invasions. Their assessments are challenging, but most suffer from major flaws. Among the most important are the following: (1) the inclusion of actual damage costs together with various ancillary expenditures which may or may not be indicative of the real economic damage due to NIS; (2) the inclusion of the costs of unnecessary or counterproductive control initiatives; (3) the inclusion of controversial NIS-related costs whose economic impacts are questionable; (4) the assessment of the negative impacts only, ignoring the positive ones that most NIS have on the economy, either directly or through their ecosystem services. Such estimates necessarily arrive at negative and often highly inflated values, do not reflect the net damage and economic losses due to NIS, and can significantly misguide management and resource allocation decisions. We recommend an approach based on holistic costs and benefits that are assessed using likely scenarios and their counter-factual.

Design Development and Analysis of Future Reliable Electric Vehicle

Universal climate change has already had noticeable effects on the environment. Net damage costs of climate change are likely to be considerable and to swell over time and emissions from transportation sector and use of fossil fuels in this scenario is just like adding fuel to fire. This work is a small effort made not only to portray the development of future reliable technologies in eVehicle that provides a cleaner solution with less carbon footprint but also to explain and establish the importance of the eVehicle as the most efficient and clean means of transportation with the help of plan and performance analysis. This paper presents the detailed analysis of different components of Battery operated eVehicle. The proposed EV Design addresses issues like range, drive train efficiency, fast exploration of higher system voltages ,charging times and reduced vehicle weight and tries to develop it as an option that is significantly safe, energy efficient, environmentally-friendly and easily controllable and to do so design, analysis and MATLAB simulation is carried out on battery operated eVehicle. As a BEV has a complex structure for analysis a realistic model is considered the accuracy simulation results are verified with theoretical outcome.

Blackwater Diving: An Exciting Window Into the Planktonic Arena and Its Potential to Enhance the Quality of Larval Fish Collections

“Blackwater diving,” or nighttime SCUBA diving in epipelagic environments, has become highly popular in recent years because lay participants encounter animals that are difficult and expensive to observe through other methods. These same observations can be priceless for researchers working with these species, so an interface between the scientific communities and recreational divers would be mutually beneficial. In this paper, we describe one such interface through the photography, collection, and DNA barcoding of larval fishes from the island of Hawaii. The images and videos from this activity provide an exciting window into the epipelagic environment and the way larval fishes appear and swim within it. Blackwater diving allows us to see the often-elaborate appendages and other specializations of these larvae as they appear in situ, prior to extensive net and fixation damage. However, blackwater diving remains an almost exclusively recreational pursuit, particularly popular among underwater photographers, who have little interest in (or object to) collecting specimens for scientists. Nonetheless, a logical next step is careful hand collection of specimens for scientific study. Growing numbers of recreational divers around the world have access to an otherwise expensive-to-research habitat. Here we present, for the first time, in situ and post-fixation photos of larval fishes that were hand collected and fixed in 95% ethanol by blackwater divers operating out of Kona, Hawaii, with DNA barcode identifications congruent with morphology and pigmentation where possible. With the right motivation, blackwater diving could augment research in the pelagic ocean and significantly enhance natural history collections and our knowledge of the larvae of marine fishes.

Adapting water tariffs to climate change: Linking resource availability, costs, demand, and tariff design flexibility

Abstract Utilities face challenges that may cause net damage costs able to defy our society and environment. An ever more frequent impact is water resource scarcity due to an increasingly uncertain climate, overexploitation and contamination of resources, as well as lack of infrastructure. Thus, in the water supply sector, the robustness and resilience of systems depends on ‘preparedness’ measures able to establish a link between resources availability, utility costs, water tariffs (or other sources of revenue) and demand. In this study, the interplay regarding the instability of environmental phenomena, water supply and demand management is established to model tariffs in a novel flexible framework. The social, economic and environmental impacts are assessed related to costs, demand, and water resources availability. The Sao Paulo metropolitan area (Brazil) case-study is assessed, particularly the Cantareira reservoir system. Water supply tariffs and operational adjustments are proposed on an ‘ex-ante time frame’. By providing a rationale to price changes related to resource variability (e.g., scarcity-related) the often reliance on heuristics or simplified decision-making models is avoided. The results achieved highlight that water supply tariffs can be planned according to climatic and hydrologic information, utility costs, water demand, rational and flexible tariff design, to avoid unnecessary constraints on utilities, allowing to defer investment requirements. Benefits accrued to customers are: reductions from 10% to 44% in lower consumption levels (usually connected to high-value uses) and, when in resource scarcity situations, increases in higher consumption blocks from 3% to 106%.

Are Cloth Tarpaulin Mounted Nets Effective for Discard Reduction in Trammel Nets?

Discarding is a significant problem due to net damage and labour loss in trammel net fisheries. In this study, the effects of 15, 25, and 35 cm high cloth tarpaulin rigged between the lead line and the net were investigated in reducing the discard amount of trammel nets for red mullet (Mullus barbatus) in the south-eastern Black Sea. During the study, twenty fishing trips were carried out on-board a commercial vessel between May 11 and June 20, 2018. Results showed that there were no significant differences in the amount of discards between the commercial and experimental nets (P>0.05) However, cloth tarpaulin mounted nets (CTMN) were found to be significantly successful to reduce the amount of shore crab (Liocarcinus depurator) and the veined rapa whelk (Rapana venosa) (P<0.05). Although it is insignificant, a decline of capture was also observed in the amount of target species in CTMN compared to the commercial net (CN). Finally, the advantages and concerns of this gear modification, and potential reasons for the reduction of target and discard species are discussed.

International trade and air pollution damages in Iran

In recent dacades,the unbalanced pattern of foreign trade and its impact on the unfair emission of pollutants in different countries, has been considered by policymakers.in addition to the economic effects of trade, its environmental effects should also be considered in calculating the real trade balance or green trade in the present study, using the input-output technique. monetary losses resulting and the added value created in the trade process, are estimated in nineteen sectors. The net environmental damage is equal to 4.8% of the net value added and 1.7% of Iran's trade deficit in 2019. The results show that Iran, despite having a trade deficit, is a net importer of pollution. Estimates in the second stage confirm the higher export losses ($ 60.2) compared to the avoided import losses ($ 38.7) for each monetary unit of trade. In fact,Iran is turned to “port of pollution” because of it’s structure. In terms of trade relations with other countries, most of the pollution was imported from Iraq and Afghanistan, while the most polluted exports were to Germany, Switzerland and France, respectively. In trade with China, there are also reciprocal effects (lower income trade and greater environmental damage). Given the current difficult economic and political conditions, the best strategy to simultaneously achieve economic and environmental goals is to develop import alternatives in the groups of pharmaceuticals and health, agriculture, recreational services, arts and tourism, wood, paper and leather textile products. Because they have the lowest proportion of environmental damage to value added among economic groups with a negative trade balance. Also, the minimum amount of environmental damage for each monetary unit of trade is observed in the mentioned groups. The comparison of the study findings with the results of other researches confirms the high potential of the pharmaceutical and health materials group in achieving both economic and economic goals during import substitution policy.

Extraction of People’s Perception Toward Horseshoe Crab Existence in Northeast Coast of India

Understanding local community attitudes toward wildlife and environment is critical for making context-sensitive conservation planning and management decisions while facilitating better human–wildlife coexistence among Indian coastline communities. We conducted questionnaire-based interviews with 388 local households from12 different villages in Balasore, Odisha between September 2018 and February 2019. A theoretical framework was constructed by categorizing variables to explain attitudes and par them with key factors to derive local attitudes toward horseshoe crabs. We found that 53% of respondents were comfortable with horseshoe crab presence in their area, 27% were uncomfortable and the remaining 20% were having mixed-feelings. Respondents favored horseshoe crabs with tangible benefits such as aesthetic, monetary and cultural significance. Respondents with oppressive attitudes relate horseshoe crabs with fishing net damage. Both, principle component and step-wise analyses revealed that age, gender, and education were suitable indicators for local community perceptions with horseshoe crabs. We encourage socioeconomic monitoring particularly during rapid economic and infrastructure development to minimize knowledge erosion and to cherish local ecological knowledge for better production of scientific explorations concerning human-wildlife co-existence in India.

Worker flows, reallocation dynamics, and firm productivity: new evidence from longitudinal matched employer–employee data

AbstractThis article investigates the impact of the worker flows of a firm on productivity by using unique longitudinal matched employer–employee data. The analysis has split a firm’s total worker flows into three components: workers’ replacements (excess worker flows), hirings introduced to increase the firm’s employment level (net hirings), and separations of workers intended to decrease the firm’s workforce (net separations). This has allowed the impact of workers’ replacements, which represent the most prominent and compelling feature of worker mobility, to be isolated from the other two components. Endogeneity has been dealt with by using a modified version of Ackerberg et al.'s (2015, Econometrica, 83(6), 2411–2451) control function method, which explicitly accounts for firm-fixed effects. The main findings are that (i) excess flows have an inverted U-shape impact on productivity, (ii) net hirings foster firm productivity, and (iii) net separations damage it. The impacts are heterogeneous and vary widely on the basis of the types of replacements, the categories of workers involved, and the types of firms experiencing such flows. Overall, the findings of this article highlight the importance of reallocation dynamics to obtain better employer–employee matches, and call for a reconsideration of policies concerning the flexibility of the labor market.