El-Sayed et al. accounted feed cost as the highest operational cost like the present study findings. The selected farms’ average annual production, cost, and income were 10kg/decimal, 1435/decimal, and 433/decimal . Details of the economic analysis are presented in Table 2. Hossain et al. found 16.5 kg/decimal/year as maximum production 12.7 kg/decimal/year as minimum production from the traditional polyculture, which is close to present study findings. Polyculture practiced farms showed more production and revenue among the selected farm. The findings related to farming cost, fish production and income meant that feed cost should be minimized to improve fish production and revenue. A community-based feed mill establishment in the study area is highly recommended to balance the production cost and revenue. Different water quality parameters were measured to identify the suitability of fish farming in the study area. Parameters were measured, and mean values were present in Table 3. Dewan et al. recorded a temperature range of 25.9–34.5 ◦C in a fish polyculture pond. TDS showed greater value, especially in the poultry cum fish farm due to the uses of the poultry litter in the fish pond, The ideal range of temperature, dissolve oxygen, transparency, and pH for the fish farming in the pond mentioned by Bhatnagar and Devi also agreed with present study findings. The findings suggest that the research area’s water quality parameters are suitable for aquaculture. The present study identified the feasibility of integrated farming in hilly regions to produce multiple crops simultaneously. Integrated fish farming is ecologically sound and improves soil fertility by making nitrogen and phosphorous available . Rural women might contribute to fisheries-related activities besides their household works. According to Allison,barley fodder system aquaculture and fisheries can contribute to the employment generation for youths.

Identified prospects in this study necessitate the establishment of community-based aquaculture to get maximum outcomes from these prospects. Rahman et al. reported the lack of proper initiatives to conduct training for fish farmers in the aquaculture sector of Bangladesh. Insufficient supply and low-graded seed, inadequate loan facilities, lack of technical knowledge and training, and multiple ownership were significant constraints for fish farming. All the cited findings above show similarities with the limitations of aquaculture found in the present study. Thus, the present study’s findings infer the adoption of proper strategies toovercome the constraints of aquaculture in the study area. After analyzing the collected data, a community-based aquaculture model was formulated based on the problems, prospects, and SWOT analysis of the present fish farming of the study area . As there was no hatchery in the study area, farmers usually depended on remote sources for collecting seed. Transportation of seeds from remote areas reduced seeds’ quality and increased cost . So, the establishment of hatcheries in the study area was essential to overcome the seed supply constraint for fish farming. Moreover, the local peoples were not financially capable of establishing hatcheries in private ownership. Therefore, a community-based initiative is required to establish a hatchery in the study area. A well-established hatchery might be ensured seed costs by reducing average travel distance. Besides the local source of good quality seed, local people’s employment will be secured. In the study area, 75% of farmers said feed cost was the 2nd most crucial problem in aquaculture because they lacked capital for feed purchasing . Moreover, there was no local feed mill and feed manufacturer in the study area. Feed cost was estimated highest operational cost of the total cost . A community-based feed mill establishment might be an appropriate solution to this problem. A community-based feed mill may ensure the availability of fish feed, reduce the transportation cost, and reduce the total production cost of fish farming. It can confirm the proper and specific ratio of feed ingredients for particular fish species and create employment opportunities for local people.

A community-based feed mill can be established using a low-cost pellet machine. Fish-feed can be prepared from locally available raw materials using such feed mills. Farmers themselves can operate the feed mill when they are trained on the machine operation and proper ratio of the feed ingredients. A community-based feed mill may ensure the best use of locally available feed ingredients and help the farmers with a continuous feed supply. Consequently, local farmers are expected to increase fish production. Moreover, it creates a market for the raw materials sellers of fish feed . Most fish farmers were not interested in integrated aquaculture in the study area. Poultry cum fish culture, denoted as poultry fish farm, was found 25% of the total selected farm . In some cases, practiced poultry fish farming in the study was not safe as they directly deposited poultry litter in the fish pond to minimize feed cost. According to FAO , livestock-fish farming is needed to be more precisely designed or managed to avoid health risks for humans. Adeyemi et al. raised health concerns about poultry cum fish farms as there is a possibility of transferring pathogens to humans. Integrated aquaculture could be reduced overall production costs and generate higher profits, but it must be practiced safely. So, introducing a safe integrated aquaculture system in the study area is required to increase fish production, profit and improve the natural productivity of the soil and water. Linkage among stakeholders is considered essential for the aquaculture and fisheries sector. In the research area, lack of adequate linkage was identified as one of the major problems . Efficient linkage among stakeholders is necessary to achieve sustainable fish production. The collaborative effort and strong linkage will ensure the stakeholders’ knowledge, experience, and resources. Yeasmin et al. recommended training of farmers to get fish farming guidelines in four villages of Mymensingh. As the present study was conducted in marginal areas, engaging farmers with the government and non-governmental training stakeholders could be helpful to improve aquaculture production. Lack of education in fish farmers hinder them from utilizing resources, using technologies and getting the desired production in the study area. Fishermen’s education could improve fish production by using resources, applying aquaculture technology, understanding harvesting and post-harvesting methods, product marketing, and social advancement.

Communication among producers, processors, traders, and other interested parties was crucial for successful fish farming in the study area. If two ways of communication could be established, it would significantly increase the facilities for the fish farmers and traders of the study area. A comprehensive market chain should be developed through community-based incentives to ensure more profit, fair distribution of profits, and most importantly, reduce the extortions by mediators in the market chain. Consequently, the involvement of people in fish farming will be increased, and sustainable livelihoods will be ensured. Sea-based fish farming can be exposed to certain events and conditions that have negative impacts on fish welfare . Some of these hazards can lead to situations necessitating vessel responses such as moving, delousing or slaughtering the fish . In 2016 Chile experienced the most severe harmful algae bloom to date, killing 100,000 metric tons of Atlantic salmon . In the early summer of 2019 a HAB killed an estimated 8 million farmed salmon along the Norwegian coast, and in 2021 Chile saw another HAB that resulted in the transfer of 5.4 million salmon to safer sites away from the affected area . The following winter, sea-based fish farmers on the Faroe Islands lost approximately 1 million fish to winter ulcer at one single occasion . However, the severity of hazards may vary, and locations can experience situations with no serious effects on the fish welfare, such as minor algae blooms. Thus, in this paper the term “emergency” is reserved for serious realizations of the hazards, which will lead to loss of biomass if the emergency response is inadequate. After the mentioned emergencies in Norway and the Faroe Islands the lack of emergency preparedness was said to contribute to the high losses . Hence analyzing the response preparedness for large scale biomass emergencies in sea-based aquaculture systems could help operators enhance their emergency preparedness and response capabilities. Improvements in emergency management in sea-based aquaculture systems is becoming more important, given changes in the risk picture induced by the move of fish farms into more exposed locations and the impact of rising sea temperatures. The traditional way of assessing the emergency response capability of a system is through expert opinion and rules based on experience. For example, Wang et al. determines the emergency response capability for oil-spills in an area based on rules for the necessary amount of available resources. Haixiang et al. breaks down the rescue capability into subcomponents, and grade them based on expert opinion. A similar approach is used in Kang et al. where linguistic variables are used to evaluate oil-spill emergency response capability.

Omorodion et al. use expert opinion to assess safety terms of the failure probability of operations performed by Emergency Rescue andResponse Vessels. A method for combining machine learning and historical accident data to predict emergency scenarios,hydroponic barley fodder system and thereby support emergency response decision-making is presented in Li et al. . An alternative to experience-based assessment is to test the emergency response performance. Siljander et al. proposes the use of geographic information system based methods for evaluating the response times in maritime search and rescue to support strategic planning in Finnish waters. The presented approach considers weather conditions and vessel types. Zhou et al. present a three-step framework for assessing maritime search and rescue capabilities, covering response times, demand, and coverage. Response time is estimated using GIS. Simulation models are used to evaluate system design under environmental impacts in Berle et al. , Bergstr¨ om et al. and Brachner.Berle et al. assesses the vulnerability of a maritime liquid natural gas transportation system by quantifying the impact of disruption scenarios and mitigating measures. Bergstr¨ om et al. proposes an approach for the design of robust arctic maritime transportation systems where the system performance is tested for different ice conditions and ice mitigation strategies. Brachner presents a model for evaluating the response capacity to helicopter ditches in the Barents Sea for different configurations of response unit positioning over a year with changing weather conditions. The fleet deployment with maximal covering problem and epoch-era analysis is combined in Pettersen et al. to optimize allocation of emergency response vessels, thereby providing insights into the effectiveness of alternative fleet designs. In another paper, Pettersen et al. study how latent capabilities can support large-scale emergency response. While they look at the case of the Macondo oil spill, the principle of repurposing assets for novel emergency situations can also be useful in aquaculture, e.g., the role of live fish carriers in emergency response. This paper contributes to the literature by applying simulation-based performance analysis to determine the emergency preparedness for large scale biomass emergencies in sea-based fish farming.

The presented method analyzes three stages of emergency response and covers both non-dedicated emergency response vessels and dedicated emergency response vessels . DERVs are not used by the industry today, but could provide additional benefits in emergency response. Sea-based fish farming systems can be defined as sets of hatcheries, fish cages, slaughterhouses, and vessels, where the vessels constantly change both status and position according to the various operations they perform in the system. Operation types cover daily maintenance and routine tasks performed by small vessels belonging to the location, more complex operations necessitating the assistance of larger external vessels, and finally operations directly handling large volumes of fish which are performed by large, specialized vessels such as live fish carriers. For responding to large-scale fish welfare emergencies, only large vessels handling large volumes of fish are of interest due to the scale of such emergencies. Therefore, the presented method is intended for live fish carriers, stun & bleed vessels, processing vessels, and the likes. These vessels follow work schedules set up by the fish farmers, meaning that the emergency response capability they provide is time dependent and hard to estimate for a given point in time without considering the dynamics of the system. They may be busy performing planned operations at the time emergency response is initiated, in which case they must complete their current operations before responding to the emergency event.