As recurrent disease outbreaks impart economic adversity across the global shrimp farming sector in general, and in Asia in particular, clarifying determinants of outbreak susceptibility carries significance for sustainability in economic growth and social and environmental prospects. This study employs logistic regression to assess the probability of disease occurrence in intensive white leg shrimp (WLS) (Litopenaeus vannamei) aquaculture under the impact of explanatory factors grouped in (1) farmers' perceptions of climatic events, (2) adaptation measures (3) farmer biodata, (4) farm site characteristics, (5) biosecurity measures, and (6) culture method. The analysis was performed using a survey of 267 Vietnamese small-scale intensive shrimp farms in the Mekong region. Significant contributors to lowering the chance of shrimp disease occurrence include (1) regularly carrying out feed conversion ratio calculations, (2) increasing participation in training programs and extension services, (3) implementing adaptive measures related to changes in feeding schedules, and (4) increasing stocking density. The main risk factors increasing the chance of shrimp disease are the duration of the crop and more years in operation. This quantitative evidence contributes to identifying important focal points for policymakers and intensive shrimp farmers in monitoring and managing the shrimp industry under the potential impacts of climate change.

The snow crab (Chionoecetes opilio, Majidae) has recently entered the Barents Sea, and a crab fishery is developing. Information on how the crab appeared and where it is moving is limited. We study how the characteristics of the fleet may affect the further development of the fishery. A spatial model is constructed as a grid of cells given a carrying capacity for crab determined by environmental data, assumed to reflect crabs' preferences. The biological dynamics are modelled using cellular automata, describing the growth and movements of the crabs. The fleet dynamics is represented by scenarios of fleet behaviour and aptitude, using standard theories of harvest production and economics. Pattern-oriented modelling is used to calibrate the model. The fishery started in the Loophole, but is anticipated to expand as the crabs populate adjacent areas. We use simulations to explore a potential geographical expansion of the fishery. The fleet is assumed to continually expand the current fishing area by initiating fishing in adjacent areas, relying only on their own judgement to locate promising fishing grounds. We find an inability to successfully quantify the amount of crabs in the areas subject to exploration and the willingness to take risks to be two forces contributing to a long-term utilization of the stock. Both forces appear to make the fishers explore non-lucrative grounds, potentially leading them to lucrative grounds. However, information from other sources indicating the presence of crabs at various locations appears to be necessary to ensure a more complete exploration of the fishery.

Shrimp aquaculture systems vary from primitive (extensive/improved extensive) to more industrialized (intensive/semi-intensive) farms, and the impacts of environmental shocks may differ between them. This article applies the Cobb-Douglas stochastic production frontier function to evaluate the determinants that impact the inefficiency of these intensive and extensive systems in Vietnam. Data is from a survey of 436 white-leg shrimp (Litopenaeus vannamei) farms in the Mekong Area. Our findings show that farmers with self-reported experiences of drought have higher production efficiency, while experiences of irregular weather reduce efficiency. In addition, education and feeding practice/stocking density adjustment measures increase extensive efficiency. Furthermore, longer crop duration impacts the two systems differently, increasing intensive farm efficiency but decreasing extensive farm efficiency. Interestingly the efficiency effects differ for the two technologies, with two exceptions; efficiency increases for both locations further from the sea and decreases with disease occurrence.

Data Envelopment Analysis (DEA) studies of fisheries usually apply output oriented capacity utilization based on physical measures. Although physical measures capture important input factors employed in fishing activities (such as boat size, engine power), economic measures directly reflect the cost of inputs employed. This case study investigates whether economic measures are vital or whether capacity efficiency is sufficiently well reflected solely by the use of physical measures. The analysis makes use of a double bootstrap DEA technique and compares input oriented capacity utilization based on physical versus economic measures. The double bootstrap technique was chosen as it allows statistical inference based on the estimated capacity utilization. The results show that economic measures give a lower capacity utilization than that obtained by physical measures. However, no significant difference was found in the capacity utilizations between the two measures. Truncated regression models indicated that factors such as skipper experience and family size did not significantly affect these two measures of capacity utilization at the 5% level. This study concludes that physical variables are capable of capturing the essential economic differences between vessels.

The Norwegian bottom-trawl fleet is managed through individual vessel quotas and is generally engaged in codfish fisheries, where several species contribute to the revenue of the fishery. The revenue from the fishing exhibits substantial intra-annual variation and carries a significant degree of risk due to the presence of intrinsic volatilities in the marine environment, such as seasonal fluctuations in stock size and constant changes in market conditions over the course of a year. In the face of volatile revenue, fishers may allocate fishing effort and use a quota portfolio to minimize revenue risk. However, decisions underlying effort allocation, such as when to fish what and how much to harvest to match the catch size and remaining quota, are challenging. In this regard, a decision-making framework based on a bio-economic model is used to explore the revenue risk minimization behavior of the Norwegian codfish trawl fleet targeting three different species (cod, saithe, and haddock), given the constraints set by the quotas. The study comprises trawl catches and fishing effort as well as the prices for the frozen products of codfish to investigate the adopted harvest strategy under two different scenarios. The results indicate that a risk-minimizing strategy leads to inefficient allocation of fishing quotas and fishing effort and that potential economic losses from minimizing revenue risk outweigh the benefits. Moreover, our findings prove that enhancing revenue is more important than minimizing revenue risk for the trawlers. We argue that the spatial and temporal freedom of the trawl vessels, together with a vertically integrated trawl industry, may explain the prioritization of revenue enhancement over revenue risk minimization. The seasonal spawning aggregation of NEA cod and how this affects market prices shape the trawlers' harvest strategy of increasing fishing revenue.

Fisheries are characterized by variations in space and time. This study investigates the characteristics of seasonality in cod trawl fisheries in two distinct areas: the coast along the northern Norway and the high sea area of the Barents Sea. Catch per unit effort (CPUE) is used to proxy variation in stock abundance. A CPUE function has been estimated in the frequency‐domain framework, to detect the presence of seasonality. Our analysis reveals that seasonality in stock abundance is only present in the northern coast of Norway. We conclude that as a consequence of seasonality in stock aggregation during the first quarter of the fishing year, possible economic losses caused by reduced prices—stemming from a large supply of cod—are larger than the economic benefits from cost reduction per unit of harvest. We speculate that declined price and consequently potential economic losses encourage trawlers to substitute cod by other high‐value fisheries during the winter months. As the price of cod starts to rise after the first quarter, trawlers begin to target cod in the high sea areas, a region with less seasonality.

This study analyzes fresh and brackish water aquacultures?especially carp, tilapia, and shrimp production?in major Asian aquaculture-producing countries. Different indicators have been used, involving dimensions that may be affected by climate change. High diversity is believed to indicate high adaption capacity, while resilience is estimated by known biological properties of each species. The results confirm that China, by far, has the largest diversity of species and values, followed by Bangladesh, Indonesia and Vietnam. Evaluation of the resilience of major species in light of the impacts climate change may have on warming, seawater intrusion and reduced fish meal supply, indicates that shrimp species are more resilient than tilapia, carp and catfish. In general, resilience of aquaculture products in Asia seems to be high, and the aquaculture production could adapt to climate change impacts by proper modifications in farming systems and infrastructure facilities in the future.

This study identifies differences in vessel efficiency amongst purse seiners in Vietnamese fishery.Deterministic data envelopment analysis (DEA) was used to assess relative capacity utilisation of each vessel, and double bootstrap DEA was adopted to overcome some of the drawbacks of nonparametric DEA.The study was based on a survey of costs and earnings from 52 purse seiners in 2016, revealing an average vessel profit margin of 11 %.By adopting double bootstrap DEA while assuming variable returns to scale, mean capacity utilisation was found to be 0.72 (with 95 % confidence interval from 0.67 to 0.79).This indicates that to sustain the current catch levels, expected inputs should be reduced by 21-33 %.The study shows that vessel size, fishing experience, and family size of skippers, all are factors affecting the capacity utilisation.

Anticipating future changes in marine social‐ecological systems (MSES) several decades into the future is essential in the context of accelerating global change. This is challenging in situations where actors do not share common understandings, practices, or visions about the future. We introduce a dedicated scenario method for the development of MSES scenarios in a participatory context. The objective is to allow different actors to jointly develop scenarios which contain their multiple visions of the future. The method starts from four perspectives: “fisheries management,” “ecosystem,” “ocean climate,” and “global context and governance” for which current status and recent trends are summarized. Contrasted scenarios about possible futures are elaborated for each of the four single perspectives before being integrated into multiple‐perspective scenarios. Selected scenarios are then developed into storylines. Focusing on individual perspectives until near the end allows actors with diverse cultures, interests and horizons to confront their own notions of the future. We illustrate the method with the exploration of the futures of the Barents Sea MSES by 2050. We emphasize the following lessons learned: first, many actors are not familiar with scenario building and attention must be paid to explaining the purpose, methodology, and benefits of scenarios exercises. Second, although the Barents Sea MSES is relatively well understood, uncertainties about its future are significant. Third, it is important to focus on unlikely events. Fourth, all perspectives should be treated equally. Fifth, as MSES are continuously changing, we can only be prepared for future changes if we collectively keep preparing.

Avoiding whinges from various and potentially conflicting stakeholders is a major challenge for sustainable development and for the identification of sustainability scenarios or policies for biodiversity and ecosystem services. It turns out that independently complying with whinge thresholds and constraints of these stakeholders is not sufficient because dynamic ecological-economic interactions and uncertainties occur. Thus more demanding no whinge standards are needed. In this paper, we first argue that these new boundaries can be endogenously exhibited with the mathematical concepts of viability kernel and viable controls. Second, it is shown how these no whinge kernels have components, such as harvesting of resources, that should remain within safe corridor while some other components, in particular biodiversity, have only lower conservation limits. Thus, using radar charts, we show how this no whinge kernels can take the shape of a tree that we name viability tree. These trees of viability capture the idea that the unbounded renewal potential of biodiversity combined with a bounded use of the different ecosystem services are crucial ingredients for the sustainability of socio-ecosystems and the design of no whinge policies reconciling the different stakeholders involved.

Harvest Control Rules are predefined heuristic decision rules to provide quota advices for managed fisheries. Frequently statistical methods and biological assumptions expressed in mathematical models, are used to provide the Harvest Control Rules with initial information (indicators values). The aim of this article is to investigate a possible way forward of replacing these inputs by quantities of measurable observations, e. g. catch-at-age statistics. The article presents a method by which recruitment indexes and stock biomass indicators are obtained by nonparametric use of annual catch-at-age records, without filtering the raw data (observations) through mathematical models. Two related methods, applied on three empirical cases, are provided: First, showing that recruitment strengths of the Northeast Arctic cod, haddock, and saithe stocks, obtained by fuzzy logic methodology, are satisfactory captures by the use of catch-at-age data. Second, stock size indicators are estimated for the three species by the same catch-at-age data. The second task turns out to be more challenging than the first, but also in the case of stock size evaluation, the suggested procedure provides reasonable results when compared to standard stock assessment methods.

A stage structured fishery model with three stages; recruits, immature fish and mature fish is formulated and utilized to analyse maximum sustainable yield (MSY) and optimal harvesting composition in a fishery with two heterogeneous fleets. The stage structured model developed bundles the age classes found in age structured models into stage classes based on their level of maturity, but also the pattern according to which they are harvested. Two fleets, high sea and coastal vessels, harvest respectively the immature and mature stages. The maximum sustainable yield (MSY) is studied in light of both perfect and imperfect fishing selectivity. In addition, we analyse the biomass loss of a sharing rule where the high sea trawler fleet is granted a certain share of the harvested biomass. The paper provides a theoretical extension to the literature on age structured models, and presents several new analytical results related to stage structured models which are supported by a numerical illustration inspired by the North-East Arctic cod fishery.

Climate change is expected to influence spatial and temporal distributions of fish stocks. The aim of this paper is to compare climate change impact on a fishery with other factors impacting the performance of fishing fleets. The fishery in question is the Northeast Arctic cod fishery, a well-documented fishery where data on spatial and temporal distributions are available. A cellular automata model is developed for the purpose of mimicking possible distributional patterns and different management alternatives are studied under varying assumptions on the fleets' fishing aptitude. Fisheries management and fishing aptitude, also including technological development and local knowledge, turn out to have the greatest impact on the spatial distribution of the fishing effort, when comparing the IPCC's SRES A1B scenario with repeated sequences of the current environmental situation over a period of 45 years. In both cases, the highest profits in the simulation period of 45 years are obtained at low exploitation levels and moderate fishing aptitude.

We review current knowledge about climate change impacts on Arctic seafood production. Large-scale changes in the Arctic marine food web can be expected for the next 40-100 years. Possible future trajectories under climate change for Arctic capture fisheries anticipate the movement of aquatic species into new waters and changed the dynamics of existing species. Negative consequences are expected for some fish stocks but others like the Barents Sea cod (Gadus morhua) may instead increase. Arctic aquaculture that constitutes about 2% of global farming is mainly made up of Norwegian salmon (Salmo salar) farming. The sector will face many challenges in a warmer future and some of these are already a reality impacting negatively on salmon growth. Other more indirect effects from climate change are more uncertain with respect to impacts on the economic conditions of Arctic aquaculture.

Harvest control rules have become an important tool in modern fisheries management, and are increasingly adopted to provide continuity in management practices, to deal with uncertainty and ecosystem considerations, and to relieve management decisions from short-term political pressure. We provide the conceptual and institutional background for harvest control rules, a discussion of the structure of fisheries management, and brief introductions to harvest control rules in a selection of present day cases. The cases demonstrate that harvest control rules take different forms in different settings, yet cover only a subset of the full policy space. We conclude with views on harvest control rules in future fisheries management, both in terms of ideal and realistic developments. One major challenge for future fisheries management is closing the gap between

Fisheries operate under fluctuating environmental conditions, targeting fish stocks that appear in varying densities in different areas, often with abrupt and unexpected local changes. Physical conditions, markets and management regulations constrain vessels in different and varying ways. These factors all contribute to forming the fleet diversity we find in most fisheries. Here, a simulation model of the Northeast Arctic cod fishery is used in order to investigate how this diversity is formed and maintained, assuming rational economic behaviour under varying combined constraints. The study also focuses on how the ability of vessels to find fish influences fleet diversity, profitability, stock development and seasonal profiles of the fishery. Results indicate that an increased ability to target the most profitable fishing grounds may influence fleet diversity positively or negatively, depending on overall exploitation level. High exploitation rates also increase the temporal fluctuations in fleet diversity and profits, which are amplified as the fish-finding ability increases.

Harvest control rules have become an important tool in modern fisheries management, and are increasingly adopted to provide continuity in management practices, to deal with uncertainty and ecosystem considerations, and to relieve management decisions from short-term political pressure. We provide the conceptual and institutional background for harvest control rules, a discussion of the structure of fisheries management, and brief introductions to harvest control rules in a selection of present day cases. The cases demonstrate that harvest control rules take different forms in different settings, yet cover only a subset of the full policy space. We conclude with views on harvest control rules in future fisheries management, both in terms of ideal and realistic developments. One major challenge for future fisheries management is closing the gap between ideas and practice.

The rapidly changing Arctic marine ecosystems face new challenges and opportunities that are increasing and shifting governance needs in the region. A group of economists, ecologists, biologists, political scientists and resource managers met in Stockholm, SE, Sept 4–6, 2014 to discuss the governance of Arctic marine resources in a spatial context. We report on the findings here.

The stock assessment data provided by ICES’s Arctic Fisheries Working Group represents a unique source of insight into the interplay between environmental factors, stock dynamics, fisheries and management decisions. This paper explores how the life history of year-classes constituting the Northeast Arctic cod stock could be used as performance measures for fisheries management. Five biological indicators are suggested for management evaluation, together with time series of environmental variables (ocean temperature and salinity). A brief evaluation of the indicator values indicates successful management of the cod stock, where most of the indicators develop in a positive direction, reflecting a sound stock situation in line with expressed management objectives.