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Cumulative human pressures and climate change can induce nonlinear discontinuous dynamics in ecosystems, known as regime shifts. Regime shifts typically imply hysteresis, a lacking or delayed system response when pressures are reverted, which can frustrate restoration efforts.Here, we investigate whether the northern Adriatic Sea fish and macroinvertebrate community, as depicted by commercial fishery landings, has undergone regime shifts over the last 40 years, and the reversibility of such changes.We use a stochastic cusp model to show that, under the interactive effect of fishing pressure and water warming, the community reorganized through discontinuous changes.We found that part of the community has now reached a new stable state, implying that a recovery towards previous baselines might be impossible. Interestingly, total landings remained constant across decades, masking the low resilience of the community.Our study reveals the importance of carefully assessing regime shifts and resilience in marine ecosystems under cumulative pressures and advocates for their inclusion into management. [ABSTRACT FROM AUTHOR]

U.S. fisheries management has made tremendous strides under the current management framework, which centers on single stocks rather than ecosystems. However, conventional management focuses on one fishing sector at a time, considers a narrow range of issues, and is separated into individual fishery management plans often leaving little opportunity to consider overarching management goals across fisheries. Ecosystem-based Fisheries Management (EBFM) provides mechanisms to address these but has not been widely adopted. Here, we review and analyze the development of Fisheries Ecosystem Plans (FEPs) as a means to implement EBFM. In doing so, we provide a blueprint for next-generation FEPS that have the potential to translate EBFM to action. We highlight FEPs as a structured planning process that uses adaptive management to operationalize EBFM. This “FEP Loop” process starts by identifying the key factors that shape a fishery system and considering them simultaneously, as a coherent whole. It then helps managers and stakeholders delineate their overarching goals for the system and refine them into specific, realistic projects. And it charts a course forward with a set of management actions that work in concert to achieve the highest-priority objectives. We conclude that EBFM is feasible today using existing science tools, policy instruments, and management structures. Not only that, nearly all of the steps in the proposed “FEP Loop” process are presently being carried out by U.S. fishery managers. The process of reviewing regional experiences in developing and applying the FEP loop will lead to adaptations and improvements of the process we propose. [ABSTRACT FROM AUTHOR]

Abstract: Resource managers and policy makers have long recognized the importance of considering fisheries in the context of ecosystems; yet, movement towards widespread Ecosystem‐based Fisheries Management (EBFM) has been slow. A conceptual reframing of fisheries management is occurring globally, which envisions fisheries as systems with interacting biophysical and human subsystems. This broader view, along with a process for decision making, can facilitate implementation of EBFM. A pathway to achieve these broadened objectives of EBFM in the United States is a Fishery Ecosystem Plan (FEP). The first generation of FEPs was conceived in the late 1990s as voluntary guidance documents that Regional Fishery Management Councils could adopt to develop and guide their ecosystem‐based fisheries management decisions, but few of these FEPs took concrete steps to implement EBFM. Here, we emphasize the need for a new generation of FEPs that provide practical mechanisms for putting EBFM into practice in the United States. We argue that next‐generation FEPs can balance environmental, economic, and social objectives—the triple bottom line—to improve long‐term planning for fishery systems. [ABSTRACT FROM AUTHOR]

Understanding spatio-temporal dynamics of biotic communities containing large numbers of species is crucial to guide ecosystem management and conservation efforts. However, traditional approaches usually focus on studying community dynamics either in space or in time, often failing to fully account for interlinked spatio-temporal changes. In this study, we demonstrate and promote the use of tensor decomposition for disentangling spatio-temporal community dynamics in long-term monitoring data. Tensor decomposition builds on traditional multivariate statistics (e.g. Principal Component Analysis) but extends it to multiple dimensions. This extension allows for the synchronized study of multiple ecological variables measured repeatedly in time and space. We applied this comprehensive approach to explore the spatio-temporal dynamics of 65 demersal fish species in the North Sea, a marine ecosystem strongly altered by human activities and climate change. Our case study demonstrates how tensor decomposition can successfully (i) characterize the main spatio-temporal patterns and trends in species abundances, (ii) identify sub-communities of species that share similar spatial distribution and temporal dynamics, and (iii) reveal external drivers of change. Our results revealed a strong spatial structure in fish assemblages persistent over time and linked to differences in depth, primary production and seasonality. Furthermore, we simultaneously characterized important temporal distribution changes related to the low frequency temperature variability inherent in the Atlantic Multidecadal Oscillation. Finally, we identified six major sub-communities composed of species sharing similar spatial distribution patterns and temporal dynamics. Our case study demonstrates the application and benefits of using tensor decomposition for studying complex community data sets usually derived from large-scale monitoring programs. [ABSTRACT FROM AUTHOR]

European sardine (Sardina pilchardus) and round sardinella (Sardinella aurita) comprise two-thirds of total landings of small pelagic fishes in the Canary Current Eastern Boundary Ecosystem (CCEBE). Their spawning habitat is the continental shelf where upwelling is responsible for high productivity. While upwelling intensity is predicted to change through ocean warming, the effects of upwelling intensity on larval fish habitat expansion is not well understood. Larval habitat characteristics of both species were investigated during different upwelling intensity regimes. Three surveys were carried out to sample fish larvae during cold (permanent upwelling) and warm (low upwelling) seasons along the southern coastal upwelling area of the CCEBE (13°-22.5°N). Sardina pilchardus larvae were observed in areas of strong upwelling during both seasons. Larval habitat expansion was restricted from 22.5°N to 17.5°N during cold seasons and to 22.5°N during the warm season. Sardinella aurita larvae were observed from 13°N to 15°N during cold seasons and 16-21°N in the warm season under low upwelling conditions. Generalized additive models predicted upwelling intensity driven larval fish abundance patterns. Observations and modeling revealed species-specific spawning times and locations, that resulted in a niche partitioning allowing species’ co-existence. Alterations in upwelling intensity may have drastic effects on the spawning behavior, larval survival, and probably recruitment success of a species. The results enable insights into the spawning behavior of major small pelagic fish species in the CCEBE. Understanding biological responses to physical variability are essential in managing marine resources under changing climate conditions. [ABSTRACT FROM AUTHOR]

Modern resource management faces trade-offs in the provision of various ecosystem goods and services to humanity. For fisheries management to develop into an ecosystem-based approach, the goal is not only to maximize economic profits, but to consider equally important conservation and social equity goals. We introduce such a triple-bottom line approach to the management of multi-species fisheries using the Baltic Sea as a case study. We apply a coupled ecological-economic optimization model to address the actual fisheries management challenge of trading-off the recovery of collapsed cod stocks versus the health of ecologically important forage fish populations. Management strategies based on profit maximization would rebuild the cod stock to high levels but may cause the risk of stock collapse for forage species with low market value, such as Baltic sprat (). Economically efficient conservation efforts to protect sprat would be borne almost exclusively by the forage fishery as sprat fishing effort and profits would strongly be reduced. Unless compensation is paid, this would challenge equity between fishing sectors (). Optimizing equity while respecting sprat biomass precautionary levels would reduce potential profits of the overall Baltic fishery, but may offer an acceptable balance between overall profits, species conservation and social equity (). Our case study shows a practical example of how an ecosystem-based fisheries management will be able to offer society options to solve common conflicts between different resource uses. Adding equity considerations to the traditional trade-off between economy and ecology will greatly enhance credibility and hence compliance to management decisions, a further footstep towards healthy fish stocks and sustainable fisheries in the world ocean. [ABSTRACT FROM AUTHOR]

An ecosystem approach to management (EAM) aims to secure a healthy ecosystem along with sustainable use of its goods and services. Although the main principles of EAM are agreed upon and desirable, wider implementation of EAM is still a challenge. The difficulties stem from unclear definition and communication of the EAM, lack of routines or protocols to develop ecosystem-based advice, inappropriate institutional structures, and communication issues between scientists, advisers, and managers. Integrated ecosystem assessment (IEA) is an instrument that has proven to help in the implementation of EAM. For successful implementation of EAM and IEA in the European regional seas context, an international forum is required that develops tailor-made EAM tools specific to the different regional ecosystems to overcome fragmented national strategies. We describe a multinational peer network of working groups developed within the International Council for the Exploration of the Sea (ICES) under the auspice of Science Steering Group on Regional Sea Programmes. Available is a wealth of data, expertise, scientific methods, and models for each regional sea. This network can be instrumental in advancing IEA for the implementation of EAM in the North Atlantic seas. [ABSTRACT FROM PUBLISHER]

Abstract: Abrupt and rapid shifts in food web and community structure, commonly termed regime shifts, have been increasingly reported for exploited marine ecosystems around the world. Here, we present a review on regime shifts in Northern hemisphere marine ecosystems, most of them using a multivariate approach to statistically analyse time series. We show that rapid shifts occurred in synchrony during the late 1980s/early 1990s, suggesting a common large-scale climate driver and essentially matching times of change in the North Atlantic Oscillation and other atmospheric indices, which modified, for example, the local temperature regimes. We further show that trophic cascades triggered by overfishing and causing a switch of trophic regulation are regularly involved in ecosystem reorganizations. Eutrophication and the introduction of alien species can be important as well, potentially affecting tipping points or the food web structure. Our review highlights how multiple drivers potentially interact in a way that one driver undermines resilience (e.g. overfishing) and the other (e.g. climate change) gives the final impulse for an abrupt change. Further, ecosystem regime shifts can be particularly difficult to reverse when alternative stable states are involved. Understanding the drivers and mechanisms leading to regime shifts is crucial for developing ecosystem-based management strategies and establishing early-warning systems to avoid catastrophic ecosystem changes and achieve a sustainable exploitation of ecosystem services. [Copyright &y& Elsevier]

The Baltic Sea is a large brackish semienclosed sea whose species-poor fish community supports important commercial and recreational fisheries. Both the fish species and the fisheries are strongly affected by climate variations. These climatic effects and the underlying mechanisms are briefly reviewed. We then use recent regional – scale climate – ocean modelling results to consider how climate change during this century will affect the fish community of the Baltic and fisheries management. Expected climate changes in northern Europe will likely affect both the temperature and salinity of the Baltic, causing it to become warmer and fresher. As an estuarine ecosystem with large horizontal and vertical salinity gradients, biodiversity will be particularly sensitive to changes in salinity which can be expected as a consequence of altered precipitation patterns. Marine-tolerant species will be disadvantaged and their distributions will partially contract from the Baltic Sea; habitats of freshwater species will likely expand. Although some new species can be expected to immigrate because of an expected increase in sea temperature, only a few of these species will be able to successfully colonize the Baltic because of its low salinity. Fishing fleets which presently target marine species (e.g. cod, herring, sprat, plaice, sole) in the Baltic will likely have to relocate to more marine areas or switch to other species which tolerate decreasing salinities. Fishery management thresholds that trigger reductions in fishing quotas or fishery closures to conserve local populations (e.g. cod, salmon) will have to be reassessed as the ecological basis on which existing thresholds have been established changes, and new thresholds will have to be developed for immigrant species. The Baltic situation illustrates some of the uncertainties and complexities associated with forecasting how fish populations, communities and industries dependent on an estuarine ecosystem might respond to future climate change. [ABSTRACT FROM AUTHOR]

Global and regional change clearly affects the structure and functioning of ecosystems in shelf seas. However, complex interactions within the shelf seas hinder the identification and unambiguous attribution of observed changes to drivers. These include variability in the climate system, in ocean dynamics, in biogeochemistry, and in shelf sea resource exploitation in the widest sense by societies. Observational time series are commonly too short, and resolution, integration time, and complexity of models are often insufficient to unravel natural variability from anthropogenic perturbation. The North Sea is a shelf sea of the North Atlantic and is impacted by virtually all global and regional developments. Natural variability (from interannual to multidecadal time scales) as response to forcing in the North Atlantic is overlain by global trends (sea level, temperature, acidification) and alternating phases of direct human impacts and attempts to remedy those. Human intervention started some 1000 years ago (diking and associated loss of wetlands), expanded to near-coastal parts in the industrial revolution of the mid-19th century (river management, waste disposal in rivers), and greatly accelerated in the mid-1950s (eutrophication, pollution, fisheries). The North Sea is now a heavily regulated shelf sea, yet societal goals (good environmental status versus increased uses), demands for benefits and policies diverge increasingly. Likely, the southern North Sea will be re-zoned as riparian countries dedicate increasing sea space for offshore wind energy generation — with uncertain consequences for the system's environmental status. We review available observational and model data (predominantly from the southeastern North Sea region) to identify and describe effects of natural variability, of secular changes, and of human impacts on the North Sea ecosystem, and outline developments in the next decades in response to environmental legislation, and in response to increased use of shelf sea space. [ABSTRACT FROM AUTHOR]

Abstract: Modern fisheries research and management must understand and take account of the interactions between climate and fishing, rather than try to disentangle their effects and address each separately. These interactions are significant drivers of change in exploited marine systems and have ramifications for ecosystems and those who depend on the services they provide. We discuss how fishing and climate forcing interact on individual fish, marine populations, marine communities, and ecosystems to bring these levels into states that are more sensitive to (i.e. more strongly related with) climate forcing. Fishing is unlikely to alter the sensitivities of individual finfish and invertebrates to climate forcing. It will remove individuals with specific characteristics from the gene pool, thereby affecting structure and function at higher levels of organisation. Fishing leads to a loss of older age classes, spatial contraction, loss of sub-units, and alteration of life history traits in populations, making them more sensitive to climate variability at interannual to interdecadal scales. Fishing reduces the mean size of individuals and mean trophic level of communities, decreasing their turnover time leading them to track environmental variability more closely. Marine ecosystems under intense exploitation evolve towards stronger bottom–up control and greater sensitivity to climate forcing. Because climate change occurs slowly, its effects are not likely to have immediate impacts on marine systems but will be manifest as the accumulation of the interactions between fishing and climate variability — unless threshold limits are exceeded. Marine resource managers need to develop approaches which maintain the resilience of individuals, populations, communities and ecosystems to the combined and interacting effects of climate and fishing. Overall, a less-heavily fished marine system, and one which shifts the focus from individual species to functional groups and fish communities, is likely to provide more stable catches with climate variability and change than would a heavily fished system. [Copyright &y& Elsevier]