Posts Tagged 'fisheries'

Climate change increases the risk of fisheries conflict

The effects of climate change on the ocean environment – especially ocean warming, acidification, and sea level rise – will impact fish stocks and fishers in important ways. Likely impacts include changes in fish stocks’ productivity and distribution, human migration to and away from coastal areas, stresses on coastal fisheries infrastructure, and challenges to prevailing maritime boundaries. In this paper, we explore these and other related phenomena, in order to assess whether and how the impacts of climate change on fisheries will contribute to the risk of fisheries conflict. We argue that climate change will entail an increase in the conditions that may precipitate fisheries conflict, and thereby create new challenges for existing fisheries management institutions. Several potential changes in fisheries management policy are recommended to avert the growing risk of fisheries-related conflicts.

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Ocean warming and acidification may drag down the commercial Arctic cod fishery by 2100

The Arctic Ocean is an early warning system for indicators and effects of climate change. We use a novel combination of experimental and time-series data on effects of ocean warming and acidification on the commercially important Northeast Arctic cod (Gadus morhua) to incorporate these physiological processes into the recruitment model of the fish population. By running an ecological-economic optimization model, we investigate how the interaction of ocean warming, acidification and fishing pressure affects the sustainability of the fishery in terms of ecological, economic, social and consumer-related indicators, ranging from present day conditions up to future climate change scenarios. We find that near-term climate change will benefit the fishery, but under likely future warming and acidification this large fishery is at risk of collapse by the end of the century, even with the best adaptation effort in terms of reduced fishing pressure.

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Effects of climate change and fishing on the Pearl River Estuary ecosystem and fisheries

Climate change poses a challenge to the management of marine ecosystems and fisheries. Estuarine ecosystems in particular are exposed to a broad range of environmental changes caused by the effects of climate change both on land and in the ocean, and such ecosystems have also had a long history of human disturbance from over-exploitation and habitat changes. In this study, we examine the effects of climate change and fishing on the Pearl River Estuary (PRE) ecosystem using Ecopath with Ecosim. Our results show that changes in net primary production and ocean warming are the dominant climatic factors impacting biomass and fisheries productivity in the PRE. Additionally, physiological changes of fishes and invertebrates that are induced by climate change were projected to be modified by trophic interactions. Overall, our study suggests that the combined effects of climate change and fishing will reduce the potential fisheries catches in the PRE. Reducing fishing efforts can reduce the impacts of climate change on selected functional groups; however, some prey fishes are expected to experience higher predation mortality and consequently decreases in biomass under low fishing intensity scenarios. Thus, our study highlights the non-linearity of the responses of estuarine ecosystems when climate change interacts with other human stressors.

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Bridging from monitoring to solutions-based thinking: lessons from CalCOFI for understanding and adapting to marine climate change impacts

Multidisciplinary, integrated ocean observing programs provide critical data for monitoring the effects of climate change on marine ecosystems. California Cooperative Oceanic Fisheries Investigations (CalCOFI) samples along the US West Coast and is one of the world’s longest-running and most comprehensive time series, with hydrographic and biological data collected since 1949. The pairing of ecological and physical measurements across this long time series informs our understanding of how the California Current marine ecosystem responds to climate variability. By providing a baseline to monitor change, the CalCOFI time series serves as a Keeling Curve for the California Current. However, challenges remain in connecting the data collected from long-term monitoring programs with the needs of stakeholders concerned with climate change adaptation (i.e., resource managers, policy makers, and the public), including for the fisheries and aquaculture sectors. We use the CalCOFI program as a case study to ask: how can long-term ocean observing programs inform ecosystem based management efforts and create data flows that meet the needs of stakeholders working on climate change adaptation? Addressing this question and identifying solutions requires working across sectors and recognizing stakeholder needs. Lessons learned from CalCOFI can inform other regional monitoring programs around the world, including those done at a smaller scale in developing countries.

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Impact of climate change and ocean acidification on ocean-based industries and society in Norway

This report presents a review of the scientific literature on how key ecosystems, ecosystem services and ocean-based industries in Norway are affected by climate change and ocean acidification today and under future scenarios. The project has also compiled knowledge on how ocean-based actions can help mitigate and reduce the magnitude of climate change, ocean acidification and environmental problems. Further possible trade-off related to ocean-based action were identified as well as how climate change and ocean acidification may potentially affect these ocean-based opportunities. Finally, the report presents published findings on possible future impacts on society and implications for policy and management.

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Potential socioeconomic impacts from ocean acidification and climate change effects on Atlantic Canadian fisheries

Ocean acidification is an emerging consequence of anthropogenic carbon dioxide emissions. The full extent of the biological impacts are currently not entirely defined. However, it is expected that invertebrate species that rely on the mineral calcium carbonate will be directly affected. Despite the limited understanding of the full extent of potential impacts and responses there is a need to identify potential pathways for human societies to be affected by ocean acidification. Research on these social implications is a small but developing field. This research contributes to this field by using an impact assessment framework, informed by a biophysical model of future species distributions, to investigate potential impacts facing Atlantic Canadian society from potential changes in shellfish fisheries driven by ocean acidification and climate change. New Brunswick and Nova Scotia are expected to see declines in resource accessibility but are relatively socially insulated from these changes. Conversely, Prince Edward Island, along with Newfoundland and Labrador are more socially vulnerable to potential losses in fisheries, but are expected to experience relatively minor net changes in access.

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Multispecies yield and profit when exploitation rates vary spatially including the impact on mortality of ocean acidification on North Pacific crab stocks

A multi-species size-structured population dynamics model that can account for spatial structure and technical interactions between commercial fisheries was developed and applied to the snow and southern Tanner crab fisheries in the eastern Bering Sea. The model was then used as the basis for forecasts to calculate reference points related to yield and profit under the effects of ocean acidification on snow and southern Tanner crab. Stochastic projections that account for variation about the stock-recruitment relationship were undertaken for a constant F35% harvest strategy, a strategy that sets effort to maximize profit ignoring the effects of environmental variability such as ocean acidification, and the Acceptable Biological Catch control rule, which includes a reduction in fishing mortality rate when stocks are below target levels. Single- and four-area models led to similar fits to abundance and catch data, and provide similar estimates of time-trajectories of mature male biomass. The model is used to compute Maximum Sustainable Yield (MSY) and an upper bound on Maximum Economic Yield (uMEY). The effort levels that achieve MSY and uMEY were sensitive to whether a spatial or non-spatial model was used to calculate reference points and hence how technical interactions among species were accounted for. Dynamic projections based on various management strategies indicated that adopting a uMEY target level of effort leads to some robustness to the effects of ocean acidification, although similar results can be obtained using the Acceptable Biological Catch control rule, which reduces harvest rates as biomass levels decline.

Continue reading ‘Multispecies yield and profit when exploitation rates vary spatially including the impact on mortality of ocean acidification on North Pacific crab stocks’

Climatic projections of Indian Ocean during 2030, 2050, 2080 with implications on fisheries sector

Climatic projections are essential to frame resilient strategies towards futuristic impacts of climate changes on fish species and habitat. The present study projects the variations of climatic variables such as Sea Surface Temperature (SST), Sea Surface Salinity (SSS), Sea Level Rise (SLR), Precipitation (Pr), and pH along the Indian Ocean. Climate projections for 2030, 2050 and 2080 were obtained as MIROC-ESM-CHEM, CMIP5 model output for each Representative Concentration Pathways (RCP) scenarios. Each climatic variable was assessed for any change against the reference year of 2015. The RCP scenarios showed an increasing trend for SLR and SST while a decreasing trend for SSS and pH. The study focuses on assessing the impacts of projected variations on marine and aquaculture system. The climate model projections show that the SST during 2080 is likely to rise by 0.69°C for the lowest emissions scenario and 2.6°C for the highest emissions scenario. Elevated temperature disturbs the homeostasis of fish and subjects to physiological stress in the habitat resulting in mortality. These thermal limits can predict distributional changes of marine species in response to climate change. Projections showed no significant changes in the pattern of precipitation. Changes in sea level rise and sea surface salinity reduce water quality, spawning and seed availability, increased disease incidence and damage to freshwater aquaculture system by salinization of groundwater. The results show that variation in SST and pH have a potential impact on marine fisheries while SSS, SLR, Precipitation affects the aquaculture systems. The synergic effects of climatic variations are found to have negative implications on capture fisheries as well as aquaculture system and are elucidated through this work.

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The dynamics and impact of ocean acidification and hypoxia: insights from sustained investigations in the Northern California Current Large Marine Ecosystem

Coastal upwelling ecosystems around the world are defined by wind-generated currents that bring deep, nutrient-rich waters to the surface ocean where they fuel exceptionally productive food webs. These ecosystems are also now understood to share a common vulnerability to ocean acidification and hypoxia (OAH). In the California Current Large Marine Ecosystem (CCLME), reports of marine life die-offs by fishers and resource managers triggered research that led to an understanding of the risks posed by hypoxia. Similarly, unprecedented losses from shellfish hatcheries led to novel insights into the coastal expression of ocean acidification. Partnership for Interdisciplinary Studies of Coastal Oceans (PISCO) scientists and other researchers in the CCLME responded to the rise of OAH with new ocean observations and experiments. This work revealed insights into the expression of OAH as coupled environmental stressors, their temporal and spatial variability, and impacts on species, ecological communities, and fisheries. Sustained investigations also deepened the understanding of connections between climate change and the intensification of hypoxia, and are beginning to inform the ecological and eco-evolutionary processes that can structure responses to the progression of ocean acidification and other pathways of global change. Moreover, because the severity of the die-offs and hatchery failures and the subsequent scientific understanding combined to galvanize public attention, these scientific advances have fostered policy advances. Across the CCLME, policymakers are now translating the evolving scientific understanding of OAH into new management actions.

Continue reading ‘The dynamics and impact of ocean acidification and hypoxia: insights from sustained investigations in the Northern California Current Large Marine Ecosystem’

Building tools to model the effects of ocean acidification and how it scales from physiology to fisheries

Ocean acidification is a direct consequence of elevated atmospheric carbon dioxide caused by anthropogenic fossil fuel burning and is one of multiple climate-related stressors in marine environments. Understanding of how these stressors will interact to affect marine life and fisheries is limited. In this thesis, I used integrated modelling approaches to scale the effects of biophysical drivers from physiology to population dynamics and fisheries. I focused on ocean acidification and how it interacts with other main drivers such as temperature and oxygen. I used a dynamic bioclimatic envelope model (DBEM) to project the effects of global environmental change on fisheries under two contrasting scenarios of climate change—the low optimistic climate change scenario in line with the 2015 Paris Agreement to limit global warming to 1.5˚ C, and the high climate change scenario on par with our current ‘business-as-usual’ trajectory. First, I developed an ex-vessel fish price database and explored methods using various ocean acidification assumptions. Ex-vessel fish prices are essential for fisheries economic analyses, while model development of ocean acidification effects are important to better understand the uncertainties surrounding acidification and the sensitivity of the model to these uncertainties. These tools and methods were then used to project the impacts of ocean acidification, in the context of climate change, on global invertebrate fisheries—the species group most sensitive to acidification. My results showed that areas with greater acidification have greater negative responses to climate change, e.g. polar regions. However, ocean warming will likely be a greater driver in species distributions and may overshadow direct effects of acidification. While greater climate change will generally have negative consequences on fisheries, Arctic regions may see increased fisheries catch potential as species shift poleward. Canada’s Arctic remains one of the most pristine marine regions left in the world and climate-driven increases in fisheries potential will have major implications for biodiversity and local indigenous reliance on marine resources. In the face of global environmental change, my thesis provides databases, modelling approaches, scenario development, and assessments of global change necessary for adaptation and mitigation of climate-related effects on marine fisheries.

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Ocean acidification in the IPCC AR5 WG II

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