Posts Tagged 'fisheries'

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.

Continue reading ‘Potential socioeconomic impacts from ocean acidification and climate change effects on Atlantic Canadian fisheries’

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.

Continue reading ‘Climatic projections of Indian Ocean during 2030, 2050, 2080 with implications on fisheries sector’

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.

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

Co-culture in marine farms: macroalgae can act as chemical refuge for shell-forming molluscs under an ocean acidification scenario

With ongoing climate change, aquaculture faces environmental challenges similar to those of natural ecosystems. These include increasing stress for calcifying species, e.g. macroalgae and shellfish. In this context, ocean acidification (OA) has the potential to affect important socioeconomic activities, including shellfish aquaculture, due to changes in the seawater carbonate system. However, coastal environments are characterised by strong diurnal pH fluctuations associated with the metabolic activity of macroalgae; that is, photosynthesis and respiration. This suggests that calcifying organisms that inhabit these ecosystems are adapted to this fluctuating pH environment. Macrophyte-dominated environments may have the potential to act as an OA buffering system in the form of a photosynthetic footprint, by reducing excess of CO2 and increasing the seawater pH and Ωarg. This can support calcification and other threatened physiological processes of calcifying organisms under a reduced pH environment. Because this footprint is supportive beyond the macroalgal canopy spatial area, this chemical refuge mechanism can be applied to support shellfish aquaculture, e.g. mussels. However, this approach should be tested in commercial shellfish farms to determine critical aspects of implementation. This includes critical factors such as target species and productivity rates. The degree of OA buffering capacity caused by the metabolic activity of macroalgae might depend on community structure and hydrodynamic conditions, creating site-specific responses. This concept might aid the development of future adaptive strategies, supporting marine ecological planning for the mussel aquaculture industry in Chile.

Continue reading ‘Co-culture in marine farms: macroalgae can act as chemical refuge for shell-forming molluscs under an ocean acidification scenario’

A fine kettle of fish: the fishing industry and environmental impacts

Highlights

• Most fishing stocks are still being exploited above sustainable levels.

• Oceans are acting as sinks for numerous human-generated environmental hazards.

• Nutrient loading or microplastics are direct threats to the quality of fish stocks.

• Climate change is rapidly changing ecological dynamics in world oceans.

• Adaptive management is needed to meet seafood demand and global food security.

Abstract

Overexploitation or full exploitation of fishing stocks first became an important problem in the second half of the 20th century, with certain fisheries collapsing and others being exploited in an unsustainable manner. This situation led to dwindling fish landings worldwide, although final seafood demand has not suffered this decrease thanks to the growth of aquaculture. Currently, new threats to marine biota are emerging that could ultimately lead to further stress on fishing stocks. The current opinion paper explores these growing threats, which include the spread of dead zones throughout coastal areas, marine litter, especially micro- and nanoplastics that are ingested by marine organisms and ultimately by humans, or the effects of climate change on world oceans, including acidification due to carbon dioxide absorption from the atmosphere or alteration in ocean circulation due to melting glaciers. Consequently, it is critical for stakeholders in the fishing sector to gain awareness of what is at stake in the upcoming decades. In fact, not only will fisheries have to expand their approach from single-species stock assessment to ecosystem-based approaches, but other metrics will have to be brought forward to maintain competitiveness and minimize food security concerns.

Continue reading ‘A fine kettle of fish: the fishing industry and environmental impacts’


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OA-ICC HIGHLIGHTS

Ocean acidification in the IPCC AR5 WG II

OUP book