Posts Tagged 'fisheries'

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.

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’

Evaluating present and future potential of arctic fisheries in Canada

Highlights

• Climate change will increase access to Arctic marine fish stocks in Canada.

• Projections show positive increases in fisheries catch and value potential with climate change.

• Range shifts driven by ocean warming will lead to increased catch potential.

• Ocean acidification may reduce projected increase in catch potential.

• Ecological, economic, social and cultural impacts of exploitation must be considered.

Abstract

The Arctic remains one of the most pristine marine regions in the world, however climate change and increasing favourable conditions is triggering increasing exploration and development of commercial fisheries. Canada’s Arctic marine capture fisheries are currently small relative to fisheries in other regions in Canada but small scale, predominantly Inuit fisheries are more wide spread. In this study, catch data was first used to estimate the current state of Arctic marine fisheries. Next, an integrated modelling approach was used to estimate the current and future fisheries potentials under high and low climate change scenarios. Comparisons of the current (2004–2015) annual reported tonnage and modelled estimates (±standard deviation) suggest that annual sustainable fisheries catch potential could be much greater at 4.07 (±2.86) million tonnes than the current catch of 189 (±6.26) thousand tonnes. Under a high climate change scenario, future (2091–2100) fisheries potential was projected to increase to 6.95 (±5.07) million tonnes of catch, while under low climate change scenario catch potential was similar to estimates of current catch potential. However, the greatest source of variance in catch potential estimates came from parameter uncertainty, followed by scenario and model uncertainty. These results contribute to understanding Canada’s Arctic marine ecosystems in the face of a rapidly changing environment, yet proper steps must be taken to ensure cultural preservation for Inuit communities as well as ecological, economic, and social sustainability.

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Critically examining the knowledge base required to mechanistically project climate impacts: a case study of Europe’s fish and shellfish

An amalgam of empirical data from laboratory and field studies is needed to build robust, theoretical models of climate impacts that can provide science‐based advice for sustainable management of fish and shellfish resources. Using a semi‐systematic literature review, Gap Analysis and multilevel meta‐analysis, we assessed the status of empirical knowledge on the direct effects of climate change on 37 high‐value species targeted by European fisheries and aquaculture sectors operating in marine and freshwater regions. Knowledge on potential climate change‐related drivers (single or combined) on several responses (vital rates) across four categories (exploitation sector, region, life stage, species), was considerably unbalanced as well as biased, including a low number of studies (a) examining the interaction of abiotic factors, (b) offering opportunities to assess local adaptation, (c) targeting lower‐value species. The meta‐analysis revealed that projected warming would increase mean growth rates in fish and mollusks and significantly elevate metabolic rates in fish. Decreased levels of dissolved oxygen depressed rates of growth and metabolism across coherent species groups (e.g., small pelagics, etc.) while expected declines in pH reduced growth in most species groups and increased mortality in bivalves. The meta‐analytical results were influenced by the study design and moderators (e.g., life stage, season). Although meta‐analytic tools have become increasingly popular, when performed on the limited available data, these analyses cannot grasp relevant population effects, even in species with a long history of study. We recommend actions to overcome these shortcomings and improve mechanistic (cause‐and‐effect) projections of climate impacts on fish and shellfish.

Continue reading ‘Critically examining the knowledge base required to mechanistically project climate impacts: a case study of Europe’s fish and shellfish’


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Ocean acidification in the IPCC AR5 WG II

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