Posts Tagged 'fisheries'

Future harvest of living resources in the Arctic Ocean north of the Nordic and Barents Seas: A review of possibilities and constraints

Global warming drives changes in oceanographic conditions in the Arctic Ocean and the adjacent continental slopes. This may result in favourable conditions for increased biological production in waters at the northern continental shelves. However, production in the central Arctic Ocean will continue to be limited by the amount of light and by vertical stratification reducing nutrient availability. Upwelling conditions due to topography and inflowing warm and nutrient rich Atlantic Water may result in high production in areas along the shelf breaks. This may particularly influence distribution and abundance of sea mammals, as can be seen from analysis of historical records of hunting. The species composition and biomass of plankton, fish and shellfish may be influenced by acidification due to increased carbon dioxide uptake in the water, thereby reducing the survival of some species. Northwards shift in the distribution of commercial species of fish and shellfish is observed in the Barents Sea, especially in the summer period, and is related to increased inflow of Atlantic Water and reduced ice cover. This implies a northward extension of boreal species and potential displacement of lipid-rich Arctic zooplankton, altering the distribution of organisms that depend on such prey. However, euphausiid stocks expanding northward into the Arctic Ocean may be a valuable food resource as they may benefit from increases in Arctic phytoplankton production and rising water temperatures. Even though no scenario modelling or other prediction analyses have been made, both scientific ecosystem surveys in the northern areas, as well as the fisheries show indications of a recent northern expansion of mackerel (Scomber scombrus), cod (Gadus morhua), haddock (Melanogrammus aeglefinus) and capelin (Mallotus villosus). These stocks are found as far north as the shelf-break north of Svalbard. Greenland halibut (Reinhardtius hippoglossoides), redfish (Sebastes spp.) and shrimp (Pandalus borealis) are also present in the slope waters between the Barents Sea and the Arctic Ocean. It is assumed that cod and haddock have reached their northernmost limit, whereas capelin and redfish have potential to expand their distribution further into the Arctic Ocean. Common minke whales (Balaenoptera acutorostrata) and harp seals (Pagophilus groenlandicus) may also be able to expand their distribution into the Arctic Ocean. The abundance and distribution of other species may change as well – to what degree is unknown.

Continue reading ‘Future harvest of living resources in the Arctic Ocean north of the Nordic and Barents Seas: A review of possibilities and constraints’

Risks of ocean acidification in the California Current food web and fisheries: ecosystem model projections

The benefits and ecosystem services that humans derive from the oceans are threatened by numerous global change stressors, one of which is ocean acidification. Here, we describe the effects of ocean acidification on an upwelling system that already experiences inherently low pH conditions, the California Current. We used an end-to-end ecosystem model (Atlantis), forced by downscaled global climate models and informed by a meta-analysis of the pH sensitivities of local taxa, to investigate the direct and indirect effects of future pH on biomass and fisheries revenues. Our model projects a 0.2-unit drop in pH during the summer upwelling season from 2013 to 2063, which results in wide-ranging magnitudes of effects across guilds and functional groups. The most dramatic direct effects of future pH may be expected on epibenthic invertebrates (crabs, shrimps, benthic grazers, benthic detritivores, bivalves), and strong indirect effects expected on some demersal fish, sharks, and epibenthic invertebrates (Dungeness crab) because they consume species known to be sensitive to changing pH. The model’s pelagic community, including marine mammals and seabirds, was much less influenced by future pH. Some functional groups were less affected to changing pH in the model than might be expected from experimental studies in the empirical literature due to high population productivity (e.g., copepods, pteropods). Model results suggest strong effects of reduced pH on nearshore state-managed invertebrate fisheries, but modest effects on the groundfish fishery because individual groundfish species exhibited diverse responses to changing pH. Our results provide a set of projections that generally support and build upon previous findings and set the stage for hypotheses to guide future modeling and experimental analysis on the effects of OA on marine ecosystems and fisheries.

Continue reading ‘Risks of ocean acidification in the California Current food web and fisheries: ecosystem model projections’

Climate change impacts on tropical and temperate fisheries, aquaculture, and seafood security and implications – A review

Fish is an important source of animal protein for billions of people and in some tropical countries like Bangladesh, the Pacific islands, and the Maldives, fish provides more than 60% of animal protein supply. Climate change [the rise in temperatures (T°C), ocean acidification (OA), sea-level rise (SLR) and extreme events (EE)] is an additional threat and risk to world fisheries, aquaculture, and seafood security, in addition, to existing threats posed by other stressors. The T°C will have both the negative and positive effects on fisheries and aquaculture, of which, the temperate areas/countries will benefit, while the tropical regions/countries will be losers due to shifting in fish species from the tropical areas to the temperate areas to escape the warmer water. The T°C would cause coral bleaching and mortalities and may enhance seafood contamination (by algal toxins and metals). The OA would adversely affect many organisms that use calcium carbonate for their skeletons and would cause a decrease in abundance of commercially exploited seafood organisms (shellfish and finfish). SLR would cause salinisation of freshwater fisheries and aquaculture facilities and would damage or destroy many coastal ecosystems including mangroves and salt marshes, which are essential habitat for wild fish stocks. Climate change is projected to increase the frequency and intensity of EE. Besides, EE would destroy seagrass and seaweed beds and mangroves (which are important nursery areas for fishes). The economic loss and impacts on fisheries, aquaculture and seafood security due to T°C, OA, SLR, EE could be substantial in both tropical and temperate areas/countries. This review reveals that fisheries in the least developed tropical countries/regions such as Bangladesh, the Maldives, the Pacific islands, and parts of Africa would be most vulnerable due to lack or limited resources, capacity and capabilities to adapt to climate change and high dependency on fish, fisheries, fishing and aquaculture as a source of food, animal protein, revenues, and livelihoods To achieve sustainability in fisheries and aquaculture in line with the new global sustainable development goals (2016-2030), it will be essential to identify appropriate adaptation and mitigation measures. Such measures may include promotion of climate-smart fisheries and climate-smart aquaculture, and conservation of seagrass and seaweed beds, salt marshes, and mangroves. Community awareness and education on climate change, an introduction of climate change courses in schools, colleges, and universities and incorporation of climate change risks in all the current and future development projects/plans would be vital to minimise threats and risks of climate change on fisheries, aquaculture, and seafood security.

Continue reading ‘Climate change impacts on tropical and temperate fisheries, aquaculture, and seafood security and implications – A review’

Future harvest of living resources in the Arctic Ocean north of the Nordic and Barents Seas: a review of possibilities and constraints

Global warming drives changes in oceanographic conditions in the Arctic Ocean and the adjacent continental slopes. This may result in favourable conditions for increased biological production in waters at the northern continental shelves. However, production in the central Arctic Ocean will continue to be limited by the amount of light and by vertical stratification reducing nutrient availability. Upwelling conditions due to topography and inflowing warm and nutrient rich Atlantic Water may result in high production in areas along the shelf breaks. This may particularly influence distribution and abundance of sea mammals, as can be seen from analysis of historical records of hunting. The species composition and biomass of plankton, fish and shellfish may be influenced by acidification due to increased carbon dioxide uptake in the water, thereby reducing the survival of some species. Northwards shift in the distribution of commercial species of fish and shellfish is observed in the Barents Sea, especially in the summer period, and is related to increased inflow of Atlantic Water and reduced ice cover. This implies a northward extension of boreal species and potential displacement of lipid-rich Arctic zooplankton, altering the distribution of organisms that depend on such prey. However, euphausiid stocks expanding northward into the Arctic Ocean may be a valuable food resource as they may benefit from increases in Arctic phytoplankton production and rising water temperatures. Even though no scenario modelling or other prediction analyses have been made, both scientific ecosystem surveys in the northern areas, as well as the fisheries show indications of a recent northern expansion of mackerel (Scomber scombrus), cod (Gadus morhua), haddock (Melanogrammus aeglefinus) and capelin (Mallotus villosus). These stocks are found as far north as the shelf-break north of Svalbard. Greenland halibut (Reinhardtius hippoglossoides), redfish (Sebastes spp.) and shrimp (Pandalus borealis) are also present in the slope waters between the Barents Sea and the Arctic Ocean. It is assumed that cod and haddock have reached their northernmost limit, whereas capelin and redfish have potential to expand their distribution further into the Arctic Ocean. Common minke whales (Balaenoptera acutorostrata) and harp seals (Pagophilus groenlandicus) may also be able to expand their distribution into the Arctic Ocean. The abundance and distribution of other species may change as well – to what degree is unknown.

Continue reading ‘Future harvest of living resources in the Arctic Ocean north of the Nordic and Barents Seas: a review of possibilities and constraints’

Estimating the ecological, economic and social impacts of ocean acidification and warming on UK fisheries

Assessments of the combined ecological impacts of ocean acidification and warming (OAW) and their social and economic consequences can help develop adaptive and responsive management strategies in the most sensitive regions. Here, available observational and experimental data, theoretical, and modelling approaches are combined to project and quantify potential effects of OAW on the future fisheries catches and resulting revenues and employment in the UK under different CO2 emission scenarios. Across all scenarios, based on the limited available experimental results considered, the bivalve species investigated were more affected by OAW than the fish species considered, compared with ocean warming alone. Projected standing stock biomasses decrease between 10 and 60%. These impacts translate into an overall fish and shellfish catch decrease of between 10 and 30% by 2020 across all areas except for the Scotland >10 m fleet. This latter fleet shows average positive impacts until 2050, declining afterwards. The main driver of the projected decreases is temperature rise (0.5–3.3 °C), which exacerbate the impact of decreases in primary production (10–30%) in UK fishing waters. The inclusion of the effect of ocean acidification on the carbon uptake of primary producers had very little impact on the projections of potential fish and shellfish catches (<1%). The <10 m fleet is likely to be the most impacted by-catch decreases in the short term (2020–50), whereas the effects will be experienced more strongly by the >10 m fleet by the end of the century in all countries. Overall, losses in revenue are estimated to range between 1 and 21% in the short term (2020–50) with England and Scotland being the most negatively impacted in absolute terms, and Wales and North Ireland in relative terms. Losses in total employment (fisheries and associated industries) may reach approximately 3–20% during 2020–50 with the >10 m fleet and associated industries bearing the majority of the losses.

Continue reading ‘Estimating the ecological, economic and social impacts of ocean acidification and warming on UK fisheries’

Fishing in acid waters – a vulnerability assessment of the Norwegian fishing industry in the face of increasing ocean acidification

Ocean acidification (OA) describes a change in the ocean’s carbonate chemistry. While its chemical processes are largely understood, the biological and socio-economic consequences particularly in relation to fishery are less known. Norway is a major fishing nation worldwide and potentially affected by OA. To improve the understanding of OA’s socioeconomic consequences, we conducted a risk assessment among the Norwegian counties using a modified version of a risk assessment framework introduced in the IPCC’s Special Report on the Management of Risk from Disasters and Extreme Events (SREX), which considers risk to be the sum of ‘hazard’, ‘exposure’, and ‘vulnerability’. Our results show that about 13 out of 19 counties are likely to experience moderate to high risk from OA. We highlight that the success of integrated risk assessments highly dependends on the availability of detailed environmental, economic and societal data. In the case of Norway, modeling data regarding the progress of OA, improved information on potential biological impacts on a larger number of species and statistical data on social variables are required. We conclude that although still in its infancy, integrated risk assessments are important prerequisites for any form of interdisciplinary research on OA and the development of successful response strategies.

Continue reading ‘Fishing in acid waters – a vulnerability assessment of the Norwegian fishing industry in the face of increasing ocean acidification’

Socio-economic impacts—Fisheries

Fishers and scientists have known for over 100 years that the status of fish stocks can be greatly influenced by prevailing climatic conditions. Based on historical sea surface temperature data, the North Sea has been identified as one of 20 ‘hot spots’ of climate change globally and projections for the next 100 years suggest that the region will continue to warm. The consequences of this rapid temperature rise are already being seen in shifts in species distribution and variability in stock recruitment. This chapter reviews current evidence for climate change effects on fisheries in the North Sea—one of the most important fishing grounds in the world—as well as available projections for North Sea fisheries in the future. Discussion focuses on biological, operational and wider market concerns, as well as on possible economic consequences. It is clear that fish communities and the fisheries that target them will be very different in 50 or 100 years’ time and that management and governance will need to adapt accordingly.

Continue reading ‘Socio-economic impacts—Fisheries’


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Ocean acidification in the IPCC AR5 WG II

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