The management and conservation of the world's oceans require synthesis of spatial data on the distribution and intensity of human activities and the overlap of their impacts on marine ecosystems. We developed an ecosystem-specific, multiscale spatial model to synthesize 17 global data sets of anthropogenic drivers of ecological change for 20 marine ecosystems. Our analysis indicates that no area is unaffected by human influence and that a large fraction (41%) is strongly affected by multiple drivers. However, large areas of relatively little human impact remain, particularly near the poles. The analytical process and resulting maps provide flexible tools for regional and global efforts to allocate conservation resources; to implement ecosystem-based management; and to inform marine spatial planning, education, and basic research.

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A Global Map of Human Impact on Marine Ecosystems

During the next 50 years, which is likely to be the final period of rapid agricultural expansion, demand for food by a wealthier and 50% larger global population will be a major driver of global environmental change. Should past dependences of the global environmental impacts of agriculture on human population and consumption continue, 10(9) hectares of natural ecosystems would be converted to agriculture by 2050. This would be accompanied by 2.4- to 2.7-fold increases in nitrogen- and phosphorus-driven eutrophication of terrestrial, freshwater, and near-shore marine ecosystems, and comparable increases in pesticide use. This eutrophication and habitat destruction would cause unprecedented ecosystem simplification, loss of ecosystem services, and species extinctions. Significant scientific advances and regulatory, technological, and policy changes are needed to control the environmental impacts of agricultural expansion.

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Forecasting agriculturally driven global environmental change

Global production of farmed fish and shellfish has more than doubled in the past 15 years. Many people believe that such growth relieves pressure on ocean fisheries, but the opposite is true for some types of aquaculture. Farming carnivorous species requires large inputs of wild fish for feed. Some aquaculture systems also reduce wild fish supplies through habitat modification, wild seedstock collection and other ecological impacts. On balance, global aquaculture production still adds to world fish supplies; however, if the growing aquaculture industry is to sustain its contribution to world fish supplies, it must reduce wild fish inputs in feed and adopt more ecologically sound management practices.

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Effect of aquaculture on world fish supplies

Emerging recognition of two fundamental errors under-pinning past polices for natural resource issues heralds awareness of the need for a worldwide fundamental change in thinking and in practice of environmental management. The first error has been an implicit assumption that ecosystem responses to human use are linear, predictable and controllable. The second has been an assumption that human and natural systems can be treated independently. However, evidence that has been accumulating in diverse regions all over the world suggests that natural and social systems behave in nonlinear ways, exhibit marked thresholds in their dynamics, and that social-ecological systems act as strongly coupled, complex and evolving integrated systems. This article is a summary of a report prepared on behalf of the Environmental Advisory Council to the Swedish Government, as input to the process of the World Summit on Sustainable Development (WSSD) in Johannesburg, South Africa in 26 August 4 September 2002. We use the concept of resilience—the capacity to buffer change, learn and develop—as a framework for understanding how to sustain and enhance adaptive capacity in a complex world of rapid transformations. Two useful tools for resilience-building in social-ecological systems are structured scenarios and active adaptive management. These tools require and facilitate a social context with flexible and open institutions and multi-level governance systems that allow for learning and increase adaptive capacity without foreclosing future development options.

https://bioone.org/journals/AMBIO-A-Journal-of-the-Human-Environment/volume-31/issue-5/0044-7447-31.5.437/Resilience-and-Sustainable-Development--Building-Adaptive-Capacity-in-a/10.1579/0044-7447-31.5.437.pdf

Resilience and sustainable development: building adaptive capacity in a world of transformations

Fisheries have rarely been 'sustainable'. Rather, fishing has induced serial depletions, long masked by improved technology, geographic expansion and exploitation of previously spurned species lower in the food web. With global catches declining since the late 1980s, continuation of present trends will lead to supply shortfall, for which aquaculture cannot be expected to compensate, and may well exacerbate. Reducing fishing capacity to appropriate levels will require strong reductions of subsidies. Zoning the oceans into unfished marine reserves and areas with limited levels of fishing effort would allow sustainable fisheries, based on resources embedded in functional, diverse ecosystems.

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Towards sustainability in world fisheries

Although many fisheries stocks have declined precipitously throughout the world, fish farming--and especially shrimp and salmon farming--has boomed. The increasingly large scale of these enterprises is now having unforeseen ecological consequences on ocean resources through habitat destruction, effluent discharge, exotic species introductions, and heightened fish catch for feed use. Ending unsustainable production practices will require reorienting regulatory policies and fiscal incentives in shrimp- and salmon-producing counties, and enhancing restrictions on environmentally unsound practices.

Nature's Subsidies to Shrimp and Salmon Farming

The aquaculture industry is under increasing pressure to make production more resource efficient and environmentally responsible. Application of better management practices is the main approach for improving the environmental performance of aquaculture. There are, however, few numerical indicators for comparing resource use and waste generation for culture of common species and by different grow-out techniques. Indicators are proposed for evaluating the efficiency with which feed, protein, fish meal, nutrients, liming materials, water, land, and energy are used in aquaculture. In addition, methods for evaluating amounts of nutrients and other possible pollutants generated by production facilities are suggested. The indicators are designed to reveal the quantities of resources used, or of waste discharged, per tonne of production. This will simplify comparisons among species and production systems and facilitate comparisons with other kinds of animal agriculture.

Indicators of Resource Use Efficiency and Environmental Performance in Fish and Crustacean Aquaculture

Shrimp Aquaculture and the Environment

Jason Clay identifies eight steps that, taken together, could enable farming to feed 10 billion people and keep Earth habitable.

Jason Clay

Papers

Effect of aquaculture on world fish supplies

Nature's Subsidies to Shrimp and Salmon Farming

Indicators of Resource Use Efficiency and Environmental Performance in Fish and Crustacean Aquaculture

Shrimp Aquaculture and the Environment

Freeze the footprint of food