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Examples of Aquaculture:
 Photo: The Abalone Farm, Inc.
525 tanks hold over 2 million abalone at The Abalone Farm.
 Photo: Salmon Farm Protest Group
Aquaculture farms, such as this one off the coast of Loch Alsh, Scotland uses net pens grow to salmon. |
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photo: Arlo H. Hemphill
 Fisheries & Aquaculture
Fisheries
The oceans comprise almost 97 percent of the biosphere, are home to aq majority all of the major groups of animals, plants and microbes, and contain levels of biological diversity that rival those of tropical forests. Due to overfishing and increasing pollution levels, global catches have been declining since the late 1980s, and marine ecosystems are increasingly under siege. Several key fisheries in the North Atlantic have had to be closed due to stock declines. This has caused fisheries to move further offshore, thus increasingly impacting deep sea ecosystems. The food security of numerous developing countries has been destabilized in the process, as the vital protein provided by seafood - notably small fishes - becomes more expensive, or outright unavailable because of exports to developed countries.
Even as marine fish stocks decline, global demand for fish products continues to rise. Between 1990 and 1997 fish consumption outgrew wild capture harvests by 22 percent, a situation only made possible by the rapid growth in aquaculture production. The rapid rise in aquaculture over the past 30 years has filled some of the voids left by depleted fisheries and spurred what some have referred to as a "blue revolution" by increasing the availability of fish throughout the world. Since 1970 aquaculture production has grown rapidly to reach over 42 million metric tons and account for nearly 30 percent of global seafood production. Roughly two-thirds of farmed fish production takes place in China, with the remainder being divided somewhat evenly between developing and developed countries with the latter farming mainly carnivorous fish. While the current focus of the industry appears to be on high-value, carnivorous species such as shrimp and salmon, omnivorous species such as carp account for the majority of global aquaculture production.
The continued rise in aquaculture production poses significant threats to biological diversity in the following ways:
• Fish meal and fish oil consumption - Aquaculture consumes large amounts of fish meal and fish oil sourced from pelagic fisheries, many of which are experiencing an overall decline which has implications for the larger marine ecosystems in which they represent an important food source for larger fish, seabirds, and marine mammals.
• Fish escapes & biological pollution - Large numbers of fish escape from aquaculture facilities each year and establish populations in marine and freshwater systems. This can result in increased competition for habitat and food sources within the aquatic ecosystem, the weakening of gene pools in cases where farmed species interact with native wild populations of the same or similar species, and the eventual elimination of native freshwater species in cases where the species become invasive pests.
• Spread of disease from aquaculture operations to native fish populations - Disease outbreaks at aquaculture facilities affect both the fish being farmed as well as the greater aquatic ecosystem and can negatively impact native freshwater and marine species.
• Nutrient and chemical pollution - Most intensive aquaculture systems are open systems, which result in nutrient and chemical-rich pollution entering the aquatic ecosystem. This can lead to decreased levels of dissolved oxygen, eutrophication of fresh water sources and even the formation of hypoxic, or dead, zones in the marine environment.
• Loss of seabirds and aquatic mammals - Predator controls at large aquaculture facilities often rely on both lethal and non-lethal controls to be effective. This can impact populations of sea birds and aquatic mammals.
• Overharvest of fish fry - In areas where hatcheries fail to meet the demand for fry, some farms continue to rely on wild sources, which can directly impact marine and freshwater ecosystems when these fry are overharvested and can eventually lead to the loss of species within an ecosystem.
• Loss of natural habitat and impacts on natural ecosystems. The siting of ponds, netpens, cages and other aquaculture facilities often results in losses of biological diversity by either converting species. Rich natural habitats such as mangroves to aquaculture ponds or large netpens over rich benthic communities, including coral reefs. |
CONCLUSION
Aquaculture depends on healthy marine and freshwater environments to maintain productivity, yet can unduly impact these ecosystems via their need for feed inputs, land, water and fry for production, and their reliance on biological systems to absorb any excess nutrients released from the farms. In addition, these aquatic ecosystems are also impacted through the transfer of diseases from the farms and the escape of farmed species into the wild. All of these effects can have significant impacts on marine and terrestrial biological diversity. Yet the industry can take action to control and minimize these impacts through the adoption of best management practices, participating in initiatives that identify key areas for conservation, and adopting procurement practices that reward environmentally sustainable production systems.
RECOMMENDED ACTIONS
Environmentally sustainable aquaculture that provides a net benefit to both business and biodiversity would adopt the following recommendations:
• Site new aquaculture facilities within a landscape-level conservation planning framework - Ensure that new aquaculture facilities are sited according to landscape or ecosystem management plans that ensure the conservation of biological diversity. Where no management plans that incorporate biodiversity conservation currently exist, the industry should work with local stakeholders to assess the biological diversity of the area and develop a coastal management plan to ensure the conservation of key sites and species.
• Minimize the use of fish meal and fish oil in aquaculture feeds - Support research to substitute plant-based proteins for these ingredients, select feeds based on their minimal use of fish meal and fish oil, and communicate to feed mills preferences for feeds containing fish meal or fish oil sourced from sustainable fisheries.
• Minimize the introduction of farmed species into the wild - Adopt technologies that minimize the escape of farmed species into the wild, support future research into escape prevention technologies, and support aquaculture of lower trophic level fishes such as catfish and tilapia.
• Minimize the spread of disease into the greater aquatic ecosystem - Adopt management practices and technologies that prevent the outbreak of diseases and their spread into the greater aquatic environment.
• Minimize nutrient rich wastes and chemical pollution in aquatic ecosystems - Adopt technologies and best practices that minimize the release of nutrient rich effluents and chemical pollution into freshwater and marine environments, closely monitor nutrient and dissolved oxygen levels on and around farms, and support efforts to assess the carrying capacity of aquatic ecosystems to process these nutrients to further inform the siting of future aquaculture facilities.
• Support the use and further development of non-lethal predator controls - Adopt best management practices that provide non-lethal predator control on fish farms and support efforts to create protected areas for affected wildlife.
• Ensure that fish fry is sourced only from hatcheries - Ensure that all fry is sourced from hatcheries and support efforts to increase hatchery production levels to eliminate the need to seek fry from wild stocks.
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