Responsible use of resources for
\nsustainable aquaculture

Comparisons of production, water and energy efficiencies of aquaculture
\nversus an array of fisheries and terrestrial agriculture systems show that nonfed
\naquaculture (e.g. shellfish, seaweeds) is among the world’s most efficient
\nmass producer of plant and animal proteins. Various fed aquaculture systems
\nalso match the most efficient forms of terrestrial animal husbandry, and trends
\nsuggest that carnivores in the wild have been transformed in aquaculture to
\nomnivores, with impacts on resource use comparable to conventional, terrestrial
\nagriculture systems, but are more efficient. Production efficiencies of edible
\nmass for a variety of aquaculture systems are 2.5–4.5 kg dry feed/kg edible
\nmass, compared with 3.0–17.4 for a range of conventional terrestrial animal
\nproduction systems. Beef cattle require over 10 kg of feed to add 1 kg of edibleweight, whereas tilapia and catfish use less than 3 kg to add a kg of edible
\nweight. Energy use in unfed and low-trophic-level aquaculture systems (e.g.
\nseaweeds, mussels, carps, tilapias) is comparable to energy use in vegetable,
\nsheep and rangeland beef agriculture. Highest energy use is in fish cage and
\nshrimp aquaculture, comparable to intensive animal agriculture feedlots, and
\nextreme energy use has been reported for some of these aquaculture systems
\nin Thailand. Capture fisheries are energy intensive in comparison with pond
\naquaculture of low-trophic-level species. For example, to produce 1 kg of catfish
\nprotein about 34 kcal of fossil fuel energy is required; lobster and shrimp
\ncapture fisheries use more than five times this amount of energy. Energy
\nuse in intensive salmon cage aquaculture is less than in lobster and shrimp
\nfishing, but is comparable to use in intensive beef production in feedlots. Life
\nCycle Assessment of alternative grow-out technologies for salmon aquaculture
\nin Canada has shown that for salmon cage aquaculture, feeds comprised 87
\npercent of total energy use, and fuel/electricity, 13 percent. Energy use in landbased
\nrecirculating systems was completely opposite: 10 percent of the total
\nenergy use was in feed and 90 percent in fossil fuel/electricity. Freshwater use
\nremains a critical issue in aquaculture. Freshwater reuse systems have low
\nconsumptive use comparable to vegetable crops. Freshwater pond aquaculture
\nsystems have consumptive water use comparable to pig/chicken farming and the
\nterrestrial farming of oil seed crops. Extreme water use has been documented
\nin shrimp, trout, and striped catfish operations. Water use in striped catfish
\nis of concern to Mekong policy-makers, as it is projected that these catfish
\naquaculture systems will expand and even surpass their present growth rate to
\nreach an industry of approximately 1.5 million tonnes by 2020.
\nWater, energy and land usage in aquaculture are all interactive. Reuse and
\ncage aquaculture systems use less land and freshwater but have higher energy
\nand feed requirements, with the exception of “no feed” cage and seawater
\n(e.g. shellfish, seaweeds) systems. Currently, reuse and cage aquaculture
\nsystems perform poorly in overall life cycle or other sustainability assessments
\nin comparison to pond systems. Use of alternative renewable energy systems
\nand the mobilization of alternative (non-marine) feed sources could improve the
\nsustainability of reuse and cage systems considerably in the next decade.
\nResource use constraints on the expansion of global aquaculture are different
\nfor fed and non-fed aquaculture. Over the past decade for non-fed shellfish
\naquaculture, there has been a remarkable global convergence around the
\nnotion that solutions to user (space) conflicts can be solved not only through
\ntechnological advances, but also by a growing global consensus that shellfish
\naquaculture can “fit in”, not only environmentally but also in a socially
\nresponsible manner, to many coastal environments worldwide, the vast majority
\nof which are already overcrowded with existing uses.
\nFor fed aquaculture, new indicators of resource use have been developed and
\npromulgated. Before this resource use in fed aquaculture was being measured
\nin terms of feed conversion ratios (FCRs) followed by FIFO (“fish in fish out”)
\nratios. First publications a decade ago measured values of FIFO in marine fish
\nand shrimp aquaculture. More comprehensive indicator assessments of fish
\nfeed equivalencies, protein efficiency ratios and fish feed equivalences will allow
\nmore informed decision-making on resource use and efficiencies. Over the past
\ndecade, aquafeed companies have accelerated research to reduce the use of
\nmarine proteins and oils in feed formulations, and have adopted indicators
\nfor the production efficiencies in terms of “marine protein and oil dependency
\nratios” for fed aquaculture species. Current projections are that over the next
\ndecade, fed aquaculture will use less marine fishmeals/oils while overall
\naquaculture production will continue its rapid growth.
\nOver the past decade, new, environmentally sound technologies and resourceefficient
\nfarming systems have been developed, and new examples of the
\nintegration of aquaculture into coastal area and inland watershed management
\nplans have been achieved; however, most are still at the pilot scale commercially
\nor are part of regional governance systems, and are not widespread. These
\npilot-scale models of commercial aquaculture ecosystems are highly productive,
\nwater and land efficient, and are net energy and protein producers which follow
\ndesign principles similar to those used in the fields of agroecology and agroecosystems.
\nGood examples exist for both temperate zone and tropical nations
\nwith severe land, water and energy constraints.
\nIncreasing technological efficiencies in the use of land, water, food, seed and
\nenergy through sustainable intensification such as the widespread adoption
\nof integrated multi-trophic aquaculture (IMTA) and integrated agricultureaquaculture
\nfarming ecosystems approaches will not be enough, since these will
\nimprove only the efficiency of resource use and increase yields per unit of inputs
\nand do not address social constraints and user conflicts. In most developing
\ncountries, an exponentially growing population to 2050 will require aquaculture
\nto expand rapidly into land and water areas that are currently held in common.
\nAquaculture expansion into open-water freshwater and marine waters raises
\nthe complex issues of access to and management of common pool resources,
\nand conflicts with exiting users that could cause acute social, political and
\neconomic problems. The seminal works of 2009 Nobel Laureate Elinor Ostrom
\ncould provide important insights for the orderly expansion of aquaculture into a
\nmore crowded, resource-efficient world striving to be sustainable, and rife with
\nuser conflicts.

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