The Blue Revolution
Over 220 species of finfish & shellfish are farmed.
Almost 31,000,000 mt of the world’s total wild fisheries
production is used for animal feed each year; 15% of which is used
in fish feed.
Aquacultured fish are an
inexpensive source of highly
nutritious animal protein, have
become an important factor for
improving food security, raising
nutritional standards, &
alleviating poverty, especially in
the poorest countries.
World Capture & Aquaculture Production (with China)
Freshwater & Marine Aquaculture Production by State (1998)
Significant regional variation.
States in the Mississippi Delta represent bulk of production (catfish).
Washington State ($30md) & Maine ($64.1md) are major salmon farming states.
Value is total aquaculture sales in millions of dollars.
U.S. Aquaculture Production by Species & Growth Since 1989
“Sustainable development is the management & conservation of
the natural resource base & the orientation of technological &
instructional change in such a manner as to ensure the
attainment & continued satisfaction of human needs for
present & future generations. Such sustainable development
conserves land, water, plant, and animal genetic resources, is
environmentally non-degrading, technically appropriate,
economically viable, and socially acceptable.”
[FAO (1991): Reducing environmental impacts of coastal aquaculture.]
Fish Meal & Fish Oil in Fish Feed
Fish meal & fish oil requirements:
Many intensive & semi-intensive aquaculture systems use 2-5 times more fish protein
to feed the farmed fish than is supplied by the farmed product.
For the most commonly farmed fish, 1.9 kg of wild fish is required for every 1.0 kg of
farm-raised fish (only true for salmon & shrimp).
In total, aquaculture is a net producer, generating 3.5-4.0 kg of food fish for each kg
of pelagic fish used in fishmeal.
Poultry & swine industry is the largest consumer of fishmeal; proportionally, fishmeal
is higher in aquaculture feed.
Herbivores & omnivores:
Carp (80%) and tilapia (65%) are farmed without the use of modern compound feeds.
Generally, catfish farms use protein meal from soybeans, cottonseed, and peanuts.
Carnivorous fish & marine shrimp:
Dominant form of protein in diet from fishmeal.
Dietary essential amino acids & fatty acids (EPA & DHA) are not found in vegetable
Flow Chart of Capture
& Farmed Fisheries
Products from Aquatic
(units are mmt of fish)
Predicted Growth in Aquaculture Production of Species fed Compound Feeds
Volume of Percent of
Annual rate of growth Production FCR Total feed
2000-2010 on fish feed (dry feed to wet fish) in 000 mt
in 000 mt on fish feed
in 000 mt
2000 2010 2000 2010 2000 2010 2000 2010 2000 2010
Salmon 7% 876 1,723 100% 100% 876 1,723 1.4 1.1 1,226 1,896
Marine fish 5% 856 1,394 60% 80% 514 1,115 2.2 2.0 1,130 2,231
Other marine fish 20% 105 650 100% 100% 105 650 2.2 2.0 231 1,300
Shrimp 5% 1,034 1,684 80% 90% 827 1,516 1.8 1.6 1,489 2,425
Eel 2% 216 263 80% 90% 173 237 2.0 1.2 346 284
Milkfish 2% 379 462 40% 75% 152 347 2.0 1.6 303 554
Trout 5% 450 733 100% 100% 450 733 1.4 1.1 630 806
Tilapia 7% 974 1,916 40% 60% 390 1,150 2.0 1.5 779 1,724
Catfish 5% 371 604 85% 90% 315 544 1.6 1.4 505 761
Carp 7% 13,983 27,507 25% 50% 3,496 13,754 2.0 1.5 6,992 20,630
Total 19,244 36,936 7,297 21,767 13,6631 32,611
Relationship Between Aquaculture Production, Pelagic
Fish Landings & Fishmeal Production: 1984-2000
Fishmeal production has changed very little over the past 15 years.
Fishmeal use has been reallocated with aquaculture’s use increasing from
10% in 1988 to 35% in 1998. But this may represent an environmentally
friendly use since fish are more efficient feed converters than terrestrial
Net Loss from
Ocean to Plate
Predicted Growth in Wild Fish Used in Fishmeal & Fish oil for Aquaculture
Thousands of tons of wild Ratio of wild fish used for Thousands of tons of Ratio of wild fish used for
fish used for fishmeal fishmeal to final production wild fish used for fish oil fish oil to final production
of fish fed on fishmeal of fish fed in fish oil
2000 2010 2000 2010 2000 2010 2000 2010
Salmon 2,308 2,674 2.6 1.6 2,548 3,146 2.9 1.8
Marine fish 2,388 4,192 4.6 3.8 1,876 2,781 3.7 2.5
Other marine fish 597 2,750 5.7 4.2 191 1,295 1.8 2.0
Shrimp 1,748 2,280 2.1 1.5 249 606 0.3 0.4
Eel 813 536 4.7 2.3 141 191 0.8 0.8
Milkfish 169 132 1.1 0.4 50 91 0.3 0.3
Trout 888 949 2.0 1.3 789 1,004 1.8 1.4
Tilapia 259 282 0.7 0.2 66 75 0.2 0.1
Catfish 71 - 0.2 - 42 - 0.1 0.0
Carp 1,645 2,425 0.5 0.2 - 855 0.0 0.1
Total 10,885 16,220 1.5 0.7 5,951 10,043 0.8 0.5
Enrichment & changes in biodiversity.
Release of soluble inorganic nutrients.
Interaction with food web.
Competition between planktonic herbivores (bivalves).
Direct from high density farming.
Indirect from organic waste decomposition.
Disturbance of wildlife & habitat modification/destruction.
Increases in some bird populations (cormorants, herons, kingfishers, pelicans) beyond
their normal carrying capacity.
Mangrove habitat loss.
Interaction between escaped farmed stock & wild species.
Domesticated farmed fish interbreed with wild fish.
Introductions & transfers.
Non-native (exotic) species (from fish to disease)
Pesticides, antibiotics & hormones
Untreated wastewater containing uneaten feed and fish feces
contribute to pollution near coastal ponds & cages (25-33% of
feed consumed by fish is ejected as feces).
Nitrogen wastes exceed assimilative capacity of receiving
waters can lead to deterioration in water quality.
Approximately 3-10 kg of phosphorus and 39-55 kg of
nitrogen are released to the environment for every metric
to of fish produced.
Waste Stream: Pollution from Farming Fish
in Net Pens
• Estimated that a typical
salmon farm produces as
much waste (fecal solids)
as 65,505 people.
• Decomposition can result
in hypoxia in sediments.
• Lotic system recover
more quickly than lentic
Water Column Dissolved Inorganic Nitrogen in the Vicinity of
Salmon Farms, Puget Sound, Washington State (1995)
Dissolved Inorganic Nitrogen (um/L)
Year (Farm) 100’ upstream 20’ downstream 100’ downstream
1995 (A) 9.58 14.87 11.43
1994 (B) 21.34 22.87 23.04
1989 (C) 22.51 25.83 23.87
1994 (D) 12.54 11.80 12.15
1995 (E) 5.47 5.16 5.18
1995 (F) 10.70 10.83 11.85
1995 (G) 6.06 6.21 5.71
1994 (H) 9.78 11.34 10.80
Mangroves & coastal wetlands Eutrophication
transformed into milkfish & Water diversion
shrimp ponds (SE Asia).
Mangroves serve as nurseries
to juvenile fish & shellfish.
In coastal regions of Thailand
65,000 ha of mangroves have
been converted to shrimp
Most of the loss is due to
clearing for rice production,
grazing, urban development,
fuel, construction materials,
wood pulp & tourism.
Chemicals & Antibiotics
Antibiotic resistance for water-borne pathogens.
Antibiotics in feed can reduce microbial degradation of
uneaten feed and feces.
Antibiotics can build up in tissue of farmed fish and persist.
Oxytertacycline, oxolinic acid, trimethoprim, sulphadiazine,
Metals in fish feed and cleansers can enter ecosystem.
Copper, zinc, cadmium, & mercury.
A shift to organic standards.
Some Chemicals Used in Aquaculture & Potential
Environmental & Health Effects
Escapes of cultured fish occur because of:
Accidental loss associated with
Escapes estimated at 3 – 5% from cage
Number of Fish Escaping from Washington State &
British Columbia Fish Farms
Year Washington State1 British Columbia2
1996 107,000 53,104
1997 369,000 56,891
1998 22,639 91,168
1999 115,000 35,730
2000 0 68,947
2001 0 57,968
2002 0 18,380
2003 0 ND
2004 24,552 39,400
2005 2,500 ND
1: Atlantic salmon
2: Atlantic & Chinook salmon
Farmed Salmon: Quantity by Country
Large-scale mangrove conversion for shrimp & fish farming in Ecuador
have displaced rural communities that depended on the mangrove
resources for their livelihood.
Economic impact of disease outbreak in Taiwanese shrimp industry.
Land subsidence (sinking) & salinization of groundwater in Taiwan from
shrimp & eel culture.
Financial losses to Norwegian cage-farming industry from Hitra disease
Public health issues from red-tide outbreaks where shellfish culture
Resource ownership is often ambiguous.
World’s 20 Largest Salmon Farming Companies
Displacement of wild populations.
Escaped farmed fish can reduce the viability of wild populations
especially those with small populations due to overfishing, habitat loss
or other causes.
Escaped farmed fish may breed with wild fish, thereby introducing
domesticated genes & reducing adaptations to the natural
Transgenic fish (GMO).
Escaped farmed fish may breed with wild fish and spread the
Parasites & disease.
Transfer to wild fish & appearance of rare, but deadly, diseases in
densely cultured farmed fish.
Enhancement & Supplement Stocking
Hatcheries raising Pacific salmon & steelhead trout release >5 billion
juvenile fish into the North Pacific every year.
Sharp declines in reproductive success of wild broodstock occurs after a
short time in captivity.
37.5% fitness decline per captive-reared generation.
Unintentional domestication selection & relaxation of natural selection,
due to artificially modified & well-protected rearing environments for
hatchery fish, may be occurring.
To prevent domestication & fitness decline repeat use of captive-reared
fish for reproduction should be avoided.
But repeat capture of wild fish for broodstock is strongly criticized.
Some Genetically Modified Organisms
Tested for Use in Aquaculture
Estimated 2000 Fish-meal & Fish-oil Use
in World Aquaculture
Strategies for the Future
Formulate aquaculture development & management plans.
Apply environmental impact assessment to aquaculture
Select suitable sites & monitor ecological change.
Apply best management practices (BMP) to aquaculture
Establish guidelines for governing use of natural resources.
Establish guidelines for use of bioactive compounds.
Assess & evaluate the consequences of using transfers &
Regulate effluent discharge.
Ecological Link Between Intensive Fish & Shrimp
Aquaculture & Capture Fisheries
(Blue line = main flows from aquatic production base through fisheries & aquaculture to human consumption of
seafood; Red lines = negative feedback; Values = mmt of fish, shellfish & seaweeds).
Farm down the food web.
More herbivores & omnivores;
Lower demand for fishmeal & fish oil.
More research into oilseeds, meat byproducts, & microbial
Integrate production systems; polyculture.
More recirculating production systems; especially in urban
More inland farm operations.
Effluent can be treated more effectively inland than in
Practices from the
Past for a
Traditional rice-fish system
can provide mutual benefits
to all organisms.
are established & allow for a
balanced use of aquatic
Black Angus beef versus Atlantic Salmon
Hanging weight of Black Angus is 70% of live weight; edible meat is 42% of
Gutted Atlantic salmon is 84% of live weight; salmon fillet is 50% of live
Benthos under a salmon cage chemically remediates in 6 month – 1 year; &
biologically remediates in 2 years.
An old growth forest cleared for cattle pasture will remediate in >200 years.
Type of food Live weight Edible portion Yield Spatial footprint Remediation time
(kg) (kg) (ha) (years)
Atlantic salmon 2,500,000 1,250,000 0.50 1.6 2
Angus beef cattle 2,976,190 1,250,000 0.42 6,982 >200