Lecture 8: Aquaculture

Aquaculture BasicsAquaculture = “refers to the breeding, rearing, and

harvesting of animals and plants in all types of water environments including ponds, rivers, lakes, and the ocean” (NMFS)Producing seafood for human consumption Enhancing wild fish, shellfish, and plant stocks for

harvestRestoring threatened and endangered aquatic speciesRebuilding ecologically-important shellfish habitatProducing nutritional and industrial compounds Providing fish for aquariums

Fastest growing food sector in the past 40 years

Why Aquaculture?Increasing global population + increased per

capita seafood consumption = constant, growing demand for seafood 

“With capture fisheries production stagnating, major increases in fish food production are forecast to come from aquaculture. Taking into account the population forecast, an additional 27 million tons of production will be needed to maintain the present level of per capita consumption in 2030.” (UNFAO)

www.seachoice.org

www.labor4sustainability.org

www.thatorganicgirl.com

NMFS

www.cbf.org

Why Aquaculture?Is a resource efficient means of food

productionProtein Feed Conversion Ratio  

Salmon 1.2It takes 1.2 pounds of feed to produce 1 pound of salmon

Beef 8.7It takes 8.7 pounds of feed to

produce 1 pound of beef

Pork 5.9It takes 5.9 pounds of feed to

produce 1 pound of pork

Chicken 1.9It takes 1.9 pounds of feed to produce 1 pound of chicken

Global Aquaculture Production

Aquaculture in the U.S.U.S. aquaculture industry (both freshwater and

marine) meets only 5% to 7% of U.S. demand for seafood75% of that is freshwater farmed catfish, trout, and

tilapiaMarine aquaculture is only approx. 20% of U.S.

aquaculture production and supplies approx. 1.5% percent of the entire U.S. seafood supplyTwo-thirds of marine aquaculture is molluscan shellfish

such as oysters, clams, and mussels.The remainder is shrimp and salmon, with lesser

amounts of barramundi, seabass, seabream, and other species

Source: NMFS

Risks/Problems Associated with Aquaculture

Destruction of habitatPollution/

Eutrophication of nearby waters

Increased fishing pressure on wild stocks

Introduction of non-native species and genetically-modified species

Disease and parasitesConflicts with local

predators

Risk: Destruction of HabitatDestruction of

mangrove forests and wetlands for shrimp and fish farming

www.terrain.org

© Bertrand Coûteaux

Dierberg & Kiattisimkul 1996

Risk: Pollution and EutrophicationIncluding nutrients,

pharmaceuticals (antibiotics), pesticides, and herbicides

www.wri.org

www.fao.org

Increasing nitrogen inputs from fish farming 1990-2004 shown by sea area (www.scotland.gov.uk)

Risk: Increased Fishing Pressure on Wild StocksApprox. one-third of the world’s fish catch is used to

produce fishmeal and fish oil (both are used to make feed for farmed fish) In 2004, the aquaculture industry used 87% of the

world’s fish oil and 53% of the world’s fishmealFish stocks used as feed - mostly anchovies,

pilchards, mackerel, herring, and whiting 1 kg farmed tuna → up to 22kg of wild-caught fish

 1 kg farmed salmon → 4kg of wild-caught fish

 1 kg farmed marine shrimp →up to 2kg of wild-caught

fish Source: WWF

Risk: Non-Native and Genetically Modified SpeciesMany farmed fish escape from their

enclosuresBasically become invasive species and can

have the same types of effects on local ecosystems

Can dilute natural gene poolEscapes of farmed fish 2002-2007 in Scotland (www.scotland.gov.uk)

Risk: Disease and ParasitesTwo main parasites in fish

aquaculture industry:Sea lice – ectoparasitesSaprolegnia (water molds)

Increased susceptibility to disease due to crowded conditions, stress, limited water flowDisease pathogens may be

native or non-native

Seachoice.org

Americanaquariumproducts.com

Risk: Conflicts with PredatorsHigh concentrations of prey animals and

waste food associated with aquaculture operations attract wild organisms ranging from seals, seabirds, and sharks to molluscs and crustaceans. Predators can damage enclosures and feed on

cultured organisms growing on the substrate

These predators are often killed (sometimes illegally)