What are the environmental impacts aquaculture? Most fish that humans eat are carnivores and feed on meat. Farmed fish are often fed on fishmeal made from low value fish such as sand eels, herring and anchovies. We hate aquaculture!!! WHY? We hate aquaculture!!! WHY? We hate aquaculture!!! WHY?

Which is the most efficient? Beef farming Lamb farming Salmon farming Why? Lamb farming because sheep are herbivores and the food chain is shorter. What other issues created by this energy inefficiency? A large mass of low value less popular fish are being used to produce a smaller mass high quality luxury fish such as salmon. This results in Depletion of low value fish stocks Loss of food supply for some local people What energy subsidies are required for fishing and aquaculture?

Both fishing and aquaculture have a range of levels of intensities From the Teachers Notes The energetics of aquatic food production The energy efficiency ratios of fishing and fish farming Both fishing and aquaculture have a range of levels of intensities Both usually require large energy subsidies Both involve higher trophic levels than in agriculture Aquaculture usually requires food energy inputs from fishing

What are the environmental impacts of aquaculture What are the environmental impacts of aquaculture? Write down at least 5 that you can think of Match the heading with the statement from the teachers notes on your grid. Identify more information that you need to find (in the form of a question) Research the answers to your question using the resources provided. Overfishing of food species Predator control Parasites Gene pool contamination Introduced species Habitat loss Pesticides Antibiotics Organic waste inorganic waste

Excess Nutrients Excess nutrients falling towards seabed result in: Eutrophication Increased primary (phytoplankton) production Changes in phytoplankton populations Deoxygenation of water column Increase in algal blooms, some toxic Decreased primary production near shellfish beds Increased chemical oxygen demand Increased microbial activity Increased biological oxygen demand Changes in macrofaunal populations Production of H2S and methane 40+ meters from cages Algal blooms

Food Wastage Food wastage can be minimized by: Feed timing synchronized to natural rhythmicity Optimize feed pellet size Optimal feed shape, color, contrast, texture, taste Distribution of feed should be maximized to ensure total use Sustained exercise

Quiz Explain the impacts shown in each graph

Quiz Explain the impacts shown in each graph Uneaten food and faeces resulted in a population explosion of bacteria that created a high BOD = lowering dissolved oxygen (DO) levels Increase in electrical conductivity =increase in levels of inorganic nutrients (ions) Turbidity = uneaten food/faeces

Example 1 - Salmon Grown mostly in industrial countries, principally in Norway, for consumption in those countries Salmon are carnivores, fed fishmeal made from anchovies, herring or fish processing wastes So to get one ton of salmon it may take up to 5 ton of wild fish Farmed salmon are bred for fast growth and not for survival in the wild. So if they escape when cages are damaged by storms or predators such as seals, they can breed with wild salmon, weakening the latter’s capacity to survive High concentrations of faeces and uneaten food can cause organic pollution – reducing BOD – or cause eutrophication Anaerobic or toxic sediments can kill benthic communities Lice infestations have to be controlled by pesticides –which can contaminate the ocean

Example 2 - Shrimp Grown largely in developing countries - Thailand, Ecuador and Indonesia - for export to developed countries Shrimp are often produced by clearing coastal mangrove forests Mangroves protect coastlines and serve as nurseries for local fish Mangrove destruction destroys habitat leads to erosion causes a decline of local fisheries that will actually exceed the gains from shrimp production, leading to a net protein loss Shrimps are also fed fishmeal, so increasing pressure on ocean fish stocks

Lessons Learned Use herbivorous fish Use polyculture Rear fish in combination with rice Use only fishmeal made from bycatch Use mangrove buffer zones Replant damaged mangroves Polyculture: oyster, kelp and abalone Mangrove Rice field and fish lake

Further Research Marine Conservation Society www.mcs.uk.org: UK pressure group working to protect marine environment and its wildlife publish the Good Fish Guide Marine Stewardship Council www.msc.org: International charity to ensure fisheries are managed sustainably RSPB Fisheries www.rspb.org.uk: good sections on the effect of fisheries policies on seabird populations