1. 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?

2. 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?

3. 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

4. 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

5. 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

6. 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

7. Quiz
Explain the impacts shown in each graph

8. 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

9. 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

10. 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

11. 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

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