1. Fish Farming: Intro to Aquaculture
Methods, Pro’s and Con’s

2. History
Fish are a vital component of the human diet - nearly half the world’s population gets the majority of its protein from seafood
As population increases, so does demand for seafood…
But Many species - perhaps 70% or more - have been fished to their sustainable limits or beyond.
Fish stocks are declining

3. Why are our fish stocks declining?
Overfishing:
Bigger fishing vessels
Better technology to find fish
Better nets
Higher demand
Lag time in population drop
FAO State of World Fisheries and Aquaculture (SOFIA) – 2006

4. Question
What do we do?

5. The answer: Aquaculture?
Proponents of fish farming say that the industry not only supplies an important food resource, it also benefits wild stocks by reducing fishing pressures.
However, Many fishermen and environmentalists disagree
claim that aquaculture can degrade the habitat, health, and genetic vigor of wild species

6. Salmon Debate Farm-raised Salmon Wild Salmon
Survival rate from egg to adult of 1-2%
Declining wild populations due to overfishing and habitat degradation
Live and dead fish important part of stream and ocean food chains
Seabirds and marine mammals caught and killed during fishing activities
No dyes, no antibitoics, healthier
Survival rate from egg to adult of 80-90%
Concentrated waste cause algal blooms and low oxygen ‘dead zones’
Higher levels of pollutants in tissues
Less expensive and more widely available to consumers
Color from dyes, feed antibiotics, fewer essential fatty acids and oils

7. Types of Aquaculture

8. Open net pens or cages Anchored in offshore coastal areas Pro’s:
Salmon, tuna
Pro’s:
Cheap
no by-catch
does not deplete wild stocks
Con’s:
Waste passes to environment
Escapees
Disease & parasites

9. Ponds Manmade ponds, recirculating seawater Pro’s: Con’s:
Shrimp, catfish, tilapia
Pro’s:
Cheap
no by-catch
does not deplete wild stocks
Provides jobs
Con’s:
Location of ponds can destroy important habitat (mangroves)
Untreated water contaminates local environment
But, it CAN be treated

10. Raceways Divert water from a waterway Pro’s: Con’s:
Must be treated before being released back to waterway
Rainbow trout
Pro’s:
no by-catch
does not deplete wild stocks
Provides jobs
Con’s:
Can be costly to build
Untreated water
Escapees (invasive species)

11. Recirculating Systems
Enclosed tanks
Water is cleaned & reused
Striped bass, salmon, sturgeon
Environmentally sound
Pro’s
Can help rebuild wild populations
Provides jobs
Conserves wild stocks
Con’s
Requires a lot of energy and thus $$

12. Shellfish Culture Ropes, plastic trays, mesh bags Pro’s Problems:
Shellfish require only clean water to survive
Pro’s
Easy to do
Can clean up nutrient rich water
Protects wild populations
Problems:
Waste accumulation
disease

13. Why should we bother? Food Long term economics
Overfishing correlates with:
Low biodiversity in the environment
Harmful algal blooms
Beach closures
Darker color = more protein obtained from seafood

14. Why should we bother?
While some recover after collapse, many do not (or at least, have not)
Cod
Atlantic Bluefin tuna
Pacific Northwest Salmon
There used to be wars over Atlantic cod, now they are almost gone….

15. Seafood Choices

16. The Promise and Perils of Fish Farming

17. Issue: Imported Fish
The seafood Americans eat largely comes from abroad
Problem: many nations that supply us with farmed fish do not adequately regulate these operations
Solution: policymakers and fish farmers worldwide need to implement strong standards for aquaculture operations

18. Issue: Economic and ecological damage
Some fish farming does economic and ecological damage in the long run
example, in Thailand, Ecuador and many other tropical nations, coastal forests of mangroves were cut down in the past and replaced with shrimp farms. Water degrades and farm closes: no farm OR mangrove
Problem: unregulated aquaculture can destroy ecological and human communities
Solution: responsible aquaculture

19. Issue: Water Pollution
Problem: Some production systems allow uneaten food, fish waste and drugs and chemicals to pass into surrounding waters, where they can harm ecosystems and impair water quality
Solution:
Use closed recirculating systems
Grow more than one species (mussels raised on ropes suspended in the ocean can help cleanse waters polluted by salmon raised in net pens.
Minimize use of antibiotics and anti-parasite drugs

20. Issue: Depleting wild fish stocks
Problem: Deplete food resources for wild cousins of farmed fish
Farming predatory fish like salmon can use huge amounts of small, oily wild fish like anchovies, menhaden, mackerel and herring, leaving no food for wild fish
~1/3 of the current annual catch has been used for animal feed
Solution:
Farm vegetarian or semi-vegetarian fish such as tilapia and catfish or filter-feeders like mussels or clams
Feed predatory fish a semi-vegetarian diet supplemented with fish byproducts

21. Issue: Invasive Species
Problem: Escaped farmed fish can pose serious threats to wild fish populations by competing with them for food and habitat and transmitting disease and parasites
Solution:
Farm species native to the region to reduce the potential harm from introducing a new fish species.
Use closed systems like tanks, rather than "leaky" net pens or cages, to prevent escapes.
Mark fish and require public reporting of escapes, to identify culpable suppliers.

22. Issue: Endangering Sea Animals
Problem: To keep them from feeding on captive fish, wildlife such as seals, sea lions and birds are often harassed with firecrackers or loud underwater speakers that can cause disorientation, pain or hearing loss.
Solution:
Site farms far from places where marine mammals live or hunt, or birds congregate.  
Use tight nets to prevent access by predators to ponds, tanks, and net cages.