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Fish Farming: Intro to Aquaculture

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Title: Fish Farming: Intro to Aquaculture


1
Fish FarmingIntro to Aquaculture
  • Methods, Pros and Cons

2
History
  • Fish are a vital component of the human diet -
    nearly half the worlds 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 http//www.fao.org/DOCREP/007/y5600
e/y5600e00.htm
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
  • Salmon, tuna
  • Pros
  • Cheap
  • no by-catch
  • does not deplete wild stocks
  • Cons
  • Waste passes to environment
  • Escapees
  • Disease parasites

http//www.ambhanoi.um.dk/NR/rdonlyres/92ADABED-4F
6A-4F6A-A04D-2A83242C1687/0/aquaculture3.jpg
9
Ponds
  • Manmade ponds, recirculating seawater
  • Shrimp, catfish, tilapia
  • Pros
  • Cheap
  • no by-catch
  • does not deplete wild stocks
  • Provides jobs
  • Cons
  • Location of ponds can destroy important habitat
    (mangroves)
  • Untreated water contaminates local environment
  • But, it CAN be treated

http//www.biology.duke.edu/bio217/2005/ncm3/pond_
liner.gif
10
Raceways
  • Divert water from a waterway
  • Must be treated before being released back to
    waterway
  • Rainbow trout
  • Pros
  • no by-catch
  • does not deplete wild stocks
  • Provides jobs
  • Cons
  • Can be costly to build
  • Untreated water
  • Escapees (invasive species)

http//www.lib.noaa.gov/korea/korean_aquaculture/r
aceway.files/baqbk001.jpeg
11
Recirculating Systems
  • Enclosed tanks
  • Water is cleaned reused
  • Striped bass, salmon, sturgeon
  • Environmentally sound
  • Pros
  • Can help rebuild wild populations
  • Provides jobs
  • Conserves wild stocks
  • Cons
  • Requires a lot of energy and thus

http//www.ag.auburn.edu/fish/image_gallery/data/m
edia/77/Recirc_Kent_Seatech_jpg.jpg
12
Shellfish Culture
  • Ropes, plastic trays, mesh bags
  • Shellfish require only clean water to survive
  • Pros
  • Easy to do
  • Can clean up nutrient rich water
  • Protects wild populations
  • Problems
  • Waste accumulation
  • disease

http//www.whoi.edu/cms/images/oceanus/2005/6/v43n
1-kitepowell3en_10837.jpg
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.

http//www.codgen.olsvik.info/cDNA20libraries.htm
l
15
Seafood Choices
16
The Promise and Perils of Fish Farming
  • http//www.edf.org/page.cfm?tagID16150

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.
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