IKENWEIWE Bolatito Nafisat (PhD) DEPARTMENT OF AQUACULTURE AND FISHERIES MANAGEMENT UNIVERSITY OF AGRICULTURE, ABEOKUTA - PowerPoint PPT Presentation

Loading...

PPT – IKENWEIWE Bolatito Nafisat (PhD) DEPARTMENT OF AQUACULTURE AND FISHERIES MANAGEMENT UNIVERSITY OF AGRICULTURE, ABEOKUTA PowerPoint presentation | free to download - id: 43c271-ZTgxN



Loading


The Adobe Flash plugin is needed to view this content

Get the plugin now

View by Category
About This Presentation
Title:

IKENWEIWE Bolatito Nafisat (PhD) DEPARTMENT OF AQUACULTURE AND FISHERIES MANAGEMENT UNIVERSITY OF AGRICULTURE, ABEOKUTA

Description:

Water Quality Maintenance The ... 5.0cm day the additional minimum daily requirement to maintain the level of the hectare ... that water for aquaculture should ... – PowerPoint PPT presentation

Number of Views:212
Avg rating:3.0/5.0

less

Write a Comment
User Comments (0)
Transcript and Presenter's Notes

Title: IKENWEIWE Bolatito Nafisat (PhD) DEPARTMENT OF AQUACULTURE AND FISHERIES MANAGEMENT UNIVERSITY OF AGRICULTURE, ABEOKUTA


1
IKENWEIWE Bolatito Nafisat (PhD) DEPARTMENT OF
AQUACULTURE AND FISHERIES MANAGEMENT UNIVERSITY
OF AGRICULTURE, ABEOKUTA
  • AQUACULTURE

titobola2007_at_yahoo.com, 08033770265
2
AQUACULTURE
  • FIS 309
  • (3 Units)

3
Course Outline
  • Sources of water for Aquaculture
  • Fertilization and Liming

4
Sources of Water
  • There are two principal sources of water that can
    be used in fish farming
  • ground water and
  • surface water

5
  • Surface waters have the advantage of being well
    oxygenated although they may be polluted from
    different sources.
  • Surface waters include
  • lotic waters (steams, brooks, rivers),
  • lentic waters (lakes, ponds) and
  • salt or brackish waters.
  • Rainfall and run-off may also be included but
    since they are highly seasonal, they should be
    used with caution if they are the sole source of
    water.

6
  • Lotic waters have high oxygen content because the
    water turbulence encourages gaseous exchange,
    except when they become slow flowing.
  • They usually have some form of organic
    allochthonous production which may serve as food
    for the cultured species.
  • However, they often carrying a high load of
    suspended solids, some of their natural fauna may
    be parasitic or the cultured species and the
    indigenous species may be carriers of disease.

7
  • Salt and brackish waters share the problems of
    both lotic and lentic waters, and, in addition,
    are corrosive to many metals.
  • Consequently, special materials will have to be
    used for pipes, tanks and other equipment.

8
  • Ground waters are usually pollution free although
    some may contain noxious gases like hydrogen
    sulphide and methane, as well as toxic metals.
  • The level of noxious chemicals contained in
    groundwater is highly correlated to the geology
    of the area.
  • The major disadvantage of groundwaters is their
    low dissolved oxygen content.

9
  • Ground waters include
  • springs,
  • depressions below the water table and
  • wells.
  • Depressions are uncommon and their use is
    questionable since water disappears when the
    water table drops.
  • Wells can be free-flowering (artesian) or pumped.

10
The Quality and Quantity of Water
  • Water quality
  • The quality and quantity of available water is of
    utmost importance in fish culture.
  • The quantity of water required will depend on
  • the fish species to be cultured and
  • on the management practices (static or
    flow-through, intensive or extensive

11
  • If total losses from seepage and evaporation
    amount to 5.0cm day the additional minimum daily
    requirement to maintain the level of the hectare
    pond described above is 500m3 or 500,000litres or
    5.81 sec-1

12
  • If the water supply is from borehole, the
    discharge capacity of the borehole will indicate
    whether or not sufficient water will be
    available.
  • The exact yield of a borehole may not be known
    until after money has been spent.
  • It is therefore best to seek the advice of a
    geologist with a working knowledge of the area or
    to get some information form other people who own
    boreholes in the area.

13
  • If the water source is a stream, the quantity of
    water available can be calculated from the
    continuity equation.
  • Q A.V
  • Where Q is the quantity of water available (m3),
    A is the cross sectional area (m2) and V is the
    velocity (msec-1).

14
  • Table 1 Discharge rate in a canal of different
    depths and cross-sectional area.

Water-depth (m) Wet cross section are (m2) Water transported Msec-1) (m3)
0.1 0.11 23 2800
0.2 0.26 78 5700
0.3 0.43 120 11100
0.4 0.64 192 16500
0.5 0.87 260 24400
15
  • Thus, if a 0.2m deep canal is used to fill 1ha
    pond (including water to compensate for the
    initial saturation of the pond) it will take
    18750/5700 3.3days to fill the pond. If there
    were 20 ponds, it would take approximately 66
    days to fill them.
  • This may be undesirable and consideration will
    have to be given to providing a reservoir to
    supply the water.
  • When pipes are used for the canal, a much greater
    volume can be supplied. The volume of water
    passing through a pipe is
  • Water flow (cross section x 100) / 100
    (r2x3.14 x 100)/1000

16
  • Table 3.2 Water flow in pipes of various diameters

Pipe diameter (cm) Water flow 1sec-1 (m3day-1)
2.5 0.5 43
5.0 8.0 150
10.0 11.5 690
15.0 18.0 1500
20.0 31.0 2600
30.0 70.0 6000
40.0 130.0 11000
50.0 196.0 17000
60.0 280.0 24000
17
Water quality
  • Criteria for water quality depend on the use to
    which the water is intended.
  • Hence, what is good for one situation may not be
    good for another.

18
  • It must be mentioned that water for aquaculture
    should be adequate in
  • dissolved oxygen,
  • pH,
  • temperature and
  • should not contain
  • excessive dissolved and suspended solids or
  • toxic substances.
  • It is possible that some water quality problems
    can be easily solved, hence quality may not be as
    critical as quantity

19
  • It is generally agreed that the growth of fish
    produced in an extensive system without
    supplementary feed is at the expense of the
    nutritive flora and fauna of the water body.
  • However, few scientific works have successfully
    related primary production to fish production
    (Ryder, 1976). Consequently, prediction of the
    ability of a natural body of water to produce
    fish is based on empirical methods

20
  • The most applicable are the leger-Huet formulae
    (Huet, 1986). These are the productivity of
    running water and artificial ponds as
  • K B x L x k (for running waters)
  • K 0.1Na x B x k (for artificial ponds)

21
  • Where
  • k is the annual productivity (kgkm-1) of water
    course or kgm2,
  • B is the biogenic capacity,
  • I is the average width of the water course (m),
  • k the coefficient of productivity and
  • Na the size of the ponds.
  • The biogenic capacity is an expression denoting
    the nutritive value of the water examined for its
    feeding qualities for fish.

22
POND PREPARATION AND MANAGEMENT
23
Liming
  • About two weeks before refilling the pond a layer
    of lime should be spread over the pond bottom
  • Although not a fertilizer, it helps to accelerate
    decomposition of waste materials and the
    mobilization of nutrients from the pond soil.
  • It raises the pH above the tolerable limits for
    disease vectors or eggs and spores of parasites,
    thus assisting in their eradication.

24
  • Lime comes in several forms and the application
    rates depend on the pH of the soil and the type
    of time used.
  • In ponds where the soil pH is around neutral the
    application rates are of the order listed below.
  • Crushed limestone-CaCO3 1200kg ha-1
  • Agricultural lime- CaCO3 2500 kg ha-1
  • Hydrated lime -Ca(OH)2 100kg ha-1
  • Quicklime-CaO 200 kg ha-1

25
  • If the pond has a pH of about 4.5 or less,
    approximately 4.5 tonnes of agricultural lime
    will be required.
  • If the pond had been limed before, subsequent
    annual liming are usually much less, i.e 20-25
    of the initial application rate.
  • Hydrated lime is the best because it tends to be
    the most concentrated and cheapest form.
  • Care should be taken if quicklime is used because
    it can burn on contact with the skin

26
Fertilization
  • The yield of any fish pond depends on its natural
    productivity, which is linked to nutrient
    availability in the pond soil and water. It thus
    allows an increase in fish density without the
    need for supplementary feeds.
  • The most important nutrients for growth of food
    organisms are phosphorus (P), nitrogen (N) and
    potassium (K). if there nutrients are in short
    supply or absent they can easily be increased by
    fertilization using organic and inorganic
    substances.

27
  • Fertilizers are applied to the pond water or soil
    to stimulate and maintain plant growth and
    establish the secondary food chain.
  • However, the mechanism of organic and inorganic
    fertilizers in achieving this production are
    quite different.

28
INORGANIC FERTILIZERS
  • Inorganic fertilizers are usually of chemical
    origin that dissolve in the pond water and
    provide nutrients almost immediately. This
    stimulates phytoplankton (algal) growth and
    zooplankton production, both of which are direct
    sources of food for fish

29
  • the main limiting element in established ponds is
    phosphorus and this can be provide in several
    forms, including basic powdered single
    superphosphate or granular triple superphosphate

30
ORGANIC FERTILIZERS
  • Organic fertilizers are usually waste plant or
    animal products include manure from cows, sheep,
    ducks, chickens and humans and grasses the
    non-utilized parts of crops such as rice husks
    that have rotted down this mechanism of
    fertilization is the basis of integrated fish
    farming.
  • The important points to remember about organic
    fertilizers are slowly as they rot down and
    release the nutrients.

31
Applying the fertilizer
  • There are several ways of applying the
    fertilizer.
  • In drained which are just about to be filled both
    organic and inorganic fertilizers can be spread
    over the pond bottom.
  • In a pond which has been filled and stocked with
    fish the usual way for inorganic fertilizers such
    as superphosohates broadcast it evenly over the
    pond surface.

32
NON DRAINABLE PONDS
  • In ponds that cannot be drained or insufficient
    water is available to refill it, conditioning is
    no less important.
  • In this case sediments wastes which have
    accumulated on the bottom of the pond during the
    grow-out season should be scraped out and placed
    on the bank or surrounding fields.

33
  • If necessary quicklime is broadcast over the
    ponds at a rate of approximately 600kg ha-1 and
    then fertilized according to the procedures
    described for drainable ponds.

34
Water Quality Maintenance
  • The survival, growth and consequent production o
    fish depend, to a large extent, on the physical,
    chemical and biological status of the water in
    the culture enclosure.
  • Every cultured fish species has its own peculiar
    water quality requirements

35
  • Man has very little control over salinity of fish
    ponds. It is therefore imperative to culture a
    fish in a salinity medium in which it naturally
    occurs
  • Other critical features of the holding unit that
    will influence production include water depth,
    transparency, dissolved on concentration,
    alkalinity, free dissolved carbon dioxide, odour
    and levels that will favour high fish production

36
DEPTH
  • Depth of water in the pond must be kept steady
    through regular replenishment with fresh and
    clean water to top up for water lost by seepage
    and evapotranspiration.
  • If water level is not uncontrolled, it may
    overflow and eventually break down the dam or the
    dyke.

37
TRANSPARENCY
  • The Secchi disc is the instrument sued for
    measuring turbidity or transparency.
  • A high transparency (gt80cm) is an index of low
    production. This can be improved by adding
    fertilizers.
  • Low transparency (lt20cm) may be de to suspended
    silt, clay, plankton or organic matter. This also
    encourages low fish production.

38
DISSOLVED OXYGEN
  • High phytoplankton production may reduce
    dissolved oxygen content in the pond water at
    night because they use oxygen for respiration but
    do not product it by photosynthesis.
  • The dissolved oxygen content is inversely
    proportional to temperature, and high temperature
    during the early afternoon may cause the oxygen
    content to fall below the critical level.
  • It is recommended that the dissolved oxygen level
    is measured in the early morning and again around
    14.00 hrs. For minimal stress and good growth it
    should be above 4-5mg 1-1.

39
Aeration
  • Aeration can be achieved in a number of ways, but
    the method used will depend on financial
    resources, access to electricity and intensity of
    production.
  • It can be achieved with electrically driven
    paddle wheel agitators or similar device which
    cause good mixing of the water and allow gaseous
    oxygen to dissolve in the water and carbon
    dioxide to escape.

40
pH
  • Water with a pH range of 6.5-8.0 is most suitable
    for fish production
  • low pH can be improved through the addition of
    lime
  • high pH can be lowered through addition of
    ammonium sulphate, ammonium nitrate and urea
    fertilizers.

41
POLLUTANTS
  • With industrialization, intensification of
    agriculture and widespread industrial and
    agro-chemicals and detergents, it is inevitable
    that some waste products of these ventures find
    their way into local surface underground water
    bodies by run-off or seepage, and eventually into
    ponds.
  • As a rule, water flowing ponds must be analyzed
    routinely for pollutants.
  • If the water in the found to be polluted, it
    should be drained and replenished with fresh
    clean water, preferably from an alternative
    source.

42
Weed control
  • Weeds are macroscopic plants and macrophytes
    whose existence, especially in large quantities,
    may interfere with pond management operations
    such as feeding, test cropping and testing.
  • They compete with phytoplankton for available
    nutrients depriving planktivorous fishes of their
    natural food,
  • provide havens pests and encourage
    evapotranspiration.

43
  • Aquatic weeds include plants, e.g Pistia
    stratiotes (water lettuce), pond weed (Lemma sp)
    filmentous algae, submerged weeds, e.g
    Ceratophyllum,emergent water lily (nymphea lotus)
    and marginal or fringe vegetation
  • Submerged and emergent weeds can be effectively
    checked through fertilizer application.

44
  • Copper sulphate and synthetic algicides e.g.
    simazine and Aquazine can be used to control
    excessive growth of filamentous algae and
    phytoplankton.
  • The use of copper sulphate and synthetic
    algicides also create low dissolved oxygen levels
    after their application.
  • Synthetic algicides tend to have longer residual
    action when compared with the use of copper
    sulphate in the control of filamentous algae and
    phytoplankton.

45
  • Biological control of aquatic weeds through the
    introduction of grass eating fish such as grass
    carp (Ctenopharyngodon idella), Tilapia zillii
    and Heterotis niloticus is most often recommended
    in polyculture systems.
  • Aquatic weeds can also be controlled through
    manual removal or mechanically through the use of
    specially designed amphibious machines.

46
Routine production activities
  • Stocking
  • The main objective of fish farming is the
    sustained production of a good yield of fish from
    the production unit,
  • For sound production scheduling the stocking rate
    should be calculated accurately base on the
    expected grow increment and mortality over the
    growing season.
  • Expected output from pond
  • Number to be stocked -------------------------
    --------------- x survival rate
  • Expected increase in weight of individual fish

47
  • General rules which apply when transferring fish
    from one place to another.
  •  Check the disease status of the fish prior to
    introduction to avoid contamination.
  • If possible starve the fish for 24 hours before
    movement
  • Handle the fish as little as possible
  • Prevent the fish form becoming too warm through
    exposing to sunlight.
  • Stock or transfer the fish in the early morning
    when the temperatures are lower and the fish less
    active.
  • Provide the fish with plenty of oxygen/air if
    they are being transferred over long distances.

48
Further Readings
  • Olokor, J.O., J.A. Ihuahi, F.S. Omojowo, B.A.
    Falayi and E.O. Adeowo (2007). Hand book of
    Practical Fisheries Technology. Fisheries
    Technology Division, Remi-Thomas Press
  • http//www.fishbase.org/summary/species

49
Thank you
About PowerShow.com