General Principles

1
General Principles (Chapter 2)

• Non-graded Quiz 3

2
General Principles (Chapter 2)

• General Topics
• Culture system classification
• Type of structures used
• Intensity of culture operations
• Water management strategy
• Site selection and economics
• Hatchery systems
• Selection of species for aquaculture
• Development of new aquacultural species

3
General Principles

• Structures
• Typically more than one structure will be used
  during the life span of a cultures species.
  Structures used in aquaculture include
• Ponds
• Tanks
• Raceways
• Cages
• Pens
• Substrate

4
General Principles

• Structures
• Ponds usually earthen impoundments (including
  natural ponds)
• Oldest aquaculture structure
• Hole in ground, enclosed waterway, embankment
• Used mainly in culture of fishes and crustaceans
• Water input and discharge primarily by gravity
• Impermeable soils
• Soils that support pond ecosystems (this is
  important feature that determines productivity)

5
General Principles

• Structures
• Tanks
• Second to ponds as most commonly used structure
  in aquaculture
• Usually above ground on a solid base
• Indoors or outdoors
• Wide range of sizes
• Flow-through or recirculating systems (more
  later)
• Uses include culture of microalgae, macroalgae,
  various stages of fishes and invertebrates

6
General Principles

• Structures
• Raceways elongated tanks with canalized flow
• Usually continuous water flow from one end to the
  other
• Designed to keep unidirectional water flow along
  raceway
• Suitable for fish such as salmonids that live in
  shallow streams swimming against current
• Need source of good water quality and quantity
  (most raceways are flow-through)
• Potential problem deterioration of water quality
  along length
• Typically used for high-value fishes

7
General Principles

• Structures
• Cages
• Original cages poles or stakes driven into
  sediment with netting stretched around them (now
  known as net pens or hapas)
• Modern cages are floating structures with net
  suspended underneath
• Square, rectangular or round of variable sizes
• Typically used for grow-out phase (months or
  years)
• Require maintenance but not water pumping
• Require location with good water quality
  (protected inshore locations, large freshwater
  lakes and ponds)
• Potential problems net fouling , predators,
  diseases and parasites, algal blooms

8
General Principles

• Structures
• Pens or hapas
• Used in shallow water, typically in ponds
• Relatively small
• Practiced typically in developing countries (low
  cost)

9
General Principles

• Structures
• Substrates racks, suspended culture
• Used to provide attachment surfaces for
  bottom-dwelling (e.g., bivalves) and attached
  species (e.g., seaweeds) that are grown in the
  field for most of their culture

10
General Principles

• Intensity of culture operations
• Definition The term intensity describes the
  density of cultured organisms per unit volume or
  unit area. It is meaningful for comparing
  culture levels for a given species or related
  species. It is not very useful for comparing
  culture levels for different groups of organisms.
  Tilapia at 100 kg/m3 in recirculating systems is
  considered intensive, whereas shrimp at only 1-2
  kg/m3 in ponds is considered intensive.
• Energy (cost) considerations Natural aquatic
  ecosystems consist of primary producers
  (primarily plants, including phytoplankton),
  various levels of consumers (primary or
  herbivores secondary or carnivores tertiary or
  higher level carnivores), and decomposers. These
  various trophic levels are arranged into a food
  chain. As a rule of thumb, the amount of energy
  that can be transferred from one level to the
  next in the food chain is only 10 (the remaining
  90 is lost into metabolism, heat generation,
  waste, reproduction, etc.).
• Implications for aquaculture The greater the
  intensity of culture operations, the greater the
  requirement for energy input into the system.
  For intensive operations, it is thus much more
  efficient and cheaper to grow organisms low on
  the food chain. Approaches differ between
  developed and developing countries.

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General Principles

• Intensity of culture operations
• Classification
• Intensive
• Extensive
• Semi-intensive

12
General Principles

• Intensity of culture operations
• Intensive systems
• Requires high energy input (feeds, aeration,
  water filtration, water pumping, etc.)
• No energy recycling (totally non-self-supporting)
• All nutrition comes from introduced feeds, with
  no utilization of natural diets
• Simple food chain feed ? cultured organism
• Thus, low energy losses/high feed conversion
  ratios
• High rearing densities and production yields (per
  unit volume or area)
• Water quality requirements for target species
  determines level of stocking (stocking ponds lt
  cages lt raceways/tanks).
• Use of ponds, (shrimp), cages (marine fish),
  raceways (trout), tanks (eels) but remember
  that usually different structures are used
  depending on growth stage of cultured species.
• Can be outdoor or indoor

13
General Principles

• Intensity of culture operations
• Extensive systems
• Relies on natural ecosystem processes for
  maintenance of water quality and provision of
  most nutrients
• Thus, limited energy input is needed to maintain
  animal growth and survival
• Low stoking densities
• Common structures for extensive culture include
  ponds (low value fish carp, tilapia) and
  substrate (bivalves, seaweeds)

14
General Principles

• Intensity of culture operations
• Intensive versus extensive systems
• Example Feedlot cattle (intensive) versus
  free-range cattle (extensive)
• Both can be profitable depending on difference
  between cost of production and value of product

15
General Principles

• Intensity of culture operations
• Semi-intensive systems
• There is no clear line separating intensive from
  extensive culture
• Middle ground semi-intensive
• Semi-intensive culture systems rely to some
  degree on natural processes and productivity, but
  there is also supplementation, such as
• Aeration
• Addition of fertilizers (organic or inorganic)
• Addition of feeds (supplemental feeds)
• Semi-intensive culture is almost exclusively
  applied in ponds and allows for increase in
  stocking density relative to extensive systems

16
General Principles

• Intensity of culture operations
• Polyculture
• Used in semi-intensive and extensive systems
• Refers to the deliberate culture of target and
  complementary species. Complementary species
  differ from target species especially in regards
  to their nutrition so as to minimize competition
  for resources (e.g., detritivores that clean up
  waste and maintain pond quality)
• Polyculture increases production by maximizing
  utilization of nutritional niches within the pond
• A relatively new approach to polyculture culture
  of a second complementary species isolated from
  the main target species. For example, effluent
  from shrimp ponds (main target species) can be
  routed through separate ponds for culture of
  bivalves, plants, microalgae, etc. Second round
  of culture not only improves the quality of
  effluent water by removing waste but may also
  produce additional commercial crops.

17
General Principles

• Intensity of culture operations
• Integrated agri-aquaculture systems (IAASs)
• Polyculture is based on the integration of target
  and complementary aquaculture species in single
  or separate bodies of water
• Integrated agri-aquaculture systems involve
  traditional agricultural crops (plants, animal)
  and aquaculture. In these systems plant and
  animal waste is used to fertilize ponds, but
  sometimes aquacultural animals (fish and
  freshwater crustaceans) are grown directly in
  plant fields (e.g., rice fields)
• IAASs are typically applied in the setting of
  semi-intensive operations, but intensive
  operations can also be incorporated into an IAAS.
  For example, when using aquacultural effluent
  from an intensive pond system for the irrigation
  of plant crops
• Modern aquaculture has moved toward
  disintegration of aquaculture into monoculture
  systems, but problems of limited water
  availability seems to be reversing this trend in
  some places

18
General Principles

• Water exchange/flow systems
• Classification
• Static
• Open
• Semi-closed
• Recirculating (closed)

19
General Principles

• Water exchange/flow systems
• Static systems
• Static system is one in which there is no water
  replacement during the growth of an organism
  (except for water added to offset evaporation)
• Static pond culture is usually extensive because
  of difficulties in maintaining water quality
• Most global aquaculture occurs in ponds using
  static systems

20
General Principles

• Water exchange/flow systems
• Open systems
• The open environment (lake, ocean, etc.). There
  is no artificial circulation of water through or
  within the system.
• Structures used in this system include cages,
  racks, etc.
• In some cases, such as salmon culture in cages,
  the open system is intensive (high density of
  fish with artificial feeds)
• In other cases, such as bivalve culture in racks,
  the open system is extensive (bivalves feed on
  plankton)
• Operation costs of open system is usually low
  since no pumping is required
• Capital costs are high for open intensive systems
  and low for open extensive systems.
• Problems (1) lack of control over water quality,
  so site selection is a very important
  consideration (2) predation and disease.

21
General Principles

• Water exchange/flow systems
• Semi-closed systems
• Systems where culture water is confined in
  discrete units and some degree of water exchange
  occurs are defined as semi-closed systems. These
  systems fall between static (no exchange) and
  open (in the open environment) systems in terms
  of water exchange.
• Ponds, tanks and raceways where significant
  exchange of water are carried out are considered
  as semi-closed systems.
• Since the farm is not located in the natural
  environment, there is some control over water
  quality by regulating the amount exchanged.
• In large semi-closed systems with semi-intensive
  to intensive culture, water flow is generally
  high (5-10 per day for semi-intensive ponds and
  30-40 per day in intensive ponds)

22
General Principles

• Water exchange/flow systems
• Recirculating (closed) systems
• Systems are characterized by minimal water
  exchange, but unlike static systems the water
  flows internally, usually through waste removal,
  biofilter, and disinfection units to help
  maintain water quality.
• Costs of construction and operation are high, but
  yield and product value can also be high and
  offset costs.

23
General Principles

• Hatcheries
• So far we have discuss information primarily
  associated with the grow-out or production
  aspects of aquaculture (e.g., farming operations)
• Hatcheries are those aquaculture facilities
  associated with reproduction, larval rearing, and
  supply of juveniles to farms
• Considerations for hatcheries (site selection,
  etc.) are similar as those for nursery and
  grow-out facilities
• General design requirements
• Area for holding broodstock
• Spawning area
• Food production area (plankton, etc.)
• Larval rearing area
• Early nursery area
• Hygiene is major concern. Must be designed to
  minimize possibility of disease transfer between
  different areas.
• Water quality and feeding regimen are important
  management considerations

24
General Principles

• Selection of species balance between biology
  and economics
• Biology
• Water temperature and quality requirements
• Growth rate (fast or slow growing species?) rule
  of thumb, more than 2 years to market size not
  good (rule may be modified according to risks and
  final value of product)
• Feeding habits and cost 3 phases
• Hatchery/nursery
• Juvenile
• Grow out (usually similar to juvenile in fishes)
• Reproductive biology reliable source of
  juveniles or seed is very important. Wild
  sources of feed sometime used (table oysters,
  milkfish in Asia) but availability can be
  unpredictable and affect aquaculture operations.
• Hardiness adaptability to captive environments
  is important. Domesticated lines are very useful.

25
General Principles

• Selection of species balance between biology
  and economics
• Economics
• Production objectives
• Industrial products
• Pharmaceutical products
• Aquaculture products
• Ornamental species
• Wild stock enhancement (usually of concern to
  public agencies)
• Marketing is there a market for the product
  being considered?
• Cost-return analysis (computer software available)

26
General Principles

• Development of new aquaculture species
• If culture techniques are already established for
  target species, especially if the species is
  already cultured in the region, the establishment
  of an aquaculture operation is made easier.
• If culture is desired for new species not
  previously raised in captivity, basic culture
  techniques need to be developed first.

27
General Principles

• Development of new aquaculture species
• Stages in the development of new culture species
• Screening stage
• Collection of available information about species
  life history, ecology, husbandry. Consider
  information obtained in relation to the
  characteristics of proposed aquaculture site.
• Legal considerations
• Market considerations local, global demand?
• If market does not currently exist, can it be
  developed?
• Economics
• Research biology and husbandry (water quality
  requirements, optimal stocking densities,
  reproductive physiology and broodstock
  management, nutrition and growth)
• Pilot trial semi-commercial validation of
  aquaculture potential using small culture units
  and animal numbers
• Commercial trial full-size culture units and
  larger number of animals identifies production
  costs and profits and problems of husbandry of
  large numbers of animals preliminary market
  development
• Full-scale production uses full number of
  commercial size culture units.

28
General Principles

• Development of new aquaculture species
• Time scale for development could be well over
  10 years
• Screening stage up to 2 years
• Research no less than 5 yeas for species not
  previously studied
• Pilot trial at least 2 growing generations
• Commercial trial at least 2 growing generations