Intro to Aquaculture

Question 1

Define aquaculture

Answer 1

• controlled rearing of aquatic organisms
  
  • fastest growing animal industry
  • global market

Question 2

What is extensive aquaculture?

Answer 2

• focuses on fishery management rather than aquaculture management
• low biomass:volume ratio (< 500-1000 lb/acre)
• minimal management required
  
  • feed/aeration not required
  • ideal for recreational pond

Question 3

What is intensive aquaculture?

Answer 3

• Continuum where management becomes more like traditional farm management
• >>>1000 lb/acre
• problems include crowding, water quality, nutrition, infectious dz
• feeding, water quality, aeration required

Question 4

What are the advantages of extensive production?

Answer 4

• little to no investment in equipment and feed
• fish can be trapped which is also very low tech/requires minimal capital investment
• water quality problems are minimized by low stocking and feeding rates
• natural food available in pond should be sufficient for growth of fish
• used as source of protein from community managed ponds

Question 5

What is an example of an extensive production?

Answer 5

livebearer production in Florida

Question 6

What are the advantages and disadvantages of intensive production?

Answer 6

• A:
  
  • if indoors, more control/elimination of predation
  • massive incr in production
• D:
  
  • incr risk of dz and dz transmission
  • system failure can lead to catastrophic loss, sometimes in minutes
  • high start-up and operating costs
  • complete diet required

Question 7

What is an example of an intensive production operation?

Answer 7

• egg layer production - Angelfish Production
  
  • initial rearing in hatcheries
  • incr use of re-circulating systems for intensive rearing of select specials
  • biosecurity is critical

Question 8

What are various types of production systems used for aquaculture production in the U.S.?

Answer 8

• Earthen ponds - channel catfish, hybrid striped bass, shrimp
• Raceways - rainbow trout
• Cages or net pens - salmon
• Re-circulating tank systems - tilapia
• Underwater lease - clams

Question 9

What are the advantages and disadvantages of pond production?

Answer 9

• A:
  
  • “free” or “cheap” production
    
    • no need to continuously circulate
  • filtration system not required
  • some natural food available
• D: min control of environment
• predation can exceed 70%
• difficult to maintain inventory
• “off flavor” hard to control: caused by some algal blooms, fish cannot be marketed for consumption

Question 10

Describe earthen pond production systems

Answer 10

• Intensity of management determined by stocking density (>3000 lbs/acre = intensive)
• dissolved O2 often limiting (>5mg/L = goal)
• minimal control of rearing conditions
• most common method used for production aquaculture in US

Question 11

What are the advantages and disadvantages of raceway production systems?

Answer 11

• A:
  
  • often use “free” water from river/other source
  • use high flows instead of investment in filtration systems
  • again, relatively inexpensive if not needing to continuously pump water
• D:
  
  • poor control of water source
  • introduce dz and contaminants if using surface water
  • concerns w/ effluent (contamination or dissemination of dz to surface waters)
  • crowding facilitates rapid spread of dz
  • tx can be difficult b/c of large volumes of water used

Question 12

What are the advantages and disadvantages of cage culture production systems?

Answer 12

• A:
  
  • tidal flush provides “free” water exchange
  • risk of contamination or dz intro from local water
  • easy to harvest
• D:
  
  • very controversial in populated areas
  • exposure to wild fish, potential dz introduction
  • potential for contamination from local water
  • susceptible to storm damage
  • predation
  • concern for damage to local environment
  • very crowded, potential for rapid spread of dz
  • difficult to tx

Question 13

What are the advantages and disadvantages of re-circulating production systems?

Answer 13

• A:
  
  • complete control of environment
  • elimination of predation
  • very efficient grow out for suitable species
  • tx easier and less expensive than other systems
• D:
  
  • very high capital investment required
  • high risk (power failure)
  • intensive management requirements
  • expensive to operate and maintain
  • biosecurity is critical

Question 14

Describe an all-in-all-out production strategy

Answer 14

• system drained at end of production cycle, all fish removed
• disinfection and removal of sediment and muck
• in Florida, may get 2-3 crops per pond per year for ornamental species

Question 15

Describe a continuous production strategy

Answer 15

• system rarely drained (ie. once in 10-15 yrs)
• following harvest, “top off” a pond w/ approximate # of fingerlings to replace fish removed by harvest
• industry standard for catfish production

Question 16

What are the advantages and disadvantages of continuous production strategy?

Answer 16

• A:
  
  • no “down time” to dry out pond
  • simply replace the # of animals harvested w/ similar # of fingerlings
  • practical for very large ponds
• D:
  
  • lose track of inventory
  • pond banks erode
  • massive accumulation of organic matter
  • maintenance (when required) is major
  • major dz control can be very difficult

Question 17

What are the advantages and disadvantages of all-in-all-out production strategy?

Answer 17

• A:
  
  • better control of inventroy
  • avoid build up of organic matter
  • can produce mulltiple crops in same pond
  • much better for biosecurity
• D:
  
  • labor intensive
  • more effluent from pond

Question 18

Describe channel catfish aquaculture production

Answer 18

• most importnat aquaculture industry in the US
• ranked 10th globally
• production centered in Miss valley
• catfish are hardy, spawn easily in container, produce large egg mass, easily relocated to hatchery
  
  • takes +/- 18 mo

Question 19

What are specific health concerns for channel catfish?

Answer 19

• Water quality
  
  • low dissolved O2, off flavor, ammonia/nitrate
• Infectious dz:
  
  • bacterial: Columnaris, ESC
  • parasitic: protozoans, monogeneans common
  • fungal and viral less common

Question 20

Describe tilapia

Answer 20

• very hardy fish, tolerant of poor water quality conditions (high ammonia, low dissolved O2)
• thrives on low-quality feed
• high reproductive capacity –> stunting, single sex populations preferred
• exotic to FL, but has become endemic in most of state freshwater systems
• thermal limited: temps < 50 deg F +/- fatal

Question 21

What are special health concerns for tilapia?

Answer 21

• Strep innae:
  
  • systemic bacterial dz
  • neuro signs common
  • zoonotic concern
    
    • human fatalities assco. w/ fin sticks, immunocompromised patients
• Franciscella:
  
  • ​systemic granulomatous dz
  • fish may survive but carcass condemned

Question 22

Describe carp and koi

Answer 22

• same fish
• extremely important food fish (esp in China)
• koi specially bred for color
  
  • very popular pets in US, important cultural values (Japan)
  • Shows:
    
    • European style: fish isolated from each other
    • Japanese styles: fish placed in same tub for judging

Question 23

What are some special health concerns for carp and koi?

Answer 23

• viral dz (reportable dz!)
  
  • ​Spring Viremia of Carp (SVC)
  • Koi Herpes Virus (KHV) - endemic to US
• Bacterial dz: Aeromonas salmonicida
• Commercial vaxs available

Question 24

Describe Koi Herpes Virus

Answer 24

• Cyprinid Herpes Virus 3
  
  • endemic to US
  • warm water dz
  • primary target = gills
  • reportable: but no action taken

Question 25

Describe Spring Viremia of Carp

Answer 25

• Rhabdovirus carpio
  
  • foreign animal dz
  • cool water dz
  • non-specific signs
  • reportable: depopulation required!

Question 26

What are the basic components of a fish health management program?

Answer 26

• water quality/life support
• nutrtion
• sanitation
• quarantine/biosecurity

Question 27

What are basic water quality parameters?

Answer 27

• dissolved O2
• temp
• CO2
• pH
• total alkalinity
• total hardness
• total ammonia nitrogen (TAN)
• unionized ammonia nitrogen (toxic ammonia)
• nitrate
• nitrite
• salinity

Question 28

What are sources of dissolved oxygen and where does it go?

Answer 28

• Sources: diffusion, agitation, photosynthesis (“green” water only)
• Where does it go?: respiration, organic processes, other “sinks” - chemical tx (ie. formalin)

Question 29

What is the issue with stratification?

Answer 29

• cold water is more dense than warm water –> sinks
  
  • high dissolved O2 in warm water, low in cold
• O2 demand builds up in cold water - no input of O2, bacterial processes use up available O2 anc create demand
• when water mixes, oxygen demand is fulfilled, removing O2 from the system
• common cause of catastrophic fish kills following big storms

Question 30

What are the sources of ammonia?

Answer 30

• fish = primary contributor in aquariums (>85% across gills)
• in heavily stocked production ponds, feed may exceed 100 lb/acre/day = feed is primary source
• decomposition of organic matter (sediment diffusion)
• uneaten food
• hetertrophic bacteria

Question 31

Describe the concept of Total Ammonia Nitrogen

Answer 31

• NH₃ = ammonia = unionized ammonia (UIA)
• NH₄⁺ = ammonium = ionized ammonia
• toxicity is pH and temp dependent, dissolved oxygen is a limiting factor
  
  • ​incr pH and temp –> incr UIA
• ammonia toxicity due to UIA may occur as low as 0.05 mg/L

Question 32

Describe the adverse effects of high ammonia levels in the water

Answer 32

• Increases ammonia level in bloodstream and tissues
  
  • osmoregulation is affected
  • blood pH incr
  • need for O2 incr
  • O2 transport decr
• chronic low level ammonia
  
  • inhibits growth
  • incr susceptibility to dz

Question 33

What are ways to avoid ammonia toxicity?

Answer 33

• reduce stocking density
• harvest frequently (ponds only)
• don’t overfeed
• maintain optimal dissolved O2
• add biofiltration
• water change