1 - Fish

Question 1

What are the ocean based (salt water) farmed fish?

Answer 1

-Salmon
>Chinook: pacific (BC’s biggest industry)
> Coho: ATlantic
-shellfish (oysters, mussels)
-shrimp

Question 2

What are the land based (fresh water) farmed fish?

Answer 2

-Tilapia
-carp
-catfish
-trout
-arctic char

Question 3

How long does the Pacific Salmon process/cycle take?

Answer 3

-3 years
>1st year (1.5years): fresh water, then ‘smolt’ and move to sea
>mature at sea for 4 years and then return to fresh water

Question 4

How is fish age measured?

Answer 4

-degree days
>temperature x days
Ex. 10degrees C x 10 days = 100 degree days old

Question 5

Where are the eggs developed in the female and released?

Answer 5

-released into abdomen and expressed through VENT into gravel
>guarded by female until male comes and deposits ‘milt’ (seminal fluid)
*females die after this

Question 6

How are females raised? (2 ways)

Answer 6

1. In hatchery (good biosecurity)
2. Matured at sea and brought back for breeding (less good)

Question 7

How is the ‘breeding’ done?

Answer 7

-eggs from females are stripped out into a bowl
>WASHED to minimize vertical transmission
>females are euthanized
-males are milked and ‘milt’ is washed before mixing with eggs
>can be collected several times

Question 8

How are the fish euthanized?

Answer 8

-anesthetic bucket: clove oil
*rendered for pet food or fish oil

Question 9

All fish in the industry are female, how do you ‘make’ them become male?

Answer 9

-treat them with methyl testosterone=become male=produce milt
*very restrictive gene pool

Question 10

When do salmon usually breed? How can that be manipulated

Answer 10

*fall: based on photoperiod
-manipulate by
>photoperiod
>temperature
>water chemistry
>use of GnRH and prostaglandins

Question 11

What is typically the fertility rate?

Answer 11

-90-95%
>will drops off as you move out of the season
*4 spawnings a year

Question 12

How are eggs hatched?

Answer 12

-placed in trays on a membrane over media
-shake and infertile eggs will become cloudy=removed
-fertile eggs=’eyed’
-eggs hatch and swim through membrane into media
>have LARGE YOLK SAC that provides all food in first stage of life (don’t need to feed them)

Question 13

When is the time of greatest loss? (eggs-hatching)

Answer 13

-once yolk sac is depleted, the abdomen closes ‘buttoned up’
-90% should still survive
*then swim to surface and start to look for food=start feeding them

Question 14

What are fish feed?

Answer 14

-pellets
>80% plant based
>15-20% fish based (never feed fish back their type of fish)

Question 15

Salmon are carnivorous, where do they get their marine fats from?

Answer 15

-can’t make omega 3 and omega 6=need to get it from their diet
1. Fish meal: ‘cut offs’ from commercial fishing (NOT as much anymore)
2. Approved bait fish fisheries where there is NO human market
3. Future: grow plankton and krill to make food

Question 16

How much loss do you expect due to ‘culls’ pre-molt?

Answer 16

-20%
-continually graded for size and defects
>small ones fall through and are euthanized

Question 17

What are the 2 types of hatcheries?

Answer 17

1. Fresh water: continual flow of water and discharge
2. Recirculating: use biofilter to remove NH3, NO3, CO2 (easier to manipulate)
   >need less water, VERY COMPLEX ENGINEERING
   >can’t use antibiotics=kills the filter

Question 18

What is smolting?

Answer 18

-massive physiological change as they move from fresh water to salt water
-huge OSMOLALITY of body systems
-usually around 100g

Question 19

Smolting window for Atlantic salmon vs. Pacific salmon

Answer 19

-Atlantic: very TIGHT window
-Pacific: can control environment and push it back
>downside=risk of skin disease due to stress (ex. fungus)
*waste from hatchery=great for fertilizer after composting

Question 20

How are fish transferred to sea?

Answer 20

-pumped out of tanks into trucks, then barges out to the sea pens
*12 months to 2 years in pens

Question 21

What are the pens at sea like?

Answer 21

-typical: 40x40m, with 50-80,000 fish
-15-20m deep
-walls tapering to a cone 30m deep
*typical fish farm=500,000 fish at sea
-floats at top that are tethered to sea floor

Question 22

What does the management look like for fish at sea?

Answer 22

-feed daily
-leave them alone
-keep nets clean
-remove any dead fish

Question 23

How do you harvest the fish at sea?

Answer 23

-crowd fish to one side
-suck up fish into harvester
>dewatering table
>percussive stunning and bleeding!
*do it right away

Question 24

What does a fish vet do?

Answer 24

*purest form of population medicine
-lots of daily necropsy work
-visit sites: routine and disease outbreaks
>land or ocean
-paperwork and regulations

Question 25

Importance with fish necropsies

Answer 25

-FAST: as they rot fast
-done on site
-specialized pathologists to do histo
-diagnostic tests for viruses, bacteria and protozoa

Question 26

What is the most common disease in BC salmon?

Answer 26

-PRV
>very low disease
>very common

Question 27

What are some of the important disease in BC?

Answer 27

-IHNV: controlled by EFFECTIVE vaccines
-VHS: no vaccine, manage with good husbandry
>if no stress=no disease
>stressed=shed alot=outbreak

Question 28

How are diseases generally controlled?

Answer 28

-vaccines
-good management

Question 29

What are the different forms or ways to vaccinate?

Answer 29

-in feed: experimental
-intra nasal: experimental
-immersion: used in small fish (2 treatments, short acting=works in hatcheries)
-injectable=most vaccines
>intra-peritoneal
*anesthetize fish and inject by hand
>need to be very skilled=60g fish, small margin window

Question 30

What is your rule of thumb for treatment options?

Answer 30

-if at sea=use fresh water
-if at hatchery=use salt water
*very effective for parasites (ex. sea lice: crustacean)

Question 31

How do you treat at sea?

Answer 31

-specailized boat with reverse osmosis
-suck up fish, treat, and return
*water can be filtered and reused

Question 32

How do you treat in the hatchery?

Answer 32

-put fish in ‘chlorine tea’ to treat bacterial gill disease
Ex. like ‘feedlot pneumonia’

Question 33

Can put antibiotics in feed=last resort

Answer 33

• mainly florphenicol=short acting
  -oxytet and sulfas=poor palatability, long acting and better for some diseases (ex. bacterial kidney disease)
  *used in hatcheries and oceans
  >not in recirculating systems

Question 34

What are some diagnostic techniques?

Answer 34

-gross necropsy and histo path
-routine bacteriology
-virology: PCR
>infectious salmon anemia=not in BC
>mainly looking for exotic diseases
*continually discovering new diseases (deep sequencing and electron microscopy)

Question 35

What are some ‘facts’ about salmon welfare?

Answer 35

-development of new international welfare codes to ensure 5 freedoms and humane slaughter
*fish do feel pain

Question 36

What is the size of the industry?

Answer 36

-12 vets in BC
-huge and growing fast
-wild fish production=plateaued, and will decrease due to overfishing
*since 2010 farmed fish is a bigger industry than wild fish
**BIGGEST AGRICULTURAL EXPORT FROM BC
-$1 billion exported to USA (swine is $5b)

Question 37

What communities is fish farming really important for?

Answer 37

-isolated communities
>*especially indigenous communities
*farms are remote as they need PRISTINE WATER

Question 38

What is the limiting factor to fish production?

Answer 38

-fish health
-environmental health and ‘social license’

Question 39

Fresh water fish production: worldwide

Answer 39

-much larger than salt water
-easier system (can put fish into a ‘dug out’)
-warmer water=faster growth and can feed on algae
-long history of domestication=robust, easy, few diseases
-stay in one place=minimal predation issues

Question 40

Where is fresh water production very important?

Answer 40

-vital protein source in developing countries
*talapia (carp, trout, catfish)
*talk of ‘blue revolution’: provide protein for the worlds population boom