Fish 1

Question 1

Ocean based farmed fish

Answer 1

**salt water

-Salmon (chinook in pacific-BC!, coho in atlantic)
-shellfish (oysters, mussels, gooey duck clam) and shrimp

Question 2

Land based farmed fish

Answer 2

**fresh water; some are trying to do salt water on land too

-tilapia
-carp
-catfish
-trout
-arctic char

Question 3

Cycle of Pacific salmon

Answer 3

Slow: 3 yrs

-1st year in fresh water (extended to 1.5yrs in a hatchery)
-smolt &move out to sea
-Mature to ~4 yrs old then return to fresh water
-females develop egg, released into abdomen, and then released through vent into gravel
-female guards eggs waiting for male to come and deposit milt (seminal fluid
-females die

Question 4

Degree days

Answer 4

-How fish age is measured based on being cold blooded

-temperature they are in multiplied by number of days

Question 5

Types of breeding methods of Salmon

Answer 5

1.Females artificially raised entirely in hatchery= good biosecurity

2. Females matured at sea and brought back for breeding= not as good biosecurity

Question 6

Breeding Salmon

Answer 6

1. Fish mature around 4-5 yrs and flesh quality deteriorates
   -some males mature early= jacking; means they can stay in fresh water and reproduce= evolutionary advantage
2. Eggs are stripped from female into bowl, washed to minimize vertical transmission of disease
3. Males milked for milt, and washed before fertilization
   **can collect from males several times
4. Mix eggs and milt

Question 7

What happens to females once they are stripped of eggs?

Answer 7

euthanasia bucket (clove oil)
-can be used for pet food, fish oils
-otherwise fertilizer if use of hormones etc.

**males are used multiply times and then euthanized

Question 8

Salmon sexes in industry

Answer 8

1. All fish are female (4N chromosome)
   -treat some females with methyl testosterone= male
2. All offspring are female

Question 9

In breeding

Answer 9

-companies will use genetic selection to select for characteristics and prevent inbreeding

-very restricted gene pool from original development
*Original pool from Sacramento River in the 80s, and now they are

Question 10

Salmon as seasonal breeders

Answer 10

-breed in Fall based on photoperiod
-can be manipulated by photoperiod, temp, water chemistry, use of GnRH and Prostaglandins

Question 11

Fertility rate in salmon farming

Answer 11

90-95%
-drops off out of season

Question 12

Egg Hatching steps

Answer 12

1. Eggs in trays on a membrane over media
2. Fertile=eyed Infertile= cloudy
3. Eggs hatch and swim through membrane into media
   **yolk sac=food

Question 13

Early life feeding

Answer 13

-When yolk sac is depleted, abdomen closes (buttoned up)
**time when greatest loss of fish occurs (usually 90% survive)

-fish will start swimming to surface looking for feed

Question 14

Fish pellets

Answer 14

-fish need to learn to eat pellets but then they become completely dependent on them
**escaped fish often found with wood pellets in gut

Question 15

Grading/selecting for fish

Answer 15

-graded for size and defects
-use automatic machine requiring fish to swim through different grate sizes
*small ones dropped through= euthanasia/culls
*usually 20%

Question 16

Fish Environment

Answer 16

-need to be in raceways with flowing water to swim against

Question 17

2 types of hatcheries

Answer 17

1. Flow through= Fresh water= continual flow of water and discharge
2. Recirculating= use a biofilter to remove NH3, NO3, CO2. Little water. Cannot use antibiotics as kills filter

Question 18

Smolting

Answer 18

-massive physiological change as they move from fresh to salt water
-alters osmolarity of body system
-fish are small at this stage (100g)

Question 19

Smolting atlantic vs pacific

Answer 19

Atlantic salmon= tight window
Pacific salmon= can control/push back and keep them at hatchery longer.Stress= skin disease/fungus

Question 20

Transfer of salmon from land to sea

Answer 20

**Want to do whole process land based but poor flesh quality and poor welfare
-fish are pumped out of tanks to trucks, then to barges and out to sea pens

Question 21

Pens

Answer 21

-12 mths to 2 yrs spent in pens
-pens have floats at top, tethered to the floor,

-many options:
1. Largest= 200m circumference with 300-400,000 fish

2. common 40X40 or 120m circumference with 50-80,000 fish

Question 22

Depth of nets`

Answer 22

15-20meters deep and then tapered to a cone around 30m deep

Facility in water is approx 100m deep

Question 23

Typical number of fish at a farm

Answer 23

500,000 fish at sea

Question 24

General management of fish in pens

Answer 24

-feed daily
-leave fish alone
-keep nets clean and remove dead fish

Question 25

Norway fjord example

Answer 25

1 fjord in Norway has more salmon than the entire west coast of BC

Question 26

Salmon harvest

Answer 26

1. Crowd fish into pens
2. Use fish pump to suck fish up into harvester
3. dewatering table and percussive stunning an bleeding (or electricity)

**better than commercial fishing

Question 27

Fish euthanasia

Answer 27

Use compounds in water such as Clove oil or MS222/TMS

-quick and safe
-recover by putting fish in clean water