Fish 2

Question 1

What do fish vets do?

Answer 1

1.Individual medicine= Specialization in ornamental and aquarium fish

2.Population medicine= Aquaculture

Question 2

Day to day as a fish vet

Answer 2

1. Daily necropsy work- ID disease and intervene. Culling or emergency harvest and general health status
2. Visit sites- routine and disease outbreaks. Land or ocean.
3. Husbandry and feeding assessment
4. Paperwork. Regulations. Legal challenges.

Question 3

Post mortems

Answer 3

-All deads harvested and available for PM
-Use freshest because they rot fast
-sometimes live sampling
-all vets do PMs, but specialized pathologists do histology

Question 4

How are dead fish harvested?

Answer 4

Divers recover deads from bottom of net or use air pumps to bring them to the surface.

Question 5

Issues with post mortems and fish

Answer 5

-Lots of genetic diversity in fish so lots of variability in disease response

Question 6

Purpose of Post mortems

Answer 6

-needed for disease surveillance programs
-used with diagnostic tests to detect viruses, bacteria, parasites

Question 7

Disease burdens

Answer 7

Some diseases very common but not very important

Eg. PRV in BC salmon. Low disease but very common

Question 8

New diseases in fish

Answer 8

-Need to use Koch’s postulates and determine significance

-discover new diseases through deep sequencing and electron microscopy- then find out if important

Question 9

Disease and geography in fish

Answer 9

Many diseases are associated with geography
Eg. lots more disease in Atlantic salmon

Question 10

Important BC diseases

Answer 10

1. Infective Hepatic Necrosis Virus -vaccine controlled
2. Viral Hemorrhagic Septicemic virus-no vaccine, but managed with good husbandry (reduce stress)

**important management and vaccines in hatcheries due to high stocking density

Question 11

Fish vaccine methods

Answer 11

1. in feed (experimental)
2. Intranasal (experimental)
3. Immersion (used in small fish; 2 treatments. Short acting so works in hatcheries against bugs in fresh water but not salt because later in life they wont be exposed)
4. Injectable (most common)
   >intraperitoneal- oil adjuvant vaccine
   >used for 4 vibrio spp and IHN

Question 12

How to give injectable vaccines to fish?

Answer 12

-anesthetize fish, inject by hand
-fish ~60g so small window for injection. Takes skill; trying to develop machine

Question 13

Treatment for parasites

Answer 13

If in fresh water, add salt water
If in salt water, add fresh water

eg. sea lice (crustacean), fungi, etc.

Question 14

Specialized boats for treatment

Answer 14

Have reverse osmosis capability to suck up fish from ocean, treat, and return
-water is filtered and returned
-bathe fish in either fresh water or salt water

Question 15

Hatchery treatments

Answer 15

-Use tanks, put fish in choline tea to treat bacterial gill disease

Question 16

Antibiotics in feed

Answer 16

-last resort
-metaphylaxis
-uses massive amounts and is deposited into environment

Question 17

Drug of choice

Answer 17

Florphenicol
-used in oceans mostly and sometimes hatcheries (hatchery has other sterilization methods like filtering, UV, ozone chlorination)
-cannot use in recirculating systems
-short duration

Question 18

Oxytetracycline and sulfas

Answer 18

-poor palatability
-long acting for some diseases such as kidney disease
-poor for environment because fish don’t want to eat so will stay in water

Question 19

Diagnostic technique

Answer 19

1. gross necropsy and histo pathology

2.Bacteriology: blood agar, TSA, special agars

3. Virology: PCR routine screen

Question 20

Virology screening in BC

Answer 20

ISA (infectious salmon anemia) is not in BC

HPR present is same disease but 1 base pair deletion that does not cause disease but can revert

*Mainly looking for exotic disease

Question 21

Salmon welfare

Answer 21

-development of new international welfare codes to ensure 5 freedoms and ensure humane slaughter

*No normal feeding behaviour= salmon adapt to pellets and even though they are predatory, they will not eat herring even when starved

Question 22

Salmon nutrition

Answer 22

-Pellets (80% plant based, 15-20% fish based)
*never salmon/feed back method

-omega 3s and 6s (marine fats)

Question 23

Where is fish meal sourced from?

Answer 23

**industry moving away from fish meal (poultry and swine much higher)

1.From cut offs from commercial fishing (non salmon)

2. Approved bait fish fisheries especially South America
3. Grow plankton and krill and make food.