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138 Cards in this Set

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List the 4 General Pathways of Infection and Disease.
1) Pathogen Bloom and Progressive Microecology
2) Latency and Recrudescence
3) Spill-over and Spill-back
4) Interaction with Intermediate Hosts
Describe the pathway of Pathogen Bloom and Progressive Microecology.
Pathogen encounters favorable conditions for replication --> overwhelms mucus surfaces and gains a foothold --> exhausted mucus and inflammation --> vulnerable to other opportunists --> back to start
Describe the pathway of Latency and Recrudescence.
Pathogen gains internal foothold through horizontal or vertical transmission --> pathogen remains viable but hidden from host response --> pathogen reemerges during periods of stress resulting in disease
Describe the pathway of Spill Over and Spill Back.
Wild fish enter the netpen and shed pathogen to captive fish --> Spillover --> multiplication of the pathogen --> spillback from captive fish to wild fish.
Describe the pathway of Intermediate Hosts
Birds, molluscks, tubefex worms - all part of pathogen's development cycle and can transmit to fish in net pens...therefore you want to keep them out of the pen (netting, molluscides, etc)
Give 2 examples of Parasites involved in Pathogen Bloom
Trichodina, Chilodonella
Give 2 examples of Bacteria involved in Pathogen Bloom
Bacterial Gill Disease (Flavobacterium branchiophilum), Columnaris disease (flesh-eating disease)
Give an example of a fungus involved in Pathogen Bloom
Saprolegnia
What are the functions of mucus?
1) Carries useful substances like growth inhibitors, lysozymes, complement
2) Once pathogens deactivated they are sloughed with continual mucus production
3) Mucus limits pathogen growth(therefore when overwhelmed, fish surface is compromised)
Causes of mucus depletion?
1) Rough Handling
2) Injury from predators
3) Environmental factors (sunburn)
What is the common response of both Bacterial and Nodular (Amoeba) Gill Disease?
Gill Proliferation - will decrease gill surface area for pathogens to attach too, less surface area for toxicity, aid with osmoregulation. Will also decrease gas exchange and excretory ability.
What is a unique feature about fish gills that have undergone damage e.g. proliferation?
Recovery and Repair through stacking of non-differentiated cells and attachment of pillar cells leading to lamellar regeneration.
What is the immune component fish lack?
Lymph Nodes
How do pathogens establish latency?
1) Evade the host immune response (intracellular - macrophages)
2) Become part of normal intestinal flora - penetrate epithelium during stress (like when the fish write stupid exams)
3) Fish are infected but do not show clinical signs (carriers)
Give Bacterial, Viral and Parasititic Examples of Latency and Recrudesence Pathogens, please and thank you.
Bacti: Furunculosis, BKD(Renibacterium salmoninarum)
Viro: Infectious pancreatic necrosis virus
Parasites: Kudos thyrsites
What disease does Renibacterium salmoninarum cause?
Bacterial Kidney Disease - gram + bacti in macrophages --> form granulomas in kidney, slow developing. Most significant cause of disease in pen-reared Pacific Salmon.
No treatment for clinical disease - best to avoid it alltogether - fallow, trt broodstock b/f spawning, keep single year classes, etc

An example Latency and Recrudesence
What group of people prefer Chinook/Coho Salmon?
The Asians
What group of people prefer Atlantic Salmon?
The Whities.
Who is the number 1 salmon producer?
Chile
What is the bacterial agent of Furunculosis?
Aeromona salmonicida - Gram -ve, NOT intracellular pathogen; key feature is latency as it becomes part of normal gut flora. Hallmark is brown pigmented colonies
Managment steps to avoid Furunculosis in a hatchery?
1) Change source of fish (cert furunc free fishies)
2) Modify the H2O source/improve filter/flow rates
3) Vaccinate fish at hatchery and trt with Abx
4) Decrease stress (decrease stocking density)
5) screen for disease with corticosteriod and water temp increase to see if develop clinical disease
Provide disease examples of spill over and spill back.
- Viral: Infectious Salmon Anemia Virus
- Parasitic: Sea Lice (Lapeophthelrus salmonis)
- Bacterial: Microsporidial Gill Disease - Loma salmonae
How can you manage sea lice?
Cleaner fish - goldsinny wrasse for smaller fish, Ballan wrasse for larger
Trt with SLICE or Callicide
Bath trt with Alphamax, hydrogen peroxide
Describe Microsporidial Gill Disease.
Netpen disease affecting large, near market size salmon --> parasitic cysts in gills of fish and usually die right before they go to market. Occurs in both fresh and saltH2O species and can survive in the spore form in the environment for a long time and over a wide temp range. Very little host response during development in a host cell.

Example of Spill-over and Spill-back
Name 2 Diseases transmitted by intermediate hosts, and describe them, bitch.
Eye Fluke (Diplostomum) - MOLLUSK intermediate host, final host is a BIRD. So, birds shit in the water (go figure) and then snails eat the eggs that the bird shit into the water, the snails release cercana and then the fish ingest these -->parasite goes to the eye because it has less immune survellience. Cause blindness, so the birds can eat the fish and the cylce continues. Fun fun.

"Whirling Disease" Myxobolus cerebralis: progressive destruction of cartilage, final host is RAINBOW TROUT, intermediate host is TUBIFEX WORM.
What is so wonderful about rainbow trout? And not-so-wonderful?
Wonderful:
-12 mo to market, 1lb
-feed conversion ratio is AWESOME (<1 sometimes)
-Steelhead version can be grown in brackish water

Not-so-wonderful?
- They are disgusting (in my personal opinion) - Dr. Spears described it as "less tasty" low in Omega 3, white fleshed, require fish-meal based diet
Advantages/Disadvantages of Chinook Salmon?
Advantages:
- found naturally in local waters
- strains easily moved from salt water to fresh water at an early age
- strong market in Japan
- large flavorful fish (provided you like fish)

Disadvantages:
- Mort rates high post transfer
- prone to disease, poor feed conversion ratio, need lower stocking dens.
- early sexual maturation
Good Pts and Bad about Atlantic Salmon?
Good:
- Tasty tasty, rich in Omega 3, best carcass compostion
- better feed conversion than chinook, can tolerate higher stocking densities

Bad: Not marketable everywhere
Describe the Smolt Stages
S1: ready to go to seawater after full year in hatchery
S2: ready to go so sea after 2 years in hatchery
S0: ready to go to sea in spring time of the same year they hatched
S1/2: ready to go in fall of the same year they hatched
What is a pin head?
No, not Mark fast.

AKA a revert, smolts that didn't take very well to seaH2O - lose wt and heads look too big for their body.
What is stocking density?
Ratio of biomass of fish to space available in netpen/tank.
What is feed conversion ratio?
Increase in biomass relative to the amount of food.
How old are broodstock usually and what do they weigh?
4-5 years, 8-12lbs
What is dry spawning?
Anesthesia and removal of eggs from fish and transport to hatchery.
How do you fertilize the fish eggs?
Fish sex! NOT!

Milt is added from several males (skanky bitches) and stirred gently. Water is then added to harden the eggs
Why do you want to shock the eggs?
To determine which ones are fertilized by holding them outside the water for a few moments - the unfertilized ones will turn white due to yolk membrane rupture. Remove the unferts to avoid problems with fungi.
What are "swim up fry?"
First feeding fry - last few days before feeding when yolk sac is internalized and fry move to surface and take a gulp of air. Best feeding success at 12C, light and hand-feeding.
Common problems with Swim up fry?
- non-feeders, fungi/bacti growth, non-inflated swimbladders, gill infections, feed impaction/swimbladder infect
How much to Parr weigh and what are they capable of?
4g, swim and compete for feed, have mark down their sides
What is smoltification?
when parr transform to smolt to allow them to survive in seawater - usually in the spring when 100g. Know they are ready to smolt when lose their parr marks, skinny, swim with the current, gills have more chloride cells, stable Na levels in seawater.
Should you vaccinate in the smolt window?
No
What do most netpens require?
1) An anchor to hold that shit in place
2) Predator nets around the pen and above it
3) Walkways, storage barns, dwellings for workers
4) proper storage for feed
Should pellet size increase with fish size?
Oui Oui, but of course.
What is Grisle?
Another dumb name for a fish.
- small salmon that have matured sexually and cullled during sorting
What pathologies has rapid growth been associated with?
Cardiomyopathy and Fatty Liver
What do net pen operators consider their number 1 problem?
PREDATORS!!!!!!
What kind of adjuvant can cause granulomatous peritonitis?
Oil-based
When are smolt transferred?
Mid-April to mid-June when H2O temp is approximately equal in hatchery and sea. KEEP O2 LEVELS HIGH DURING TRANSPORT
What should the stocking density be for smolt?
20kg/m3
What are normal losses of smolt?
1-3%
What is a problem with growing salmon to market size in the maritimes?
Superchill (its gets cold here, duh). Water freezes and ice crystals form in the blood of the fish. And then they die.
What is the elevator for fish called?
Pesculator
Is a mort spike common during hatching?
Yes, yes it is.
What is a sac-fry?
Hatched fish that carry a yolk sac around for nutrition - have problems swimming therefore if they do it too early there will be malformations.
What is the largest producer of rainbow trout?
Idaho.
How much of salmon body weight is in muscle?
65%
When doing bath treatments, how can you tell if you've overdosed your fish?
Darken, dash frantically, gasp for air, jump out of water, drift down to far end of raceway, mort spikes
ppm = mg/L = g/m3???
yes.
What are some problems with abx feeds?
fish may not eat it, dominant fish eat too much (greedy bastards), food sits in raceway, abx washes off, creates bad flavor, fish spit it out.
What can you do to avoid some problems with abx feed trts?
Feed at normal times, give some unmedicated feed with it, use vegetable oil to mask the taste
What can you do post-trt with abx feed to see if it worked?
Sample some fish to see if bacti remain.
How long does it take Dr. Fast to shave his head?
Good question!
What are the 3 main genera of cultured salmonids?
Oncorhynchus
Salmo
Salveinus
Oncorhynchus mykiss =
Rainbow trout
Oncorhynchus tshawytscha =
Chinook Salmon
Oncorhynchus kisutch
Coho Salmon
Oncorhynchus nerka =
Sockeye salmon
Salmo salar =
Atlantic Salmon
Salvenius alpinus =
Arctic Charr
Salvenius fontinalis =
Brook Charr (AKA Brook trout, speckled trout)
Salvenius namaycush =
Lake charr (lake trout)
Vet work in Culture for Re-Stocking involves what primarily?
Treatment of Broodfish
Vet work in Fee-for-fishing ponds is primarily what?
Management of diseases (eye-flukes, trematodes, anchor worms, etc)
T/F. Atlanitc salmon and rainbow trout are nearly tied for fish produced annually.
True
How long does it take for rainbow trout to go from egg to market? Is this fast or slow?
12 mo, fast.
How do you calculate the weight of a tubular fish?
1cc = 1gram
How do you calculate the weight of a chunky fish?
Length x Height x Thickness
How do you calculate the weight of a platter-shaped rounded fish?
3.14 x r^2 x thickness
How do you calculate the dose of antibiotics for feed?
Kg of fish (Biomass) x Dosage (mg/kg) = X mg
1 ppt = what?
1 g/L
How do you calculate the volume of a round tank?
V(m^3) = 3.14 x r^2 x height
How do you calculate the volume of a raceway or an aquarium?
V (m^3) = L x W x H
What molecule commonly builds up in an aquarium setting due to metabolism and waste material breakdown?
Nitrogen
How do you control ammonia and nitrite levels?
Biological filter
PM Lab:
Blue patches on the dermis are usually associated with___?
External parasites (esp Flukes)
PM Lab:
Black spots on the dermis are usually associated with ___?
Internal parasites (Digenetic trematodes) Black spots are actually melanin granules.
PM Lab:
White cottony growth on fish is typically due to what pathogen?
Saprolegnia
What are pale gills associated with?
Anemia (usually due to viruses)
What are brown gills associated with?
Nitrite Poisoning
How many chambers does a fish heart have?
2
PM Lab:
What organs are best for investigated septecaemia?
Kidney and Spleen
When are medicated feeds used?
Internal infections, when fish are too small or too numerous to inject, specific meds that cannot be given by injection or intestinal infection/parasitism
Withholding food for how long will increase the appetite of the fish?
12-24 hours. Good to do prior to giving medicated feed.
As a person, what precautions should you take when preparing medicated feed?
Gloves, lab coat, breathing apparatus
What do you need to consider when administering abx feed to fish intended for later human consumption?
Withdrawal period
How long are fish placed in a dip bath for usually? Do they need constant aeration with this trt?
<1min, yes need constant aeration
How long is a short term bath?
What systems is it commonly used in?
What is required during treatment?
30min-several hours.
Aquaria, tanks, raceways
Ample aeration, water flow turned off during trt.
What is the least expensive & safest bath treatment and what system is it used in?
Prolonged bath treatment - Re-circulation system.
Why would you used a bath treatment?
External infections, gills, skin, fins, parasites, bacti, fungi, fish off feed therefore this may be the only option
What pathogens does Chloramine T treat?
Myxobacteria, Costia, Trichodina, White spot and Gyrodactylus
What pathogens does copper sulfate treat?
ectoparasites eg. sea lice
What pathogens does salt treat?
Costia, Trichodina, Chilodonella, Dactylogyrus, Saprolegnia
What pathogens does potassium permanganate treat?
Protozoa and Monogenean parasites
How do you simply terminate a bath treatment?
Turn H2O flow back on.
If dO is the cause of a fish kill, what levels is it at?
1-2ppm w/in few hours of the event. Larger fish die first.
If a lethal toxicant is the cause of a fish kill, what is affected?
pH. Smaller fish die first, plankton populations affected as well.
In the menhaden die-offs, in high salinity water, what did the causative fungal infection result in on the fish (i.e. lesions)?
Aphanomyces - deep focal ulcerations and granulomas within organs.
What does VHSv stand for and where did this problem occur?
Viral Hemorrhagic Septicaemia Virus - Great Lakes Watershed
What did certain people think was occuring with the increased rates of wild pink salmon morts?
Juvenile pink salmon moved down the river system and encounteerd fish on fish farms just as they are entering sea water and were exposed to sea lice from the farms. Due to their small size and number of parasites, the pink salmon died.
Define Ripeness.
How close the hen is to releasing eggs.
Define Dry Eggs.
Eggs collected from the hen prior to addition of sperm
Define Water Hardening.
Addition of water to eggs after fertilization to determine which eggs are fertilized or not (unfert will turn cloudy)
Define Green Eggs.
Eggs before the eyes appear.
Define Eyed Eggs
Eggs when the eye spots appear
Define Ripeness.
How close the hen is to releasing eggs.
Define Dry Eggs.
Eggs collected from the hen prior to addition of sperm
Define Water Hardening.
Addition of water to eggs after fertilization.
Define Green Eggs.
Eggs before the eyes appear.
Define Eyed Eggs
Eggs when the eye spots appear
Define Shocking Eggs
Agitating the eggs during early development - unfertilized eggs will appear cloudy.
Define Sac-fry.
After hatching - fry has an egg sac that it drags around
Define Alevin/Swim up fry.
Fry that has absorbed their yolk sac so they start looking for food.
Define Parr.
Small fish that has a vertical band
Define Lensing Site
Makes the transition to seawater easier - layer of freshwater from river entering the ocean and then move the smolt further into seawater
Define In the Round.
Fish in processing that is still intact.
Define down-grades.
Fish that lost and eye, had a ulcer, bad fins - affects how much of the fish can be processed for consumption.
What is the formula for specific growth rate?
(ln(wt at end of interval) - ln(wt at start of interval))/length of interval x 100%
What is the mort rate?
% fish that die each MONTH
What is the feeding rate?
Amount of food relative to biomass (feed 2% of body weight)

Biomass(g) x 0.02 = g food/day
What are the 4 main criteria for selecting broodstock to preform well under captive husbandry conditions?
- good growth rate
- good smolt time
- disease resistance
- delayed sexual maturity.
At what time of year do you want the broodstock to spawn?
Late fall.
What do the egg trays require?
Good water flow, high O2 levels, temp b/w 8-10C
What 2 things do you have to be careful of developing in the egg trays?
excess iron and fungi
At what time does hatching occur?
430 degree days
At what time do sac fry emerge?
800 degree days
Describe what happens with Kudoa thysites.
"Soft Flesh Syndrome" - an example of latency and recrudesence. Occurs 3-6 days after slaughter when there is flesh liquefaction and white patches caused by cysts lodged in the muscle.
What is the most significant disease of netpen reared pacific salmon?
Bacterial Kidney Disease - Renibacterium salmoninarum (intracellular)

No practical treatment for clinical disease - single year classes and fallowing period and trt of broodstock may help decrease.
What is the causative agent of Furunculosis?
Aeromonas salmonicida