Major Costs in Aquaculture Major Repeating Costs in Aquaculture Include: New Seed Growing or Purchasing To Make Effective Decisions You Need to Know About Reproduction of the Target Species Feeds To Make an Effective Decision You Need to Know About Life History Stages and Their Nutrition Requirements Disease To Make Effective Decisions You Need To Understand The Immune Response of the Target Species The Causative Agent of the Disease and Optimal Avoidance Strategies
Disease in Aquaculture Stress effects of repeated stress responses Immune System antibody and cellular responses Diseases viral, bacterial, protozoan, parasitic Types of Treatments drug, external, sanitation Biosecurity controlling disease & vectors Intensive Husbandry Methods crowding, handling, vaccinating
Disease in Aquaculture Disease has Grown Proportionally with Intensive Aquaculture of Diverse Species Why? Increased Stocking Densities Infected Carriers (eg Broodstock) Infected Facilities (or Ineffective Sanitation) Inappropriate or Poor Nutrition Substandard Water Quality Biggest Problem: Greater Disease Susceptibility via Compromise of Native Immune System Under Stressful Intensive Culture Conditions
Stress Defined Stress Any Stimulus Changing Normal Metabolism, Growth, Immune Function, Reproductive Capacity or Behavior Stress Can be Acute or Chronic Stress Response Primary Response: Change in Circulating Levels of Cortisol and Catecholamines Secondary Response: Changes in Glucose, Lactate Major Ions, Tissue Levels Glycogen & HSPs. Tertiary Response: Changes in Growth, Disease Resistance or Behavior
Stress and Illness Repeatedly turning on the stress-response, or failing to appropriately turn it off, over time will cause the stress-response to be as damaging as stressors. Many Stress-Related Diseases are Disorders of Excessive Stress-Response. Response to a Stressor is Dynamic and Measuring It May Represent Only a Snap-Shot in the Reaction Stressors can be Physical, Chemical or Biological
Stressors Chemical Stressors: Poor Water Quality, Pollution Diet Consumption, Metabolic Waste Biological Stressors: Population Density, Other Species Micro-organisms, Macro-organisms Physical Stressors: Temperature, Light, Sounds Dissolved gases Procedural Stressors: Handling, Shipping, Disease Treatments
Prevention of Stress Good Water Quality: Minimize Organic Debris and Nitrogenous Waste, Maintain ph, Temp, O 2 Levels Good Nutrition: Feed High Quality Diets, Species Specific Essential Nutrients Proper Sanitation: Implement Biosecurity Procedures Remove All Debris Disinfect Equipment Before Introducing New Groups of Fish.
Hole in the Head Disease Affects Marine & FW Fish in Captivity Only in Cultivated Fish Never in Wild Stocks Adjustment to Diet with Vitamins A, C & D Sometimes Helps. Autoimmune Disease Brought on by Stress?
Disease
Disease Types in Aquaculture Infectious Diseases Parasitic Diseases Non-Infectious Diseases Most Environmentally Based Controlled Via Good Management
Infectious Disease Types Viral Diseases: Cannot ID Without Lab Tests Vaccines Do Not Exist for Most Bacterial Diseases: Infections Often Internal & Unseen Require Treatment with Medicated Water - Feeds Parasitic Diseases: Relatively Easily Controlled with Proper Application of Chemicals Biosecurity Fungal Diseases: Most Often a Secondary Problem
Common Viral Diseases in Aquaculture Channel Catfish Viral Disease Infectious Hematopoietic Necrosis Infectious Hypodermal Hematopoietic Necrosis Infectious Pancreatic Necrosis Infectious Salmon Anemia Koi Herpes Virus Lymphocystic Virus Midgut Gland Necrosis Baculovirus Necrotizing Hepatopancreatitis Spawner Mortality Virus Spring Viraemia of Carp Taura Syndrome Virus Viral Hemorrhagic Septicemia White Spot Syndrome Virus White Tail Virus Yellowhead Virus
Common Bacterial Diseases in Aquaculture Bacteremia Chilodonelliasis Columnaris Disease Dropsy Enteric Redmouth Enteric Septicemia of Catfish (ESC) Fin Rot Furunculosis Hepatopancreatic Rickettsia Necrotizing Hepatopancreatitis Ulcer Disease of Goldfish Vibriosis
Parasitic Diseases in Aquaculture Anchor Worms Fish Grubs Fish Lice Fish Velvet Flukes Henneguya Ich Ichthyobodo Disease Ichthyophoniasis Nematodiasis Rust Disease Tapeworms Trichodiniasis Water Molds Whirling Disease White Spot Winter Disease
Foreign Invaders: Three Lines of Defense
Skin: First Line of Defense Largest Organ in Body Physical and Chemical Barriers Physical Hard to Penetrate Armor Scales & Collagen Indigestible Keratin Chemical Barrier Mucus
Second Line of Defense Innate Immune Response Defenses No Matter What the Invader Natural Killer Cells Cytotoxic Lymphocyte Macrophages Amoeboid Phagocyte Engulfers Dendritic Cells Inflammation - Leukocyte Histamine Release Fever Caused by Histamines. The Fever Kills Invaders by Denaturing Proteins.
Natural Killer (NK) Cell
Macrophage
Neutrophil
Third Line of Defense: Immune Response
Immune Response Fish Response Similar to Mammals - Shrimp & Molluscs Much Less Elaborate The Immune Response can be Highly Specific Specific Antibodies In Response to a Specific Antigen The Immune System Identifies All Foreign Substances and Differentiates Self from Non-Self Immune System Works with Different White Blood Cells In a Highly Integrated Manner
Immune Response System Two Coordinated White Blood Cellular Systems 1) Humoral or Antibody Immunity (Using B Cells) 2) Cell-Mediated Immunity (Using T Cells) Both Cellular Systems Work by Identifying Antigens Non-Self Debris, Cells or Molecules Auto-Immune Disease When Immune Cells No Longer Recognize Self
Macrophages Are Engulfers B Cells Antibody Response T Cells Cellular Response
Antibody Response of the Immune System B Cells Create the Antibody Response B Cells Effectors Produce Antibodies B Memory Cells Subsequent Antibody Production Antibodies Immunoglobulin 2 Heavy Chains, 2 Light Chains Heavy Chains: Constant Region (types: α, δ, ε, γ, μ) and Variable Region Light Chain: Constant Region (types: κ, λ) and Variable Region
Cellular Response of the Immune System T Cells Activated by Antigen Presenting Cells Helper T Cells Turn on B Cells - Activate Killer T Cells Killer T Cells Effector Destroys Antibody Marked Cells Memory T Cells Stimulates Rapid Mobilization Against Reinfections Suppressor T Cells Effector Maintains Tolerance of Self
Phagocytosis
Immune Response in Fish Finfish and Shellfish Account for 25% World Aquatic Production With Intensification Comes Deterioration Culture Environment & Increased Disease Poor Water Quality Stresses Fish Immune Response in Fish Includes Expansion of Cells for the Response Expression of Both Responses Coordination by Signaling Molecules
Response Following Encounter with Pathogen Fish Contacts Pathogen Innate Immunity Failure (Disease and Death) Success (No Disease) Initiation and Instruction of the Specific Immune Response Humoral Response (Extracellular Pathogens and Toxins) Acquired Immunity, Immunologic Memory, and Protection (Survival) Cell-Mediated Immune Response (Intracellular Pathogens and Viruses)
Factors Influencing Disease Resistance and Immune Response of Fish
Salmon Lice as Chronic Stressors
Stressor - Salmon Louse
Stressors Salmon Lice
What Are Sea Lice? Crustacean, Copepod ~ 550 species 3 Genera External Parasites of Fish Lepeophtheirus salmonis (salmon louse) Natural Parasite to Salmonids Genera: Salmo, Salvelinus, Oncorhynchus Caligus elongatus (sea louse) Parasite to Many Marine Fishes Reported in 73 Different Fish Families
Current Sea Lice Treatment Methods Chemical Treatment Drug Bath or Dip Drug Incorporated in Feed Biological Treatment Cleaner Fish Not Viable in Colder Regimes
Treatment - Bath & Dip Drugs Organophosphates Neurotoxins Blocking Acetylcholinesterase Mostly Kill Mobile Stages Toxic to Many Crustaceans Sevin or Carbaryl: Anti-Arthropod Poison Hydrogen Peroxide Strong Oxidizer - Effectively Removes But Does Not Kill Sea Lice Toxic to Salmon Under High Concentrations Elevated Temperatures, Exposure Time Very Temperature Sensitive
Treatment Drugs in Feed Ivermectin Targets Cl - Channels in Arthropods Effectively Removes Sea Lice Slow Depuration from Fish Muscle Can Persists in Feces; Kills Others Diflubenzuron Inhibits Chitin Synthesis Effective on all Stages of Sea Lice Can Remain in Sediments May Harm Non Target Species
Cost of Sea Lice & Their Treatments Loss Factors Total Loss in Value/Yr Reduced growth $180,000 Reduced FCR $37,500 Downgrading $6,000 Secondary disease $27,000 Mortality $81,000 Treatment 1 $12,000 Treatment 2 $10,000 Treatment 3 $10,000 TOTAL $363,500
Stress and Illness Summary Macrophage defense functions in sea lice infested fish are impaired, predisposing fish to intracellular infections with a disease producing microsporidian. Mustafa, A., Speare, D., Daley, J., Conboy, G., & Burka, J. 2000. Enhanced susceptibility of seawater cultured Oncorhynchus mykiss (rainbow trout), to the microsporidian Loma salmonae, during primary infection with the sea louse, Lepeophtheirus salmonis. Journal Fish Diseases. 23: 337-341.
Sea Lice Infested Salmon Plasma Cortisol Concentration nmol/l Continuous Turning-On of Stress Response?
Immune Response in Shrimp Fish and Shrimp Differ in Their Ability to Carry Out Immune Response Capacity to Recognize, Expand Recognition Express Specific Recognition, and Coordinate Immune Defense Lower in Shrimp Often Assumed That Fish and Shrimp Have Similar Immune Competencies Inappropriate Decisions Made on How Defense Mechanisms Might be Enhanced in Shrimp
Specific Response of the Immune System
Glycoprotein Receptors
Macrophage
Macrophage
Step 1 Pathogens eaten by Macrophage Step 2 Displays portion of Pathogen on surface Pathogens Step 3 Helper-T cell recognizes Pathogen
Activates Killer T- Cell Activates B- Cell Kills Infected Cells Memory T-Cell Memory B-Cell Antibodies
Cellular vs Antibody Immunity Cellular Immunity Antibody or Humoral Immunity Carried out by T Cells T Helper Cells Activate T Killer Cells T- Killer Cells Destroy Infected Cells Carried out by B cells T Helper Cells Activate B Cells to Produce Antibodies Abs Released in Blood Stream Antibodies Bind Antigens Deactivating Them.
Primary vs Secondary Immune Response Primary Immune Response Immune Response to a First Time Invader No Measurable Response for Several Days Over 2 Weeks, Antibody Production Grows Secondary Immune Response Rapid Response on Second Invasion Antibody Production Quickly Increases Increase is Dramatic
Immune Response Summary 1 Antigens Exposed to Immune System Cells Macrophage Ingests Antigen and Displays it Helper T Cell Recognizes Antigen and Activates Helper T Cell Activates Killer T & B Cells Killer T Cells Divide and Proliferate Killer T Cells Divide Making Suppressor & Memory T Cells Killer T Cells Kill Infected Cells
Immune Response Summary 2 B Cells Divide and Proliferate B Cells Divide Making Plasma Cells & Memory B Cells Plasma Cells Produce Antibodies Memory T & Memory B Cells Speed Response if Antigen Reappears Suppressor T Cells Halt Immune Response when Antigens not Present