Aquaculture Flashcards
what does aquaculture include?
basics
- globally, fisheries are declining and human population is growing
- seafood consumption is increasing
- many rely on seafood for protein (20%)
- growing industry: accounts for more than half of seafood produced (growing at 4-5%)
- produces wide variety of products: oysters, mussels, seaweed, abalone etc.
- not just for food, animals can be raised for conservation, recreation, scientific, or regenerative purposes (like kelp)
Types of systems
recirculating aquaculture systems (RAS)
- water flushed throughout the tank and goes through mechanical filter then biological filter
- helps gain more O2 and inputs more water
pond systems
- huge ponds in the ground
- fish like catfish, bass, sturgeon
flow-through/raceway
- can siphon H2O from river
- water flows in and flows out
- good for animals with high O2
aquaponics
- beneficial O2 compound plants can use
- good if have limited H2O
ex: fish tank has water flowing to aquaponic (with plants) => water flows back to fish tank
open water (fish)
- out at sea
open water (shellfish/seaweed)
- have cages in the open water to catch shellfish & wait for seaweed to grow
integrated multi-trophic aquaculture (IMTA)
- big tank, fish produce waste used to make system more environmental friendly
- waste acts as nutrients for algae and shellfish
Major challenges
- intensive (high stocking density), semi-intensive (low stocking density), extensive production system (systems sitting out in the environment)
- disease outbreaks
- sources of disease (ambient, environmental pathogens, contamination)
- factors influencing disease outbreaks:
- aquatic environment: transmission is easier relative to terrestial pathogens
- stress from crowding, handling, diet, weather, etc.
- emergent pathogens
- resistant diseases, limited treatment solutions
Major fish diseases
Lactococcus
- pathogenic strain of bacteria
- highly infectious and deadly
- unknown source but likely came from birds
- first reported case in CA (2020)
- first case in North America was in Mexico (2016)
- in 2021: 3.2M thought culled
- resistant against every treatment
Host:
- rainbow trout, all life stages
- adaptive/innate immunity
- standardized diet
Environment:
- intensive system
- warm: facilitates spread
- high stocking density
Pathogen:
- bacteria
- resistant to antibiotics
- locally transmitted
Sea Lice
- parasitic crustacean
- naturally present in marine environments
- attach onto any fish => problematic for salmon
Host:
- Atlantic salmon, all life stages
- adaptive/innate immunity
- standardized diet
Environment:
- semi intensive system
- high stocking density
Pathogen:
- crustacean
- known life cycle
- locally transmitted
- developed treatment that target life stages
Disease Treatments
- environment manipulation
- temperature, salinity: create environment not suitable for pathogen to spread
- biological control: cleaner fish for parasite control
- antimicrobial products
- broad spectrum: disinfection, sterilizing, external parasites
- therapeutic: bacterial infections
- culling infected individuals if none of the above works
AMR in aquaculture
- AMR around the world.
- Chile, china, India: AMR detectable in the environment near aquaculture
- AMR and US aquaculture
- strict regulations, AMR present in emerging pathogens
- policies and actions to slow development of AMR
- required Rx for antibiotics
- environmental/system monitoring
- alternative strategies for disease treatment (use less AMR, products will slow it)
Aquaculture and one health
- AMR & impacts on people/environment
- not a major consumer of antibiotics
- AMR reservoir
Animals:
- biosecurity, healthy stock, minimal chemical hazards, optimize systems, protected
Environment:
- optimize water usage, water quality, protect biodiversity, minimize energy use & spatial footprint
Humans:
- nutritious food, equitable income, gender equalization, quality employment, knowledge & skill generation
Three levels of defense against disease
Level 1: comprehensive protocols
- biosecurity: standardized cleaning and contamination protection
- PPE, secure buildings (boot wash station, prevent people from moving freely)
- frequent disinfection of tanks, equipment, tools (stop spread of disease)
- quarantine procedure for sick or imported animals
- personnel training on biosecurity principles
- appropriate use of AM products (b/c can kill)
- biocidal products (cleaning chemicals like bleach, alcohol, iodine etc.)
- disease-response: quick and appropriate response to clinical signs of disease
- animals are frequently and thoroughly checked for distress
- all personnel able to recognize clinical signs: provide sufficient info for personnel to have decent understanding of animal bio
- outline response steps to follow when clinical signs are observed
- quickly initiate treatment if disease is confirmed (consulting vet, initiating quarantine etc.)
Level 2: good husbandry strategies
- stress management: precautions taken to mitigate stressful events
- aspects that cause: size grading, transport, overstocking, bad weather etc.
- stress can induce immune function & make fish susceptible to disease
- important to identify sources of stress & minimize
- ex: lower stocking density, protect tanks fr. elements, use animal sedatives & provide sufficient employee training prior to fish handling
- proper diet: meets species & age specific nutritional needs
- aquafeed diet should contain all required nutrients: carbs, lipid, protein, micronutrients
- nutritional requirements are species & age dependent: diets should be formulated w/ this in mind (current area of research)
- research on sustainable ingredients
- replace fisheries-derived ingredients w/ plant, insect, and other ingredients
- impact on gut health and immune function (plants => toxins in unprocessed)
- optimal environment: appropriate species and age specific water conditions
-monitor water conditions: temperature, O2, salinity, pH, nitrate/nitrite/ammonia, hardness- species specific optimization
- animal requirements (suitable range of water quality parameters)
- animal welfare (mental stimuli, suitable colors/textures/sound) - probiotics/prebiotics to regulate water quality
- some bacteria can reduce high levels of nitrogenous compounds
- compete w/ pathogens for space/nutrients
- species specific optimization
level 3: effective antimicrobial products
- biocides: cleaning products for aquaculture system biosecurity
- important for level 1
- therapeutics (antimicrobials): FDA approved for use as disease treatment
- therapeutics (antibiotics): classified as MIADs, FDA approved for use only as disease treatment and only under vet guidance
- not used for growth production => illegal & not effective, can even hurt fish
- new regs implemented in 2017 require vet prescription for antibiotics (MIADs)
alternative methods to AMR
stock selection
- genetic variations in fish lead to some being resistant to certain pathogens/stressors
- strains of fish can be bred to enhance these characteristics once identified
- ex: hybrid catfish are crosses of Blue/Channel catfish that have been shown to be more resistant to common diseases
- advances in genetic technology helps identify regions in genome that correlate w/ disease resistance
- individuals w/ these genes can be bred to produce populations w/ enhanced traits
vaccines
types
- whole killed (inactivated)
- whole attenuated (live)
application methods
- oral: medicated feed
- difficult to maintain vaccine efficacy and to ensure appropriate dose, very easy to administer
- immersion: medicated bath
- difficult to maintain vacine efficacy, easy to administer
- injection: Intraperitoneal or intramuscular (belly or back)
- labor intensive but generally yields best immune response
Approved in US
- only 7 approved for commercial use
- 5 for salmonids, 2 for catfish
- 6 utilize a killed, weakened, or non-pathogenic antigen, mixed w/ an adjuvant (immunostimulant)
- one DNA vaccine approved for use in salmon against IHN virus
novel antimicrobials
- antimicrobial peptides
- already produced by most cells of most tissues in vertebrates
- stimulate immune system and kill wide variety of pathogens
- antivirulence therapy
- compounds that “disarm” pathogen
- target specific virulence pathways that enable a pathogen to cause disease
- ex: toxin and enzyme production/secretion, bacterial communication
- both categories have more specific mechanism of action and are less likely to lead to widespread AMR
dietary supplements
- gastrointenstinal microbiome
- collection of mutualistic bacteria inhabiting the GI tract
- impacts many physiological processes like digestion, nutrient, absorption, growth, and immune response
- protects against some indigested pathogens
- probiotic/prebiotic influence the collection of bacteria
- probiotics: bacteria known to be beneficial to an organism
- prebiotic: substances consumed/utilized by bacteria
