Aquaculture Flashcards
What types of aquaculture are we seeing?
Mariculture - in situ aquaculture (usually means marine aquaculture)
Aquaculture has been historically polyculture, but is now predominantly mono-culture. Starting to see a shift back to polyculture.
What are the types of intedgrated aquaculture?
IMTA - Simulate an ecosystem - control / reproduce an ecosystem. Basically non-existent at industry level.
Direct integration - no further input from humans. (on a slope - cows at top of the field ect)
Indirect integration - taking energy physically and moving it (manure)
Almost all moden day aquaculture is indirectly integrated.
What classsic terrestrial farming problems are reduced or absent?
Greenhouse gasses, human disease hosting, eutropication
Physiologically much closer to farm animals than fish.
1.2 kg feed to 1 kg salmon. 5.9 feed to 1 kg beef, but animals are much closer in sync to the enviroment.
How does land and water use affect why we do aquculture?
Land use
- Almost every person on the planet lives near water
- 7 Billion people today, 8.1 by 2025, 9.6 by 2050 (we need to find 75 million tons more fish, i.e. ~2x current production)
- Agricultural land was 0.44 ha person-1 since 1960, now 0.25 ha person-1 >50 % live within 3 km of surface freshwater ~80 % live within 100 km of the sea
Water use
- ~70 % of all available freshwater is used for agriculture
- Today this is 7, 130 km3, by 2050 this will be 13, 500 km3
- Is this a problem? - will need more freshwater than is availible
Why do aquaculture - physiological dmeand.
Physiological demand
- Historically we have always produced more protein than we need, by 2030 we will be deficient
- Today aquaculture accounts for about ~50 % of global ‘fish’ production, by 2030 this is expected to be 63 %
- Fisheries and aquaculture provide 4.3 billion people with 15 % of their average annual protein intake (~20% global animal protein)
- (Apparently) important to LEDC’s, because of the breadth of nutrients not found elsewhere
- 30 countries where fish are > 1/3 total animal protein, 22 of these are LEDC
However
- Protein derived from plants (beans, peas, nuts etc.) far outweighs protein derived from all animal sources combined (total from ‘fish’ ~6.5 %)
- Actually no studies showing that more fish consumption = better nutritional status in LEDC’s
- Health studies which apply to LEDC diets do not necessarily apply to MEDC diets and vice-versa
Why do aqucaulture - economic demand.
Economic demand
- Aquatic products (capture and aquaculture) collectively account for the most traded food commodity on the planet (not including coffee?)
- Value of all ‘fish’ in 2012 was $129 billion (~45 % would have been aquaculture)
- Generally recognised that aquaculture alleviates poverty, but evidence for links between national-level impacts and house-hold level impacts are minimal (and probably more than a bit dodgy)
- Aquaculture facilities often have a fierce class divide, money doesn’t filter down. No labour buffer, only the wealthy can take it up.
- For every one aquaculture job there are two more in supporting industries
- Huge disparities in actual numbers reportedly employed in aquaculture (24 million, Bush et al 2013; 100 million, Handisyde et al 2017)
- Social dynamics are a major factor in the uptake of aquaculture
- Wealth, status, community, education, gender, tradition, etc.
Why do aqaculture fisheries stagnating.
oGlobal fish supply has increased from 12.7 kg person-1 year-1 in 1961 to
21.4 kg person-1 year-1 in 2010
oFrom 1960-1990 this was almost all from fisheries, since 1990 (especially since 2000) almost all from aquaculture (the “Blue Revolution”)
oGlobally aquaculture has grown 9.5 % per year since 1980
Why do aquaculture - food security
More stable, more controllable, year-round production compared to fishing
Why is aquaculture more stable than terrestrial agriculture?
The amount of species gives a buffer to the problems caused by disease. (Swine flu ect)
But debated as to whether it fixes or moves the problem due to the relatedness to capture fish.
Why do we aquaculture - all the reasons.
- Good feed to produce ratio
- Terrestrial farming problems reduced or absent
- Freshwater availbility
- Physiological demand
- economic demand
- Fisheries stagnating and food and fish consumption rising
Where do we aquaculture - China
- Largest producer, processor, consumer, and exporter of ‘fish’
- 1/3 of all ‘fish’ are produced in China, >70 % from aquaculture equating to about half the total value of aquaculture
- Aquaculture production has quadrupled since 1990, but space use has only doubled - efficiency
- Known for erroneous data collection and reporting; “NEI” accounts for 31 % of total marine capture.
- Massive reliance on fishmeal for feed (coming later); unclear if China adds to global food production or depletes it.
Where do we aquaculture - Europe
- Highest producers are Norway, Spain, France, UK (8 % total European production, but still imported 80 % of all fish in 2012)
- Spain and France is mainly bivalves
- Stagnated at around 1.2 % (maybe less) since 2000
Why do we not do as much aquacultute in Europe?
Shortage of space or public image
Where we can aquaculture is taken up by other things
Traditional methods of aquaculture -
- Introduce fish to rice paddies - common in literature but not actually that common - hard to keep fish and rice happy.
- more typical to cover whole rice pady to aquaculture - now illegal in China.
- Ponds
- more extensive than intensive, about food not money.
- Pig pen over aquaculture
- not really very popular
- Grass carp, come in and graze on feilds.
- Traditional polyculture.
- Principle hundreds of years old in China, japan and Korea
- Not stimulating an ecosystem on a wider scale but may have been popular.
- Seaweed culture - common.
Modern methods, how do we aquaculture?
- Basic containment - in situ (ponds, mariculture)
- Have to be positioned in deep water with good water flow, putting aquaculture in the same place as shipping lanes.
- French / Spain mussel spat - culture them anywhere in the world and sold as French mussels.
- Intensive, Monoculture, Varying levels of control
- Full control; ex-situ, often indoors in tanks, total determination of abiotic factors
- *
Compare traditional vs moden aquaculture requirements.
- High-density, Circulation, aeration, treatment, additives, feed, Monoculture, Larvae bought from hatcheries
- As a pose to Low-density, Few controls, no feed, Some poly-culture, Larvae caught from the sea
What are the aims of aquaculture in LEDC’s?
oAlthough production dominated by LEDC’s, export is to MEDC’s – shifts focus from food to money
oLEDC policy is focussed on max money, and (sometimes) minimal ecological damage.
What is and isn’t often considered when carrying out aquacultur in LEDC’s?
oNo concern for diversity in production – health problems, vulnerability in the operations and in the market
oNo concern for social factors, e.g. class division
oNo concern for sustainability
May consider ecological damage, things need to be kept clean to reproduce, and can be damaging to tourism industry. Exporting to MEDC means it has to abide by export standards.
Moden methods- the dependance on feed
Aquaculture as a sector is totally dependent on feed
- 50-80 % of costs from feed
- 100 % of salmon farms use feed, 83 % of marine shrimp, even 38 % of carp
- > 2/3 of finfish and crustacean aquaculture is dependent on feed
Feed comes from
- Capture fisheries; ‘trash’ fish, anchovy, sardine, herring, menhaden – at least 71 species in China (probably?); largest importer of fishmeal, huge imports and even fishing rights from other fisheries (Peru, Chile, USA, Russia)
- Terrestrial farming, arable and livestock; mostly waste products which is good, but absorption efficiency is low and the quality of the fish can be reduced
- In 2012 ~70 % of aquaculture activity was supplemented by crop-based feeds
- Most of the other 30% (i.e. 23 %) is bivalves (not fed), much of the rest will be algae
- Overlap between ingredients for terrestrial feeds and aquaculture feeds, but only 4 % goes to aquaculture
- Massive push right now to end the dependency on fish-based feed (next lecture)
Martyn paper - problems ranking
Jones et al 2015
- Formed 25 key problems from suggestion from practitioners and scientists, and then asked the same people to rank the issues.
- UK industry’s and scientist, but most of them are global issues, at the wide scale.
- Single biggest problem is knowledge exchange.
- 5 are environmental and policy and 5 feed and disease
- Very few came down to husbandry.
- Scientists were more reserved than practitioners.
- Last question that basically says ‘why is it that when we eat fish we get more benefit than if we ground that fish up and made a pill.’ Practitioner score lower as it would put them out of business.
What is pellet feed?
oPellet-feed production increased from 7.6 million tonnes in 1995, to 27.1 million tonnes in 2007. Projected to be >70 million tonnes by 2020
oMost pellet feeds are based on “trash” fish
oWidely regarded in the literature as the single most pressing concern
What are the problems associated with pellet feed?
- Total reliance on the main activity aquaculture is meant be replacing!
- Leaves aquaculture vulnerable to fluctuations in the climate (more later)
- Depletes fish stocks relied upon for human consumption in many LEDC’s, particularly in Africa and South America
- a bad year for trash fish would result in a bad year for aquaculture
- In large carnivorous fish, > 50% (as high as 80%) of the costs are on feed
- Salmon, trout, and shrimp use 50% of all fishmeal, but are only 10% total production
- ‘feed from wastes’ feeding leftover fish bones etc. back to fish causes bioaccumulation of contaminants ect.
Prion - one step down from a virus. A length of genetic code which can cause problems, protein that has been coded incorrectly. Material that cycles round through food causes amount of prions and diseases (mad cow disease). Humans eat other humans - build-up of acetylcholine (jitters)
What alternative to fish based pellets are there|?
- Current push towards plant-based feeds
- Palm oil (!) instead of fish oil, soya instead of flesh, etc.
- Issues with absorption efficiency, resultant fish-quality (good example is in Norwegian Salmon, see Asche et al, 2013)
- Next Generation Sequencing being used to appreciate the physiological dynamics of feeding fish plant-based nutrients
- Worth noting that some feed comes from wastes (40 % and rising in China)
- Human inedible products of crop and livestock production, usually separated-out during processing
- Bioaccumulation of contaminants, cross-species contamination of pathogens and maybe prions (note differences in policy between Europe and China)
- Human inedible products of crop and livestock production, usually separated-out during processing
What other additives and problems are involved in aquaculture?
Medication
- Especially antibiotics
- Leads to antibiotic resistance, including through horizontal gene transfer
- Some human pathogens affected
- Probiotics
Antifoulants and Disinfectants
- Many copper-based
Anaesthetics
- Historically problematic, but now improving (in MEDC’s)
- Rising use of clove oil and menthol
Hormones and pigments
- Environmental, safety, and animal welfare concerns
(Genetic Modification)
- 24 fully sequenced spp., but many more modified
- Increase in antibiotic resistance in cholera - chloroforms are evolving resistance to antibiotics in the water column.
- Anaesthetics are used to calm fish, turning them into battery hens. Currently using clove oil and menthol due to less ethical concerns.
- Pigments are used to colour fish (salmon).
What are the two main sources of wastes from aquaculture?
Wastes from the organisms themselves (tend to be continuous release)
- Faeces
- Nitrogenous excretions (ammonia)
- Detritus from scales/carapace moults etc.
- Mortality
- Disease and parasite transmission (more later)
- all the above from organisms attracted to the farm (predators, epiphytes, etc.)
Wastes from husbandry activities (tend to be pulsed release)
- 75 % of antibiotics are lost to the environment
- Copper and other metals from feed and antifoulants end up in sludges
What are the impacts from the wastes on the enviroment?
- 52-95% of the Nitrogen and 85% of the Phosphorous inputs are lost, 2/3 total feed
- Cause Harmful Algal Blooms, hypoxia, eutrophication, benthic ‘sludge’, and a host of other problems
- In-situ worse than ex-situ
- Real possibility of auto-pollution in some systems
- Ecological knowledge - when things are released makes a huge difference to the damage that is caused, antimicrobial compounds are released when eggs are laid or spawning happen ect.
- Trade of with water movement- cage damage and escapees vs wastes removal.
Norwegian salmon
- In 1989 Norwegian salmon farms produced 150,000 tonnes
- Equivalent pollution of 2.7 million people
- i.e. 64 % of the population of Norway that year!
- Now production is at 1 million tonnes
- Large proportions offshore, submerged (very high-tech)
- Some cages are 60,000m3 and hold 1000 tonnes of fish
- $3 million of fish per cage…
Aquaculture - space use
oDeforestation for inland and estuarine farms (e.g. Penaeus monodon)
oHabitat loss
oChange in sediment dynamics and water flow
oCoastal erosion (Van Wesenbeeck et al 2015)
oCompetition for space in already crowded waterways
oShipping, tourism, fishing, industry, renewables, etc.
oImpacts on aesthetics
Pollution- the other way around
Pollution (the other way round)
- Mass mortalities due to industrial pollution very common in LEDC’s
- Leading to more ex-situ production in Thailand – what are the problems with this?
Invasive species
- Pervasive problem caused by all farming.
- 99 % of all farmed species (terrestrial and aquatic, animal and plant/algae) are introduced
- What are the key characteristics of an invasive species?
- But also the activity itself causes and facilitates the introduction of novel species
- Oyster – complicated lamellae like structure, provide a heterogenous habitat for life. The Spanish and French brought Japanese Oysters with invasive Sargassum Muticum, spreading throughout year. (breaks apart in autumn and causes eutopication
- Innovasive’s share similar characteristics to farmed species (fast growing, high levels of trophic growth, highly fecund, broad physiological tolerances)
The escape of fish from cages
- Problematic for local biodiversity
- Also represents lost revenue for the farmer
- Variable impacts, both in nature and scale depending on circumstance
Altlantic salmon - problems from escapees
- Particularly problematic for Atlantic salmon (Salmo salar)
- 94 % of adult fish are maricultured
- Damage to, and disruption of cages, leads to escape
- A single storm in Scotland lead to 685,000 escapees
- Norway reported average escapes of 500,000 in the 90’s, > one million in 2005
- Wild populations now genetically impacted; cultured salmon (esp. juveniles) display reduced fitness in the wild
- Spread disease and parasites to wild populations (more later…)
- Hyrbid salmon between wild salmon and GM salmon
Problem of predation
Predation is a significant source of lost revenue
- Removal of animals
- Main culprits are birds
- Most susceptible are bivalves
- Stress
- Particularly large apex predators near fish pens
- How can you reduce this problem without welfare/policy issues?
- Big problem – not reported. (either due to lack of reporting or going unoticed)
How will climate change affect the landscape of global aquaculture?
oActual, rigorous, peer-reviewed evidence on past, present, and future impacts is minimal
oImpacts will vary on a case-by-case basis
oConsider shifts in
oTemperature
oRainfall
oStorms
opH
oSalinity
oOcean Circulation
oEl Niño… etc. etc.
oAnd the interactions with
oCapture fisheries
oHusbandry practices
oSpecies distributions
oMarket demands… etc. etc.
What must the treatment of disease and parasitism consider?
- Logistics
- Economic
- Environment
- Future-proofing (e.g. development of resistance)
- Policy (linked to all the above, more to follow…)
- Requires intimate knowledge of the pathogen-host relationship
What do common practises of treating parasitism include?
Additives
- Antibiotics, probiotics, chemical treatments, vaccinations
- Increasing incidences of disease impacting small businesses, expensive treatments only available to larger companies.
Zoning
- Limits the transfer of material between farms
‘Service species’
- e.g. Cleaning wrasse
- More cleaner species used due to regulations, common in salmon farms.
Culling/removal of infected/dead animals
- Removal – difficult, hard to tell which animal is dead / sick. Very difficult for bivalves.
Why are bivalves particulay problematic?
- Bivalves are particularly problematic
- 43 % of all mariculture are bivalves (FAO 2013)
Most common practices don’t work
- Additives
- Most are too dilute (filter feeders)
- Vaccines have no affect (molluscs lack adaptive immunology)
- Zoning
- Works well for some pathogens, but many are transmitted by mobile wild species
- ‘Service species’
- Cannot access soft tissues
- Culling/removal of infected/dead animals
- Cannot tell which are infected
- Often cannot even tell which are dead!
How has oyster aquculture been affect by disease and parasatism?
- oEuropean oyster aquaculture once dominated by Ostrea edulis
- oCultured by the Romans
- oHighly susceptible to disease and parasitism
- oMass mortalities in the 1920’s, 1970’s, and 1980’s
- oIndustry switched to the Portugese Crossastrea agulata
- oHighly susceptible to disease and parasitism
- oMass mortalities
- oIndustry switched to the Japanese C. gigas
- oIs now an invasive species, and has lead to the introduction of many more (discussed earlier)
- oIndustry currently blighted with herpesvirus (OsHV-1)
- oLarge mortalities since 2008…
What are salmon farms constantly battling?
- oSalmon farms are constantly battling lice; Lepeophtheirus salmonis
- oCopepod; ectoparasitic on salmon and trout
- oFeeds on skin, muscle, and other soft tissues
- oCauses secondary infection, stress, reduced swimming capacity, changes in blood-glucose and electrolyte levels, reduced haematocrits, suppression of immune system (possibly)
- oFarms are ‘hotspots’ for lice, which spill over into wild populations
*
What are the treatments for salmon lice?
Treatments include
- Chemicals in feed
- Injections
- Chemical baths (formaldehyde, hydrogen peroxide)
- No one treatment works in all cases, rise of drug-resistant lice
- Genome now fully-sequenced to aid development of new drugs
The use of cleaner wrasse as ‘service species’ is common
- Ballan wrasse Labrus bergylta very popular
- Grow up to 60 cm, making them ideal for salmon culture
- Stocked at 1-4:100 salmon
- Highly efficient
- Major exception in Norwegian policy on aquaculture (more later)
- But…
- The wrasse must be kept healthy
- The wrasse will very quickly switch diets if cages are epiphytised
- And the practice isn’t as ‘green’ as you would think…
- The wrasses have to be sourced from elsewhere
- Many wrasses are vulnerable to over-exploitation
Novel treatments include (but definitely not limited to)
- Mechanical removal
- Trapping/filtering of lice
- Submerged pens
- Lasers… no, really
disease and parasitism of humans
- Practitioners of aquaculture (and fishing) are at much higher risks of communicable diseases, parasites, and injury
- Largely ignored problem, disease and parasite issue is most prevalent in LEDC’s
- Life of constant injury, exposure to warm, nutrient-rich, often polluted water, and often very poor hygiene, food storage, and food-preparation techniques
- Schistosomiasis; Economic loss second only to malaria in the tropics. One of the most ‘neglected’ diseases in the world, definitely in the tropics
Policy
Fisheries Policy’
Policy-makers include MEDC policy is notoriously stifling
Obtaining a license to start a fish farm can take years
No one regulatory body for most countries - what are the main policy cluseters?
oIn the EU the main policy clusters are the ‘Blue Growth Strategy’ and the ‘Common
oFisheries committees
oAgricultural agencies
oEnvironment agencies
oVeterinary regulators
oFood safety commissions
Local-level councils
oUse of chemical additives (e.g. antibiotics) strictly controlled
oExact beneficial mechanisms can place similar additives under different regulations
oStrict regulations on disease transfer often prohibits multiple species per farm/site
oAll MEDC’s require an Environmental Impact Assessment
oHugely complicated, if not impossible, when more than one species is being cultured - nothing in the EU framework about algae
What is LEDC policy focussed on?
LEDC policy is notoriously focussed on money
Very few (if any) regulations on
- Additives
- Water treatment
- Animal welfare
- Polyculture/IMTA
- Feeds
- Working conditions
Future aquaculture - talk about future aquaculture
oCurrently mariculture is mostly shallow coastal, and dominated by seaweeds and bivalves (89 %, FAO 2013)
oBut offshore (especially submerged) mariculture suffers with far fewer intrinsic problems than shallow coastal/brackish/freshwater aquaculture
- oLack of space
- oLack of freshwater
- oPollution (both ways)
- oCoastal erosion
- oAesthetics
- oHarmful algal blooms
- oPredation
- oFluctuations in (many) abiotic parameters
- Etc. etc.
What is the biggest problem with offshore aquaculture?
- Biggest problem is the need high technology and (therefore) money
- Some ‘ready-to-deploy’ systems currently on the market, but still considerable challenges for uptake in MEDC’s, and especially in LEDC’s (not least market demand)
Integrated Multitrophic Aquaculture IMTA
- Basic principle is to use the wastes from one aquaculture activity to directly facilitate the culture of another, at a different trophic level
- Massive potential variety in set-ups, levels of control, in-situ/ex-situ (even a combination of the two), the use of microalgae, the integration with aquaponics (so called ‘hydroponics’)
- Every setup will need to consider internal as well as external interactions, and need to be dynamic
- But huge advantages if you get it right
- For example, fish only assimilate about ¼ of nitrogen in feed. Seaweed can remove most of the rest, and 1kg of fish culture can support 5kg of seaweed.
- Modern high-tech IMTA systems have been piloted since the 1970’s
- Most work very well, lots of promising data
- Almost no full-scale profitable systems running in MEDC’s (SeaOr was the best example)
WIDER READING: IMTA
Samocha et al., 2015- Integrated multi-trophic aquaculture (IMTA) system example
The study:
- IMTA (in which species from two or more trophic levels grow in one farm and where the waste of one feeds another) of the Pacific white shrimp, Litopenaeus vannamei, and the macroalga Gracilaria tikvahiae
- Nutrient uptake and macroalgal growth performance over short period (7-18 days)
- Both species are commercially viable
Results:
- Both L. vannamei and G. tikvahiae grow relatively fast and free of disease and epiphytes
- Nitrogen waste from L. vannamei is converted into algal biomass
- The study shows it is biologically and technically feasibility of IMTA.
- 35% of the nitrogen input was recovered by shrimp and algal biomass
Nutrient uptake and macroalgal growth performance were studied in short term (7–18 days) experiments with two Integrated Multi-Trophic Aquaculture (IMTA) systems stocked with the Pacific white shrimp, Litopenaeus vannamei, and the macroalga Gracilaria tikvahiae. Feed input totaled 67.5 kg with 4.3 kg of nitrogen. Shrimp yield was about 11.75 g m− 2 d− 1 and survival surpassed 98%. The study demonstrates the biological and technical feasibility and the operation-performance envelope of the studied shrimp-macroalgae IMTA system. A rudimentary nutrient budget suggests a recovery of nearly 35% of the nitrogen input by shrimp and algal biomass. Additional refinements could raise further the fraction of feed N that is recovered in shrimp and algal yields.
WIDER READING: does aquaculture add resilience to the global food system?
Troell et al., 2014- Does aquaculture add resilience to the global food system?
The study:
- Does growth of aquaculture enhance or undermine the potential for global food security?
- Examined the role of aquaculture in the global food portfolio and assess its contribution to food supplies and price
Results:
- Yes
- Supplies year round fish supplies and incomes for producers = reduce pressure on wild fish stocks
- Cold blooded and physiologically supported by water = more efficient food converters and have higher edible yields then most terrestrial animals = more cost efficient
- Utilisation of a variety of feeds which differ from those used in agriculture and human consumption then aquaculture could increase food security. E.g. molluscs, use natural ecosystem (detritus, plankton) not directly used by humans
- No
- Ocean acidification + increased GHG induced by climate change may threaten shellfish culture
- More reliance on fish/crop-based feeds- leads to social issues- Income generations by fish/crops for food vs for feed = Less food for humans if feed fetches higher price
- Will increase food security if not designed to manage social injustices and limit environmental impacts (Capture fisheries-overfishing, Associated problems with terrestrial agriculture (origin of feeds)- e.g., nutrient loss, GHG emissions)
WIDER READING: future trends of aquaculture (positives and negatives)
Edwards, 2015- Aquaculture environment interactions: Past, present and likely future trends
The study:
- Looks at the past, present and future aquaculture
- How different techniques can provide different options in the future
The results:
- Offshore mariculture = great potential – movement away from coastal aquaculture
- Production needs to change from seaweed + bivalve (Not significant human food source) to crustaceans and finfish (currently 11% of total mariculture production – FAO, 2013)
- Marine Harvest looking for tropical salmon
- Positives
- Unlimited space- many suitable coastal environments already being used for aquaculture
- Less external pollution from coastal areas (Domestic + industrial effluents)
- If Norwegian style cages installed in tropics (calm water belt between 10̊ N and 10̊ S) tropics could have great potential
- Negatives
- High-energy offshore environments have large+ variable swells, wind, waves = Large + sophisticated cages needed= lots of money
Wider Reading: reduce waste discharge
Amirkolaie, 2011- How to reduce waste discharge by utilising feed properties
The study:
- Potential solutions to the waste production problems from feed
- Decreasing use of fish-meal (decreasing fish stocks), move towards plant based feeds (Problems- less digestible)
- How to reduce waste from plant base feed
Results:
- Solid waste mostly composed of undigested starch and fibre from grain and plant ingredients
- Feed composition can alter physical properties of faces-stable faeces have larger particles, settle quicker and removed more efficiently- less DOM and SPM in system- gelatinised starch increases % faeces removed
- Waste output can be reduced by using highly digestible food, more consistent faeces and a careful balance of N and P (Causes of Eutrophication)
WIDER READING: parasites
Čolak et al., 2018- Effects of the cymothoid isopod (Ceratothoa oestroides) on cultured meagre (Argyrosomus regius) - Parasites in aquaculture example
The study:
- The effects the cymothoid isopod parasite had on cultured meagre growth across two sites in Eastern Adriatic Sea (Croatian mariculture)
- At existing Sea bass and Sea bream farms- Containing C. oestroides in Sea bass
The results:
- Parasitized fish were consistently smaller (length) than unparasitized fish
- Weight of parasitized meagre were smaller than unparasitized fish
- 60 total deformed fish- 51 had parasites (85%) at site 1
- 72 total deformed fish- 68 had parasites (94%) at site 2
- Can cause major economic losses = reduction in biomass, fish deformed so not suitable for market
WIDER READING: immune response
Harikrishnan et al., 2011– Plant extracts in fish aquaculture to enhance immune response
The study:
- The effect of Hericium erinaceum (Monkey head mushroom) extract supplemented feeds on the nonspecific immune response in olive flounder and the resistance against Philasterides dicentrarchi olive flounder
- Fish divided into 4 groups of 25 and fed with H. erinaceum enriched diets (0%-control, 0.01%, 0.1%, 1%)
The results:
- H. erinaceum enriched diets modulates the non-specific defence mechanism in olive flounder against P. dicentrarchi
- Fish treated with immunostimulants showed enhanced phagocytosis
- Had increase survival rates in infected fish which were fed the enriched diets
- 90% mortality in control group
- 45% mortality in group fed with 0.1% enriched diets
- 30 mortality in group fed with 1% enriched diets
