Aquaculture Flashcards
what is intensive aquaculture?
- high levels of controlled inputs
- productivity high
- efficiency low
give an example of intensive aquaculture
salmon + rainbow trout
what is extensive aquaculture?
- low levels of input
- productivity low
- efficiency high
- often over a large area
give an example of extensive aquaculture
oyster farms
what are the 5 factors (NOT ABIOTIC) controlled in fishing?
- Species selection
- Breeding/genetic control
- Disease control
- Control of competition
- Control of nutrition
why is species selection important?
- desirable characteristics i.e. rapid growth rate
2. local conditions i.e. salinity
give an example of a species selected
salmon suited to cool H2O = temperate environments
why is breeding/genetic control important?
- to create monosex cultures
2. to create triploid fish = infertile
how can breeding and gender be controlled?
injected with hormones to change gender
i.e. rainbow trout females injected with male hormones, genetically female = females produces
if stocking density too ____ diseases spread more easily as there’s more _____
high, contact
give 5 ways to control disease
- reduce stocking density
- biological control i.e. wrasse consumes lice
- pesticides
- antibiotics
- circulating H2O currents
name the 4 ways to control competition/ predation
- culling
- fencing
- better cage designs
- bird netting scarrers
why have high stocking densities?
more yield per unit area
why are herbivorous fish easier to feed?
likely to find food in lagoons
why are carnivorous fish harder to feed?
artificial feeding using low value fish i.e. anchovy (contain correct proteins/oils to maximise efficiency of growth)
name the 4 abiotic factors that should be controlled
- temp
- dissolved O2
- daylength
- water flow
why is controlling temp important? (2)
- different species = different range of tolerance
2. warmer temps increase metabolic rate BUT reduce O2 levels
why is controlling dissolved O2 levels important? (2)
- need to be aerated at high stocking densities
2. OM removed (no deoxygenation)
why is day length important? (2)
- effects reproduction
2. longer daylength delays maturation = increases size of fish
why is waterflow important? (2)
- fish swim in same direction = less collisions
2. same direction = allows higher stock density
aquaculture replacing fishing relies on…
food requirements + trophic levels
what is the issue of replacing fishing with aquaculture when feeding carnivores?
overfishing of less economical fish i.e. sandeel, reduction in pop. of puffins
define food conversion ratio
quantity of food required to produce a unit of growth
why is aquaculture better than agriculture when it comes to trophic levels?
fish have low basal metabolic rates (no energy lost to keep warm) = higher food conversion ratios
examples of elimination of predators (2)
- removal of crabs in oyster aquaculture
- culling of seals
a method to reduce elimination of predators in aquaculture
better cage designs prevent predators entering + consuming stock
what is the issue of farming non indigenous fish
could escape and outcompete/predate native ones
how can we safely farm non-indigenous fish so they don’t harm the wild pop.? + example
- make them infertile (triploid)
- breed fish that can’t breed in that climate/area
+ Japanese Oysters in UK (cannot breed in cold temps)
importance of controlling lice? (2)
- reduce fish growth
2. can spread to other pops.
name 3 ways to control lice
- biological control (wrasse eat lice)
- hydrogen peroxide wash
- organophosphate pesticide
how can the gene pool be reduced? (2)
- selecting the same characteristics
- inbreeding
how to increase gene pool?
chose a variety of characteristics
how can the wild gene pool be effected?
escaped fish could breed with wild ones
how to prevent wild gene pool impacts? (2)
- triploid fish
2. better cage designs
what is the issue with OM pollution?
causes deoxygenation
solutions to prevent OM pollution? (3)
- cages located near currents
- feeding monitored = less waste
- effluent treatment works
what is the issue with using pesticides?
could kill wildlife
solutions for pesticides (2)
- mechanical cleaning
2. biological control
example of habitat loss due to aquaculture
10% of mangroves destroyed to create shrimp farms
how to avoid habitat loss
careful site selection, avoiding vulnerable/valuable areas
how to reduce food supply impacts? (2)
- farming herbivorous fish i.e. tilapia
2. plant products in pellets
using antibiotics on fish could cause antibiotic resistant bacteria which could…
spread to humans
describe polyculture
rearing different species together which increases productivity
the importance of selective rearing of predators in polycultures?
increase production of larger fish by eating smaller fish which could compete with the larger ones i.e. catfish
the importance of bottom feeding organisms in polycultures?
disturbs sediments, increase nutrients = increase growth of plants
give an example of a bottom feeder
common carp
describe what an integrated multi trophic aquaculture is
polyculture system with different trophic levels which benefit from each other
describe what fed aquaculture is in multi trophic aquaculture
species given food i.e. salmon
describe what inorganic extractive is in multi trophic aquaculture
species that absorb inorganic nutrients i.e. algae
describe what organic extractive is in multi trophic aquaculture
species that consumes OM i.e. filter shellfish
describe what aquaponics is
- H2O used in aquaculture used in hydroponic system (contains OM)
- plants use nutrients from OM
- increased productivity
- H2O returned to aquaculture
- aquaculture H2O = doesn’t contain OM
name 2 suitable hydroponic species
lettuce, watercress
name 2 suitable aquaculture species
carp, tilapia
