Aquaculture Flashcards
(40 cards)
What is aquaculture?
Rearing of aquatic organisms for food.
What are the key features of extensive aquaculture?
Low inputs.
Some control of predators and competition.
Herbivorous fish.
What are the key features of intensive aquaculture?
High yield.
Control inputs.
Selective breeding.
Control of pests and abiotic factors.
What are some of the characteristics of fish that the market demand?
Good taste and appearance.
MEDCs prefer carnivorous fish for taste.
LEDCS prefer herbivorous fish are preferred.
How does the position in the food chain (trophic level) affect fish?
Species lower down on the food chain are ideal as they are more energy efficient.
Carnivorous fish are often higher on the trophic level.
What makes something higher on the trophic level?
At each stage of the food chain energy is lost through respiration, movement etc.
What are some of the features that fish are selected for in aquaculture?
Growth rate.
Resistance to disease.
Wide range of tolerance.
Why are single sex/mono-sex cultures common?
Higher growth rate in one sex.
Prevention of energy diversion.
Better flavour.
Less aggression.
How are mono-sex cultures achieved?
By giving a female fish (XX) testosterone it allows her to be masculinised and therefore produce sperm. This means that a masculinised female (XX) can fertilise a normal females (XX) eggs and this would create only female offspring as they is no Y chromosome involved.
How is disease controlled in aquacultures?
Use of antibiotics.
Biological control or organophosphate pesticides.
How are predators controlled?
By adjusting the cage design to make sure no predators can enter.
What are the main issues with feeding carnivorous fish?
You have to catch fish to feed them.
How could you overcome the issue of feeding carnivorous fish?
Use low value fish to feed them or by catch which wouldn’t be used for food for humans.
How is temp controlled in aquacultures and why?
A heater can be used as warm temps can increase growth rate.
How is light controlled in aquacultures and why?
Artificial light can be used to manipulate day length which can delay sexual development and increase the size the fish reach.
How is oxygen controlled in aquacultures and why?
Use of aerated tanks or water sprays to provide more dissolved oxygen for respiration.
How is water flow rate controlled in aquacultures and why?
Pumps can be used to keep the water flowing in one direction which prevents collisions so reduces injuries and improves appearance
Why are high stocking densities used?
To make the most of the space and increase the yield.
Why is restriction fish movement used?
To restrict energy being wasted on movement and more growth.
Why are concentrated pellets of formulated food used?
Nutrients provided for maximum growth as well as they is less waste as they are easier to digest.
Why are antibiotics used?
Can be used to control and stop spread of disease caused by bacteria.
Why is the water current speed controlled?
To produce more muscular fish as it makes them stronger as well as preventing collisions.
How can aquacultures cause a build up of organic waste?
Wasted food can cause a build up.
What are the consequences of a build up of organic waste?
Deoxygenation.
Increased turbidity which can block light used for photosynthesis.
