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Aquaculture Flashcards

(62 cards)

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1
Q

What is Imta?

A

integrated multi tropic aquaculture
it is a polyculture system where species in different trophic levels benefit from each other

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2
Q

What is polyculture?

A

Rearing species together that arent competitors, this increases productivity

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3
Q

Give an example of polyculture

A

silver carp feeding on phytoplankton
bighead carp feeding on zooplankton
grass carp feeding on vegetation

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4
Q

What is aquaponics?

A

hydroponics combined with aquaculture.
The water from aquaculture is used in hydroponics because it contains inorganic nutrients from fish faeces.
Drained filtered water by the plants is pumped back into aquaculture.

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5
Q

What does hydroponics remove from the water pumped back into aquaculture?

A

Nutrients that could cause deoxygenation

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6
Q

Examples of species used in aquaponics?

A

Leafy greens
Tilapia, carp

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7
Q

What is the food conversion ratio and how do you calculate it?

A

the quantity of food required to produce a unit of growth.
Mass of food/mass of growth

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8
Q

What is the photic zone?

A

Above 100m, where light can penetrate water and photosynthesis occurs

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9
Q

What is the aphotic zone?

A

below 100m, cannot photosynthesise

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10
Q

What is coastal upwelling?

A

Death of organisms produces DOM which sinks to the seafloor. Deep ocean currents are deflected by a seamount causing the nutrients from DOM to be upwelled to photic zone.

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11
Q

What is demersal trawling?

A

A net dragged along the seabed to catch species like cod, haddock

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12
Q

What is demersal long lines?

A

A line of baited hooks along the seabed to catch species like cod, haddock

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13
Q

What is pelagic trawling?

A

Used a large net dragged in the water.
Used for species that form shoals in water like herring.

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14
Q

What is the bycatch of pelagic trawling?

A

Low by catch
Can catch predator species like dolphins

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15
Q

What are drift nets?

A

Long curtain like nets that are supported by floats and catch tuna/herring

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16
Q

What is purse seining?

A

Uses a net laid around a shoal of fish, top is held by floats bottom is held by weights and is then pulled tight.
Catches species like tuna, herring

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17
Q

What is pelagic long lines?

A

A line of baited hooks to catch tuna/squid

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18
Q

What are k-selected species?

A

Species that high breeding age, live longer, have fewer young, reach sexual maturity later
Orange roughy, greenland shark

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19
Q

Why is overfishing of k-selected species bad?

A

They may reach a catchable size before they are sexually mature so overfishing can remove whole populations

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20
Q

What are r-selected species?

A

Species that breed at a young age, have many young, pregnant many times a year, dont live long.
herring, yellow fin tuna

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21
Q

describe the greenland shark

A

lives to be over 400yrs old but doesnt reach sexual maturity until 100-150 yrs and has few young

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22
Q

Why would by-catch be unwanted?

A

Fish caught are too small to sell
Catch quotas already reached for species caught
Species caught has no commercial value

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23
Q

Why is killing immature fish bad?

A

This reduces the future catches because the young that were killed dont have a chance to grow to catchable size

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24
Q

What is the bycatch of drift nets?

A

Drift nets will catch everything, whales, dolphins, turtles.
High bycatch

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25
What is the bycatch of pelagic long lines?
Albatross which drown after being caught on lures put out for fish.
26
Is albatross a k or r selected species?
k-selected, dont breed until 7-10 yrs so bycatch is a big problem
27
What is pelagic trawling bycatch?
Preadator bycatch
28
What is demersal trawling bycatch
High bycatch,
29
What is shrimp bycatch?
Uses nets with very small mesh so fee bycatch animals can escape, includes crabs, starfish Very high bycatch
30
What is ghost fishing?
Fishing gear that has been lost or discarded that will still continue to catch organisms. Dead organisms caught act as bait causing more organisms to get caught.
31
Whats a NTZ?
A no take zone, they protect the breeding populations and allows populations to recover
32
Name some NTZ
Great barrier reef easter island lamlash bay
33
Whats a closed season?
A ban on fishing for part of the year which allows fish to grow and breed.
34
Whats the maximum catchable size?
A max size of species that can be caught which ensures there is a breeding population.
35
What do fishermen have to do to lobsters with eggs on?
They must be released and a v-notch is cut into the tail to show that they are valuable to the population and must be released when they dont have any eggs.
36
Why would breeding rate decline?
If too many adult fish are caught as there less breeding because juvenile fish arent mature enough to breed
37
What is the MSY?
Greatest mass thay can be removed without the population suffering from long term decline.
38
How to calculate MSY?
S2= S1 + (A+G) - (C+M) s1- biomass at start of yr a- biomass by young g- added biomass from growth c- biomass caught m- biomass loss through death
39
What is the orange roughy?
A deep water k-selected fish species live to 150 but dont breed until 30
40
Why would collecting data on fish be difficult?
fish populations move long distances and between territories of different countries distribution of fish is uneven impractical to collect large representative data
41
What data can you get from CAUGHT fish?
Catch size- If this decreases yearly then the population is decreasing Mean fish size- if more smaller fish are being caught it may indicate that the larger fish are being caught faster than they are being replaced Mean fish age- age can be determined by growth rings or otoliths in their ears. If the mean age is declining overfishing is happening
42
What can collecting planktonic fish eggs do?
It can help to estimate the number of young fish to be recruited into the adult population They are caught by a plankton net
43
What are the environmental impacts of fishing?
Food web impacts Damage to seabed/coral/seagrass Population decline bycatch
44
How can ghost fishing be reduced?
Radio-tracked nets so they can be collected Biodegradable nets
45
Describe the methods to reduce bycatch
Big enough mesh size so fish can escape Mesh at right angles to the direction of movement stops mesh from closing Escape panels Decoys to distract birds Sinkers to hold down hooks Curved hooks to stop birds getting caught Fish at night when birds aren't out Maximum engine size which limits the boat size Maximum days at sea EUCFP
46
What are TEDs and how do they work?
Turtle exclusion device, they are spring loaded escape panels which allows turtles/fish to escape
47
What are acoustic deterrent devices and how are they used?
'Dolphin pingers', they release high frequency sounds to alter the dolphins something is there
48
What is aquaculture?
Controlling the ecosystem to allow more food to enter the human food chain
49
What type of fish is more common in MEDCs?
Carnivores fish like salmon and trout because they taste nicer
50
What type of fish is more common in LEDCs?
Herbivorous fish like carp or talipa because they feed on naturally occurring vegetation. Low food inputs needed=cheaper
51
What are the characteristics of fish chosen in aquaculture?
Disease resistant Rapid growth rate Good appearance
52
What are rainbow trout?
Female trout have better flavour so some females are given testosterone which allows them to produce sperm with the X chromosome, so when fertilising eggs they will all be female.
53
What are triploid fish?
Triploid fish have 3 sets of chromosomes and are infertile. This is done by heating the eggs right after fertilisation.
54
Why are triploid fish good?
They are infertile so if any escape from a fish farm they will not be able to breed with the wild populations.
55
How is aquaculture controlled to prevent disease/pests/damage to fish
Lower stocking densities so disease isn't spread as easily Lower stocking densities to stop collisions between fish and to stop the transfer of pests Controlling the flow of water to go into the older fish so young fish don't get diseases from the older fish. Tanks with circulating water to encourage fish to swim in the same direction to stop injuries
56
What can be used to eat the lice off of fish?
Wrasse
57
What is used in outdoor fish farms to prevent predatation?
Nets or fences Killing of seal is also allowed with a permit
58
How are abiotic factors controlled in aquaculture?
Higher temps for higher metabolic rate and more growth Dissolved oxygen, aerated tanks by water sprays and food waste/faeces is removed to stop deoxygenation Daylength, longer days to delay maturation, increase size. Water flow in one direction to stop collisions
59
Why would daylength be controlled in salmon tanks?
Salmon stop growing once sexually mature so by controlling daylength you slow down maturity but increase the size of the salmon
60
What is salmon aquaculture?
Intensive system which controls many factors to maximise productivity. -Salmon need high dissolved o2 so water cant be too high in temp-scotland -Flow rate kept high to increase muscles in fish -Selective use of pesticides/antibiotics to kill diseases -Salmon are fed pellets made from low value fish as they are carnivores.
61
How can food chain efficiency be increased in salmon aquaculture?
By adding food from lower trophic levels like plant foods and vegetable oils.
62
Why cannot blue fin tuna aquaculture not continue without a wild population?
Because they do not breed well in captivity as they migrate to breed, are sensitive to noise, temp and currents which are hard to replicate. The young fish are caught and are bred in large cages in the sea.

Environmental Science (21 decks)

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