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Marine Biology > Lecture 12 - Fisheries and Aquaculture > Flashcards

Lecture 12 - Fisheries and Aquaculture Flashcards

1
Q

How many years have we been fishing?

A

40,000 years

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2
Q

Who described fisheries as an inexhaustible harvest, claiming that the number of fish we catch is insignificant as the multitude of fishes is inconceivably great?

A

Thomas Huxley (1883)

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3
Q

Describe fishing using a purse seine.

A
  • In open water

- Surrounds a whole school of fish, pulls strings tight to enclose them.

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4
Q

How are most of the world’s tuna caught?

A

In purse seine nets

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5
Q

What is a disadvantage of purse seine fishing?

A

Indiscriminate.

A lot of by catch of turtles, whales, dolphins etc.

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6
Q

How do gill nets work?

A

Intercept fish.

Fine monofilament/transparent mesh that cannot be seen by fish, tangles them.

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7
Q

What is trawling?

A

The use of a net in a mobile form in open water.

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8
Q

Name some fish caught by midwater trawling.

A
  • Mackerel
  • Sardines
  • Herring
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9
Q

What is bottom trawling?

A

Large wooden beams are dragged along the seabed with a thick net or chain mesh.
Catches anything living close to the seabed.

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10
Q

How many times might the same patch of seabed be trawled in a year?

A

3-5 times

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11
Q

What is a benefit of trawling?

A

Often has large open panels at the top, allowing turtles and dolphins to escape.

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12
Q

Give three kinds of fish caught by longlines.

A
  • Swordfish
  • Marlin
  • Shark
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13
Q

How many jumbo jets can fit into some large pelagic trawl nets?

A

13

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14
Q

Describe the use of SONAR in fishing.

A

Can see the sea bed and follow contours that the fish might aggregate in, look for trenches, avoid obstructions, view fish in midwater.
SONAR bounces off of fish’s swim bladder, can detect age and size of fish.

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15
Q

How many people do global fisheries provide essential nutrition for?

A

3 billion

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16
Q

How many people rely on fish as their main source of protein?

A

1 billion

17
Q

How much are fisheries worth per year?

A

$80 billion

18
Q

How many commercial fishermen and fish farmers are there?

A

38 million

19
Q

How much more fish do we need to be catching by 2030?

A

35% more fish

From 106 million tonnes to 143 million tonnes

20
Q

What is the ratio of by catch in shrimp trawling?

A

20:1

21
Q

What is the Discard Ban for the EU?

A

States that fishermen must land things, cannot throw them back.

22
Q

What does IUU fisheries stand for?

A

Illegal, Unreported, Unregulated fishing.

23
Q

How much are IUU fisheries valued at?

A

$10-25 billion

24
Q

What is the most rapidly increasing food production market in the world?

A

Aquaculture

25
Q

How much less is the North Sea biomass of fish than without fishing for fish of size

a) 4-16kg?
b) 16-66kg?

A

a) 4-16kg = 97% less

b) 16-66kg = 99% less

26
Q

How much has the biomass of high trophic fish declined in the last 50 years?

A

By 66%

27
Q

Within 15 years of exploitation, how much do industrialised fisheries reduce biomass by?

A

80%

28
Q

What percentage of stocks are

a) Facing collapse?
b) Overexploited?

A

a) Facing collapse = 30%

b) Overexploited = 40%

29
Q

True or False:

There are no underdeveloped fisheries in the world.

A

TRUE.

30
Q

What percentage of fisheries are still developing?

A

5-10%

31
Q

Describe the work of Boris Worm et al (2006).

A

Looked at the number of collapsed taxa.

50-60% of taxa collapsed.

32
Q

Describe the work of Pauly et al (1998).

A

Described how the trophic level of the community changes within time – showed that trophic level drops.

33
Q

What is the maximum sustainable yield?

A

The population size at which it produces the maximum number of offspring available for harvest.

34
Q

What percentage more additional protein needs to be produced by the sea by 2030?

A

40%

Marine Biology (19 decks)

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