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IGCSE Biology Extended20.4.6—Fish stocks can be conserved usingTopic Practice

20.4.6—Fish stocks can be conserved using

• Explain how fish stocks can be conserved using: education, closed seasons, protected areas, controlled net types and mesh size, quotas and monitoring

Question 2(c)(ii)

[Maximum number: 4]

Carp are a type of fish. Researchers in Brazil measured the body lengths of a population of carp in a river in 1998 and again in 2008.

Histograms of their results are shown in Fig. 2.1.

Fig. 2.1

Fig. 2.1

The total population of carp in 1998 was 43000 fish.

The decrease in the carp population by 2008 was caused by overfishing.

Explain how fish stocks can be sustained.

Question 4

[Maximum number: 5]

The Canadian Government were concerned about overfishing at the Grand Banks in the Atlantic Ocean.

As a result, commercial fish stocks were monitored from 2002 until 2013.
The population data for four species of fish are shown in Fig. 4.1.

Fig. 4.1

Fig. 4.1

Question 4(c)

(a)

Overfishing can be reduced by having large holes in fishing nets.

Fig. 4.2 shows sections of two fishing nets, the drawings are both at the same scale.

Fig. 4.2

Fig. 4.2

[ 5 ]

Question 4(c)(i)

(i)

Suggest how controlling the size of the holes in fishing nets helps to reduce overfishing.

[ 1 ]

Question 4(c)(ii)

(ii)

Describe and explain how methods other than fishing net hole size, could help to prevent overfishing.

[ 4 ]

Question 5

[Maximum number: 8]

Fig. 5.1 shows the changes in the percentage of the total global fish stocks that are overfished and those that are sustainable.

Fig. 5.1

Fig. 5.1

Question 5(a)

(a)

Use the information in Fig. 5.1 to:

[ 2 ]

Question 5(a)(i)

(i)

State the percentage of fish stocks that were sustainable in 2020. \%

[ 1 ]

Question 5(a)(ii)

(ii)

State which five-year period had the greatest increase in sustainable fish populations.

[ 1 ]

Question 5(c)

(b)

Describe and explain how fish stocks can be managed sustainably and how overfishing can be prevented through conservation.

[ 6 ]

Question 37

[Maximum number: 1]

The number of Atlantic bluefin tuna fish found in the Atlantic Ocean has significantly decreased in the last 50 years.

Which method would make the biggest improvement in the conservation of tuna fish stocks?

A

decreasing the size of holes in fishing nets

B

genetic modification of tuna

C

introducing fishing quotas

D

selective breeding of tuna

Question 40

[Maximum number: 1]

The graph shows the effect of fishing on fish stocks over 20 years. In year 11, a fishing quota was introduced followed by a total ban on fishing in year 16.

Question image

What effects did these conservation measures have on the fish population?

A

The fish population became extinct.

B

The fish population started increasing immediately after the fishing quota was introduced.

C

The fish population started increasing only after a total ban on fishing was introduced.

D

There was no effect on the fish population.

Question 6(a)(iv)

[Maximum number: 3]

Atlantic cod, Gadhus morhua, is a type of fish that is an important resource for commercial fishing.

Fig. 6.1 shows the estimated mass of Atlantic cod over 40 years.
mass of Atlantic cod / million tonnes

Fig. 6.1

Fig. 6.1

Explain how fish stocks can be conserved by restocking.

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