Question 23M.3.HL.TZ1.18
| Date | May 2023 | Marks available | [Maximum mark: 6] | Reference code | 23M.3.HL.TZ1.18 |
| Level | HL | Paper | 3 | Time zone | TZ1 |
| Command term | Explain, Label, Outline, Suggest | Question number | 18 | Adapted from | N/A |
The diagram shows the relationship between commercial sea fishing activity and yield, and how this affects sustainability.
[Source: Lart, W., 2022. Overview of sustainable fisheries assessment and management; Seafish FS112_08_19. [PDF online]
Available at: https://www.seafish.org/document?id=3fc8597a-0ae7-43c7-874c-d0611c1f8cf8 [Accessed 9 March 2022].]
Label with a P on the -axis the level of commercial sea fishing activity that would result in maximum sustainability.
[1]
label P on x-axis below the peak yield;
Dotted line for guidance, not required in answer.
Do not accept if P is only on the curve
This was well done with the majority able to identity the point of maximum sustainability on the graph.
Outline the reason for the change in yield in region III of the diagram.
[1]
fish are being caught faster than they can reproduce;
Very few answered this correctly. Many simply repeated 'overfishing' which was the label for the region of the graph.
Suggest a reason that it is difficult to keep global commercial sea fishing activity at a sustainable level.
[1]
- requires agreements/policies/enforcement between countries;
- commercial companies compete to increase profit;
Few received a mark for suggesting why it was difficult to keep global fishing at sustainable levels.
Explain how the population of fish in a pond could be estimated using the capture-mark-release-recapture method.
[3]
- random sample is captured and marked/tagged (in a manner that will not harm fish);
- captured sample is released and allowed to mix with general population
OR
captured sample is released then wait a few days/weeks; - second sample is captured and both the total number and the number of marked fish counted;
- ratio of recaptured marked fish to number in second sample = the ratio of the number in the first sample marked and released to the population size
OR
Population Size =
n1 = number in first sample marked
n2 = number in second sample
n3 = number of recaptured individuals marked
Many had some idea about the "capture-mark-release-recapture" technique but failed to explain how this could be used to estimate population size. It was common to see responses that simply repeated the name of the technique.
