4.3 Aquatic food production systemsIB Environmental Systems and Societies HL: Subtopic test

1. 1
   The northern cod stock off Newfoundland, Canada, was fished heavily by large trawlers through the 1970s and 1980s. Catches fell sharply, and in 1992 the Canadian government banned commercial cod fishing (a moratorium). Thousands of fishers and fish-plant workers lost their jobs. Decades later the stock had recovered only partly.

   (a)

   Which term describes harvesting so heavily that a population can no longer replace itself?

   [1 mark]

   • AMaximum sustainable yield
   • BAquaculture
   • COverexploitation
   • DEutrophication

   (b)

   What is the maximum sustainable yield (MSY) of a fish stock?

   [1 mark]

   • AThe highest annual catch that can be sustained over time
   • BThe total number of fish in the stock
   • CThe lowest catch that keeps fishing fleets profitable
   • DThe number of fish caught by one vessel in a day

   (c)

   Explain why the northern cod fishery collapsed.

   [2 marks]

   Total for question 1: 4 marks

2. 2
   A North Atlantic coastal state licenses a commercial harvest of harp seals within the waters it controls. The seals are killed for fur and meat. Hunters say the harvest supports coastal communities, and that the seal population is large. Animal welfare groups campaign against the hunt.

   (a)

   Under the UN Convention on the Law of the Sea (UNCLOS), a coastal state has an exclusive economic zone (EEZ) extending approximately how far out to sea?

   [1 mark]

   • A37 km
   • B185 km
   • C220 km
   • D370 km

   (b)

   Which statement is an argument against the seal harvest based on animal rights?

   [1 mark]

   • ASeals compete with fishers for fish
   • BSeals are sentient animals with a right not to be killed or made to suffer
   • CThe harvest provides income for coastal communities
   • DThe seal population is large enough to be harvested sustainably

   (c)

   Explain two reasons why harvesting seals, whales and dolphins raises ethical issues.

   [2 marks]

   Total for question 2: 4 marks

3. 3
   A fisheries scientist assesses a fish stock in a regional sea. Her surveys estimate the stock at 600,000 tonnes in year 1, 520,000 tonnes in year 2 and 430,000 tonnes in year 3. The estimated maximum sustainable yield (MSY) is 90,000 tonnes per year. Reported catches in the three years were 85,000, 110,000 and 130,000 tonnes. Fishers report that fish are harder to find. The survey method has an estimated error of plus or minus 20%.

   (a)

   Calculate the mean annual catch over the three years and state by how much it exceeds the MSY. Predict what will happen to the stock if catches continue at this level.

   [3 marks]

   (b)

   Explain why harvesting at MSY carries risks and why accurate stock assessment is needed to manage them.

   [4 marks]

   Total for question 3: 7 marks

4. 4
   Atlantic bluefin tuna are large, long-lived, slow-maturing fish prized for sushi. Their stocks in the Atlantic and Mediterranean were heavily overfished in the late twentieth century. From the mid-2000s the International Commission for the Conservation of Atlantic Tunas (ICCAT) introduced catch quotas, minimum sizes and a recovery plan, backed by observers on vessels and catch documentation. Governments, the fishing industry, scientists and conservation organisations all took part, and the eastern stock has since shown signs of recovery. Part of the species' range lies in the high seas, beyond any country's exclusive economic zone, and some young tuna are caught and fattened in sea cages ("tuna farming").

   (a)

   Evaluate strategies that could reduce overexploitation of fish stocks such as bluefin tuna.

   [6 marks]

   (b)

   Discuss how multi-stakeholder cooperation and the UN Convention on the Law of the Sea (UNCLOS) can help overexploited species such as bluefin tuna to recover.

   [6 marks]

   Total for question 4: 12 marks

End of questions