3 The diagram shows part of a food web in a marine ecosystem. herring zooplankton phytoplankton grey seal killer whale (orca) humpback whale cormorant (a) (i) Complete the food chain using the diagram. … … cormorant … [2] (ii) Explain how overfishing of herring might affect the population of killer whales. … … … … [2] (b) Explain two strategies to prevent overfishing. strategy 1 … explanation … … strategy 2 … explanation … … [4] [Total: 8] Section B

3(a)(i) phytoplankton  zooplankton  (cormorant)  killer whale (orca) 1 correct; 3 correct; 2 3(a)(ii) either: killer whale numbers will decrease; as fewer herring to eat; or: killer whale numbers will remain the same; as other food sources available / will eat more humpback whales; 2 3(b) any two named strategies with associated explanations, e.g.: reduce the season for fishing; prevents fish being caught in breeding season; (introduce / decrease) quotas: limits the number of fish caught; increase size of mesh in nets; allows smaller / immature, fish to escape to breed; (introduce / increase) limits to net, sizes / types; prevents all the fish from being caught in the area; (introduce / increase) licensing (of boats); restricts number of vessels / time at sea; (introduce / increase) enforcement of laws: allows monitoring of catch / stops illegal fishing; (introduce / increase) marine reserves / no-fishing areas; provides undisturbed habitat for fish; (introduce / increase) fish-farming; reduce amount of wild fish caught; 4 (a)(i) To earn marks, you must correctly complete the food chain by identifying phytoplankton, zooplankton, and killer whale (orca) in the correct sequence. (a)(ii) To score marks, you need to explain how overfishing of herring affects killer whale populations, either by stating that killer whale numbers will decrease due to less food, or that they will remain the same by eating other food sources. (b) To earn marks, you must describe two distinct strategies to prevent overfishing, each with a clear explanation, such as reducing the fishing season to prevent catching fish during breeding or introducing quotas to limit the number of fish caught.

3 The diagram shows part of a food web in a marine ecosystem. herring zooplankton phytoplankton grey seal killer whale (orca) humpback whale cormorant (a) (i) Complete the food chain using the diagram. … … cormorant … [2] (ii) Explain how overfishing of herring might affect the population of killer whales. … … … … [2] (b) Explain two strategies to prevent overfishing. strategy 1 … explanation … … strategy 2 … explanation … … [4] [Total: 8] Section B

3(a)(i) phytoplankton  zooplankton  (cormorant)  killer whale (orca) 1 correct; 3 correct; 2 3(a)(ii) either: killer whale numbers will decrease; as fewer herring to eat; or: killer whale numbers will remain the same; as other food sources available / will eat more humpback whales; 2 3(b) any two named strategies with associated explanations, e.g.: reduce the season for fishing; prevents fish being caught in breeding season; (introduce / decrease) quotas: limits the number of fish caught; increase size of mesh in nets; allows smaller / immature, fish to escape to breed; (introduce / increase) limits to net, sizes / types; prevents all the fish from being caught in the area; (introduce / increase) licensing (of boats); restricts number of vessels / time at sea; (introduce / increase) enforcement of laws: allows monitoring of catch / stops illegal fishing; (introduce / increase) marine reserves / no-fishing areas; provides undisturbed habitat for fish; (introduce / increase) fish-farming; reduce amount of wild fish caught; 4 (a)(i) To earn full marks, you must correctly identify all three missing organisms in the food chain: phytoplankton, zooplankton, and killer whale (orca). (a)(ii) To score marks, you need to explain how overfishing of herring affects killer whales, either by stating their numbers will decrease due to less food, or remain the same if other food sources are available. (b) To earn full marks, you must describe two distinct strategies to prevent overfishing and provide a clear explanation for how each strategy works.

3 The map shows some major ocean currents. Key warm ocean current cold ocean current South Atlantic Ocean Pacific Ocean South America South America (a) Use the key to draw the major currents in the South Atlantic Ocean on the map. [2] (b) Explain why the El Niño Southern Oscillation (ENSO) phenomenon reduces the number of fish along the Pacific coast of South America. … … … … … … [3] [Total: 5]

3(a) circle with arrows anticlockwise; solid lines originating from the North and dotted lines originating from the South; 2 3(b) any three from: (during El Niño) upwelling weakens; (brings up) warm water; this has few nutrients; less oxygen (in warm water); less plankton; fish have little food; 3

4 Overfishing has resulted in the depletion of many marine fish populations. (a) State two strategies used to manage the number of fish caught at sea. 1 … 2 … [2] (b) Over the last 50 years, there has been a large increase in farming marine fish species. Farming marine fish species helps reduce overfishing. (i) State two other benefits of farming marine fish species. 1 … 2 … [2] (ii) Suggest one problem associated with farming marine fish species. … … [1] [Total: 5] Section B

4(a) any two from: net types, e.g. (larger) mesh size / mesh shape; introduce / reduce quotas; closed seasons; protected areas / reserves; conservation laws; international agreements; 2 4(b)(i) any two from: better able to meet demand; consistent supply / controlled; easier to control predators / disease; more profitable; provides cheap protein; employment; easier / more efficient / safer to catch; no bycatch; 2 4(b)(ii) any one from: water pollution / effluent; increase risk of disease (due to stock density); (increased) use of antibiotics required / risk of antibiotic resistance; possibility of escape; 1

5 The map shows the locations of salmon fish farms in Scotland. 0 100 km Atlantic Ocean North Sea N Key salmon fish farm national border Scotland England (a) Describe the distribution of salmon fish farms shown on the map. … … … … … … [3] (b) The article describes changes in salmon fish farming in Scotland. Salmon fish farmers reduce the use of pesticides Sea lice are parasites that feed on the bodies of living salmon. Salmon fish farmers in Scotland want to reduce the amount of pesticides used to control sea lice. Experiments to replace these pesticides with wrasse, small fish that eat sea lice, have been successful in controlling the sea lice. Wrasse live in the sea around England. They are caught and transported to the salmon fish farms in Scotland. Scientists are worried that there are now fewer wrasse in the sea around England. They think this decrease is due to the demand for wrasse in salmon fish farms. Over the last 10 years, it is estimated that the catch of wrasse has increased from 2.0 million to 22 million fish per year. (i) Suggest reasons why the use of pesticides on fish farms may be harmful to the environment. … … … … [2] (ii) Calculate the percentage increase in the yearly number of wrasse caught over the last 10 years. … % [2] (iii) Suggest reasons why some scientists think that using wrasse to control sea lice is not sustainable. … … … … [2] (iv) Explain why fish farming is a more sustainable method of food supply than catching fish from the oceans. … … … … … … … … [4] [Total: 13]

5(a) any three from: situated on, the coast / coastlines; of western mainland Scotland / owtte; of islands, to north(east) / in North Sea; of islands, to (north)west / in Atlantic Ocean; 3 5(b)(i) any two from: pesticides enter the ocean; (possible) toxic effect on marine life; impact on, food web / ecosystem; bioaccumulation; 2 5(b)(ii) change identified as 20 000 000; (20 000 000 ÷ 2 000 000 × 100 =) 1000%; 2 5(b)(iii) any two from: wrasse are being caught from the wild; impact on ecosystems from, removal / addition, of fish; wrasse are being caught at a greater rate than being replaced; wrasse normally live in England not Scotland; fish might escape from fish farms; bycatch; 2 5(b)(iv) any four from: easier to catch / guaranteed catch; controlled feeding; controlled breeding; controlled harvesting; control of disease; faster growth / greater yield; less predation; breeding of improved stock rather than wild types; no bycatch; less damage to seabed; 4

Cambridge IGCSE Environmental Management · 0680

IGCSE Environmental Management (0680) Oceans and fisheries past paper questions

Revise IGCSE Environmental Management (0680) — Oceans and fisheries with real Cambridge past-paper questions grouped by topic, each shown with its marking scheme. Working one topic at a time targets exactly the skill each question tests.

19 free questions from 2019–2021, each with its marking scheme. Open the full topical bank to filter by subtopic, paper, and year.