Sustainable fisheries — Paper 4 · A Level Marine Science 9693

1 Surface longline fishing is a fishing method in which trawlers tow long fishing lines with baited hooks along the surface of the water. It is used to catch albacore tuna. The catch of albacore tuna from an area of the Indian Ocean around Mauritius was recorded each month, every year, from 2005 to 2011. This information was used to calculate the mean catch of albacore tuna per month. In order to determine fishing effort each month, the total number of hooks used to catch fish was recorded. This was used to calculate the mean number of hooks used for each month over the time period. The results are shown in Table 1.1. Table 1.1 standard mean deviation mean number catch per month albacore tuna of mean of hooks unit effort catch / kg albacore tuna used / kg hook–1 catch / kg Jan 6200 600 720 8.6 Feb 9000 2700 1100 8.2 Mar 5800 500 680 8.5 Apr 6200 600 700 8.9 May 5800 300 680 8.5 Jun 4000 300 550 Jul 3200 500 400 8.0 Aug 4000 800 500 8.0 Sep 5000 700 600 8.3 Oct 4500 600 550 8.2 Nov 9500 3000 1100 8.6 Dec 8500 1500 1000 8.5 (a) (i) Explain what is shown by the standard deviation of the mean albacore tuna catch. … … … … … [2] (ii) Plot a graph to show how the mean albacore tuna catch and mean number of hooks used changes. Label both y-axes fully and include the units. Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec month [5] (b) Catch per unit effort is considered to be a better comparative measure of the health of fish stocks than mean catch alone. mean albacore tuna catch catch per unit effort = mean number of hooks used Calculate the catch per unit effort for June. … kg hook–1 [1] (c) In order to determine whether the albacore tuna fishing was sustainable, the catch per unit effort for each month was calculated in 2015. Table 1.2 shows the catch per unit effort for each month during 2015. Table 1.2 catch per month unit effort / kg hook–1 Jan 9.2 Feb 9.4 Mar 9.1 Apr 8.9 May 8.6 Jun 9.2 Jul 8.9 Aug 8.2 Sep 8.3 Oct 9.1 Nov 8.6 Dec 8.9 Discuss whether the information in Tables 1.1 and 1.2 indicates that albacore tuna fishing is sustainable. … … … … … … … [3] [Total: 11]

11 marks

This question in 9693/40 Oct/Nov 2018

3 (a) Outline how the techniques of intensive aquaculture differ from those of extensive aquaculture. … … … … … … … … [4] (b) Describe the process used for the aquaculture of shrimp. … … … … … … … … … … [5] (c) Fig. 3.1 shows an aquaculture method called integrated multitrophic level aquaculture. filter feeders such as mussels and scallops that feed on small particles of waste seaweeds that remove nitrates and phosphates and photosynthesise current lobster, crabs and sea cucumbers that feed on waste particles Fig. 3.1 Discuss how this method of aquaculture meets the requirements of sustainable aquaculture and minimises its impacts on the environment. … … … … … … … … … … … … [6] [Total: 15]

15 marks

This question in 9693/40 May/June 2020

4 The conservation of primary producers is essential for the health of the marine environment and for ensuring sustainable fish stocks. (a) (i) Outline the ecological importance of primary producers. … … … … … … [3] (ii) Explain why different types of primary producers are found in the open ocean and intertidal zones. … … … … … … … … … … … … [6] (b) Discuss the advantages and disadvantages of the principal methods used to monitor fisheries to ensure sustainable fishing. … … … … … … … … … … … … [6] [Total: 15]

15 marks

This question in 9693/40 May/June 2020

3 Government ministries often place restrictions on fishing to ensure sustainable exploitation of fish stocks. (a) Describe the long-term and short-term sociological impacts of restrictions on fishing. … … … … … … … … [4] (b) Discuss the information that government ministries may use to decide how to best exploit fish stocks on a sustainable basis. … … … … … … … … … … … … … … [7] (c) Discuss the advantages and disadvantages of building artificial reefs to rehabilitate depleted fish stocks. … … … … … … … … [4] [Total: 15]

15 marks

This question in 9693/40 Oct/Nov 2020

5 High protein feed is often used in aquaculture. It can cause the release of large quantities of urea into water. Urea is a nitrogen-containing compound that is excreted by many organisms and is also released from the breakdown of protein by decomposers. When urea enters marine waters, it can affect the growth of dinoflagellates and other algae. (a) Fig. 5.1 shows a light micrograph of a dinoflagellate. Fig. 5.1 Make a large drawing of the dinoflagellate in Fig. 5.1. Do not label or shade your diagram. [3] (b) To investigate the effect of urea from high protein feed, scientists analysed the water in a sea bass farm 21 times over a period of six months. Each time the water was analysed, the urea concentration and presence or absence of an algal bloom was assessed. The concentration of urea was assessed as either less than or equal to 1.5 μmol dm–3 or greater than 1.5 μmol dm–3. The results are shown in Table 5.1. Table 5.1 urea concentration number of times water contained number of times algal / μmol dm–3 urea of this concentration bloom occurred less than or equal to 1.5 7 1 greater than 1.5 14 10 (i) Calculate as a percentage the number of times that water with a urea concentration of greater than 1.5 μmol dm–3 also had an algal bloom. … % [1] (ii) Describe the relationship between the different concentrations of urea and the occurrence of the algal blooms. … … [1] (iii) Scientists claimed that the results showed that adding excess protein feed caused algal blooms. Evaluate this conclusion. … … … … … … [3] (c) Give two requirements for the long-term sustainability of an aquaculture venture. 1 … … 2 … … [2] [Total: 10]

10 marks

Mark scheme: 5(a) 1 clear, complete outline of structure with four ‘spikes’ and the flagellum and at least same size as photo ; 2 lines thin, continuous and no shading ; 3 correct proportions and angles of body, spikes and flagellum ; 3 5(b)(i) 71(.4…) (%) ; 1 5(b)(ii) any 1 from: 1 algal blooms are most likely to happen when the concentration is greater than 1.5 (mmol dm–3) / AW ; 2 correlation between urea concentration and chance of an algal bloom ; 3 as urea concentration increases there are more (algal) blooms / AW ; 1 5(b)(iii) 1 high protein / feed, causes high urea concentrations / releases urea / causes organisms to release urea / AW ; 2 there are more blooms when urea (concentration) is higher / more / ORA ; max 2 from: 3 it is a correlation not causation ; 4 other factors may cause the blooms ; 5 urea may not be from the protein feed / or from other sources ; 3 Question Answer Marks 5(c) any 2 from: 1 (availability of) stock ; 2 (availability of) clean water ; 3 (availability of) feed ; 4 efficiency of use of feed : 5 (availability of) labour / people to work there / people to run it ; 6 disease management / AW ; 7 cleaning / filtering of waste water (so environment is not polluted) ; 8 (availability of) location ; 9 market demand / AW ; 10 access to market / ability to transport to markets ; 11 return on investment / profitability ; 2

This question in 9693/41 May/June 2022

5 Gill nets are fishing nets that are often anchored underwater for 24 hours before being checked for the catch. Fish are caught by becoming entangled in the nets. Bonefish are a species of fish that is caught commercially by using gill nets in many areas of the Pacific Ocean. The use of gill nets was banned around some islands of Hawaii in 2004 to make fishing more sustainable. Fig. 5.1 shows the total catch of bonefish around an island where the use of gill nets was banned over a 13-year period. 7000 6000 5000 4000 total catch of bonefish / kg 3000 2000 1000 0 2000 2001 2002 2003 2004 2005 2006 2007 2008 2009 2010 2011 2012 year Fig. 5.1 (a) (i) Outline the general trends in total catch of bonefish between 2000 and 2012, shown in Fig. 5.1. … … … … [2] (ii) Give one other tool, other than restricting fishing gear, that can be used to ensure that fisheries are exploited sustainably. … … [1] (b) In 2012, scientists investigated the sizes of the bonefish around the island where the use of gill nets was banned. They estimated the ratio of the number of bonefish in four length categories that would be required for a sustainable population. The expected ratios for the different length categories are shown in Table 5.1. Table 5.1 fish length category / cm <15 15 – 35 36 – 75 >75 ratio 5 4 2 1 A sample of 1500 bonefish was caught. A chi-squared test was carried out to see if the numbers of fish caught in the sample fitted the expected ratios for a sustainable population. The results are shown in Table 5.2. Table 5.2 length expected number of expected (O – E) (O – E)2 (O – E)2 category ratio bonefish in number of E / cm sample (O) fish (E) < 15 5 605 625 –20 400 0.64 15 – 35 4 485 500 –15 225 0.45 36 – 75 2 265 250 15 225 0.90 > 75 1 145 (i) Give a null hypothesis for the investigation. … … [1] (ii) Complete Table 5.2. [1] (iii) Calculate the value of chi-squared using the formula below: – E)2 χ 2 = Σ (O E χ 2 = chi-squared O = observed value E = expected value … [1] (iv) Table 5.3 is a critical value table for chi-squared. Table 5.3 p value degrees of freedom 0.900 0.500 0.100 0.050 0.010 1 0.016 0.455 2.706 3.841 6.635 2 0.211 1.386 4.605 5.991 9.210 3 0.584 2.366 6.251 7.815 11.345 4 1.064 3.357 7.779 9.488 13.277 Use Table 5.3 and your answer to (b)(iii) to assess if the fish population is sustainable. … … … … … … [3] (c) Use the information in Fig. 5.1, Table 5.2, and your answer to (b)(iv) to suggest an explanation for the effect of the ban on gill nets on bonefish catches. … … … … [2]

11 marks

Mark scheme: 5(a)(i) falls until 2005 then increases ; 2 detail e.g. decrease in 2010 / highest catch 2012 / increase to a higher level than at the start / overall increase from 2000 to 2012 ; 5(a)(ii) any 1 from: 1 restriction by season ; restriction by quotas ; restriction by licensing ; boat size ; restriction of location / refuge zones / no-take zones / marine protected areas (MPAs) ; restrictions on the size of organism ; restriction of intensity ; monitoring / logging boats ; 5(b)(i) there is no difference between the ratios of the fish in each lengths category in the sample compared to the expected 1 ratios / AW ; 5(b)(ii) 1 length number of expected 2 Expected (O − E ) category bone fish in number of ( O − E ) (O − E ) 2 ratio / cm sample (O) fish (E) E < 15 5 605 625 -20 400 0.64 15 – 35 4 485 500 -15 225 0.45 36 – 75 2 265 250 15 225 0.9 > 75 1 145 125 20 400 3.2 ; 5(b)(iii) 5.19 ; 1 5(b)(iv) any 3 from: 3 there is no significant difference (in the observed numbers and the expected numbers) ; the null hypothesis is accepted / the population is sustainable ; the calculated value is less than the critical value / less than 7.815 ; there is a probability of greater than 0.05 / 5% that the difference is due to chance ; 5(c) any 2 from: 2 increase population of bonefish / more larger fish / AW ; fish live longer / reach maturity ; more fish able to breed (so population increases) ;

This question in 9693/41 Oct/Nov 2022

5 Gill nets are fishing nets that are often anchored underwater for 24 hours before being checked for the catch. Fish are caught by becoming entangled in the nets. Bonefish are a species of fish that is caught commercially by using gill nets in many areas of the Pacific Ocean. The use of gill nets was banned around some islands of Hawaii in 2004 to make fishing more sustainable. Fig. 5.1 shows the total catch of bonefish around an island where the use of gill nets was banned over a 13-year period. 7000 6000 5000 4000 total catch of bonefish / kg 3000 2000 1000 0 2000 2001 2002 2003 2004 2005 2006 2007 2008 2009 2010 2011 2012 year Fig. 5.1 (a) (i) Outline the general trends in total catch of bonefish between 2000 and 2012, shown in Fig. 5.1. … … … … [2] (ii) Give one other tool, other than restricting fishing gear, that can be used to ensure that fisheries are exploited sustainably. … … [1] (b) In 2012, scientists investigated the sizes of the bonefish around the island where the use of gill nets was banned. They estimated the ratio of the number of bonefish in four length categories that would be required for a sustainable population. The expected ratios for the different length categories are shown in Table 5.1. Table 5.1 fish length category / cm <15 15 – 35 36 – 75 >75 ratio 5 4 2 1 A sample of 1500 bonefish was caught. A chi-squared test was carried out to see if the numbers of fish caught in the sample fitted the expected ratios for a sustainable population. The results are shown in Table 5.2. Table 5.2 length expected number of expected (O – E) (O – E)2 (O – E)2 category ratio bonefish in number of E / cm sample (O) fish (E) < 15 5 605 625 –20 400 0.64 15 – 35 4 485 500 –15 225 0.45 36 – 75 2 265 250 15 225 0.90 > 75 1 145 (i) Give a null hypothesis for the investigation. … … [1] (ii) Complete Table 5.2. [1] (iii) Calculate the value of chi-squared using the formula below: – E)2 χ 2 = Σ (O E χ 2 = chi-squared O = observed value E = expected value … [1] (iv) Table 5.3 is a critical value table for chi-squared. Table 5.3 p value degrees of freedom 0.900 0.500 0.100 0.050 0.010 1 0.016 0.455 2.706 3.841 6.635 2 0.211 1.386 4.605 5.991 9.210 3 0.584 2.366 6.251 7.815 11.345 4 1.064 3.357 7.779 9.488 13.277 Use Table 5.3 and your answer to (b)(iii) to assess if the fish population is sustainable. … … … … … … [3] (c) Use the information in Fig. 5.1, Table 5.2, and your answer to (b)(iv) to suggest an explanation for the effect of the ban on gill nets on bonefish catches. … … … … [2]

11 marks

Mark scheme: 5(a)(i) falls until 2005 then increases ; 2 detail e.g. decrease in 2010 / highest catch 2012 / increase to a higher level than at the start / overall increase from 2000 to 2012 ; 5(a)(ii) any 1 from: 1 restriction by season ; restriction by quotas ; restriction by licensing ; boat size ; restriction of location / refuge zones / no-take zones / marine protected areas (MPAs) ; restrictions on the size of organism ; restriction of intensity ; monitoring / logging boats ; 5(b)(i) there is no difference between the ratios of the fish in each lengths category in the sample compared to the expected 1 ratios / AW ; 5(b)(ii) 1 length number of expected 2 Expected (O − E ) category bone fish in number of ( O − E ) (O − E ) 2 ratio / cm sample (O) fish (E) E < 15 5 605 625 -20 400 0.64 15 – 35 4 485 500 -15 225 0.45 36 – 75 2 265 250 15 225 0.9 > 75 1 145 125 20 400 3.2 ; 5(b)(iii) 5.19 ; 1 5(b)(iv) any 3 from: 3 there is no significant difference (in the observed numbers and the expected numbers) ; the null hypothesis is accepted / the population is sustainable ; the calculated value is less than the critical value / less than 7.815 ; there is a probability of greater than 0.05 / 5% that the difference is due to chance ; 5(c) any 2 from: 2 increase population of bonefish / more larger fish / AW ; fish live longer / reach maturity ; more fish able to breed (so population increases) ;

This question in 9693/42 Oct/Nov 2022

5 Gill nets are fishing nets that are often anchored underwater for 24 hours before being checked for the catch. Fish are caught by becoming entangled in the nets. Bonefish are a species of fish that is caught commercially by using gill nets in many areas of the Pacific Ocean. The use of gill nets was banned around some islands of Hawaii in 2004 to make fishing more sustainable. Fig. 5.1 shows the total catch of bonefish around an island where the use of gill nets was banned over a 13-year period. 7000 6000 5000 4000 total catch of bonefish / kg 3000 2000 1000 0 2000 2001 2002 2003 2004 2005 2006 2007 2008 2009 2010 2011 2012 year Fig. 5.1 (a) (i) Outline the general trends in total catch of bonefish between 2000 and 2012, shown in Fig. 5.1. … … … … [2] (ii) Give one other tool, other than restricting fishing gear, that can be used to ensure that fisheries are exploited sustainably. … … [1] (b) In 2012, scientists investigated the sizes of the bonefish around the island where the use of gill nets was banned. They estimated the ratio of the number of bonefish in four length categories that would be required for a sustainable population. The expected ratios for the different length categories are shown in Table 5.1. Table 5.1 fish length category / cm <15 15 – 35 36 – 75 >75 ratio 5 4 2 1 A sample of 1500 bonefish was caught. A chi-squared test was carried out to see if the numbers of fish caught in the sample fitted the expected ratios for a sustainable population. The results are shown in Table 5.2. Table 5.2 length expected number of expected (O – E) (O – E)2 (O – E)2 category ratio bonefish in number of E / cm sample (O) fish (E) < 15 5 605 625 –20 400 0.64 15 – 35 4 485 500 –15 225 0.45 36 – 75 2 265 250 15 225 0.90 > 75 1 145 (i) Give a null hypothesis for the investigation. … … [1] (ii) Complete Table 5.2. [1] (iii) Calculate the value of chi-squared using the formula below: – E)2 χ 2 = Σ (O E χ 2 = chi-squared O = observed value E = expected value … [1] (iv) Table 5.3 is a critical value table for chi-squared. Table 5.3 p value degrees of freedom 0.900 0.500 0.100 0.050 0.010 1 0.016 0.455 2.706 3.841 6.635 2 0.211 1.386 4.605 5.991 9.210 3 0.584 2.366 6.251 7.815 11.345 4 1.064 3.357 7.779 9.488 13.277 Use Table 5.3 and your answer to (b)(iii) to assess if the fish population is sustainable. … … … … … … [3] (c) Use the information in Fig. 5.1, Table 5.2, and your answer to (b)(iv) to suggest an explanation for the effect of the ban on gill nets on bonefish catches. … … … … [2]

11 marks

Mark scheme: 5(a)(i) falls until 2005 then increases ; 2 detail e.g. decrease in 2010 / highest catch 2012 / increase to a higher level than at the start / overall increase from 2000 to 2012 ; 5(a)(ii) any 1 from: 1 restriction by season ; restriction by quotas ; restriction by licensing ; boat size ; restriction of location / refuge zones / no-take zones / marine protected areas (MPAs) ; restrictions on the size of organism ; restriction of intensity ; monitoring / logging boats ; 5(b)(i) there is no difference between the ratios of the fish in each lengths category in the sample compared to the expected 1 ratios / AW ; 5(b)(ii) 1 length number of expected 2 Expected (O − E ) category bone fish in number of ( O − E ) (O − E ) 2 ratio / cm sample (O) fish (E) E < 15 5 605 625 -20 400 0.64 15 – 35 4 485 500 -15 225 0.45 36 – 75 2 265 250 15 225 0.9 > 75 1 145 125 20 400 3.2 ; 5(b)(iii) 5.19 ; 1 5(b)(iv) any 3 from: 3 there is no significant difference (in the observed numbers and the expected numbers) ; the null hypothesis is accepted / the population is sustainable ; the calculated value is less than the critical value / less than 7.815 ; there is a probability of greater than 0.05 / 5% that the difference is due to chance ; 5(c) any 2 from: 2 increase population of bonefish / more larger fish / AW ; fish live longer / reach maturity ; more fish able to breed (so population increases) ;

This question in 9693/43 Oct/Nov 2022

2 (a) Scientists compared the sustainability of three different fishing methods for an Indian Ocean fishery. Table 2.1 shows the catch data for the different methods over one year. Table 2.1 fishing method total fishing time for all boats total mass of catch catch per unit effort / days / kg / kg day –1 purse seine 3140 105 234 33.510 rod‑and‑line 4100 30 677 7.480 spear fishing 111 516 (i) Calculate the catch per unit effort for spear fishing using the following formula. total mass of catch catch per unit effort (CPUE) = total fishing time for all boats Give your answer to four significant figures. … kg day –1 [2] (ii) The scientists suggested that the data in Table 2.1 show that rod‑and‑line fishing is more sustainable than purse seine fishing. Discuss the scientists’ suggestion, using the information in Table 2.1. … … … … … … [3] (b) The scientists investigated the type of fish caught by purse seine, and by rod‑and‑line. 500 fish were sampled from catches taken by purse seine, and 500 from catches by rod‑and‑line. Three factors were compared: • length of fish • number of different species of fish • proportion of juvenile fish in the catches. The results are shown in Table 2.2. Table 2.2 fishing method length of fish / cm number of percentage of different juvenile fish in mean standard standard species in catch catch (%) length deviation error purse seine 18 25 1.12 23 82 rod‑and‑line 75 11 9 35 The scientists calculated the mean lengths of the fish. They also calculated the 95% confidence intervals to compare the mean lengths of the fish caught by the two methods. (i) Give a null hypothesis to compare the mean lengths of fish caught by purse seine with fish caught by rod‑and‑line. … … [1] (ii) Use the formula to calculate the standard error of the mean length of fish caught by rod‑and‑line. s S M = n SM = standard error s = standard deviation n = sample size … cm [1] (iii) Use your answer to (b)(ii) to calculate the 95% confidence intervals for the mean length of fish caught by rod‑and‑line. 95% confidence interval (95% CI) = x ± (2 × SM) where x = mean SM = standard error … to … [1] (iv) The 95% confidence interval for the mean length of fish caught by purse seine is 15.76 cm to 20.24 cm. Use your answer to (b)(iii) to comment on the difference between the length of the fish caught by purse seine and the length of the fish caught by rod‑and‑line. … … … … … … [3] (v) Use the information in Table 2.2 to discuss the impact of purse seine fishing on fish stocks compared with rod‑and‑line fishing. … … … … … … [3] (c) State three restrictions that a government could place on purse seine fishing that would ensure that the fishery is exploited sustainably. 1 … … 2 … … 3 … … [3] [Total: 17]

17 marks

Mark scheme: 2(a)(i) one mark for correct division of 516 / 111 ; one mark for correct sig. figs. of 4.649 ; 2 2(a)(ii) any 3 of: rod and line takes fewer fish / purse seine fishing takes more fish ; catch per unit effort is lower for rod and line so this method is less efficient / takes less catch per trip / AW / ORA ; rod and line may catch fewer non-target species / less bycatch / ORA ; lower catch per unit effort over time may indicate that the stocks of fish caught by rod and line are lower in those areas / AW / ORA ; purse seine causes overfishing / takes more than MSY / depletes stocks / ORA ; AVP ; 3 2(b)(i) there is no difference in the mean length of fish caught by rod and line and the mean length of the fish caught by purse seine / AW ; 1 2(b)(ii) 0.49 ; 1 2(b)(iii) 74.02 (cm) to 75.98 (cm) ; 1 Question Answer Marks 2(b)(iv) any 3 of: 1 the null hypothesis is rejected ; 2 there is a probability of 0.05 that the difference in mean length is due to chance / AW ; 3 there is a (significant) difference in the mean lengths of the fish caught by rod-and-line and purse seine ; 4 as the confidence limits do not overlap ; 5 mean length caught by rod and line is greater than by purse seine ; 6 the range of sizes is greater / more variation for purse seine (as higher standard error) ; 3 2(b)(v) any 3 of: purse seine will lead to a fall in stocks / populations / overfishing / ORA ; more juvenile / immature, fish are caught/more fish are caught before they are mature / the mean length of fish is lower / smaller fish are caught / ORA ; less reproduction / fewer fish reproduce / fish caught before they can reproduce / less recruitment / ORA ; a wider variety of fish are caught by purse seine / more bycatch / more small fish species / bait fish / ORA ; affects food chains and food webs / loss of biodiversity / AW ; 3 Question Answer Marks 2(c) any 3 of: restricting seasons / times of year / AW ; restricting mesh sizes / bigger minimum mesh size ; catch quotas / restrict net sizes / catch up to MSY / licences / AW ; restricting areas / marine reserves / marine protected area / AW ; restricting size of fish / increase minimum fish length / AW ; use of licences / permits / AW ; restrict number of boats / fishing effort / hours at sea / fishing intensity / boat size / fleet size / AW ; 3

This question in 9693/42 May/June 2023

2 (a) Scientists compared the sustainability of three different fishing methods for an Indian Ocean fishery. Table 2.1 shows the catch data for the different methods over one year. Table 2.1 fishing method total fishing time for all boats total mass of catch catch per unit effort / days / kg / kg day –1 purse seine 3140 105 234 33.510 rod‑and‑line 4100 30 677 7.480 spear fishing 111 516 (i) Calculate the catch per unit effort for spear fishing using the following formula. total mass of catch catch per unit effort (CPUE) = total fishing time for all boats Give your answer to four significant figures. … kg day –1 [2] (ii) The scientists suggested that the data in Table 2.1 show that rod‑and‑line fishing is more sustainable than purse seine fishing. Discuss the scientists’ suggestion, using the information in Table 2.1. … … … … … … [3] (b) The scientists investigated the type of fish caught by purse seine, and by rod‑and‑line. 500 fish were sampled from catches taken by purse seine, and 500 from catches by rod‑and‑line. Three factors were compared: • length of fish • number of different species of fish • proportion of juvenile fish in the catches. The results are shown in Table 2.2. Table 2.2 fishing method length of fish / cm number of percentage of different juvenile fish in mean standard standard species in catch catch (%) length deviation error purse seine 18 25 1.12 23 82 rod‑and‑line 75 11 9 35 The scientists calculated the mean lengths of the fish. They also calculated the 95% confidence intervals to compare the mean lengths of the fish caught by the two methods. (i) Give a null hypothesis to compare the mean lengths of fish caught by purse seine with fish caught by rod‑and‑line. … … [1] (ii) Use the formula to calculate the standard error of the mean length of fish caught by rod‑and‑line. s S M = n SM = standard error s = standard deviation n = sample size … cm [1] (iii) Use your answer to (b)(ii) to calculate the 95% confidence intervals for the mean length of fish caught by rod‑and‑line. 95% confidence interval (95% CI) = x ± (2 × SM) where x = mean SM = standard error … to … [1] (iv) The 95% confidence interval for the mean length of fish caught by purse seine is 15.76 cm to 20.24 cm. Use your answer to (b)(iii) to comment on the difference between the length of the fish caught by purse seine and the length of the fish caught by rod‑and‑line. … … … … … … [3] (v) Use the information in Table 2.2 to discuss the impact of purse seine fishing on fish stocks compared with rod‑and‑line fishing. … … … … … … [3] (c) State three restrictions that a government could place on purse seine fishing that would ensure that the fishery is exploited sustainably. 1 … … 2 … … 3 … … [3] [Total: 17]

17 marks

Mark scheme: 2(a)(i) one mark for correct division of 516 / 111 ; one mark for correct sig. figs. of 4.649 ; 2 2(a)(ii) any 3 of: rod and line takes fewer fish / purse seine fishing takes more fish ; catch per unit effort is lower for rod and line so this method is less efficient / takes less catch per trip / AW / ORA ; rod and line may catch fewer non-target species / less bycatch / ORA ; lower catch per unit effort over time may indicate that the stocks of fish caught by rod and line are lower in those areas / AW / ORA ; purse seine causes overfishing / takes more than MSY / depletes stocks / ORA ; AVP ; 3 2(b)(i) there is no difference in the mean length of fish caught by rod and line and the mean length of the fish caught by purse seine / AW ; 1 2(b)(ii) 0.49 ; 1 2(b)(iii) 74.02 (cm) to 75.98 (cm) ; 1 Question Answer Marks 2(b)(iv) any 3 of: 1 the null hypothesis is rejected ; 2 there is a probability of 0.05 that the difference in mean length is due to chance / AW ; 3 there is a (significant) difference in the mean lengths of the fish caught by rod-and-line and purse seine ; 4 as the confidence limits do not overlap ; 5 mean length caught by rod and line is greater than by purse seine ; 6 the range of sizes is greater / more variation for purse seine (as higher standard error) ; 3 2(b)(v) any 3 of: purse seine will lead to a fall in stocks / populations / overfishing / ORA ; more juvenile / immature, fish are caught/more fish are caught before they are mature / the mean length of fish is lower / smaller fish are caught / ORA ; less reproduction / fewer fish reproduce / fish caught before they can reproduce / less recruitment / ORA ; a wider variety of fish are caught by purse seine / more bycatch / more small fish species / bait fish / ORA ; affects food chains and food webs / loss of biodiversity / AW ; 3 Question Answer Marks 2(c) any 3 of: restricting seasons / times of year / AW ; restricting mesh sizes / bigger minimum mesh size ; catch quotas / restrict net sizes / catch up to MSY / licences / AW ; restricting areas / marine reserves / marine protected area / AW ; restricting size of fish / increase minimum fish length / AW ; use of licences / permits / AW ; restrict number of boats / fishing effort / hours at sea / fishing intensity / boat size / fleet size / AW ; 3

This question in 9693/43 May/June 2023

3 Aquaculture in coastal areas is used to produce large quantities of shrimp. Shrimp aquaculture can cause environmental pollution. Scientists are researching ways to make shrimp aquaculture more environmentally sustainable. (a) (i) Outline the process for aquaculture of shrimp. … … … … … … [3] (ii) Give two strategies that can be used to help ensure the long-term success of aquaculture. 1 … … 2 … … [2] (b) Mussels are filter-feeding organisms that consume microalgae and other organic waste. Wastewater from shrimp aquaculture sites contains large amounts of ammonium ions that pollute the sea. The ammonium ions are converted to nitrate ions by bacteria. Scientists investigated the effects of growing mussels and adding microalgae on the removal of nitrate ions from wastewater produced by shrimp aquaculture. • Wastewater from a shrimp aquaculture site was collected and placed into tanks. • Different densities of mussels were added to the tanks. • The same mass of microalgae was added to each tank. • The nitrate ion concentration of the water was measured at the start and every day for the next six days. The results are shown in Fig. 3.1. 3.0 8 mussels 2.5 per square metre 2.0 nitrate ion concentration 1.5 no mussels / mg dm–3 1.0 4 mussels per square 0.5 metre 0 0 1 2 3 4 5 6 time / days Fig. 3.1 (i) Calculate the mean rate of change of nitrate ion concentration with no mussels over the six-day period. State the unit. Show your working. … [3] (ii) Describe the effects of adding different densities of mussels on the removal of nitrate ions from the water over the six-day period. … … … … … … [3] (c) The scientists also measured dissolved oxygen concentration in the water every day for the six days. The results are shown in Fig. 3.2. 12 10 8 dissolved oxygen 6 no musselsconcentration / mg dm–3 4 mussels 4 per square metre 8 mussels 2 per square metre 0 0 1 2 3 4 5 6 time / days Fig. 3.2 (i) The same mass of microalgae was added to each tank at the start. Explain the change in dissolved oxygen concentration in the water up to day three when microalgae were present with no mussels. … … … … [2] (ii) Ammonium ions are converted into nitrate ions by bacteria in the water. Nitrate ions are absorbed by algae. Mussels consume algae. Discuss the effects of adding different densities of mussels on the changes in concentration of oxygen and nitrate ions in the water. Use the information in Fig. 3.1 and Fig. 3.2 to support your answer. … … … … … … … … [4] [Total: 17]

17 marks

Mark scheme: 3(a)(i) any 3 of: 1 eggs placed / larvae grown in indoor tanks / AW ; 2 sterile conditions / AW ; 3 (postlarvae) transferred to nurseries / nursery tanks ; 4 (post)larvae / juveniles, transferred into raceway ponds / outdoor pools / natural water / growout pools / AW ; 5 feed / algae provided / AW ; 6 AVP ; 3(a)(ii) any 2 of: 1 availability of stock / AW ; 2 availability of clean water / water purification / remove wastes / AW ; 3 availability of feed / AW ; 4 efficiency of use of feed / use high quality feed / AW ; 5 availability of labour / AW ; 6 disease management / AW ; 7 availability of location / space / AW ; 8 (market) demand / AW ; 9 access to markets / transport / AW ; 10 return on investment / profit making / money to reinvest / AW ; 2 3(b)(i) 0.083 ;; (two marks) 2(.00) – 1.5(0) or 1.5 – 2 or 0.5 or ÷ 6 (for one mark only) mg dm-3 day-1 ; 3 3(b)(ii) any 3 of: 1 with no mussels, there is a (steady) decrease ; 2 with four mussels there is a greater / steeper / AW, decrease ; 3 with eight mussels there is decrease up to 2 days and then an increase ; 4 correctly manipulated data ; 3 Question Answer Marks 3(c)(i) any 2 of: 1 algae photosynthesise ; 2 photosynthesis / algae, produce / release oxygen ; 3 algae increase in population (as they absorb nitrate ions) ; 4 no / less, respiration (from mussels) (to remove oxygen) ; 2 3(c)(ii) any 4 of: 1 oxygen decreases more with 8 mussels / AW ; 2 nitrate increases with 8 mussels / AW ; 3 more / many algae consumed / AW, with 8 mussels ; 4 less nitrate removed / absorbed by algae (with 8 mussels) ; 5 faeces / waste, decomposes / decays / AW ; 6 respiration (by mussels / bacteria) removes oxygen ; 7 less photosynthesis to release oxygen with 8 mussels ; 4

This question in 9693/41 May/June 2024

3 Dublin Bay prawns, Nephrops sp., are crustaceans often caught by using bottom trawling. Fig. 3.1 shows the method of bottom trawling used. Fig. 3.1 Haddock is a fish that is an important species for fisheries in the north Atlantic Ocean. The effect of Nephrops fishing on haddock populations was investigated in an area of the Atlantic Ocean where Nephrops trawling was started in the year 2000. Between 1990 and 2020, scientists recorded: • number of haddock per square kilometre • mean length of female haddock • percentage of two-year-old female haddock that were sexually mature. The results are shown in Table 3.1. Table 3.1 year number of haddock mean length of female percentage of two‑year‑old per square kilometre haddock / cm female haddock that were sexually mature 1990 100 27 56 1995 120 28 2000 90 23 65 2005 120 19 2010 110 17 88 2015 140 16 2020 130 15 92 (a) (i) Draw a line graph to show the changes in number of haddock per square kilometre and mean length of female haddock between 1990 and 2020. Join your points with straight, ruled lines. [5] (ii) Suggest an explanation for the effect of Nephrops fishing since 2000 on the change in mean length of female haddock. … … … … [2] (iii) Some scientists claimed that the modal length of fish would be a better measure of the average length of female fish. State what information the modal length of female fish would show. … … [1] (iv) Use all the information provided to discuss whether Nephrops fishing affects the population of haddock. … … … … … … … … [4] (b) The regulations for bottom trawling for Nephrops state that the minimum mesh size must be between 7.0 cm and 9.5 cm. Describe how restrictions on fishing methods can be monitored and enforced. … … … … … … [3] [Total: 15]

15 marks

Mark scheme: 3(a)(i) linear scales for all three axes and both lines must cover at least three large squares ; labels and unit on all axes ; plots correct ; points joined by straight lines ; lines have a key ; 5 3(a)(ii) any 2 of: 1 female fish size decreases ; 2 as larger fish are trapped in the mesh / smaller fish pass through the mesh / larger fish are caught / AW ; 3 so the number of larger fish in sea decreases / proportion of smaller fish in sea increases / AW ; 2 3(a)(iii) the most frequent size of female fish / size of most fish / commonest length / AW ; 1 3(a)(iv) any 4 of: 1 population of haddock increases / AW ; 2 (but mean) size of fish decreases / AW ; 3 percentage of female fish that are mature at 2 years increases / AW ; 4 younger fish are reproducing / younger fish become sexually mature younger / AW ; 5 age profile of haddock has changed / fewer older fish / more younger fish ; 6 higher fecundity / recruitment ; 4 Question Answer Marks 3(b) any 3 of: max 2 of: 1 satellite tracking / AW ; 2 patrol boats / checking at quayside / checking when ashore / observe with helicopters / AW ; 3 inspections of gear / catch ; max 2 of: 4 fines ; 5 impounding gear / confiscating boats / confiscating equipment ; 6 imprisonment ; 3

This question in 9693/42 May/June 2024

4 The effect of a no-take zone on the sustainability of fish populations and the income of fishers (number of people fishing) was investigated in an Indian Ocean fishery near Kenya. The sustainability of fish stocks was measured by calculating the catch per unit effort (CPUE). A high CPUE was taken as an indicator of a sustainable fish population. Two similar fishing grounds were compared: • area A: an area with a central no-take zone • area B: an area where no restrictions were placed on fishing. The CPUE was measured in both areas for a period of eight years. The results are shown in Fig. 4.1. 4.5 4.0 area A 3.5 3.0 catch per unit effort 2.5 / kg fisher–1 day–1 2.0 1.5 area B 1.0 0.5 0.0 0 1 2 3 4 5 6 7 8 year Fig. 4.1 (a) (i) The CPUE was calculated using the following formula: catch in kg catch per unit effort (CPUE) = number of days fishing × number of fishers Evaluate the accuracy of using catch per unit effort as a measure of the sustainability of the fish populations. … … … … [2] (ii) Use Fig. 4.1 to describe the effects of the no-take zone on the sustainability of fish populations. … … … … [2] (iii) Suggest explanations for the change in CPUE after the introduction of the no-take zone. … … … … … … [3] (b) The effect of the no-take zone on the income of fishers was also investigated. Table 4.1 shows the mean income of each fisher per month for area A with the no-take zone. Table 4.1 years after restrictions income / US$ per fisher per month 0 240 1 225 2 250 3 400 4 425 5 410 6 465 7 525 8 520 To see if there is a correlation between the CPUE and the income of the fishers, a Spearman’s rank correlation coefficient was calculated. (i) Give a null hypothesis for the investigation. … … [1] Some of the steps of the calculation are shown in Table 4.2. Table 4.2 CPUE income / kg per / US$ per rankyear rank CPUE D D2 fisher per fisher per income day month 0 2.5 9 240 8 1 1 1 2.7 8 225 9 –1 1 2 3.0 7 250 7 0 0 3 3.1 5.5 400 6 –0.5 0.25 4 3.1 5.5 425 4 1.5 2.25 5 3.8 410 5 6 3.7 4 465 3 1 1 7 3.8 525 1 8 3.9 1 520 2 –1 1 (ii) Complete Table 4.2. [1] (iii) Use the data in Table 4.2 and the formula below to calculate the Spearman’s rank correlation coefficient for the data in Table 4.1. 6 × ΣD2 rs = 1 –  n3 – n  rs = Spearman’s rank correlation coefficient Σ = sum of (total) D = difference in rank between each pair of measurements n = number of pairs of items in the sample Show your working. … [2] (iv) Table 4.3 shows the critical values for Spearman’s rank correlation coefficient. Table 4.3 number of pairs, n rs (P < 0.05) 5 1.000 6 0.886 7 0.786 8 0.738 9 0.700 10 0.648 11 0.618 Use your calculated value from (b)(iii) and values from Table 4.3 to determine whether there is a significant correlation between the CPUE and income of the fishers. Justify your conclusion. … … … … … … [3] (v) Explain the sociological impacts of restrictions on fishing. … … … … … … … … [4] [Total: 18]

18 marks

Mark scheme: 4(a)(i) any 2 of: accurate because (max 1): 1 if fish populations are high, catch will be high / ORA / AW ; 2 number of fish caught represents the populations / AW ; 3 idea that data is standardised (so easy to compare) ; not accurate because (max 1): 4 other factors affect effort /effort is not just number of days and number of fishers / AW ; 5 ignores bycatch / dumped fish / AW ; 6 boats sizes may vary / fishing gear / methods vary / time actually spent fishing may vary AW ; 7 illegal fishing may occur / some catches are not recorded / AW ; 8 not all fish in the population are not caught / AW ; 9 other factors influence fish populations / fish may migrate / fish populations are seasonal / AW ; 2 4(a)(ii) any 2 of: 1 in Area A / no take zone, CPUE increases / fish population is more sustainable / AW ; 2 steep / AW, increase, between 4 and 5 years / after 4 years ; 3 compared with in Area B / fished area, where CPUE / population falls / population is less sustainable / AW ; 2 Question Answer Marks 4(a)(iii) any 3 of: 1 no-take zone is a breeding area / nursery area / AW ; 2 more food in zone / more prey in zone / AW ; 3 allows fish to reach maturity / reproductive age / AW ; 4 fish travel out of zone into fishing areas (so catches rise) / AW ; 5 less damage to habitats from fishing / AW ; 3 4(b)(i) there is no correlation / association, between CPUE and income ; 1 4(b)(ii) year CPUE / k g per fish er per da y rank CPUE income / US$ per fi sher per month rank income D D2 0 2.5 9 240 8 1 1 1 2.7 8 225 9 -1 1 2 3.0 7 250 7 0 0 3 3.1 5.5 400 6 -0.5 0.25 4 3.1 5.5 425 4 1.5 2.25 5 3.8 2.5 410 5 -2.5 6.25 6 3.7 4 465 3 1 1 7 3.8 2.5 525 1 1.5 2.25 ; 8 3.9 1 520 2 -1 1 1 4(b)(iii) ∑𝐷ଶ= 15 ; 0.875 ; 2 Question Answer Marks 4(b)(iv) any 3 of: 1 there is a significant positive correlation / association ; 2 the calculated value of the coefficient is greater than the critical value ; 3 0.7 is the critical value ; 4 there is a probability of less than, 0.5 / 5%, that the association is due to chance ; 5 the null hypothesis is rejected ; 3 4(b)(v) any 4 of: max 3 of (long term): 1 unemployment for short term / loss of income / fewer fishers / AW ; 2 loss of living standards lack of purchasing power / poverty / AW ; 3 unable to buy food / malnutrition due to lack of money / AW ; 4 loss of traditional ways of life / AW ; 5 migration of people away from area / AW ; 6 loss of services / schools / secondary industries / loss of businesses / loss of boat builders / harbour services / AW ; 7 increase in illegal activities / illegal fishing / AW ; 8 conflict / tension, against authorities / AW ; max 3 of (short term): 9 fishing is sustainable ; 10 secures food for future / AW ; 11 long term employment secured / job security / future generations will be able to fish / AW ; 12 new job opportunities / people retrain into new careers / AW ; 4

This question in 9693/42 May/June 2024

3 Dublin Bay prawns, Nephrops sp., are crustaceans often caught by using bottom trawling. Fig. 3.1 shows the method of bottom trawling used. Fig. 3.1 Haddock is a fish that is an important species for fisheries in the north Atlantic Ocean. The effect of Nephrops fishing on haddock populations was investigated in an area of the Atlantic Ocean where Nephrops trawling was started in the year 2000. Between 1990 and 2020, scientists recorded: • number of haddock per square kilometre • mean length of female haddock • percentage of two-year-old female haddock that were sexually mature. The results are shown in Table 3.1. Table 3.1 year number of haddock mean length of female percentage of two‑year‑old per square kilometre haddock / cm female haddock that were sexually mature 1990 100 27 56 1995 120 28 2000 90 23 65 2005 120 19 2010 110 17 88 2015 140 16 2020 130 15 92 (a) (i) Draw a line graph to show the changes in number of haddock per square kilometre and mean length of female haddock between 1990 and 2020. Join your points with straight, ruled lines. [5] (ii) Suggest an explanation for the effect of Nephrops fishing since 2000 on the change in mean length of female haddock. … … … … [2] (iii) Some scientists claimed that the modal length of fish would be a better measure of the average length of female fish. State what information the modal length of female fish would show. … … [1] (iv) Use all the information provided to discuss whether Nephrops fishing affects the population of haddock. … … … … … … … … [4] (b) The regulations for bottom trawling for Nephrops state that the minimum mesh size must be between 7.0 cm and 9.5 cm. Describe how restrictions on fishing methods can be monitored and enforced. … … … … … … [3] [Total: 15]

15 marks

Mark scheme: 3(a)(i) linear scales for all three axes and both lines must cover at least three large squares ; labels and unit on all axes ; plots correct ; points joined by straight lines ; lines have a key ; 5 3(a)(ii) any 2 of: 1 female fish size decreases ; 2 as larger fish are trapped in the mesh / smaller fish pass through the mesh / larger fish are caught / AW ; 3 so the number of larger fish in sea decreases / proportion of smaller fish in sea increases / AW ; 2 3(a)(iii) the most frequent size of female fish / size of most fish / commonest length / AW ; 1 3(a)(iv) any 4 of: 1 population of haddock increases / AW ; 2 (but mean) size of fish decreases / AW ; 3 percentage of female fish that are mature at 2 years increases / AW ; 4 younger fish are reproducing / younger fish become sexually mature younger / AW ; 5 age profile of haddock has changed / fewer older fish / more younger fish ; 6 higher fecundity / recruitment ; 4 Question Answer Marks 3(b) any 3 of: max 2 of: 1 satellite tracking / AW ; 2 patrol boats / checking at quayside / checking when ashore / observe with helicopters / AW ; 3 inspections of gear / catch ; max 2 of: 4 fines ; 5 impounding gear / confiscating boats / confiscating equipment ; 6 imprisonment ; 3

This question in 9693/43 May/June 2024

4 The effect of a no-take zone on the sustainability of fish populations and the income of fishers (number of people fishing) was investigated in an Indian Ocean fishery near Kenya. The sustainability of fish stocks was measured by calculating the catch per unit effort (CPUE). A high CPUE was taken as an indicator of a sustainable fish population. Two similar fishing grounds were compared: • area A: an area with a central no-take zone • area B: an area where no restrictions were placed on fishing. The CPUE was measured in both areas for a period of eight years. The results are shown in Fig. 4.1. 4.5 4.0 area A 3.5 3.0 catch per unit effort 2.5 / kg fisher–1 day–1 2.0 1.5 area B 1.0 0.5 0.0 0 1 2 3 4 5 6 7 8 year Fig. 4.1 (a) (i) The CPUE was calculated using the following formula: catch in kg catch per unit effort (CPUE) = number of days fishing × number of fishers Evaluate the accuracy of using catch per unit effort as a measure of the sustainability of the fish populations. … … … … [2] (ii) Use Fig. 4.1 to describe the effects of the no-take zone on the sustainability of fish populations. … … … … [2] (iii) Suggest explanations for the change in CPUE after the introduction of the no-take zone. … … … … … … [3] (b) The effect of the no-take zone on the income of fishers was also investigated. Table 4.1 shows the mean income of each fisher per month for area A with the no-take zone. Table 4.1 years after restrictions income / US$ per fisher per month 0 240 1 225 2 250 3 400 4 425 5 410 6 465 7 525 8 520 To see if there is a correlation between the CPUE and the income of the fishers, a Spearman’s rank correlation coefficient was calculated. (i) Give a null hypothesis for the investigation. … … [1] Some of the steps of the calculation are shown in Table 4.2. Table 4.2 CPUE income / kg per / US$ per rank year rank CPUE D D2 fisher per fisher per income day month 0 2.5 9 240 8 1 1 1 2.7 8 225 9 –1 1 2 3.0 7 250 7 0 0 3 3.1 5.5 400 6 –0.5 0.25 4 3.1 5.5 425 4 1.5 2.25 5 3.8 410 5 6 3.7 4 465 3 1 1 7 3.8 525 1 8 3.9 1 520 2 –1 1 (ii) Complete Table 4.2. [1] (iii) Use the data in Table 4.2 and the formula below to calculate the Spearman’s rank correlation coefficient for the data in Table 4.1. 6 × ΣD2 rs = 1 – 1 n3 – n 2 rs = Spearman’s rank correlation coefficient Σ = sum of (total) D = difference in rank between each pair of measurements n = number of pairs of items in the sample Show your working. … [2] (iv) Table 4.3 shows the critical values for Spearman’s rank correlation coefficient. Table 4.3 number of pairs, n rs (P < 0.05) 5 1.000 6 0.886 7 0.786 8 0.738 9 0.700 10 0.648 11 0.618 Use your calculated value from (b)(iii) and values from Table 4.3 to determine whether there is a significant correlation between the CPUE and income of the fishers. Justify your conclusion. … … … … … … [3] (v) Explain the sociological impacts of restrictions on fishing. … … … … … … … … [4] [Total: 18]

18 marks

Mark scheme: 4(a)(i) any 2 of: accurate because (max 1): 1 if fish populations are high, catch will be high / ORA / AW ; 2 number of fish caught represents the populations / AW ; 3 idea that data is standardised (so easy to compare) ; not accurate because (max 1): 4 other factors affect effort /effort is not just number of days and number of fishers / AW ; 5 ignores bycatch / dumped fish / AW ; 6 boats sizes may vary / fishing gear / methods vary / time actually spent fishing may vary AW ; 7 illegal fishing may occur / some catches are not recorded / AW ; 8 not all fish in the population are not caught / AW ; 9 other factors influence fish populations / fish may migrate / fish populations are seasonal / AW ; 2 4(a)(ii) any 2 of: 1 in Area A / no take zone, CPUE increases / fish population is more sustainable / AW ; 2 steep / AW, increase, between 4 and 5 years / after 4 years ; 3 compared with in Area B / fished area, where CPUE / population falls / population is less sustainable / AW ; 2 Question Answer Marks 4(a)(iii) any 3 of: 1 no-take zone is a breeding area / nursery area / AW ; 2 more food in zone / more prey in zone / AW ; 3 allows fish to reach maturity / reproductive age / AW ; 4 fish travel out of zone into fishing areas (so catches rise) / AW ; 5 less damage to habitats from fishing / AW ; 3 4(b)(i) there is no correlation / association, between CPUE and income ; 1 4(b)(ii) year CPUE / k g per fish er per da y rank CPUE income / US$ per fi sher per month rank income D D2 0 2.5 9 240 8 1 1 1 2.7 8 225 9 -1 1 2 3.0 7 250 7 0 0 3 3.1 5.5 400 6 -0.5 0.25 4 3.1 5.5 425 4 1.5 2.25 5 3.8 2.5 410 5 -2.5 6.25 6 3.7 4 465 3 1 1 7 3.8 2.5 525 1 1.5 2.25 ; 8 3.9 1 520 2 -1 1 1 4(b)(iii) ∑𝐷ଶ= 15 ; 0.875 ; 2 Question Answer Marks 4(b)(iv) any 3 of: 1 there is a significant positive correlation / association ; 2 the calculated value of the coefficient is greater than the critical value ; 3 0.7 is the critical value ; 4 there is a probability of less than, 0.5 / 5%, that the association is due to chance ; 5 the null hypothesis is rejected ; 3 4(b)(v) any 4 of: max 3 of (long term): 1 unemployment for short term / loss of income / fewer fishers / AW ; 2 loss of living standards lack of purchasing power / poverty / AW ; 3 unable to buy food / malnutrition due to lack of money / AW ; 4 loss of traditional ways of life / AW ; 5 migration of people away from area / AW ; 6 loss of services / schools / secondary industries / loss of businesses / loss of boat builders / harbour services / AW ; 7 increase in illegal activities / illegal fishing / AW ; 8 conflict / tension, against authorities / AW ; max 3 of (short term): 9 fishing is sustainable ; 10 secures food for future / AW ; 11 long term employment secured / job security / future generations will be able to fish / AW ; 12 new job opportunities / people retrain into new careers / AW ; 4

This question in 9693/43 May/June 2024

2 Plaice is a benthic flatfish caught by commercial fishing ships. Plaice gather in breeding areas during breeding seasons. Scientists investigated the effect of benthic trawling on the fishing mortality of plaice. The scientists determined the fishing mortality of male and female plaice of different ages during the breeding season and outside the breeding season. The results are shown in Fig. 2.1. during breeding season outside breeding season 0.4 0.4 Key male plaice female 0.3 0.3 plaice fishing fishing mortality mortality 0.2 0.2/ arbitrary / arbitrary units units 0.1 0.1 0.0 0.0 0 1 2 3 4 5 6 7 8 9 10 0 1 2 3 4 5 6 7 8 9 10 age of plaice / years age of plaice / years Fig. 2.1 (a) (i) Compare the fishing mortality of plaice during the breeding season and outside the breeding season. … … … … … … [3] (ii) Suggest a reason for the difference in fishing mortality of male and female plaice during the breeding season. … … [1] (iii) Suggest a reason for the difference in the fishing mortality of plaice during the breeding season and outside the breeding season. … … [1] (iv) Use Fig. 2.1 to explain why intensive harvesting of plaice during the breeding season would affect the sustainability of the population. … … … … … … [3] (b) In a further investigation, scientists investigated the gonadosomatic index (GSI) and price of plaice over a period of 48 weeks. Gonad tissues are ovaries and testes. Gonad tissue increases in size during breeding seasons. The gonadosomatic index (GSI) is the mass of gonad tissue divided by the total body mass. The results are shown in Table 2.1. Table 2.1 week mean gonadosomatic index mean price per kilogram (GSI) / USD ($) 1 0.14 1.8 12 0.03 2.5 24 0.02 3.4 36 0.03 3.8 48 0.10 2.1 (i) GSI is calculated using the formula: mass of gonad tissue GSI = total body mass Calculate the mass of gonad tissue in a plaice with a total body mass of 825 g caught during week 1. State the unit. … [2] (ii) Use Table 2.1 to draw a graph to show the GSI and price per kilogram of fish over the 48-week period. Join your points with straight, ruled lines. [6] (iii) Discuss the changes in GSI and the price of plaice over the 48-week period shown in Table 2.1 and the implications for the conservation of plaice. … … … … … … [3] [Total: 19]

19 marks

Mark scheme: 2(a)(i) any 3 of: 3 1 mortality is higher (for both) during breeding season / AW ; 2 mortality of males is higher than females during breeding season / AW ; 3 mortality of males and females is similar out of breeding season / AW ; 4 larger increase in mortality of males than females during breeding season (compared with out of season) / AW ; 5 both have low mortality for 0–1 years / mortality increases with age / lower mortality for younger fish / AW ; 6 correct manipulation of data ; 2(a)(ii) any 1 of: 1 female plaice are in deeper water / male plaice swim higher up the water column / males remain in the benthic area / ORA / AW ; males and females move to different, habitats / areas, (after breeding) / AW ; male plaice aggregate in same areas (after breeding) / ORA / AW ; male plaice are easier to catch / are targeted by fishers / females are put back by fishers / AW ; 2(a)(iii) any 1 of: 1 plaice (are aggregated) in one area (so are easier to find) / plaice area less dispersed / AW ; fishing boats target breeding areas / fishing occurs around breeding areas / AW ; 2(a)(iv) any 3 of: 3 1 overfishing will reduce population / less recruitment / reduced sustainability / AW ; 2 fewer older / mature fish / more immature / more younger fish / AW ; 3 imbalanced sex ratio / too few males / AW ; 4 so less breeding / fertilisation / lower fecundity / fewer eggs or sperm released / AW ; 5 AVP ; 2(b)(i) 115.5 ; 2 g ; 2(b)(ii) linear scales for both y axes and uses at least half of grid ; 6 all axes labelled ; accurate plots ;; points joined by straight lines ; key for lines ; 2(b)(iii) any 3 of: 3 1 lower price when GSI is high / ORA / AW ; 2 (may be due to) high catch rates before / during breeding season / price low when high catch / ORA / AW ; 3 (catches in breeding season causes) reduced reproduction / unsustainable fishing / population fall / less breeding / AW ; 4 should, ban / control, fishing during breeding season / AW ; 5 low price may be due to less demand for fish with high GSI / ORA ; 6 fish with high GSI may have lower meat content / poorer meat content / AW / ORA ;

This question in 9693/41 Oct/Nov 2024

2 Plaice is a benthic flatfish caught by commercial fishing ships. Plaice gather in breeding areas during breeding seasons. Scientists investigated the effect of benthic trawling on the fishing mortality of plaice. The scientists determined the fishing mortality of male and female plaice of different ages during the breeding season and outside the breeding season. The results are shown in Fig. 2.1. during breeding season outside breeding season 0.4 0.4 Key male plaice female 0.3 0.3 plaice fishing fishing mortality mortality 0.2 0.2/ arbitrary / arbitrary units units 0.1 0.1 0.0 0.0 0 1 2 3 4 5 6 7 8 9 10 0 1 2 3 4 5 6 7 8 9 10 age of plaice / years age of plaice / years Fig. 2.1 (a) (i) Compare the fishing mortality of plaice during the breeding season and outside the breeding season. … … … … … … [3] (ii) Suggest a reason for the difference in fishing mortality of male and female plaice during the breeding season. … … [1] (iii) Suggest a reason for the difference in the fishing mortality of plaice during the breeding season and outside the breeding season. … … [1] (iv) Use Fig. 2.1 to explain why intensive harvesting of plaice during the breeding season would affect the sustainability of the population. … … … … … … [3] (b) In a further investigation, scientists investigated the gonadosomatic index (GSI) and price of plaice over a period of 48 weeks. Gonad tissues are ovaries and testes. Gonad tissue increases in size during breeding seasons. The gonadosomatic index (GSI) is the mass of gonad tissue divided by the total body mass. The results are shown in Table 2.1. Table 2.1 week mean gonadosomatic index mean price per kilogram (GSI) / USD ($) 1 0.14 1.8 12 0.03 2.5 24 0.02 3.4 36 0.03 3.8 48 0.10 2.1 (i) GSI is calculated using the formula: mass of gonad tissue GSI = total body mass Calculate the mass of gonad tissue in a plaice with a total body mass of 825 g caught during week 1. State the unit. … [2] (ii) Use Table 2.1 to draw a graph to show the GSI and price per kilogram of fish over the 48-week period. Join your points with straight, ruled lines. [6] (iii) Discuss the changes in GSI and the price of plaice over the 48-week period shown in Table 2.1 and the implications for the conservation of plaice. … … … … … … [3] [Total: 19]

19 marks

Mark scheme: 2(a)(i) any 3 of: 3 1 mortality is higher (for both) during breeding season / AW ; 2 mortality of males is higher than females during breeding season / AW ; 3 mortality of males and females is similar out of breeding season / AW ; 4 larger increase in mortality of males than females during breeding season (compared with out of season) / AW ; 5 both have low mortality for 0–1 years / mortality increases with age / lower mortality for younger fish / AW ; 6 correct manipulation of data ; 2(a)(ii) any 1 of: 1 female plaice are in deeper water / male plaice swim higher up the water column / males remain in the benthic area / ORA / AW ; males and females move to different, habitats / areas, (after breeding) / AW ; male plaice aggregate in same areas (after breeding) / ORA / AW ; male plaice are easier to catch / are targeted by fishers / females are put back by fishers / AW ; 2(a)(iii) any 1 of: 1 plaice (are aggregated) in one area (so are easier to find) / plaice area less dispersed / AW ; fishing boats target breeding areas / fishing occurs around breeding areas / AW ; 2(a)(iv) any 3 of: 3 1 overfishing will reduce population / less recruitment / reduced sustainability / AW ; 2 fewer older / mature fish / more immature / more younger fish / AW ; 3 imbalanced sex ratio / too few males / AW ; 4 so less breeding / fertilisation / lower fecundity / fewer eggs or sperm released / AW ; 5 AVP ; 2(b)(i) 115.5 ; 2 g ; 2(b)(ii) linear scales for both y axes and uses at least half of grid ; 6 all axes labelled ; accurate plots ;; points joined by straight lines ; key for lines ; 2(b)(iii) any 3 of: 3 1 lower price when GSI is high / ORA / AW ; 2 (may be due to) high catch rates before / during breeding season / price low when high catch / ORA / AW ; 3 (catches in breeding season causes) reduced reproduction / unsustainable fishing / population fall / less breeding / AW ; 4 should, ban / control, fishing during breeding season / AW ; 5 low price may be due to less demand for fish with high GSI / ORA ; 6 fish with high GSI may have lower meat content / poorer meat content / AW / ORA ;

This question in 9693/42 Oct/Nov 2024

2 Plaice is a benthic flatfish caught by commercial fishing ships. Plaice gather in breeding areas during breeding seasons. Scientists investigated the effect of benthic trawling on the fishing mortality of plaice. The scientists determined the fishing mortality of male and female plaice of different ages during the breeding season and outside the breeding season. The results are shown in Fig. 2.1. during breeding season outside breeding season 0.4 0.4 Key male plaice female 0.3 0.3 plaice fishing fishing mortality mortality 0.2 0.2/ arbitrary / arbitrary units units 0.1 0.1 0.0 0.0 0 1 2 3 4 5 6 7 8 9 10 0 1 2 3 4 5 6 7 8 9 10 age of plaice / years age of plaice / years Fig. 2.1 (a) (i) Compare the fishing mortality of plaice during the breeding season and outside the breeding season. … … … … … … [3] (ii) Suggest a reason for the difference in fishing mortality of male and female plaice during the breeding season. … … [1] (iii) Suggest a reason for the difference in the fishing mortality of plaice during the breeding season and outside the breeding season. … … [1] (iv) Use Fig. 2.1 to explain why intensive harvesting of plaice during the breeding season would affect the sustainability of the population. … … … … … … [3] (b) In a further investigation, scientists investigated the gonadosomatic index (GSI) and price of plaice over a period of 48 weeks. Gonad tissues are ovaries and testes. Gonad tissue increases in size during breeding seasons. The gonadosomatic index (GSI) is the mass of gonad tissue divided by the total body mass. The results are shown in Table 2.1. Table 2.1 week mean gonadosomatic index mean price per kilogram (GSI) / USD ($) 1 0.14 1.8 12 0.03 2.5 24 0.02 3.4 36 0.03 3.8 48 0.10 2.1 (i) GSI is calculated using the formula: mass of gonad tissue GSI = total body mass Calculate the mass of gonad tissue in a plaice with a total body mass of 825 g caught during week 1. State the unit. … [2] (ii) Use Table 2.1 to draw a graph to show the GSI and price per kilogram of fish over the 48-week period. Join your points with straight, ruled lines. [6] (iii) Discuss the changes in GSI and the price of plaice over the 48-week period shown in Table 2.1 and the implications for the conservation of plaice. … … … … … … [3] [Total: 19]

19 marks

Mark scheme: 2(a)(i) any 3 of: 3 1 mortality is higher (for both) during breeding season / AW ; 2 mortality of males is higher than females during breeding season / AW ; 3 mortality of males and females is similar out of breeding season / AW ; 4 larger increase in mortality of males than females during breeding season (compared with out of season) / AW ; 5 both have low mortality for 0–1 years / mortality increases with age / lower mortality for younger fish / AW ; 6 correct manipulation of data ; 2(a)(ii) any 1 of: 1 female plaice are in deeper water / male plaice swim higher up the water column / males remain in the benthic area / ORA / AW ; males and females move to different, habitats / areas, (after breeding) / AW ; male plaice aggregate in same areas (after breeding) / ORA / AW ; male plaice are easier to catch / are targeted by fishers / females are put back by fishers / AW ; 2(a)(iii) any 1 of: 1 plaice (are aggregated) in one area (so are easier to find) / plaice area less dispersed / AW ; fishing boats target breeding areas / fishing occurs around breeding areas / AW ; 2(a)(iv) any 3 of: 3 1 overfishing will reduce population / less recruitment / reduced sustainability / AW ; 2 fewer older / mature fish / more immature / more younger fish / AW ; 3 imbalanced sex ratio / too few males / AW ; 4 so less breeding / fertilisation / lower fecundity / fewer eggs or sperm released / AW ; 5 AVP ; 2(b)(i) 115.5 ; 2 g ; 2(b)(ii) linear scales for both y axes and uses at least half of grid ; 6 all axes labelled ; accurate plots ;; points joined by straight lines ; key for lines ; 2(b)(iii) any 3 of: 3 1 lower price when GSI is high / ORA / AW ; 2 (may be due to) high catch rates before / during breeding season / price low when high catch / ORA / AW ; 3 (catches in breeding season causes) reduced reproduction / unsustainable fishing / population fall / less breeding / AW ; 4 should, ban / control, fishing during breeding season / AW ; 5 low price may be due to less demand for fish with high GSI / ORA ; 6 fish with high GSI may have lower meat content / poorer meat content / AW / ORA ;

This question in 9693/43 Oct/Nov 2024

5 Fig. 5.1 shows a photograph of Palau which is a nation located in the Pacific Ocean. Palau consists of a series of islands surrounded by a range of coral reefs. Fig. 5.1 Reef fish are an important part of the diet for local people in Palau. In 2017, fishing restrictions were implemented in Palau to make fishing sustainable. In some areas, all fishing was banned. (a) State two other important methods of restriction that could be used to ensure that the Palau fishery is sustainable. 1 … 2 … [2] (b) State one negative sociological impact on the people in Palau caused by restrictions on fishing. … … [1] (c) Scientists investigated the effect of the restrictions by sampling commercial species of reef fish in 2017 and 2019. In each year, fish were sampled at 150 sites around Palau by divers using cameras. The results are shown in Fig. 5.2 and Fig. 5.3. Fig. 5.2 shows the mean biomass of reef fish in 2017 and 2019. Fig. 5.3 shows the mean biomass of fish that are herbivores, fish that are secondary consumers, and high trophic level fish that consume other fish species, in 2017 and 2019. 30 25 20 mean fish 15 biomass / g m–2 10 5 0 2017 2019 year Fig. 5.2 12 Key 10 herbivore secondary consumer 8 high trophic level fish mean fish 6biomass / g m–2 4 2 0 2017 2019 year Fig. 5.3 Evaluate the effects of the fishing restrictions on the sustainability of the Palau fishery. Use Fig. 5.2 and Fig. 5.3 to support your answer. … … … … … … … … [4] [Total: 7]

7 marks

Mark scheme: 5(a) any 2 from: 2 1 method / net (volume) sizes / AW ; 2 season / time of year / breeding season / AW ; 3 location / area / breeding grounds / MPAs / AW ; 4 fishing intensity / fishing effort / boat days / boat sizes / AW ; 5 setting quotas / size of catch / / AW ; 6 fish size / set minimum sizes (that can be kept) / mesh size on net / age of fish / AW ; 7 licensing / AW ; 5(b) any 1 from: 1 • lack of food / starvation / malnutrition / lack of protein / AW ; • poverty / lack of income / AW ; • unemployment / lack of jobs / lack of work / AW ; • loss of services (in the area) / loss of tourism / AW ; • unable to care for families / AW ; • loss of culture / traditions / AW ; • conflict with government / authorities / AW ; • increased crime / more at risk of prosecutions / risk of fines / AW ; • AVP ; 5(c) any 4 from: 4 (at least 1 from) supported because 1 increase in (overall) biomass / increase in (biomass of), herbivores / secondary consumers / AW ; 2 significant increase in herbivores as error bars do not overlap / AW ; 3 more food for, secondary consumers / carnivores / higher trophic levels (due to more herbivores) / more energy for, secondary consumers / carnivores / higher trophic levels / AW ; 4 reliable / valid, as large sample size used / many areas used / AW ; (at least 1 from) not supported because 5 high trophic level fish is only a small increase / AW ; 6 error bars for high trophic level fish / secondary consumers / (overall) biomass, overlap so no significant difference / AW ; 7 large error bars suggests, wide variation / range (in biomass) / AW ; 8 only a short period of time (so not reliable) / no information about time of year / AW ; 9 no reference to, types of species / numbers of individual species / populations / AW ;

This question in 9693/41 May/June 2025

3 In 2004, purse seine fishing was banned in an Indian Ocean fishery. The impact of this ban on the mean length of grouper in the fishery was investigated. The mean lengths of grouper caught each year from 2002 to 2014 in this area and a similar area in which purse seine fishing continued were determined. The results are shown in Fig. 3.1. 620 grouper caught in area where 600 purse seine fishing was 580 banned in 2004mean length of grouper 560 / cm 540 grouper caught 520 in area where pursepurse seineseine purse seine fishingfishing bannedbanned fishing continued 500 2002 2004 2006 2008 2010 2012 2014 year Fig. 3.1 (a) (i) Summarise the effect of the ban on purse seine fishing on the mean lengths of grouper shown in Fig. 3.1. … … … … [2] (ii) Use Fig. 3.1 to explain how the ban on purse seine fishing would make fishing more sustainable. … … … … … … [3] (b) The impact of the ban on purse seine fishing on local communities was also investigated. The catch per unit effort (CPUE) and the mean daily income of fishers were determined between 2002 and 2014. The data are shown in Table 3.1. Table 3.1 year catch per unit effort (CPUE) mean daily income / kg per fisher per day / USD ($) per fisher per day 2002 3.6 10 2004 2.9 6 2006 3.0 8 2008 3.2 8 2010 3.6 10 2012 4.2 14 2014 4.2 16 (i) Draw a line graph to show the CPUE and mean daily income of fishers between 2002 and 2014. Join your points with ruled, straight lines. [6] (ii) Use Table 3.1 and your graph in (b)(i) to discuss the effect on the local community of the 2004 ban on purse seine fishing. … … … … … … … … [4] (iii) Give one way in which the ban on purse seine fishing can be monitored. … … [1] [Total: 16]

16 marks

Mark scheme: 3(a)(i) any 2 of: 2 mean length of grouper increases in (area with) restrictions / AW ; increases (above area with no ban) after, 2005 / from 2006 ; AVP ; 3(a)(ii) any 3 of: 3 1 mean length of fish population increases / AW / ORA ; 2 more older fish present / fish live longer / fish have time to grow / AW / ORA ; 3 more fish reaching reproductive maturity / fish allowed to reproduce / more breeding stocks / more reproduction / more gametes / AW / ORA ; 4 increased recruitment / higher population / higher fish stocks / AW / ORA ; 5 AVP ; 3(b)(i) 1 linear y axes for CPUE and mean daily income, labelled with units, and horizontal axis as year ; 6 2 all three scales enable plots to cover at least half grid ; 3 plots correct  ½ square for CPUE ; 4 plots correct  ½ square for mean daily income ; 5 points joined with straight lines (with no extrapolation) ; 6 key for both sets of data ; 3(b)(ii) any 4 of: 4 1 initially / until 2004, CPUE AND income fell / CPUE AND income are lower until 2010 / AW ; 2 so, few fish may be present / more fishing trips made / few fish are caught / fishing methods may be less efficient (compared with purse seine fishing) / AW ; 3 (in the long term / over whole period), CPUE AND income increase / AW ; 4 fish populations increase / more fish present / fewer trips needed / more efficient fishing / AW ; 5 (initially), less money in local economy / less employment / AW ; OR (over long term), more money is brought into the local economy / more employment / more jobs / AW ; 6 (initially) less food / less protein / less able to feed families / AW ; OR (over long term), more food for people / more protein in diet / AW ; 7 (initially) increases sociological problems, e.g. more crime / more illegal fishing / loss of housing / low standard of living / AW ; OR (over long term), improved sociological issues, e.g. less crime / better housing / better infrastructure / AW ; 8 (ban means) fishing industry is sustainable / will last for future generations / AW ; 3(b)(iii) any 1 of: 1 sea patrols / coastguard checks ; satellite tracking ; inspection of, catch / log books / fishing gear ; onboard (human) observers ; electronic monitoring systems e.g.: CCTV / geotags ;

This question in 9693/41 Oct/Nov 2025

3 In 2004, purse seine fishing was banned in an Indian Ocean fishery. The impact of this ban on the mean length of grouper in the fishery was investigated. The mean lengths of grouper caught each year from 2002 to 2014 in this area and a similar area in which purse seine fishing continued were determined. The results are shown in Fig. 3.1. 620 grouper caught in area where 600 purse seine fishing was 580 banned in 2004mean length of grouper 560 / cm 540 grouper caught 520 in area where pursepurse seineseine purse seine fishingfishing bannedbanned fishing continued 500 2002 2004 2006 2008 2010 2012 2014 year Fig. 3.1 (a) (i) Summarise the effect of the ban on purse seine fishing on the mean lengths of grouper shown in Fig. 3.1. … … … … [2] (ii) Use Fig. 3.1 to explain how the ban on purse seine fishing would make fishing more sustainable. … … … … … … [3] (b) The impact of the ban on purse seine fishing on local communities was also investigated. The catch per unit effort (CPUE) and the mean daily income of fishers were determined between 2002 and 2014. The data are shown in Table 3.1. Table 3.1 year catch per unit effort (CPUE) mean daily income / kg per fisher per day / USD ($) per fisher per day 2002 3.6 10 2004 2.9 6 2006 3.0 8 2008 3.2 8 2010 3.6 10 2012 4.2 14 2014 4.2 16 (i) Draw a line graph to show the CPUE and mean daily income of fishers between 2002 and 2014. Join your points with ruled, straight lines. [6] (ii) Use Table 3.1 and your graph in (b)(i) to discuss the effect on the local community of the 2004 ban on purse seine fishing. … … … … … … … … [4] (iii) Give one way in which the ban on purse seine fishing can be monitored. … … [1] [Total: 16]

16 marks

Mark scheme: 3(a)(i) any 2 of: 2 mean length of grouper increases in (area with) restrictions / AW ; increases (above area with no ban) after, 2005 / from 2006 ; AVP ; 3(a)(ii) any 3 of: 3 1 mean length of fish population increases / AW / ORA ; 2 more older fish present / fish live longer / fish have time to grow / AW / ORA ; 3 more fish reaching reproductive maturity / fish allowed to reproduce / more breeding stocks / more reproduction / more gametes / AW / ORA ; 4 increased recruitment / higher population / higher fish stocks / AW / ORA ; 5 AVP ; 3(b)(i) 1 linear y axes for CPUE and mean daily income, labelled with units, and horizontal axis as year ; 6 2 all three scales enable plots to cover at least half grid ; 3 plots correct  ½ square for CPUE ; 4 plots correct  ½ square for mean daily income ; 5 points joined with straight lines (with no extrapolation) ; 6 key for both sets of data ; 3(b)(ii) any 4 of: 4 1 initially / until 2004, CPUE AND income fell / CPUE AND income are lower until 2010 / AW ; 2 so, few fish may be present / more fishing trips made / few fish are caught / fishing methods may be less efficient (compared with purse seine fishing) / AW ; 3 (in the long term / over whole period), CPUE AND income increase / AW ; 4 fish populations increase / more fish present / fewer trips needed / more efficient fishing / AW ; 5 (initially), less money in local economy / less employment / AW ; OR (over long term), more money is brought into the local economy / more employment / more jobs / AW ; 6 (initially) less food / less protein / less able to feed families / AW ; OR (over long term), more food for people / more protein in diet / AW ; 7 (initially) increases sociological problems, e.g. more crime / more illegal fishing / loss of housing / low standard of living / AW ; OR (over long term), improved sociological issues, e.g. less crime / better housing / better infrastructure / AW ; 8 (ban means) fishing industry is sustainable / will last for future generations / AW ; 3(b)(iii) any 1 of: 1 sea patrols / coastguard checks ; satellite tracking ; inspection of, catch / log books / fishing gear ; onboard (human) observers ; electronic monitoring systems e.g.: CCTV / geotags ;

This question in 9693/42 Oct/Nov 2025

3 In 2004, purse seine fishing was banned in an Indian Ocean fishery. The impact of this ban on the mean length of grouper in the fishery was investigated. The mean lengths of grouper caught each year from 2002 to 2014 in this area and a similar area in which purse seine fishing continued were determined. The results are shown in Fig. 3.1. 620 grouper caught in area where 600 purse seine fishing was 580 banned in 2004mean length of grouper 560 / cm 540 grouper caught 520 in area where pursepurse seineseine purse seine fishingfishing bannedbanned fishing continued 500 2002 2004 2006 2008 2010 2012 2014 year Fig. 3.1 (a) (i) Summarise the effect of the ban on purse seine fishing on the mean lengths of grouper shown in Fig. 3.1. … … … … [2] (ii) Use Fig. 3.1 to explain how the ban on purse seine fishing would make fishing more sustainable. … … … … … … [3] (b) The impact of the ban on purse seine fishing on local communities was also investigated. The catch per unit effort (CPUE) and the mean daily income of fishers were determined between 2002 and 2014. The data are shown in Table 3.1. Table 3.1 year catch per unit effort (CPUE) mean daily income / kg per fisher per day / USD ($) per fisher per day 2002 3.6 10 2004 2.9 6 2006 3.0 8 2008 3.2 8 2010 3.6 10 2012 4.2 14 2014 4.2 16 (i) Draw a line graph to show the CPUE and mean daily income of fishers between 2002 and 2014. Join your points with ruled, straight lines. [6] (ii) Use Table 3.1 and your graph in (b)(i) to discuss the effect on the local community of the 2004 ban on purse seine fishing. … … … … … … … … [4] (iii) Give one way in which the ban on purse seine fishing can be monitored. … … [1] [Total: 16]

16 marks

Mark scheme: 3(a)(i) any 2 of: 2 mean length of grouper increases in (area with) restrictions / AW ; increases (above area with no ban) after, 2005 / from 2006 ; AVP ; 3(a)(ii) any 3 of: 3 1 mean length of fish population increases / AW / ORA ; 2 more older fish present / fish live longer / fish have time to grow / AW / ORA ; 3 more fish reaching reproductive maturity / fish allowed to reproduce / more breeding stocks / more reproduction / more gametes / AW / ORA ; 4 increased recruitment / higher population / higher fish stocks / AW / ORA ; 5 AVP ; 3(b)(i) 1 linear y axes for CPUE and mean daily income, labelled with units, and horizontal axis as year ; 6 2 all three scales enable plots to cover at least half grid ; 3 plots correct  ½ square for CPUE ; 4 plots correct  ½ square for mean daily income ; 5 points joined with straight lines (with no extrapolation) ; 6 key for both sets of data ; 3(b)(ii) any 4 of: 4 1 initially / until 2004, CPUE AND income fell / CPUE AND income are lower until 2010 / AW ; 2 so, few fish may be present / more fishing trips made / few fish are caught / fishing methods may be less efficient (compared with purse seine fishing) / AW ; 3 (in the long term / over whole period), CPUE AND income increase / AW ; 4 fish populations increase / more fish present / fewer trips needed / more efficient fishing / AW ; 5 (initially), less money in local economy / less employment / AW ; OR (over long term), more money is brought into the local economy / more employment / more jobs / AW ; 6 (initially) less food / less protein / less able to feed families / AW ; OR (over long term), more food for people / more protein in diet / AW ; 7 (initially) increases sociological problems, e.g. more crime / more illegal fishing / loss of housing / low standard of living / AW ; OR (over long term), improved sociological issues, e.g. less crime / better housing / better infrastructure / AW ; 8 (ban means) fishing industry is sustainable / will last for future generations / AW ; 3(b)(iii) any 1 of: 1 sea patrols / coastguard checks ; satellite tracking ; inspection of, catch / log books / fishing gear ; onboard (human) observers ; electronic monitoring systems e.g.: CCTV / geotags ;

This question in 9693/43 Oct/Nov 2025