2. The material in this slide show is provided free for educational use only. All other forms of storage or reproduction are subject to copyright - please contact the National Marine Aquarium The slide show was designed and produced for the NMA by STEP, the Science Training & Education Partnership T raining & S cience E ducation P artnership www.national-aquarium.co.uk www.step-up-to-science.com

3. Fisheries: balancing the books

4. Fisheries supply a valuable food resource, but are seldom managed in a sustainable manner

5. Fisheries and fisheries managementSetting and enforcing limitsSummaryRelated issues

6. Fisheries and fisheries management Setting and enforcing limits Summary Related issues

7. Humans have exploited many different types of resource species in the sea

9. Current annual fish catches total 80- 90 million tonnes, and provide 20% of human protein consumption

10. Over 100 million people depend on ocean fisheries and aquaculture for their livelihoods

11. Subsistence fisheries usually take relatively small amounts of fish This means that the fishery is sustainable - the fishery does not result in a long-term decline in the resource species

12. Modern fishing equipment means that far more fish can be caught, to supply an expanding market

13. About 50% of exploited fish stocks are close to their maximum biological production level

14. A further 25% of exploited fish stocks are over-fished

15. A recent study estimates that ‘industrial’ fishing has reduced the biomass of large predatory fish to 10-20% of pre-fishery values, usually within fifteen years

16. Myers & Worm (2003) (Nature vol 423, p 280) reproduced with permission

17. Fishery management should ensure that fishing does not deplete populations below sustainable levels, and should protect endangered populations

18. Fisheries and fisheries management Setting and enforcing limits Summary Related issues

19. Managing a fishery in a sustainable manner means that catches must be regulated so that the fish population remains stable This requires an understanding of the current status of the population and its biology

20. Population size Population age distribution Growth rate at given ages Reproductive rate at given ages Mortality rate at given ages

21. Fish populations respond to increasing intensity of fishing in a predictable way

23. Recovery of exploited fish populations depends on how fast new, young fish are being produced This depends on how many breeding fish there are, and how fast and at what age they breed

25. A sustainable fishery must ensure that fishing mortality and spawning stock biomass are kept within safe limits

27. Catch limits can be based on the need to preserve the breeding population above the value B lim, and keep fishing mortality below the value F lim

29. The ‘Safe Zone’ is bounded by values of F and B that allow for natural variability and uncertainty in data and models

30. Fishery management can use various approaches to regulate a fishery

31. Set quotas or allowable catch levels Establish ‘no-fishing’ areas Establish a ‘closed season’ Set minimum fish size-limit, or specify net mesh size Close fishery entirely

32. Excluding young fish from the catch is achieved by using nets that allow small fish to escape However, fish may be injured even though they are not caught

33. There are several other practical problems in regulating fisheries

34. Illegal and unregulated fishing Inadequate scientific data Minimum size limits may not be effective in excluding under-sized fish Target species may be caught by other fisheries Natural environmental variability may make prediction unreliable

35. In some cases, catches of individual species may be prohibited, but there is no way to prevent them being caught Supposedly protected fish have to be discarded, even though they are already injured or dead

36. Finally, measures to protect fish populations may have important social and economic impacts

37. Fisheries and fisheries management Setting and enforcing limits Summary Related issues

38. Habitat damage Environmental effects of discarded gear Incidental mortality and by-catch There are several effects associated with fisheries which also give cause for concern Ecosystem effects

39. Large fishing gear and dynamite-fishing cause extensive damage to coral reefs and other habitats

40. Discarded and lost fishing gear and other materials form a serious hazard for marine animals

41. Marine birds and mammals, such as dolphins, can drown in nets Long-line fishing is a significant cause of population decline for some seabirds, such as albatrosses Fishing for small species may catch young stages of larger protected species, below their minimum size Few fisheries catch only the intended species

42. Fishing can also compete with other species in the ecosystem Some modern fishing regulatory measures aim to maintain the entire local ecosystem in balance, rather than simply conserving target species

43. So, is there an alternative to ‘capture’ fisheries?

44. Aquaculture would appear to be a more sustainable alternative to capture fisheries Farmed salmon production in 2000 was about 1 million tonnes, equivalent to 1% of fish catches

45. Enclosed stocks can be managed efficiently, with no incidental effects such as by-catch and under-sized fish

46. However, ‘industrial’ net-pen fish culture does have some serious environmental and ecological impacts

47. Waste food and faeces produce intense local pollution beneath pens Pesticides and antibiotics used in fish culture may affect the local ecosystem Pens are sources of parasites and disease Escaped fish may displace local populations, or interbreed Wildlife may become entangled in the pens

48. Farming carnivorous fish does not relieve pressure on fished wild stocks Each kilogramme of farmed salmon requires 3 kilogrammes of fish meal and oil

49. Fisheries and fisheries management Setting and enforcing limits Summary Related issues

50. You have seen that - Fishing is an important source of food Many fish populations have been reduced by over-fishing

51. You have seen that - Fishery management aims to provide a sustainable resource Various methods are used to regulate fisheries

52. You have seen that - Fisheries affect species other than the target Aquaculture is not always a simple, foolproof alternative to ‘capture’ fisheries

54. NOTES for USERS The material in this slide show is designed to support the teaching of science at Key Stage 4 A full description of the slide show, and linked activities for students, can be found on the National Marine Aquarium (NMA) web-site: Teachers are free to amend the slide show in whatever way they feel fit, or to use slides in other contexts. However, please note that neither the NMA nor the designers will accept responsibility for modifications, and original material remains copyright of the NMA Individual images used in the slides are copyright of NMA or STEP, except where acknowledged separately The slides have been set up to display as A4 landscape format. If they are incorporated into other slide sequences with different display settings, change in aspect ratio and text location will occur The slide sequence contains the minimum of effects and transitions. However, there are some automated animations, and teachers will wish to make sure that they are familiar with the sequence before use in class Use the PowerPoint notes viewer to obtain additional information for some slides T raining & S cience E ducation P artnership www.national-aquarium.co.uk