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Topic 4: Water and aquatic food production systems and societies Topic 4.3: Aquatic food production systems Starter: Create a spider diagram with everything you currently know about fisheries and fishing Fisheries • Place where fish are caught/harvested • Capture fisheries = wild fisheries • Aquaculture = farm fisheries How does energy get into aquatic food webs? • Phytoplankton - 99% of primary productivity in the oceans • Zooplankton - eat phytoplankton and their waste • Demand for fish and seafood is continually increasing as human population grows and diet changes. We have got much better at catching fish. • Trawler nets are incredibly efficient at sweeping the sea. They capture pretty much all life in their path. • Huge amount of bycatch. • Damage sea floor and wipe out entire habitats/ecosystems. So why not just farm fish? • Loss of habitat • Pollution (food, antibiotics and other medicines) • Spread of disease • Escaped individuals: • GMO • Outcompete native species • Some species just not suited to being farmed Pacific Salmon Farming • British Columbia (Pacific water) • Net cage aquaculture • Many escape (out compete wild varieties) • High density to maximise profit • High chance of disease • Wild salmon migrate very near by https://www.youtube.com/watch?v=_jaWs87t5UM China (and East Asia) • Long history of aquaculture. • Highly populated areas need a lot of protein, fish are an excellent source of protein. • Like beef, pork, chicken and lamb in the UK, fish is an important part of the diet in East Asia. Mitigation • International, national, local and individual. • Policy (long term solutions and suggestions) • Legislation (laws) • Fishing quotas • Changes in consumer behaviour • What can you do? • Eat only sustainably sourced fish. • Avoid certain species completely. Researching in groups of 4 Research how two fisheries have been managed and relate to the concept of sustainability. - Newfoundland and Iceland cod fisheries are two great examples. - Newfoundland highlights a disaster, and Iceland a sustainable model. Include: • Improvements to boats and fishing gear • Detection of fisheries via satellite. Management aspects: • Quotas • Designation of protected areas • Restrictions on types and size of gear (mesh size) The Grind – wild Pilot Whale hunting • https://www.youtube.com/watch?v=HYOTkwFhe-w • Our culture effects what we consider ethical. • Many cultures consider eating cetaceans normal. You need to be able to discuss a case study regarding the harvesting of a named species. Divide your page into two columns, for and against. When watching the video place arguments for and against the Grind in each column. Maximum sustainable yield • The amount we can take out without reducing the original stock. • i.e. If 1000 fish are born every year, we only take 1000 fish. Maximum sustainable yield • SY = annual growth and recruitment – annual death and emigration • SY = 𝑡𝑜𝑡𝑎𝑙 𝑏𝑖𝑜𝑚𝑎𝑠𝑠 𝑎𝑡 𝑡+1 𝑒𝑛𝑒𝑟𝑔𝑦 − 𝑡𝑜𝑡𝑎𝑙 𝑏𝑖𝑜𝑚𝑎𝑠𝑠 𝑎𝑡 𝑡𝑖𝑚𝑒 𝑡 𝑒𝑛𝑒𝑟𝑔𝑦 • In practice harvesting at the MSY is not sustainable: • Imprecise calculations based on models • Estimates based on previous experiences (no two situations are the same) • Does not allow for the dynamic nature of the harvest (age and gender ratio) • Disease can hit populations • Optimum Sustainable Yield • Maximum difference between revenue (fish caught) and cost (wages, boats etc.) • Greater safety margin • Fishing quotas based as a percentage of OSY per fleet per year.