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Aquatic Food Production systems 1.Fishing. Factors that affect productivity Key Questions. 1.What are the factors controlling marine productivity? 2.Why.

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Presentation on theme: "Aquatic Food Production systems 1.Fishing. Factors that affect productivity Key Questions. 1.What are the factors controlling marine productivity? 2.Why."— Presentation transcript:

1 Aquatic Food Production systems 1.Fishing. Factors that affect productivity Key Questions. 1.What are the factors controlling marine productivity? 2.Why is there a difference in productivity between open ocean and the continental shelf? Key Questions. 1.What are the factors controlling marine productivity? 2.Why is there a difference in productivity between open ocean and the continental shelf?

2 Instructions Please complete the tasks on this powerpoint. The choice of format is yours. It can be handwritten or typed in word. You will need pages 258 to 262 in the textbook. I have also uploaded a factsheet ‘Ocean Productivity’ This is 3 lessons worth of work. I hope to see you on Friday 23 rd for lessons as normal when we will check through these tasks!

3 TASK 1 list 3 differences between agriculture and fishing.

4 Task 2 Complete a glossary of the following key terms. You will need the text book, the factsheet and perhaps notes from your other units. 1.Biomass 2.Net Primary Productivity 3.Algae 4.Phytoplankton 5.algal blooms 6.Photic layer 7.Upwelling 8.Ocean salinity 9.Ocean density 10.Ocean thermocline

5 What are the factors controlling marine productivity? Light 1.Why are kelp, algae and seaweed only found in shallow water? 2.How does photosynthesis take place in deeper water? 3.Where and why might light penetration be reduced? 4.How does latitude affect light and marine productivity in oceans? 5.Why are highest rates of NPP at a depth of metres? (Fact Sheet) TASK Use pages 258 and 9 to answer the following questions

6 What are the factors controlling marine productivity? TASK Use pages 258 and 9 to answer the following questions Nutrients 1.Which nutrients are abundant in oceans and which are limiting factors? 2.Where are least nutrients found in the ocean? 3.Where are most nutrients found in the ocean and why? 4.How are nutrients in the ocean replaced? (fact sheet)

7 1.Which types of ecosystem yield the greatest biomass? 2.Which ecosystem covers the smallest area of the earth? 3.Which column is the most useful in deciding which ecosystem is the most productive? 4.Which ecosystem in the most productive and which is the least? 5.Explain the difference in NPP between open ocean and continental shelf. Use the following factors to help you explain; light, turbidity, depth, nutrient availability. Table 1. compares NPP figures of some terrestrial ecosystems with the oceans. Why is there a difference in productivity between open ocean and the continental shelf? TASK complete the questions below

8 PLENARY TASK Complete the grid below. Look carefully at fig 14.1 on page 259 to help Open OceanContinental shelf Description of nutrient and light conditions Reasons for nutrient and light conditions Why is there a difference in productivity between open ocean and the continental shelf?

9 Aquatic Food Production systems 2.Fishing Techniques Key Questions. 1.What are the factors controlling marine productivity? 2.Why is there a difference in productivity between open ocean and the continental shelf? Key Questions. 1.What are the factors controlling marine productivity? 2.Why is there a difference in productivity between open ocean and the continental shelf?

10 Fishing Techniques- Pelagic or Demersal? TASK make sure you know the difference between pelagic and demersal fish. Give examples of each.

11 Instructions Complete the grid on the next slide. Use the textbook, subsequent slides and websites to help you. fishing-methods/ hingMethods.pdf

12 Fishing Techniques Trawling Including Midwater trawlers Long-liningPurse seiningDrift nettingFactory ships Description of technique Selectivity of the catch Incl. named species Environmental impacts Energy inputs

13 Fishing Technology TechniqueDescriptionProblems Surrounding net Seine Used for aggregated pelagic species e.g. tuna surround fish from the sides and from underneath, thus preventing the target species from escaping by diving downwards. Bycatch e.g. dolphins Discards (undersize specimens, no marketable specimens, non target species) A very long net, with or without a bag in the centre. Operated with 2 long ropes fixed to its ends for hauling and herding demersal fish Bycatch/discards especially if mesh size small

14 Fishing Technology TechniqueDescriptionProblems Bottom otter trawls Dredge Cone-shaped net kept open by otter boards which is dragged across the ocean floor Disturbance to sediment Bycatch of fish and non-fish species Heavy, metal structures, sometimes with teeth to scrape along or cut through the bottom in order to catch mussels, scallops, oysters etc Sediment compaction and chemical changes Damage to reefs Bycatch Exposure of organisms to predation.

15 Here are some good clips to watch about the impacts of commercial fishing. They are on You tube so you may have to watch them at home. Make sure you do! https://www.youtube.com/watch?v=nkfz5fOPSck https://www.youtube.com/watch?v=IzrOuZ7cr1o https://www.youtube.com/watch?v=sJpMPPX3vtE Watch out for Trawlermen on TV


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