1. Aquatic Food Production systems 1. Fishing
Aquatic Food Production systems 1.Fishing. Factors that affect productivity
Key Questions.
What are the factors controlling marine productivity?
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. Please complete it by the end of the lesson on Friday 28th January.

3. TASK 1 list 3 differences between agriculture and fishing.

4. Net Primary Productivity Algae Phytoplankton algal blooms Photic layer
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.
Biomass
Net Primary Productivity
Algae
Phytoplankton
algal blooms
Photic layer
Upwelling
Ocean salinity
Ocean density
Ocean thermocline

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

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

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

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

9. Aquatic Food Production systems 2.Fishing Techniques
Key Question.
How do fishing techniques vary in terms of:
Selectivity of catch.
Environmental impacts,
Energy inputs?

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.

12. Including Midwater trawlers
Fishing Techniques
Trawling
Including Midwater trawlers
Long-lining
Purse seining
Drift netting
Factory ships
Description of technique
Selectivity of the catch
Incl. named species
Environmental impacts
Energy inputs

13. Fishing Technology Technique Description Problems Surrounding net
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)
Seine
Bycatch/discards especially if mesh size small
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

14. Fishing Technology Technique Description Problems Bottom otter trawls
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
Dredge
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!
Watch out for Trawlermen on TV