Download Topic-4.3-Aquatic-food-production-systems

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.