4.3 - Aquatic Food Production Systems

Marine Ecosystems include and are

Oceans, Mangroves, Estuaries, Lagoons, Coral Reefs, Intertidal Zones, Deep Ocean Floor

• very biodiverse so they have high stability and resilience

Marine Ecosystems are made up of

Continental Shelf and Deep Ocean

Deep Ocean

Low productivity due to low sunlight

Does not belong to specific countries

Continental Shelf

• 50% of marine productivity

• Upwelling increases nutrients

• Shallow which allows light for photosynthesis

• Near coast lines so countries claim rights to harvest/exploit

Governance of the Oceans

1982: UNCLOS

200 Nautical Mile Limit, outside is International Waters

what is UNCLOS

UN Convention on the Laws of the Sea declared that continental shelves belong to the country from which they extend

How does energy get into aquatic food webs

Phytoplankton and Zooplankton

Phytoplankton

Carry out 99% of primary productivity in the oceans

Zooplankton

Eat phytoplankton and their waste

Fisheries

Place where fish ares caught/harvested such as Capture Fisheries and Aquaculture

What are capture fisheries

An example is farm fisheries

What is aquaculture

An example is wild fisheries

Ways to catch fish

Trawling, Dredging, and Blast Fishing

Bycatch is the stuff we didn’t want to collect but we did

Trawling

_______ nets are incredibly efficient at sweeping the sea; they capture pretty much all life in their path

Dredging

Damages the sea floor and wipes out entire habitats/ecosystem by essentially raking the sea floor and using nets to collect them

Blast Fishing

Using explosives such as dynamite to capture fish

Cons of Farming Fish

• Loss of Habitats (Mangroves)

• Pollution (Food, antibiotics, and other medicines)

• Spread of diseases

• Escaped individuals: GMO, Outcompete native species

• Some species are just not suited to being farmed (Tuna)

Examples of International Conflicts

• 1950-1970: Britain & Iceland

• 1995: Canada & Spain

• 2012: India & Sri Lanka

• 2016: Philippines & China

Mitigation

• International, national, local, and individual

• Policy (long term solutions and suggestions)

• Changes in consumer behaviours

• Legislation (law)

  • Fishing quotas

Tragedy of the Commons

Conflict between individual need and the common good of society. If a resource is seen as belonging to all, we tend to overuse and exploit. This often occurs with lakes, rivers, and oceans

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 maximum sustainable yield is not sustainable because

• Imprecise calculations based on models

• Estimates based on previous experiences (not two situations are the same)

• Does not allow for the dynamic nature of the harvest (age and gender ratio)

• Disease can hit populations

Exclusive economic zone

200 nautical miles. The state has sole rights to exploit all natural resources

Territorial waters

12 nautical miles. From the coastline where foreign ships can transit on “innocent passage” but not spy, fish, or pollute.

Contiguous zone

Another 12 nautical miles from teritorial waters. State can patrol smuggling or illegal immigration activities