IB ESS Topic 4.3 - Aquatic Food Production Systems

marine ecosystems

oceans, mangroves, estuaries, lagoons, coral reefs, deep ocean floor

very diverse and have high stability and resiliene

continental shelf

the extension of the continents under the seas and oceans - creates shallow water

important because:

- 50% of productivity in only 15% of its area

- upwellings bring nutirent-rich water to continental shelf

- higher light penetration/insolation

- countries can claim it as theirs to exploit and harvest

UNCLOS

The UN Convention on the Laws of the Sea - in 1982 they designated the continental shelf as belonging to the country from which they extend

phytoplankton

single-celled organisms that can photosynthesis and are the most important producer in in the oceans, producing 99% of primary productivty - crucial in supporting oceanic food webs

zooplankton

single-celled animals which feed off of phytplankton and their waste - crucial in supporting oceanic food webs

DOM

dead organic matter

waste created by living organisms as they grow and die

benthic

organisms living on or in the sea bed

pelagic

organisms living surrounded by water from above the sea bed to the surface

fishery

when fish are harvested in some way - includes capture of wild fish and aquaculture (fish farming)

90% is marine - 10% is freshwater

FAO

Food and Agriculture Organisation:

- more than 70% of world fisheries are fully exploited, in decline, seriously depleted or too low to allow recovery

aquaculture

the farming of aquatic organisms in both coastal and inland areas involving human intervention in the rearing process to enhance production (FAO)

benefits of fish

high in protein, contains important lipds (fats and oils), low in bad fats, provides

on average, people eat 20 kg of fish and only 8 kg of meat

vegetarian farmed fish

solution to sustainable aquaculture - the United States Department of Agriculture has proven that there are eight species of carnivorous fish which can gain enough nutrients on a diet excluding other fish

China's production of farmed fish

62% of all farmed fish - mostly carp or catfish - often grown in rice paddies (DOM and waste provides nutrients for the rcie)

rice - fish farming

a system whereby fish are reared in rice paddies - the fish eat insect larva and algae and produce waste which the rice uses as fertiliser

the tragedy of the commons

is an economic theory of a situation within a shared-resource system where individual users acting independently according to their own self-interest behave contrary to the common good of all users by depleting that resource through their collective action

e.g. individual countries using the ocean as a resource, and so over-exploitation is occuring

over-exploitation of fisheries

fishing at an unsustainable level - over-fishing (we are too good at catching fish)

- commercial fishing has high technology to aid in catching efficiency

- fishing fleeting are larger with modern refrigeration (to stay out longer)

- within a fishing fleet there are now also processing ships

- indiscriminate fishing gear catches all organisms whether they are the target species or not (by-catch)

- trawlers drag huge nets along the seabed destroying the benthic ecosystems

maximum sustainable yield (MSY)

the increase in natural capital that can be exploited each year without depleting the original stock or its potential to replenish itself - use of this leads to sustainability

SY = annual growth and recruitment - annual death and emigration

may lead to depletion of a population in bad breeding (recruitment) years

International waters

water that no country controls, outside the 200 nautical mile exclusion zone.

Fish farming

Cultivating fish in a controlled environment and harvesting when desired size is reached

By-catch

unwanted marine creatures that are caught in the nets while fishing for another species

Optimal sustainable yield

Half the carrying capacity. Safer margin than MSY but still may have an impact on population size with other environmental impacts.

Fishing quotas

Limits on the number and size of fish that can be caught in certain areas