Exploitation of Food Resources

• Of 250,000 species of plants described only 100 are Of 250,000 species of plants described only 100 are used to feed the worldused to feed the world

• 15 plants and 8 animal species supply 90% of our food15 plants and 8 animal species supply 90% of our food

– Primary food crops:Primary food crops:

– WheatWheat - staple food of over 1/3 of global pop. - staple food of over 1/3 of global pop.

– RiceRice - large yield, grows continuously, tropics - large yield, grows continuously, tropics

– Corn / MaizeCorn / Maize - staple in S. America & Africa, fed to cattle in US - staple in S. America & Africa, fed to cattle in US

– PotatoPotato - in developed countries - in developed countries

Other foods consumed • Fish, meat and animal products (milk, eggs, cheese) - EXPENSIVE!Fish, meat and animal products (milk, eggs, cheese) - EXPENSIVE!

• 80% of meat and milk produced is consumed by only 20% of global 80% of meat and milk produced is consumed by only 20% of global populationpopulation

– Meat consumption per capita per year:Meat consumption per capita per year:

– US: 110 kgUS: 110 kg

– UK: 75 kgUK: 75 kg

– China: 21 kgChina: 21 kg

– India: 1.1 kgIndia: 1.1 kg

Inefficiencies in terrestrial systems

• More than one third of grain harvest (37%) is used for animal feed - not human consumption

• This is very inefficient as the energy of assimilation is only about 10% (Fig. 3)

• One calorie of grain-fed steak requires at least 10 calories for production

• One calorie of chicken requires 12 calories

• Meat production is very inefficient!

Terrestrial versus aquatic systems

• Most food from terrestrial systems is harvested from lower trophic levels - producers and herbivores

• Food from aquatic systems is harvested from higher trophic levels

• Efficiency of fixation of solar energy is lower in aquatic systems because of absorption and reflection by water

Improving use of food resources

• Maximize yield

• Improve storage

• Improve distribution methods

• Change eating habits (i.e. eat less meat)

• Population control