Assignment 3

Question 1

what are two major ways in which fish feed for piscivorous fish have changed for the better?

Answer 1

• reduced feed conversion ratios

- substituting non-fish ingredients

Question 2

give an example of a shift in species cultivation that reduces the need for fish-based feed?

Answer 2

by shifting from piscivorous fish to omnivorous fish, such as Penaeus monodon to Litopenaus vannamei

Question 3

In nature, forage fish play in important role in converting plankton into food for higher trophic level species. How does over exploitation affect this?

Answer 3

can lead to local stress on higher trophic species, particularly during el nino events

Question 4

How much does Chile and Peru account for of the total production of fishmeal and fish oil?

Answer 4

~40% of total production

Question 5

What will determine aquaculture’s future impact on forage fisheries?

Answer 5

• whether the use of rendered animal products can replace fishmeal
• whether genetically modified vegetable oils that provide LC omega-3s can replace fish oil
• how forage fish resources are allocated: (highest value, feed largest amount of people, or conserve natural ecosystems?)

Question 6

Why have global capture fisheries stagnated?

Answer 6

• over the past two decades global fishery stocks have been in decline
• according to FAO global capture has stagnated at 92.4 million
• we have reached the carrying capacity of the oceans, and no more fish can be produced than what we are already catching
• we are catching more than what we can sustainably produce

Question 7

why is global aquaculture still expanding?

Answer 7

by 2050 we will have reached the global carrying capacity, in which we will need to have a sustainable aquaculture in place.

Question 8

what are possible constraints for future growth of aquaculture?

Answer 8

• FIFO: our reliance upon wild fisheries to feed our aquaculture
• our reliance upon wild fisheries to feed agriculture

Question 9

How does the ‘tragedy of the commons’ relate to the sustainability of aquaculture and capture fisheries?

Answer 9

• without proper management of common resources on a global level our resources will undoubtedly collapse.
• there is conflict between economics, human consumption, and environmental conservation