History and Genetics

Question 1

What traits are controlled by an organisms genetic code?

Answer 1

• growth rate
• maximum size
• Disease resistance
• Behaviour
• colouration
• reproductive capacity
• survival

metabolic efficiency

Different traits may be desireable in aquaculture in different contexts

Question 2

What is the inbreeding depression?

Answer 2

• mating between close relatives
• greater chances of expressing ‘bad’ (recessive) alleles

Question 3

The opposite of inbreeding depression is?

Answer 3

Outbreeding enhancement

• mating of dissimilar strains
• masking of ‘bad’ alleles
• Hybrid vigour - offspring are superior to parents

Question 4

What is outbreeding depression?

Answer 4

• mating of divergent strains
• reduced fitness
• offspring not competitive

Question 5

Define Genetic improvement

Answer 5

• Individuals with desired phenotypes for a trait are identified and used as future broodstock to produce progeny that are superior for those traits*
• -*Selection programmes are only reliable if the desired traits are passed to offspring
• Some traits are positively correlated, others are negatively correlated
  e. g. growth rates and feed conversion

selection for one might impact on the other

Question 6

How is genetic diversity mainained?

Answer 6

• Avoid inbreeding depression and expression of ‘bad’ alleles
• genetic diversity implies capacity to adapt
• same principles as selective breeding in endangered species

Question 7

What are two aspects of Broodstock selection?

Answer 7

• must be suited to environment
• content dependent e.g. reseeding vs. farming

Question 8

What are the benefits of triploidy in shellfish?

Answer 8

enhanced growth

• pacific oyster (25% increase & linear growth)
• eastern oyster = fast growing
• sydney rock oyster = 41-90% increase in body weight

*doesnt always result in faster growth*

prevent hybridization

- where aquaculture stock are released to the wild, sterility will prevent hybridization with wild stock

-e.g. sterile produced rainbow trout

Question 9

What could happen when hatchery-reared animals are released into the wild?

Answer 9

• survival
• dispersal
• growth
• performance - e.g. reproductive capacity
• test physical tag retention
• interbreeding between wild and cultured stocks

Question 10

When was aquaculture first practiced?

Answer 10

Carp farming began in China in 3500 BCE

475 BCE first text book on fish farming

Question 11

what species were cultured by native Americans on the northwest coast of the US?

Answer 11

Mariculture on built rock walls

• littleneck clam
• butter clam
• cockle

these rock walls still exist in some places and work

Question 12

What was the significance of oysters to Romans?

Answer 12

• high demand
• powerful aphrodisiac
• great battle powers

Question 13

Where was the center of Roman Aquaculture?

Answer 13

Lake Lucrine near Naples

Question 14

How was oyster farming first practiced in Rome?

Answer 14

• Farming by translocation
• Small oysters harvested from natural oyster beds on coast into more accessible saline lakes
• transplanted to sea floor
• Gaius Sergius -> first to lay out oyster beds in 97 BC
• they also used heated roman oyster basins (like roman bath)

Question 15

What are ancient Hawaiian Fish Ponds?

Answer 15

• sophisticated land and ocean resource management technique
• walls and gates were created to keep fish in enclosure
• first constructed at about 1500 AD
• fishponds were exclusive property of the district chief and were not a major economic resource to the general population