Lecture 33

Question 1

What is aquaculture? Give examples of fish species that are used in aquaculture.

2 pts

Answer 1

Wild fish that are being caught are under pressure. Aquaculture has limited selection/domestication for captive rearing of wild stocks.
* Ex. Crustaceans, molluscs

Question 2

What is the difference between extensive and intensive aquaculture?

2 pts

Answer 2

• Intensive: man-made pools, tanks
• Extensive: net cages in open water

Question 3

What is the importance for aquaculture?

4 pts

Answer 3

• Great source of protein, healthy oils
  - Omega-3 fatty acids
• Supply and demand are growing
• Wild stocks have been diminished by overfishing, environmental degradation
• Increased production of managed fish
  - Steady growth: 6%/year

Question 4

What continent has the most aquaculture production?

1 pt

Answer 4

Asia - 89%

Question 5

What are some species of farmed fish that are bony, and what is the name for mostly bony fishes?

7 pts

Answer 5

Osteichthyes
* Largest vertebrate class >29,000 species
- Carps, Tilapia
- Catfish
- Sea bass, Sea bream
- Salmonids: Rainbow trout, Atlantic salmon, Arctic char
- Flatfish (Norway) - newer species, eg Turbot (eyes both on one side of their head)

Question 6

What are examples of invertebrate farmed fish?

4 pts

Answer 6

• Mussels
• Shrimp, crayfish
• Oysters
• Softshell clams

Question 7

What are the 3 pillars of sustainability?

3 pts

Answer 7

• Financial
• Social
• Environmental

Question 8

What are some issues with aquaculture?

4 pts

Answer 8

• Environmental degradation/pollution
  - Biological Oxygen Demand: Eutrophication
• Use of antibiotics
• Transmitting diseaseto wild populations
• Escapes: contamination of wild stocks

Question 9

What are some issues with aquaculture?

4 pts

Answer 9

• Environmental degradation/pollution
  - Biological Oxygen Demand: Eutrophication
• Use of antibiotics
• Transmitting diseaseto wild populations
• Escapes: contamination of wild stocks

Question 10

How good is our information on aquaculture?

2 pts

Answer 10

Most fish were recently domesticated
* Progenitor species still exist in wild - studying them is difficult (deep waters)
Some aspects are well studies
* Nikko Tinbergen - Three-spined Stickleback

Question 11

What is the three-spined stickleback?

6 pts

Answer 11

Territorial: Males compete for females - display, chase, bite
* bright colours
Courtship behaviour: Male builds a nest
* zig-zag dance, spawning in nest
Parental behaviour:
* Male protects eggs &fry, fanning (fresh H2O for babies, O2)

Question 12

What are the social structures of fish?

3 pts

Answer 12

• Solitary
• Schools
• Shoals

Question 13

What is solitary for fish?

3 pts

Answer 13

• Territorial fish
• Aggresive defense of feeding area
  - Pik (Jack fish) and juvenile salmonids
• Need some refuge, such as weeds or banks

Question 14

What are schools for fish?

6 pts

Answer 14

Large tight groups:
* Deep bodies of water
* Provide refuge to individual fish
-Predator detection
Synchronization - flooding effecton predator
* Improved foraging

Question 15

What is shoals for fish?

2 pts

Answer 15

• Intermediate between solitary and school
• “Aggregation but without synchronization

Could have the highest predation

Question 16

How does social structure vary in fish?

3 pts

Answer 16

Depends on:
* Species
* Environment
* Developmental stage

Question 17

How does the social structure for the atlantic salmon differ depending on stage of life?

4 pts

Answer 17

• Fry: form synchronized schools
• Parr: solitary in stream beds (1 to 6 years)
• Smolts: Migrate to ocean in shoals
• Become solitary
• Adults: return to streams and males become territorial

Question 18

What are the water habitats for fish?

2 pts

Answer 18

• Benthic - bottom layer, 2 dimensional
• Pelagic - water column, 3 dimensional

Question 19

What do fish use cohesion and dispersion for?

6 pts

Answer 19

• Associated with predation risk
  - Fish form groups to reduce predation risk
• Cohesion (schooling):
• Increases with shoal size, decreases with hunger
• Decreases in low light levels (reduced predation risk)
• Presence of a predator causes grouping
• Shoals may be sorted by size

Question 20

Do fish sleep?

1 pt

Answer 20

Yes, but have no eyelids

Question 21

What are commercial fish groups like?

3 pts

Answer 21

• Net pens or round tanks
• Schools: ring structure, polarized movement
• Disperse at night

Question 22

What is the social hierarchy like in fish?

3 pts

Answer 22

• Social status is important for fish
• Dominant and subdominant fish grow faster than subordinates
• Importance of dominance decreases as group size increases

Question 23

What is the most common problem in aquaculture?

1 pt

Answer 23

Overfeeding

Question 24

How does overfeeding cause problems?

5 pts

Answer 24

• Wasted feed affects economics
• Fish growth
• Water quality
• Environment
• Disease risk

Question 25

What is the production goal in aquaculture?

1 pt

Answer 25

Feed to maximize growth while minimizing excess/waste

Question 26

How did study on overfeeding with cameras to detect feed not consumed help?

3 pts

Answer 26

Improved feed conversion, lower mortality, better growth

Question 27

What is fish welfare like?

2 pts

Answer 27

Increasing recognition of fish abilities:
* Pain perception: similar receptors and neurons, avoidance response
* Cognition: awareness and learning

Question 28

What examples are there of cooperative behaviour in fish?

2 pts

Answer 28

• Collaborative hunting (trout and eel)
• Coral Rabbitfish - foraging partners

Question 29

What is sentience?

1 pt

Answer 29

The ability to feel and some level of self-awareness

Question 30

Who/what do we ascribe sentience to?

3 pts

Answer 30

• Mammals
• Vertebrates (cephalopds - octopi very smart)
• All multi-celled animals?

Question 31

True or false: aquauculture is a declining field

1 pt

Answer 31

False - growing field