Lecture 33 Flashcards
What is aquaculture? Give examples of fish species that are used in aquaculture.
2 pts
Wild fish that are being caught are under pressure. Aquaculture has limited selection/domestication for captive rearing of wild stocks.
* Ex. Crustaceans, molluscs
What is the difference between extensive and intensive aquaculture?
2 pts
- Intensive: man-made pools, tanks
- Extensive: net cages in open water
What is the importance for aquaculture?
4 pts
- 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
What continent has the most aquaculture production?
1 pt
Asia - 89%
What are some species of farmed fish that are bony, and what is the name for mostly bony fishes?
7 pts
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)
What are examples of invertebrate farmed fish?
4 pts
- Mussels
- Shrimp, crayfish
- Oysters
- Softshell clams
What are the 3 pillars of sustainability?
3 pts
- Financial
- Social
- Environmental
What are some issues with aquaculture?
4 pts
- Environmental degradation/pollution
- Biological Oxygen Demand: Eutrophication - Use of antibiotics
- Transmitting diseaseto wild populations
- Escapes: contamination of wild stocks
What are some issues with aquaculture?
4 pts
- Environmental degradation/pollution
- Biological Oxygen Demand: Eutrophication - Use of antibiotics
- Transmitting diseaseto wild populations
- Escapes: contamination of wild stocks
How good is our information on aquaculture?
2 pts
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
What is the three-spined stickleback?
6 pts
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)
What are the social structures of fish?
3 pts
- Solitary
- Schools
- Shoals
What is solitary for fish?
3 pts
- Territorial fish
- Aggresive defense of feeding area
- Pik (Jack fish) and juvenile salmonids - Need some refuge, such as weeds or banks
What are schools for fish?
6 pts
Large tight groups:
* Deep bodies of water
* Provide refuge to individual fish
-Predator detection
Synchronization - flooding effecton predator
* Improved foraging
What is shoals for fish?
2 pts
- Intermediate between solitary and school
- “Aggregation but without synchronization
Could have the highest predation
How does social structure vary in fish?
3 pts
Depends on:
* Species
* Environment
* Developmental stage
How does the social structure for the atlantic salmon differ depending on stage of life?
4 pts
- 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
What are the water habitats for fish?
2 pts
- Benthic - bottom layer, 2 dimensional
- Pelagic - water column, 3 dimensional
What do fish use cohesion and dispersion for?
6 pts
- 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
Do fish sleep?
1 pt
Yes, but have no eyelids
What are commercial fish groups like?
3 pts
- Net pens or round tanks
- Schools: ring structure, polarized movement
- Disperse at night
What is the social hierarchy like in fish?
3 pts
- Social status is important for fish
- Dominant and subdominant fish grow faster than subordinates
- Importance of dominance decreases as group size increases
What is the most common problem in aquaculture?
1 pt
Overfeeding
How does overfeeding cause problems?
5 pts
- Wasted feed affects economics
- Fish growth
- Water quality
- Environment
- Disease risk
