Chapter 12
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What affects light penetration?
Turbidity
What does marine life at depths rely on?
Food produced near the surface
What does algae absorb?
Nutrients from the surface
What is an example of abundant and non-abundant nutrients?
Abundant - CO2 Non-Abundant - Phosphates
How are phosphates increased in the photic zone?
Runoff from rivers Areas of upwelling
What are the 2 types of Demersal fishing?
Trawling Long Line
What is Demersal fishing?
Fishing for species who live on the seabed
What is Pelagic fishing?
Fishing for species above the seabed
What are the 4 types of Pelagic fishing?
Trawling Drift nets Purse seining Pelagic long line
What are shellfish traps?
Baited traps to catch crustaceans
What are the environmental impacts of fishing?
Population decline By-catch Ghost fishing Habitat damage
What are the 3 reasons why by-catch may not be wanted?
Immature fish Catch quota is already reacher Species with no commercial value
What is ghost fishing?
Discarded fishing gear can still trap and kill species
What habitat damage can occur?
Seabed damage Coral reef impact Seagrass beds Dynamite fishing Food web impacts
What methods are used to reduce environmental impacts of fishing.
Catch Quotas Fishing equipment design and use Restricted fishing effort Restricted Fishing methods
How can fishing equipment design and use be changed?
Mesh Size Mesh Design Escape Panels Acoustic deterrent Hook Shape Decoys Sinkers Night fishing Biodegradable and radio tracked equipment
How can fishing methods be restricted?
Ban Drift nets Bans of demersal Trawling No-take zones Turtle bycatch Closed-season Minimum catchable size Maximum catchable size Protected individuals Captive rearing and release
How can fish populations be monitored?
Breeding rates Overfishing Maximum Sustainable Yield
Why might data be difficult to collect?
Species are mobile and move long distances Distribution of fish populations is often uneven Collecting representative data may be impractical
What data can be collected from fish catches?
Catch size Catch per unit fishing effort Mean fish size Mean age
What are the principles of aquaculture?
Extensive involves minimal inputs Extensive may be for commercial purposes Intensive may involve artificial control
What 2 factors affect species selection?
Local conditions Market demand
What are some desirable characteristics?
Disease resistance Rapid growth rate Good appearance
How are rainbow trout controlled with gender?
Female fish given male hormones which allows them to reproduced only producing female offspring which taste better