Fishing

Question 1

What is the photic zone?

Answer 1

An area which light can penetrate

Question 2

What is by catch?

Answer 2

The non target organisms that are caught when fishing.

Question 3

What is upwelling?

Answer 3

A process where deep, cold water rises to the surface and transports nutrients.

Question 4

How is the density of the sea affected in colder temperatures?

Answer 4

Increased density.

Question 5

What are the abiotic factors and biomass in tropical oceans (temp &light)?

Answer 5

Temp- minimal seasonal changes
Light- minimal seasonal changes

Question 6

What are the abiotic factors and biomass in temperate oceans (temp, light & nutrients)?

Answer 6

Temp- seasonal changes
Light- seasonal changes
Nutrients- less nutrients in summer as there is less disturbance from storms etc.

Question 7

What are the abiotic factors and biomass in polar oceans (temp, light & nutrients)?

Answer 7

Temp- cold all year round
Light- dark & light periods
Nutrients- upwellings and storms so high nutrients. Less thermal stratification.

Question 8

What is thermal stratification?

Answer 8

The water on the surface of the water is heated by the sun. This means that it becomes less dense so doesn’t sink (as colder water is more dense). Therefore the surface water remains on the surface and the water below stays cold and stays below the surface water.

Question 9

What is continental margin upwelling?

Answer 9

As the wind blows along shore (parallel from the coastline) it can push coastal surface out to the sea and cause coastal upwellings.

Question 10

What is the primary production of open ocean?

Answer 10

Often low due to thermal stratification (less waves so surface heated)

Question 11

Where are the two places ocean upwelling can occur?

Answer 11

Along continental margins.
In the middle of the ocean where there is current divergence.

Question 12

What can ocean upwelling cause?

Answer 12

Affect in temperature of the surface ocean.
Enhanced biological productivity in the ocean.

Question 13

What is the carrying capacity?

Answer 13

A species population size which can be sustained.

Question 14

What are density dependent factors?

Answer 14

Limiting factors which can affect population growth e.g availability of food, predators etc.

Question 15

What is the equation used to estimate the biomass of the fish stick at any point in time? (Words)

Answer 15

Biomass now = biomass one year ago + growth + birth - mortality - catch

Question 16

What is the equation used to estimate the biomass of the fish stick at any point in time? (Symbols)

Answer 16

Sn = Sn-1 + G + R - M - C

Question 17

What two conditions must be met for the maximum sustainable yield to be obtained in fishing?

Answer 17

The growth rate of resource must be at its highest possible level.
The entire growth of the resource for a given unit of time must be harvested.

Question 18

What are the difficulties with collecting data about fish stocks?

Answer 18

Fish populations are mobile and can migrate long distances.
Uneven distribution of fish populations.
Difficult to collect a large enough proportion of the population to be representative.

Question 19

Where does the data come from for commercial catch data?

Answer 19

Catch size.
Catch per fishing effort.
Mean fish size.
Mean age.

Question 20

What features make some species more vulnerable to overexploitation?

Answer 20

Low fecundity (reproductive rates and number of young).
Slow growth rate.
Reach sexual maturity later.
Natural mortality rate.
Narrow range of tolerance.

Question 21

What do drift nets involve?

Answer 21

Nets which hang vertically in the water without being anchored to the bottom.

Question 22

What do purse seine nets involve?

Answer 22

FADs are placed in the water to lure fish and surround them with large netting and enclose them.

Question 23

What does bottom trawling involve?

Answer 23

Cone shaped nets which are pulled along the seafloor using weights or chains

Question 24

What does dermersal longlining involve?

Answer 24

Placing baited hooks along a line at intervals to catch fish.

Question 25

What do crab/lobster pots involve?

Answer 25

Cage like gears with openings so they can enter but built in a way so its difficult for them to get out.

Question 26

When are drift nets used and to catch which species?

Answer 26

Used to catch pelagic fish and used at night so the fish cant see.

Question 27

When are purse seine nets used and to catch which species?

Answer 27

Often the target fish are tuna but can also catch sharks etc. as by catch when FADs are used.

Question 28

When is bottom trawling used and for which species?

Answer 28

Used to catch bottom dwelling fish eg shrimp.

Question 29

When are demersal longlines used and to catch which species?

Answer 29

Used to catch bottom dwelling fish in the sea depths.

Question 30

When are crab/lobster pots used and to catch which species?

Answer 30

Used to catch crabs or lobsters etc.
Also allows unwanted species to escape.

Question 31

What are some of the impacts of the fishing techniques?

Answer 31

By-catch.
Ghost fishing from abandoned nets.
Damage to seafloor and habitats.

Question 32

What are pelagic fish?

Answer 32

Fish which dont live by the coast or at the bottom of the sea.

Question 33

What is ghost fishing?

Answer 33

The capture and death of organisms in lost or discarded fishing gear.

Question 34

What is bycatch?

Answer 34

When non target organisms are caught when fishing.

Question 35

What are quotas and how do they work?

Answer 35

Catch quotas set limits of the total weight of fish which can be landed.

Question 36

How can fishing equipment be altered to increase the sustainability of fishing?

Answer 36

Alter the mesh size.
Mesh design.
Escape panels.
Acoustic deterrent devices.
Turtle exclusion devices.

Question 37

How can the mesh size help with sustainable fishing?

Answer 37

If the mesh size is made larger then smaller and unwanted fish will be able to escape.

Question 38

How can the mesh design be altered to increase sustainability?

Answer 38

If the mesh direction is diagonal to the direction of the movement allows small fish to escape.

Question 39

What are some fishing restrictions used to increase the sustainability of fishing?

Answer 39

No take zones.
Bans on bottom trawling.
Closed seasons.