Global Fishery Crisis

Question 1

Major Concerns

Answer 1

Expanding capture
Calculation MSY
Exploitation Rate
Age-Specific Mortality
High Consumption rate, natural predators

Question 2

Greater Capture

Answer 2

More boats, and larger boats
1974-2010 800% increase in effort
25% increase in catch
CPUE is generally decreasing
The average age of catch is decreasing
Global CPUE is decreasing

Question 3

Expansion of tech

Answer 3

Radar: ~1945
Sonar: detect fish below surface ~1950
Loran: long-range navigation ~1970
GPS: ~1975
Satellite imagery: 2000

Question 4

Aircraft/drones as spotters

Answer 4

Use of drones to detect fish below the surface

Question 5

Increased capture efficiencies

Answer 5

125 km line with 10 000 hooks
Trawl nets engulf 12 jumbo jets
Electric fishing on trawl nets
Drifts nets up to 65km in length
Monofilament gill nets
freezer boats
factory processing boats

Question 6

Food to Mariculture/aquaculture

Answer 6

Input of fished stock exceeds farmed output by 2-3 times
22 billion kg go to aquaculture

Question 7

Calculation of MSY

Answer 7

Baranov model
MSY = rN and many others
Schaefer model
Gulland Eage
These all tend to predict 0.5 extraction

Question 8

Exploitation rate

Answer 8

Has been set above for nearly the whole time
Allow for more exploitation than possible
Single predator: about 10-15% exploitation
We target about 10x as much and the reproductive capital and methods that bypass specific fish adaptations

Question 9

Age-specific mortality

Answer 9

Natural predation: Juveniles, weak, old, post-reproductive
Us: adults, reproductive age, sub-adults

Question 10

High Consumption rate of natural predators

Answer 10

remove natural predators to increase fishery quotas
Dolphin culls in japan,Peru and denmark
Canda has many seal culls

Question 11

Ecosystem Level Factors

Answer 11

average sea surface temperature increasing
causes phytoplankton declines, which is linked to declining fish biomass
decreased aragonite and O2 in the oceans

Question 12

Spawning habitat degradation

Answer 12

This affects the flow characters of the river
The logged rivers have higher flow rate that washes away cobbles and eggs
And there is less filtration so the rivers are muddier, this reduces oxygen and flow for eggs

There needs to be 50-100 m of tree strip left beside the river to stop this

Question 13

Parasites and pathogens

Answer 13

These can affect survival of fish stocks globally

Question 14

Other management issues

Answer 14

Failure of fishery science to identify problems and implement changes

Question 15

Growth Overfishing

Answer 15

Removal of mass greater than the gain of biomass

Question 16

Recruitment overfishing

Answer 16

Remove too many adults so that recruitment of young in compromised

Question 17

Economic overfishing

Answer 17

removal of fish at a rate that costs exceeds benefit

Question 18

Overfishing

Answer 18

patterns of fishing result in escapement less than required to produce MSY

Question 19

Ecosystem overfishing

Answer 19

overfishing to impact overall ecosystem function

Question 20

Muraski definition of overfished stocks

Answer 20

Ecosystems are overfished when stocks fall below biological limits such that:

Recruitment is impaired
Rebounding times are very long
Stock recovery is difficult and jeopardized
Extinction is threatening stocks