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Flashcards in Wild Capture Fisheries Deck (9)
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1
Q

What are the stats in regards to human dependence on fish?

A

1 in 5 people in the world depend on fish as a primary source of protein
In 2008 global seafood consumption was 143 million tonnes with 47% from aquaculture
60% of fish consumption is by the developing world
Fish also provide a protein source indirectly by livestock fed with fish

2
Q

What are the stats in regards to capture fisheries?

A

Seafood from wild stocks is insufficient to meet growing demand
>70% of the worlds fish stocks are either fully exploited or depleted
Stocks of many of worlds great fisheries now at <10% of unexploited levels
As shallow water stocks are depleted, the global fishing fleet is seeking fish from deeper water

3
Q

Describe the collapse of the Peruvian anchovy

A
  • pre-1950 fish harvested only for human consumption
    annual catch - 86,000 tonnes
  • 1953 first fish meal plants developed
  • Within 9 years Peru was no. 1 fishing nation
  • At peak 1700 purse seiners (large wall of netting) exploited 7 month fishing season
  • 1970 fisheries scientists issued a warning that the estimated sustainable yield was 9.5 million tonnes
  • 1970 government allowed 12.4 million tonnes of fishing
  • 1971 - 10.5 million tonnes
  • 1972 - total collapse of fishery by El Nino event
  • 20 years to recover
4
Q

Stats on Scotland’s fishing activities

A
  • 42spp., half of them exploited
  • salmon, sea trout etc.
  • Angling contributed 112 million to Scottish Economy in 2003 of which 52 million came from salmon anglers
  • 90% decline in commercial catches taken since 1970
  • Fewer salmon now taken by commercial salmon fisheries than retained by rod sport fisherman
5
Q

Why is over fishing becoming an increasing problem?

A

Almost nowhere less than 1,500m deep that is not exploited
Technology improvements - Diesel engines, sonar location, GPS, larger more efficient nets, driftnets
Industry is now twice as large as necessary

6
Q

How is pollution depleting fish populations?

A

Anoxic dead zones around mouths of rivers such as Severn and Mississippi
Toxic plankton blooms

7
Q

How is habitat destruction a threat to sustainability?

A

In many places seabed ploughed bare by repeated trawling - destroys rich communities of corals, sea fans and sponges
Coastal development - destruction of sea grass beds, mangrove forests

8
Q

How is climate change a threat to sustainability?

A

Warmer water - less food, affects breeding, reduces oxygen water content

9
Q

What are the major threats to freshwater fish?

A
Habitat degradation 
- dams
- river regulation
- pollution
- spread of parasites and diseases
Harvest
- over fishing
- poaching
Stocking
- release of domesticated fish
- release of non-native fish