What is a Fish?

1
Fisheries
Fish as Food Commercial Fisheries Trends in World
Fisheries Solutions?
2
Commercial Fisheries

• Traps
• Trawls
• Purse seines
• Gillnets
• Longlines
• etc

3
Purse seining
4
Trawling
5
Fish size-selective grid Cod Fishery - Norway
6
Gillnetting
7
Longlining
8
Technological Improvement in Fisheries
9
Tuna catches under floating objects
10
World Fishing Fleet Capacity
40
30
Gross Registered Tonnage (106 tons)
20
10
0
1990
2000
1970
1980
1960
11
Production of Marine Fisheries
12
Global Trend in Landings
100
EEZs Claims
million tonnes)
50
Production (
1800
1840
1880
1920
1960
2000
Year
13
Catches per 100 hooks (Japanese fleet)
1952
1958
1964
1980
Myers Worm, 2003
14
Development Phases of World Fisheries
100
90
80
70
Phase III -
60
Mature
Percentage of resources
50
40
Phase II -
Developing
30
20
Phase I -
10
Undeveloped
0
1951
1953
1955
1957
1959
1961
1963
1965
1967
1969
1971
1973
1975
1977
1979
1981
1983
1985
1987
1989
1991
1993
15
State of Fish Stocks 1999
Recovering
Depleted
Overexploited
Fully exploited
Moderately exploited
Undeveloped
0
10
20
30
40
50
16
Trends in States of Fish Stocks
60
Fully Fished
50
40
Moderately fished UM
30
20
Overfished ODR
10
0
1970
1975
1980
1985
1990
1995
2000
2005
17
Ratio between Present Historical Landings
0.14
1
.
Antarctic
ANT
2.
Atlantic, Southeast
0.39
ASE
3.
Pacific, Southeast
0.43
PSE
4.
Atlantic, Northwest
0.44
ANW
5.
Atlantic, Western Central
0.71
ACW
6.
Pacific, Eastern Central
0.73
PEC
7.
Med
it
. Black Sea
0.81
MBS
8.
Pacific, Northeast
0.83
PNE
9.
Atlantic Southwest
0.86
ASW
10.
Atlantic Eastern Central
0.87
AEC
11.
Atlantic Northeast
0.92
ANE
12.
Indian Western
0.94
IW
13.
Pacific Central Western
14.
Pacific Southwest
1.00
PCW
15.
Pacific Northwest
1.00
PSW
16.
Indian Eastern
1.00
PNW
1.00
IE
0.0
0.1
0.2
0.3
0.4
0.5
0.6
0.7
0.8
0.9
1.0
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Maximum Sustainable Yield
Population Size (N)
Growth
Maximum Sustainable Yield
Time (t)
19
Maximum Sustainable Yield
Growth / Yield
Fishing effort
20
(No Transcript)
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Simple Abundance Model
22
Single Species Models

• Assessment models are biased because they do not
  incorporate the predation by other species.
• Assessment models are limited because of their
  emphasis on equilibrium solutions, such as MSY.
• Assessment models do not usually account for
  environmental changes, whether interannual or
  interdecadal.
• A correct assessment approach requires that a
  multi-species framework be used.
• Harvest recommendations from single-species
  assessment do not consider the needs of other
  species.
• Harvest recommendations from single-species
  assessment involve the deliberate fishing down of
  a population and therefore adversely change the
  ecosystem.
• The single-species approach is invalidated,
  because overfishing has occurred for at least a
  majority of the worlds fisheries.
• Single-species approaches do not account for the
  indirect effects of fishing (e.g. bottom fishing
  on habitat quality).

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(No Transcript)
24
Fishing at MSY level is it good or bad?
0
50
100
50
100
PSE AEC MBS ANT ANE ASW PNE PNW ACW PEC IE ANW PCW
IW PSW
PEC PSW ANT PCW PNW IE ANW ASW MBS ANE ASE AEC PSE
IW ACW
GOOD
BAD
GOOD
BAD
A if fishing at MSY is good B if fishing
at MSY is bad
25
Neoclassical Sustainability
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Modern Sustainability
27
Fishery induced changes in world fish composition
28
Fishing Down the Food Web
29
Shark Populations NE Atlantic
Baum et al. 2003
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Fisheries at the crossroad

• Fisheries have significantly contributed to human
  development and can still do so
• There are problem areas and avenues for positive
  change
• Change will never be at no cost but.

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The status quo is not an option !
32
Solutions?
33
Historical Succession of Coastal Ecosystems

1. Over-exploitation of large predators
2. Collapse Ecosystem Engineering species
3. Rise of Microbes

Jackson et al. 2001
34
Historical fishing consequences
Jackson et al. 2001
35
Historical fishing consequences
Jackson et al. 2001
36
Historical fishing consequences
Jackson et al. 2001
37
Jackson et al. 2001