fisheries fish as food commercial fisheries trends in world fisheries solutions?
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Fisheries
Fish as FoodCommercial FisheriesTrends in World FisheriesSolutions?
Commercial Fisheries
• Traps• Trawls• Purse seines• Gillnets• Longlines• etc…
Purse seining
Trawling
Fish size-selective gridCod Fishery - Norway
Gillnetting
Longlining
Technological Improvement in Fisheries
Tuna catches under floating objects
0
1970
1990
1980
2000
10
20
30
40
Gro
ss R
eg
iste
red
To
nna
ge (
106
ton
s)
1960
Non corrected
Corrected
World Fishing Fleet Capacity
0
20
40
60
80
100
1950 1960 1970 1980 1990 2000
Mil
lio
n t
on
nes
Capture
mariculture
Production of Marine Fisheries
Pro
du
ctio
n (
mil
lion
ton
nes
)
50
100
1800 1840 1880 1920 1960 2000
Year
EE
Zs
Cla
ims
Global Trend in Landings
Catches per 100 hooks (Japanese fleet)
1952
1964
1958
1980
Myers & Worm, 2003
Phase I - Undeveloped
Phase II - Developing
Phase III - Mature
Phase IV - Senescent
0%
10%
20%
30%
40%
50%
60%
70%
80%
90%
100%
1951
1953
1955
1957
1959
1961
1963
1965
1967
1969
1971
1973
1975
1977
1979
1981
1983
1985
1987
1989
1991
1993
Pe
rce
nta
ge
of
res
ou
rce
sDevelopment Phases of World Fisheries
0% 10% 20% 30% 40% 50%
Fully exploited
Moderately exploited
Overexploited
Depleted
Recovering
Undeveloped
State of Fish Stocks 1999
0%
10%
20%
30%
40%
50%
60%
1970 1975 1980 1985 1990 1995 2000 2005
Fully Fished
Moderately fished: U+M
Overfished: O+D+R
Trends in States of Fish Stocks
1.00
1.00
1.00
1.00
0.94
0.92
0.87
0.86
0.83
0.81
0.73
0.71
0.44
0.43
0.39
0.14
0.0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1.0
IE
PNW
PSW
PCW
IW
ANE
AEC
ASW
PNE
MBS
PEC
ACW
ANW
PSE
ASE
ANT1. Antarctic2. Atlantic, Southeast3. Pacific, Southeast4. Atlantic, Northwest5. Atlantic, Western Central6. Pacific, Eastern Central7. Medit . & Black Sea8. Pacific, Northeast9. Atlantic Southwest10. Atlantic Eastern Central11. Atlantic Northeast12. Indian Western13. Pacific Central Western14. Pacific Southwest15. Pacific Northwest16. Indian Eastern
Ratio between Present & Historical Landings
Popu
lati
on
Siz
e (
N)
Time (t)
= Maximum Sustainable Yield
Maximum Sustainable Yield
= Growth
Maximum Sustainable Yield
Gro
wth
/ Y
ield
Fishing effort
Simple Abundance Model
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 world’s fisheries.
• Single-species approaches do not account for the indirect effects of fishing (e.g. bottom fishing on habitat quality).
PSE
AEC
MBS
ANT
ANE
ASW
PNE
PNW
ACW
PEC
IE
ANW
PCW
IW
PSW
0% 50% 100
PEC
PSW
ANT
PCW
PNW
IE
ANW
ASW
MBS
ANE
ASE
AEC
PSE
IW
ACW
50% 100 %
“GOOD”
“GOOD”“BAD”
“BAD”
A: if fishing at MSY is “good” B: if fishing at MSY is “bad”
Fishing at MSY level: is it good or bad?
Neoclassical Sustainability
Modern Sustainability
Fishery induced changes in world fish composition
Fishing Down the Food Web
Shark Populations NE Atlantic
Baum et al. 2003
• 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….
Solutions?
Historical Succession of Coastal Ecosystems
Jackson et al. 2001
1. Over-exploitation of large predators
2. Collapse “Ecosystem Engineering” species
3. Rise of Microbes
Historical fishing consequences
Jackson et al. 2001
Historical fishing consequences
Jackson et al. 2001
Historical fishing consequences
Jackson et al. 2001
Jackson et al. 2001