Download Fisheries Oceanography

Survey
yes no Was this document useful for you?
   Thank you for your participation!

* Your assessment is very important for improving the work of artificial intelligence, which forms the content of this project

page
1
page
2
page
3
page
4
page
5
page
6
page
7
page
8
page
9
page
10
page
11
page
12
page
13
page
14
page
15
page
16
page
17
page
18
page
19
page
20
page
21
page
22
page
23
page
24
page
25
page
26
page
27
page
28
page
29
page
30
page
31
page
32
page
33
page
34
page
35
page
36
page
37
page
38
page
39
page
40
page
41
page
42
page
43
page
44
page
45
page
46
page
47
page
48
page
49
page
50
page
51
page
52
page
53
Document related concepts
no text concepts found
Transcript 
Fisheries Oceanography
SST anomalies off Peru coastline
ENSO impacts on pelagic fishes: variable
catch reductions (Peru)
Catch (M. tons)
12
8
El Nino
4
0
1950
(Yánez et al. 1992)
1960
1970
1980
1990
A. Bertrand
Spatio-temporal scales of effects on peruvian
pelagic fisheries
Space
Inter-decadal
regime
ENSO strength
and duration
Ocean
Stock condition
before ENSO
Fishery
pressure
Basin
Regional
Local
Adapted
reproduction
Local
Upwelling
Time
Day
Month
Season
Year
Inter-annual Decade
A. Bertrand
Pacific Decadal
Oscillations
ENSO and pelagic fisheries: regime shift
Chavez et al. 2003
Clupeidae
American shad
Alosa sapidissima
Engraulidae
baelama anchovy
Thryssa baelama
(Chavez et al. 2002)
A. Bertrand
(Chavez et al. 2002)
A. Bertrand
Pacific Decadal Oscillation
Warm Phase
Cool Phase
Wintertime Wind (arrows) and Sea SurfaceTemp (colors)
- Affect the N. Pacific, with secondary signatures
in the tropics (opposite for ENSO)
Pacific Decadal Oscillation
(PCA of N. Pacific SST)
20-30 year duration
Chavez et al 2003
A. Bertrand
Chavez et al 2003
A. Bertrand
Humans as Top Predator
EEZs Claims
Production ( million tonnes)
Global Trend in Landings
100
50
1800
1840
1880
Year
1920
1960
2000
Expansion of fisheries
Non-registered catches
(Pauly et al., 2002)
A. Bertrand
Expansion of fisheries
Non-registered catches
(Pauly et al., 2002)
A. Bertrand
Trawling
Humans as “engineer species”
• Trawling disrupts sea bottom……
• Trawling ecosystem effects:
–
–
–
–
Decrease of spatial complexity
Decrease of target and bycatch species
Increase of scavenger species
Overall loss of biodiversity (macroorganism level)
Trawled
Un-trawled
Trawling Impact
Un-trawled Area
Trawled Area
(bottom sonar images)
Bycatch of unwanted species
Turtle Excluder Device (TED)
Trawling frequency by german vessels between
1993 & 1996
(Rijnsdorp 1997)
P. Cury
Marine Protected
Areas
No Trawling Area
Gulf of Maine
Gillnetting
Bycatch of unwanted species
Expansion of fisheries
Non-registered catches
(Pauly et al., 2002)
A. Bertrand
Purse seining
Schooling behavior
Bycatch of unwanted species
Expansion of fisheries
Non-registered catches
(Pauly et al., 2002)
A. Bertrand
Longlining
Bycatch of unwanted species
Expansion of fisheries
Non-registered catches
Why steady increase?
(Pauly et al., 2002)
A. Bertrand
Catches per 100 hooks (Japanese fleet)
1952
1964
1958
1980
Myers & Worm, 2003
Shark Populations NE Atlantic
Baum et al. 2003
Fishing Down the Food Web
Fishery induced changes in world fish composition
Compensation in exploited fish communities
(Tropical Atlantic)
● Blue Marlin
△ Sailfish
○ Swordfish
Myers & Worm, 2003
Compensation in exploited fish communities
(Southern Grand Banks)
● Codfishes (Gadidae)
○ Flatfishes (Pleuronectidae)
Myers & Worm, 2003
Seafood consumption (US)
Related documents