Transcript Results of IBTS cruise 1Q 2009

Spatial patterns in the distribution and early life
characteristics of North Sea cod under the
influence of climate change
Hannes Höffle, Ph.D. student
DTU Aqua
Section Oceanography
Supervisors:
Peter Munk, DTU Aqua
Brian MacKenzie, DTU Aqua
Climate impacts on the Baltic Sea, Bornholm 09
Table of contents
1. Background: The cod stock in the North Sea
and the early life
2. Results of IBTS cruises 2004 and 2009
(preliminary)
3. Comparison of the two years and outlook to
future work
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DTU Aqua, Technical University of Denmark
name
17/04/200809
Climate impacts Presentation
on the Baltic
Sea, Bornholm
The cod stock in the North Sea – How much
is left?
• The Spawning Stock Bioass (SSB) is estimated to be around 50,000 t.
ICES 2006
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DTU Aqua, Technical University of Denmark
name
17/04/200809
Climate impacts Presentation
on the Baltic
Sea, Bornholm
The early life – a critical stage
Predation
Physiological stress
Disease
Problems in Development
Pollution
Starvation
Fuiman & Werner 2002
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DTU Aqua, Technical University of Denmark
Recruitment
Presentation name
17/04/2008
Climate impacts on the Baltic Sea, Bornholm 09
What does a cod larvae need and how might
climate influence that?
Supply from Atlantic
More and stronger extreme weather
events
Transport weakened since mid 80’s
Food: i.e. Calanus finmarchicus
Suitable Temperature
Balance of Turbulence and Stratification
Suitable Oxygen
Higher inflow and precipitation may
change position of front
Faster metabolism
More active (and more?) predators
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DTU Aqua, Technical University of Denmark
Suitable Salinity
Less soluble
Climate impacts
on the
Baltic17/04/2008
Sea, Bornholm 09
Presentation
name
How to assess the cod stock in the future?
- The SUNFISH project
Approach:
Cod (Gadus
morhua)
SUNFISH = Sustainable Fisheries,
Climate
Change and the
North Sea ecosystem
Problem:
Drift & Dispersal
Extrapolating from historical observations may be
during
early life in the future
unreliable
Objectives:
1. Understand and evaluate climate change effects
2. Quantify effects on fishes
Predictive models
Including environmental cues
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DTU Aqua, Technical University of Denmark
Sandeel (Ammodytes sp.)
name
17/04/200809
Climate impacts Presentation
on the Baltic
Sea, Bornholm
Cod eggs, larvae and pelagic juveniles – my
part of the story
3. Prey preference & Settlement
Do they run out of pelagic food?
2. Determinantes for drift and dispersal?
1. Distribution of eggs & early larvae
Fixed behaviour or hydrography?
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DTU Aqua, Technical University of Denmark
name
17/04/200809
Climate impacts Presentation
on the Baltic
Sea, Bornholm
Investigation of early life stages – IBTS 1Q 2004
• Hypothesis: Spawning areas are linked to recurrent hydrographic
features like Salinity fronts.
• Indicators for spawning areas:
• Findings:
High Gadoid egg abundances:
High plaice egg abundances:
-) Mature females in trawls
-) eggs & larvae in plankton samples
-)
-)
-)
-)
at Dogger bank
at Fisher Banks
off Norwegian coastal current
off northern Scotland
-) at Fisher Banks
-) off Norwegian coastal current
• Early stage larvae were abundant where eggs occurred in high
concentrations.
• Peak egg and larvae abundances corresponded to (frontal) hydrography.
• Salinity fronts may change due to climate change, because of shifts in
FW-inflow.
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DTU Aqua, Technical University of Denmark
Climate impacts
on the
Baltic17/04/2008
Sea, Bornholm 09
Presentation
name
Investigation of early life stages – IBTS 1Q 2004
Depth
Salinity
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DTU Aqua, Technical University of Denmark
Climate impacts
on the
Baltic17/04/2008
Sea, Bornholm 09
Presentation
name
Danish Bongo sampling IBTS 2009
31st
E6 E7 E8 E9 –
F0 F1
F2 F3 F4 F51Q
F6 F7 2009
F8 F9 G0 G1 G2
IBTS
cruise
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January – 17th February 2009
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61
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•Sampling60of cod ovaries during the day shift
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59 plankton samples taken
•In total 68
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•Sampling58between 18:00 hours and 07:00 hours
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46
89
91
41
40
38
•Preservation
of samples in Ethanol (500 µm) and
54
Formaldehyde (330 µm)
99
9
10 7
1
93
42
39
11
011
2
11
4
11
6
73
75
7
1
81 79 77
59
61
63 55
53
51
49
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3
17
6
17
9
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0
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3
19
6
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0
Latitude
•Sampling gear: Bongo Net with CTD and Depth
Sounder 56
55
44
43
21 2
11
5 17 219 22
81
1
13 281
13
22
26
4 13 0
322
13 2
5
1
16
6
0 12
30 3
5
8
13
2
41 28
8
5
26
14
24 22 20
15
9
21
56
57
37
36
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53
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•Sorting of52 single egg samples onboard (sample in
Seawater on ice)
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33
32
31
30
29
50
28
-3 -2 -1
10
49
0
1
DTU Aqua, Technical University of Denmark
2
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Longitude
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7
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9 10 11 12
Climate impacts
on the
Baltic17/04/2008
Sea, Bornholm 09
Presentation
name
Ditstribution of Eggs in the North Sea
Total eggs counted: 9462
Calculated number of eggs in Samples: 51,445
Depth
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DTU Aqua, Technical University of Denmark
Presentation
name
Climate impacts
on the
Baltic17/04/2008
Sea, Bornholm 09
Distribution of Eggs in the North Sea
Depth
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DTU Aqua, Technical University of Denmark
Presentation name
17/04/2008
Climate impacts on the Baltic Sea, Bornholm 09
Size range of Eggs sampled in 2009
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DTU Aqua, Technical University of Denmark
Presentation name
17/04/2008
Climate impacts on the Baltic Sea, Bornholm 09
How does 2009 compare to 2004?
Gadoids
Gadoids
Gadoids2009
2004
Salinity
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DTU Aqua, Technical University of Denmark
Presentation name
17/04/2008
Climate impacts on the Baltic Sea, Bornholm 09
What determines the major distributional
patterns of cod eggs and early larvae?
•2009 data is preliminary, changes may occur
•Difference in absolute number may be due to
different timing of surveys.
•Reduced number of Gadoids south of Dogger
Bank. Shift of Salinity front?
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DTU Aqua, Technical University of Denmark
Presentation name
17/04/2008
Climate impacts on the Baltic Sea, Bornholm 09
Outlook to future work
• Next cruise: IBTS 3Q 2009, 11th to 28th of August 2009
• Target: Pelagic juvenile Cod (and other Gadoids)
• New questions:
– Does cod prefer to spawn along certain salinity isolines?
– Will there be new predators on larval and juvenile cod?
– How will more events of extreme weather influence the survival?
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DTU Aqua, Technical University of Denmark
Presentation name
17/04/2008
Climate impacts on the Baltic Sea, Bornholm 09
Acknowledgements
•Peter Munk for a crash course in Surfer 7.
•Erik Selander for microscope photos.
•Zeren Gürkan and Niels Jørgen Pihl for help during
the field sampling.
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DTU Aqua, Technical University of Denmark
Presentation name
17/04/2008
Climate impacts on the Baltic Sea, Bornholm 09
Thank you for your attention!
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DTU Aqua, Technical University of Denmark
Presentation name
17/04/2008