Long-term Data Reveal Climate Forcing of Coastal Fish Populations Jeremy S. Collie Graduate School of Oceanography Narragansett, Rhode Island

1. Long-term Data Reveal
Climate Forcing of
Coastal Fish Populations
Jeremy S. Collie
Graduate School of Oceanography
Narragansett
Rhode Island
Sea Grant Climate Symposium

2. Outline
Background on the GSO fish trawl;
Trends in the abundance of species groups;
Winners and losers;
Community metrics;
Environmental correlates of community
change;
Temperature-mediated change in the coastal
marine ecosystem;
Implications for management.
Sea Grant Climate Symposium

3. A recent analysis of the fish trawl data
http://www.gso.uri.edu/fishtrawl/

4. Background on the GSO Fish Trawl
Where?
Bay Station
(Fox Island)
Sound Station
(Whale Rock)
URI/GSO
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5. Background on the GSO Fish Trawl
When?
 Once per week since 1959 ~ 2500 samples
 130 species, ~2 million individuals
What?
 One 30-minute otter trawl tow at 2 knots at
each station;
 Abundance and weight of fish and
invertebrates;
 Winter flounder length-frequency;
 Temperature, salinity, dissolved oxygen.

6. Annual mean abundance at the Sound Station
800 Squid
Pelagic fish
Benthic invertebrates
Annual mean catch per 30-min tow
Demersal fish
600
400
200
0
1959 1963 1967 1971 1975 1979 1983 1987 1991 1995 1999 2003
Year

7. Proportional Abundance by Species Group
1.0
Squid
Proportional catch by species group
Pelagic fish
0.8
Benthic invertebrates
Demersal fish
0.6
0.4
0.2
0.0
1959 1963 1967 1971 1975 1979 1983 1987 1991 1995 1999 2003
Year

8. Rates of increase/decrease of 25
species at the Sound Station
0.01 1 100
Cunner o
Red hake o
Longhorn sculpin o
Sea star o
Silver hake o
Northern searobin o
Winter flounder o
Windowpane o
Horseshoe crab o
Tautog o
American lobster o
Atlantic herring o
River herring o
Scup o
Spider crab o
Summer flounder o
Cancer crab o
Fourspot flounder o
Lady crab o
Weakfish o
Little skate o
Bluefish o
Striped searobin o
Longfin squid o
Butterfish o
-0.2 -0.1 0.0 0.1 0.2
Instantaneous rate of change

9. Annual mean abundance of 9 species
Winter flounder Butterfish Silver hake
400
300 300
300
Bay Station
200 200 200 Sound Station
100 100 100
0 0 0
Annual mean catch per 30-min tow
1960 1970 1980 1990 2000 1960 1970 1980 1990 2000 1960 1970 1980 1990 2000
Scup Cancer crab Red hake
400 500 120
400 100
300
80
300
200 60
200
40
100
100 20
0 0 0
1960 1970 1980 1990 2000 1960 1970 1980 1990 2000 1960 1970 1980 1990 2000
American lobster Longfin squid Little skate
300
60
250 60
50
40 200
150 40
30
20 100
20
10 50
0 0 0
1960 1970 1980 1990 2000 1960 1970 1980 1990 2000 1960 1970 1980 1990 2000
Year

10. Community Metrics
Taxonomic Distinctness Pelagic-demersal Ratio
90 5.00
Pelagic-to-demersal ratio
Taxonomic Distinctness
85 1.00
0.50
80
75 0.10
0.05
70
65 0.01
1960 1970 1980 1990 2000 1960 1970 1980 1990 2000
Weighted Mean Maximum Length Weighted Mean Preferred Temperature
65 13.0
Bay Station
Preferred temperature (°C)
60 Sound Station 12.5
55
Mean Lmax (cm)
12.0
50
45 11.5
40 11.0
35
10.5
30
25 10.0
1960 1970 1980 1990 2000 1960 1970 1980 1990 2000
Year

11. Environmental Indices
Spring-summer Sea Surface Temperature
18
Temperature (°C)
17
16
15
Bay Station
14 Sound Station
1960 1965 1970 1975 1980 1985 1990 1995 2000 2005
Fishing effort and Chlorophyll concentration
Chlorphyll a (mg m-2)
60
1400
Days fished
50
1200
40 1000
30 800
20 600
1960 1965 1970 1975 1980 1985 1990 1995 2000 2005
Year

12. Rank Correlations Between
Environmental Variables and Fish
Species Composition
Lag Spring- Chlorophyll Days Winter
(year) summer a (mg m-2) fished NAO
SST (°C)
0 0.28 0.33 0.03 0.16
1 0.33 NA 0.07 0.18
2 0.37 NA 0.09 0.15

13. More consumption
in the water
column
 Less
consumption on
the sea floor
The Boston Globe
13 November 2007

14. Management implications of shifts in
species composition
The shifts in species composition correlate most
strongly with spring-summer SST which increased
1.6 °C over the 47-year time series;
These decadal changes have altered the trophic
structure of the fish community, resulting in a shift
from benthic to pelagic consumers;
Fishing may have caused the decline of some
species; fisheries have also responded to the
changing species composition;
Fishery management plans need to account for
changes in fish distribution and productivity.
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15. Questions?