Long-term Data Reveal Climate Forcing of Coastal Fish Populations

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

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Long-term Data Reveal Climate Forcing of Coastal Fish Populations

  1. 1. Long-term Data Reveal Climate Forcing of Coastal Fish Populations Jeremy S. CollieGraduate School of Oceanography Narragansett Rhode Island Sea Grant Climate Symposium
  2. 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. 3. A recent analysis of the fish trawl data http://www.gso.uri.edu/fishtrawl/
  4. 4. Background on the GSO Fish Trawl Where? Bay Station (Fox Island)Sound Station(Whale Rock)URI/GSO Sea Grant Climate Symposium
  5. 5. Background on the GSO Fish TrawlWhen? Once per week since 1959 ~ 2500 samples 130 species, ~2 million individualsWhat? 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. 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. 7. Proportional Abundance by Species Group 1.0 SquidProportional 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. 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. 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. 10. Community Metrics Taxonomic Distinctness Pelagic-demersal Ratio 90 5.00 Pelagic-to-demersal ratioTaxonomic 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 55Mean 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. 11. Environmental Indices Spring-summer Sea Surface Temperature 18Temperature (°C) 17 16 15 Bay Station 14 Sound Station 1960 1965 1970 1975 1980 1985 1990 1995 2000 2005 Fishing effort and Chlorophyll concentrationChlorphyll 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. 12. Rank Correlations BetweenEnvironmental 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. 13. More consumptionin the watercolumn Lessconsumption onthe sea floorThe Boston Globe13 November 2007
  14. 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. Sea Grant Climate Symposium
  15. 15. Questions?

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