Competition among native and invasive fish

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Windermere Science Project stakeholder meeting presentations.
Winfield on the trophic ecology of invasive roach and native charr and perch. Long term study based upon gut content and stable isotope analyses

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Competition among native and invasive fish

  1. 1. Competition among native and invasive fish Ian J Winfield 1, Peter M Smyntek 2, Janice M Fletcher 1, J Ben James 1 & Jonathan Grey 2 1 2 Lake Ecosystems Group, Centre for Ecology & Hydrology, Lancaster LA1 4AP, U.K. School of Biological and Chemical Sciences, Queen Mary University of London, London E1 4NS, U.K.
  2. 2. Introduction Carnivores Planktivores Perch Changes in Pike diet Increase in roach Reduction in zooplankton Zooplankton Increase in Phytoplankton phytoplankton Increased internal Pload Chemistry Climate change Reduction in Arctic charr Warmer water Prolonged stratification Reduction in oxygen at depth Physics
  3. 3. Structure of presentation • Introduction • Roach arrival and expansion (reprise) • Methods • Population trends of native species • Diet shifts and competition • Summary
  4. 4. Introduction (1986) (1991) (2013) (1899) (2009)
  5. 5. Introduction Arctic charr (Salvelinus alpinus) Atlantic salmon (Salmo salar) Common bream (Abramis brama) Brown trout (Salmo trutta) Bullhead (Cottus gobio) European eel (Anguilla anguilla) European perch (Perca fluviatilis) Minnow (Phoxinus phoxinus) Pike (Esox lucius) River lamprey (Lampetra fluviatilis) Roach (Rutilus rutilus) Rudd (Scardinius erythrophthalmus) Sea lamprey (Petromyzon marinus) Stone loach (Barbatula barbatula) Tench (Tinca tinca) Three-spined stickleback (Gasterosteus aculeatus)
  6. 6. Roach arrival and expansion (reprise) 2n -1 t a e d y -1 ) 50 40 30 20 m 0 1 h s i F ( E U P C 10 0 1995 ‘It is not unlikely that these had been brought as live-bait for pike, as live-baiting is occasionally done by strangers.’ (Watson, 1899) 2000 Year 2005 2010
  7. 7. Roach arrival and expansion (reprise) 6000 -1) 5000 4000 3000 h s i f ( e c a d n u b A 2000 1000 0 1990 1995 2000 Year 2005 2010
  8. 8. Methods Pike Gill nets 1944+ Arctic charr Gill nets 1940+ Perch Traps 1943+ Roach Gill nets 1995+ Population trends by CPUE (etc.) Arctic charr Fishery records 1966+ Hydroacoustics 1990+
  9. 9. Methods Pike Gill nets 1944+ Arctic charr Gill nets 1940+ Arctic charr Fishery records 1966+ Gut contents analysis Perch Traps 1943+ Diet compositions Roach Gill nets 1995+ Stable Isotopes Analysis (SIA) of C, N
  10. 10. Population trends of native species -1 w k e -1) Perch 90 60 p a r t h s i f ( E U P C 30 0 1981 1986 1991 1996 2001 2006 2011
  11. 11. Population trends of native species Arctic charr
  12. 12. Population trends of native species Pike -1 d y a -1) 2.0 1.5 1.0 t e n h s i f ( E U P C 0.5 0.0 1981 1986 1991 1996 2001 2006 2011
  13. 13. Population trends of native species Pike 5250 Weight (g) 4750 of 75cm pike 4250 3750 3250 1981 1986 1991 1996 2001 2006 2011
  14. 14. Diet shifts and competition Perch Zooplanktivores 1.0 Macroinverts Daphnia Chironomids North Basin 0.8 0.6 0.4 0.2 0.0 1982 1987 Zooplanktivores 1.0 1992 1997 Macroinverts 2002 Daphnia 2007 2012 Chironomids South Basin 0.8 0.6 0.4 0.2 0.0 1982 1987 1992 1997 2002 2007 2012
  15. 15. Diet shifts and competition Arctic charr Zooplanktivores 1.0 Macroinverts Daphnia Chironomids North Basin 0.8 0.6 0.4 0.2 0.0 1982 1987 Zooplanktivores 1.0 1992 1997 Macroinverts 2002 Daphnia 2007 2012 Chironomids South Basin 0.8 0.6 0.4 0.2 0.0 1982 1987 1992 1997 2002 2007 2012
  16. 16. Diet shifts and competition Roach 1.0 Predatory zooplankton Macroinverts Daphnia Chironomids North Basin 0.8 0.6 0.4 0.2 0.0 1982 1987 1992 Predatory zooplankton 1.0 1997 Macroinverts 2002 Daphnia 2007 2012 Chironomids South Basin 0.8 0.6 0.4 0.2 0.0 1982 1987 1992 1997 2002 2007 2012
  17. 17. Diet shifts and competition Zooplankton Macroinvertebrates* October-March Adult Eudiaptomus abundance, long-term 8000 0.8 6000 0.2 0.4 0.6 4000 0.0 Numbers per litre 1.0 1.2 North Basin 1991 1994 1997 2000 Year 2003 2006 Total macroinverts. caught (3 min. kick sampling) 2009 2000 0 6000 4000 2000 0 * Environmental Change Network data from Iain D M Gunn
  18. 18. Summary • Roach introduced to Windermere over 114 years ago, but quiescent until 1990s despite significant eutrophication • Recent increase coincident with population trends in perch (little change), Arctic charr (decrease) and pike (some decrease) • Diet changes alongside roach increase: • • Arctic charr decreases in macroinvertebrates and Daphnia, increase in zooplanktivores • • Perch decreases in macroinvertebrates and Daphnia, increase in zooplanktivores Roach remarkably stable and dominated by macroinvertebrates and predatory zooplankton Interpretation of roach competitive impact on perch and Arctic charr, forcing greater food niche overlap between these native species
  19. 19. Acknowledgements • They say they want to help me but with the stuff they keep on sayin’, I think those guys just wanna keep on playin’

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