Uploaded byLancaster University
Competition among native and invasive fish
This document discusses competition among native and invasive fish species in a lake ecosystem. The key points are: 1) The invasive roach species was introduced over 100 years ago but only recently increased in population, coinciding with declines in the native Arctic charr and some decrease in pike populations. 2) As the roach population increased, diet analyses found the native perch and Arctic charr shifted from eating more macroinvertebrates and zooplankton to becoming more zooplanktivorous. 3) In contrast, the roach diet has remained stable, dominated by macroinvertebrates and predatory zooplankton. This suggests the roach increase
More Related Content
Similar to Competition among native and invasive fish
Competition among native and invasive fish
- 1. Competition among nativeand 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. Introduction Carnivores Planktivores Perch Changes in Pike diet Increasein 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. Structure of presentation • Introduction • Roacharrival and expansion (reprise) • Methods • Population trends of native species • Diet shifts and competition • Summary
- 4.
- 5. Introduction Arctic charr (Salvelinusalpinus) 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. Roach arrival andexpansion (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. Roach arrival andexpansion (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. Methods Pike Gill nets 1944+ Arctic charr Gillnets 1940+ Perch Traps 1943+ Roach Gill nets 1995+ Population trends by CPUE (etc.) Arctic charr Fishery records 1966+ Hydroacoustics 1990+
- 9. Methods Pike Gill nets 1944+ Arctic charr Gillnets 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. Population trends ofnative 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. Population trends ofnative species Arctic charr
- 12. Population trends ofnative 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. Population trends ofnative species Pike 5250 Weight (g) 4750 of 75cm pike 4250 3750 3250 1981 1986 1991 1996 2001 2006 2011
- 14. Diet shifts andcompetition 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. Diet shifts andcompetition 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. Diet shifts andcompetition 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. Diet shifts andcompetition 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. Summary • Roach introduced toWindermere 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. Acknowledgements • They say theywant to help me but with the stuff they keep on sayin’, I think those guys just wanna keep on playin’