1 / 29

Do environmental factors affect recruit per spawner anomalies in the

Do environmental factors affect recruit per spawner anomalies in the Gulf of Maine - Southern New England region ?. Jon Brodziak and Loretta O’Brien NOAA Fisheries Northeast Fisheries Science Center Population Dynamics Branch Woods Hole, Massachusetts, USA. Areas: Gulf of Maine

ivor-cross
Download Presentation

Do environmental factors affect recruit per spawner anomalies in the

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript


  1. Do environmental factors affect recruit per spawner anomalies in the Gulf of Maine - Southern New England region ? Jon Brodziak and Loretta O’Brien NOAA Fisheries Northeast Fisheries Science Center Population Dynamics Branch Woods Hole, Massachusetts, USA

  2. Areas: • Gulf of Maine • Georges Bank • Southern New England • 12 groundfish stocks • Time series: • 1931 –2001 (range) • 16-71 years

  3. Recruitment Survival • RS = recruitment / SSB • Standardized RS anomalies

  4. Randomization Tests Ho: There is no year effect in RS anomalies

  5. RS anomalies Each area and year:

  6. Year effects (P = 0.1) Randomization Tests Manly 1997

  7. Nantucket

  8. Nantucket

  9. Generalized Additive Model Analysis Response variable • Standardized RS anomaly Predictor variables • Surface and bottom temperature • Northwest Atlantic Oscillation Index : NAO • Modeled wind stress • Shelf water anomaly Linear predictor in GLM, is replaced by an additive predictor

  10. Surface and Bottom Temperature Anomaly Data • Each area: Gulf of Maine, Georges Bank, So. New England • 2 Seasons: Spring and Autumn • 4 temperature observations / area spring surface and bottom autumn surface and bottom

  11. Principal Component Analysis: Temperature Anomaly Variability explained by 1st and 2nd PC: GM: 78% GB: 92% SNE:88%

  12. NAO Index • NAO Winter Index: Average of ( Decyr-1 + Janyr + Feb yr +Maryr) • NAOyr • NAOyr-1 • NAOyr-2 http://www.cru.uca.ac.uk

  13. Wind data Moored Buoys

  14. Buoy Locations: Modeled Wind • Wind speed and direction: - recorded every 6 hours - estimated monthly mean • Species specific wind stress and direction: 1-6 month average • Derived an index of shoreward transport [cos (direction +90 deg ) * wind stress] + shoreward transport - offshore transport

  15. Shelf Water Anomaly • Shelf water : • primary water mass in MAB • Formed by 2 sources: • Scotian Shelf Water • (cold, low salinity) • Slope Water • (warm, high salinity) Mountain 2004

  16. 10 : significant NAO effects • 4 : significant temperature effect • 2 : significant wind effect • 10 : significant NAO lag 2 effect • 9 : significant NAO lag 1 effect • 2 : significant NAO effect

  17. Gulf of Maine Redfish RS ~ PCA2 + NAO1 + NAO2 + Wind

  18. Georges Bank Haddock RS ~ PCA1 + NAO + NAO2

  19. Summary • Meta-analysis useful to discern patterns among stocks • Able to detect significant year effects in the RS time series • -1987 ‘wind event’ increased advection (Polachek et al 1992) • - Investigate what factors influenced other years with extreme RS values,i.e.1998 • Environmental factors have non-linear effect on RS anomalies • Longer time series were more informative • RS time series >20 years had sign. temperature and wind effects • RS time series < 21 years: no detectable differences from a random time series • NAO global variable: proxy for local climate event • Further work /ongoing work • determine mechanisms and inter-relationships: • circulation, local wind, seasonal stratification, spawning variability, • predator/ prey composition, temperature/growth, etc.

  20. Acknowledgements • Jim Manning, NEFSC • Jerry Norton, SWFSC • Greg Lough, NEFSC • Laurel Col, NEFSC • Betty Holmes, NEFSC

More Related