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Groundfish predation on diadromous fish in the Gulf of Maine

Groundfish predation on diadromous fish in the Gulf of Maine . Christine Lipsky 1 , Brian Smith 2 , Stacy Rowe 2 , Tim Sheehan 2 , and Michael O’Malley 3 1 NOAA Fisheries Service, NEFSC, Orono, Maine 2 NOAA Fisheries Service, NEFSC, Woods Hole, Massachusetts

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Groundfish predation on diadromous fish in the Gulf of Maine

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  1. Groundfish predation on diadromous fish in the Gulf of Maine • Christine Lipsky1, Brian Smith2, Stacy Rowe2, Tim Sheehan2, and Michael O’Malley3 • 1NOAA Fisheries Service, NEFSC, Orono, Maine • 2NOAA Fisheries Service, NEFSC, Woods Hole, Massachusetts • 3Marine Scotland, Aberdeen, UK • Northeast Fisheries Science Center • Atlantic Salmon Ecosystems Forum • January 8, 2014 • University of Maine, Orono, Maine

  2. Presentation Outline • Introduction/Background • Objectives • Methods • Results • Revisit objectives • Next steps

  3. Introduction/Background • Kennebec River • Two dams removed in the past 15 years • Two million river herring counted in 2013 • Penobscot River • Two dams removed in past two years, another to be breached • “Operational Plan for the Restoration of DiadromousFishes to the Penobscot River” – stocking plan

  4. Introduction/Background • Diadromous fish may have been an important prey source for Atlantic cod (Gadusmorhua) and other groundfish • The decline in diadromous fish populations adversely affected marine predator populations (Baird 1883; Ames 2004) • Restoring coastal predator populations would require the reestablishment of a large varied forage base (which would include diadromous fish) (Hall et al., 2012)

  5. Project Objectives • Examine NEFSC Food Habits Database (FHDB) for presence of diadromous fish in the stomachs of groundfish predators • Conduct survey to quantify presence of diadromous fish in the stomachs of groundfish from nearshore areas adjacent to the Kennebec and Penobscot Rivers • Compare results from Kennebec and Penobscot, before and after restoration

  6. Methods—Areas of Interest 45 Penobscot Region 44 Kennebec Region 43 Degrees North 42 41 -72 -71 -70 -69 -68 -67 -66 -65 Degrees West

  7. Methods • Use nearshore trawling platforms to sample fish in 2010 and 2011 Maine DMR Inshore Trawl NEFSC R/V Gloria Michelle • Target times when diadromous fish are suspected to be in the area—spring, late summer/early fall • Target known predators of diadromous fish (fromFHDB) • Focus on predators >20 cm

  8. Atlantic cod Methods—Targeted Species spiny dogfish credit: theguardian.com goosefish credit: Joyce Photographics silver hake credit: Marine Creations Taxidermy credit: Donald Flescher, NEFSC/NOAA winter skate credit: thejump.net thorny skate sea raven credit: Joe Kunkel, UMass credit: Donald Flescher, NEFSC/NOAA

  9. Results—2010 and 2011 (Bransome et al., in review) • Non-empty stomachs collected: 1,128 • Stomachs containing diadromous fishes: 17 • Alewife and blueback herring were the only diadromous species definitively IDed • Diadromous fish less prevalent in diets than Atlantic herring (which are generally more abundant in the sampled area), but… • More diadromous fish found in stomachs of fish offshore of mouth of Kennebec than mouth of Penobscot River

  10. Results—2010 and 2011 (Bransome et al., in review) Start positions of Diadromous Sampling Project tows.

  11. Results—2010 and 2011 (Bransome et al., in review) Kennebec Region Start positions of tows with alosines as prey by season.

  12. Results—2010 and 2011 (Bransome et al., in review) Table 1. Percent diet by weight of alosines.

  13. Summary • More diadromous fish were found in stomachs of predators in nearshore areas than offshore • A difference in the contribution of diadromous fishes to the diets of predators in nearshore areas adjacent to the Kennebec and Penobscot Rivers is suspected although additional sampling is necessary

  14. Objectives • Examine NEFSC Food Habits Database (FHDB) for presence of diadromous fish in the stomachs of groundfish predators • Conduct survey to quantify presence of diadromous fish in the stomachs of groundfish from nearshore areas adjacent to the Kennebec and Penobscot Rivers • Compare results from Kennebec and Penobscot, before and after restoration

  15. Next Steps • Samples were collected in 2012 and 2013 in spring and fall using DMR trawl surveys, and plans are to continue sampling in 2014 and beyond • Samples from spring and fall DMR trawl surveys in 2012 have been processed; data will be analyzed after 2013 and 2014 samples are collected and processed

  16. Next Steps • Continue to quantify contributions of diadromous prey to the diets of commercially-important species • Monitor the interaction between diadromous fish and their predators in the context of restoration and dam removal

  17. Acknowledgements • Keri Stepanek, MDMR • Sally Sherman, MDMR • Justin Stevens, NOAA • Julie Nieland, NOAA

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