Distribution expansion of the invasive northern snakehead in the United States

1. Distribution expansion of the invasive northern snakehead in the United States By: Josh Newhard Steve Minkkinen Ian Park U.S. Fish and Wildlife Service Maryland Fishery Resources Office

2. Biology of northern snakehead (Channaargus) • Maximum Length- 1 meter • Typically found in temperate waters • Can tolerate cold water during winter • Mature at 2 years • Reproduce in late spring/early summer • May spawn multiple times per year

3. Biology • Aggressive nest guarders • Can breathe atmospheric oxygen Image by VDGIF

4. History • Native to Asia • Methods of introduction: • Common in aquarium trade • Live-fish food market

5. Introduction to U.S. • FL canals in 2000 • Pond in Crofton, MD in 2002 • Potomac River in 2004 • Arkansas 2008 • Pennsylvania 2008 • New York 2008

6. Control Methods • Rotenone • Non-specific piscicide • Removal • Capture and kill • Efficient?

7. Potomac Introduction/Expansion 2004 2006

8. Expansion in Potomac 2008 2010 N. Snakehead caught in Nanticoke Tributary

9. Current Potomac Research • Goals to better understand snakehead movements and population size • Creel Surveys • Cooperative Tagging Program • Radio Tagging

10. Creel Surveys 2008 Creel Survey 2009 Creel Survey Carried out by VDGIF & USFWS CPUE: Largemouth bass: 0.98/hr Northern snakehead: 0.0057/hr = 1 NSH/175 hrs • Done by Virginia Dept. of Game and Inland Fisheries (VDGIF) • CPUE: • Largemouth Bass:1.03 /hr • Northern snakehead: 0.0025/hr = 1 NSH/400 hrs

11. Cooperative Tagging Program • Partnership with state agencies • VA • MD • DC • First tagging began in Spring 2009 • Rely on agency & angler recaptures

12. Cooperative Tagging Program • 881 Tagged, 85 Recaptures (~9.6%) • Longest time at large- 387 days • Fish had moved downstream 28 river km • 90% of recaptures in same creek as initial capture • Farthest “migration” was 46.3 river km upstream from initial capture

13. 2010 Radio Tagging • 12 mature snakeheads implanted with radio tags 0 20mm

14. 2010 Radio Tagging

17. Summary/Future Directions • Distribution within Potomac is expanding • Expansion outside of Potomac? • Continued analysis of mark-recapture data for population estimates • Monitor radio tagged fish for one more year • Working with MDDNR to monitor possible impacts on largemouth bass by northern snakehead

18. Recommendations for control • Creel surveys every 2-3 years • Excellent way to monitor recreational catch rates • Targeted removal during peak capture times • During spring, pre-spawn period and during winter • Continued angler education • Helps in preventing further spread to other waterways

19. Questions?

20. 2009 Creel Survey • 264 interviews • 83% of anglers interviewed targeted largemouth bass

21. 2009 Creel Survey Do you think northern snakehead will impact… Opinions toward targeting snakeheads…

22. Arkansas • April 2008 • Spawning populations of NSH in Piney Creek • Confined in Piney Creek watershed • Tributary to Big Creek, White River, Mississippi River • Awaiting Commission approval and looking for funding to eradicate NSH in Piney Creek

23. Pennsylvania • First discovered in ponds at FDR Park in South Philadelphia • NSH found in tidal portion of Schuylkill River near Philadelphia • Angler confirmed capture, 8.3 miles upstream of Delaware River • Tributary to Delaware River

24. New York • May 2008 • Three NSH captured • Catlin Creek, Ridgebury Lake • Tributary to Hudson River • Proposing to Rotenone