Recent expansion in the distribution of the invasive northern snakehead (Channa argus) in the United States

Distribution expansion of the invasive northern snakehead in the United StatesBy: Josh NewhardSteve MinkkinenIan ParkU.S. Fish and Wildlife ServiceMaryland Fishery Resources Office

Biology of northern snakehead (Channa argus)Maximum Length- 1 meterTypically found in temperate watersCan tolerate cold water during winterMature at 2 yearsReproduce in late spring/early summerMay spawn multiple times per year

BiologyAggressive nest guarders

Can breathe atmospheric oxygen

Image by VDGIFHistoryNative to AsiaMethods of introduction:Common in aquarium tradeLive-fish food market

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

Control MethodsRotenoneNon-specific piscicideRemovalCapture and killEfficient?

Potomac Introduction/Expansion

20042006

Expansion in Potomac20082010

N. Snakehead caught in Nanticoke Tributary

Current Potomac ResearchGoals to better understand snakehead movements and population sizeCreel SurveysCooperative Tagging ProgramRadio Tagging

Creel Surveys2008 Creel SurveyDone by Virginia Dept. of Game and Inland Fisheries (VDGIF)CPUE: Largemouth Bass:1.03 /hr Northern snakehead: 0.0025/hr = 1 NSH/400 hrs

2009 Creel SurveyCarried out by VDGIF & USFWSCPUE: Largemouth bass: 0.98/hrNorthern snakehead: 0.0057/hr = 1 NSH/175 hrs

Cooperative Tagging Program

Partnership with state agenciesVAMDDCFirst tagging began in Spring 2009Rely on agency & angler recaptures

881 Tagged, 85 Recaptures (~9.6%)Longest time at large- 387 daysFish had moved downstream 28 river km90% of recaptures in same creek as initial captureFarthest migration was 46.3 river km upstream from initial capture

Cooperative Tagging Program2010 Radio Tagging12 mature snakeheads implanted with radio tags

020mm2010 Radio Tagging

Summary/Future DirectionsDistribution within Potomac is expandingExpansion outside of Potomac?Continued analysis of mark-recapture data for population estimatesMonitor radio tagged fish for one more yearWorking with MDDNR to monitor possible impacts on largemouth bass by northern snakeheadRecommendations for controlCreel surveys every 2-3 yearsExcellent way to monitor recreational catch ratesTargeted removal during peak capture timesDuring spring, pre-spawn period and during winterContinued angler educationHelps in preventing further spread to other waterways

Questions?2009 Creel Survey264 interviews83% of anglers interviewed targeted largemouth bass

Do you think northern snakehead will impact2009 Creel SurveyOpinions toward targeting snakeheadsArkansasApril 2008Spawning populations of NSH in Piney CreekConfined in Piney Creek watershed Tributary to Big Creek, White River, Mississippi RiverAwaiting Commission approval and looking for funding to eradicate NSH in Piney Creek

PennsylvaniaFirst discovered in ponds at FDR Park in South PhiladelphiaNSH found in tidal portion of Schuylkill River near Philadelphia Angler confirmed capture, 8.3 miles upstream of Delaware River Tributary to Delaware River

New YorkMay 2008Three NSH capturedCatlin Creek, Ridgebury Lake Tributary to Hudson RiverProposing to Rotenone