Can we mechanically control Can we mechanically control nuisance populations of nuisance populations of

northern pike in northern pike in southwestern lakes?southwestern lakes?

Lessons from UkraineLessons from Ukraine

Dr. Yuliya Kuzmenko

Dr. Scott Bonar

Tymifiy Spesivy

Northern pike Northern pike

Southwestern USSouthwestern US UkraineUkraine

InvasiveInvasive NativeNative

Dangerous for native species Dangerous for native species Important component in Important component in ichtiofaunaichtiofauna

Less then 1% of anglers like Less then 1% of anglers like northern pikenorthern pike

Most popular angling object Most popular angling object

Never used in commercial Never used in commercial fisheriesfisheries

Important fisheries object and Important fisheries object and very expensivevery expensive

Not usual object for cookingNot usual object for cooking 1000 recipes how to cook pike1000 recipes how to cook pike

Fisheries in UkraineFisheries in Ukraine

• About 71 000 About 71 000 rivers, with a rivers, with a total length of total length of 248 000 km. 248 000 km.

• The largest The largest rivers are the rivers are the Danube, the Danube, the Dnieper and the Dnieper and the Southern Bug. Southern Bug.

• 8 000 lakes and 8 000 lakes and estuaries, total estuaries, total area is 3 790 area is 3 790 km2 km2

Fisheries in UkraineFisheries in Ukraine

Fish production sector 31 000 t, Fish production sector 31 000 t, including: including:

• distant-water fisheries 9 000 t distant-water fisheries 9 000 t • Azov and Black Seas 16 000 t Azov and Black Seas 16 000 t • inland waters 6 000 tinland waters 6 000 t

Fisheries in UkraineFisheries in Ukraine

• Freshwater fish Freshwater fish major component of major component of Ukrainian dietUkrainian diet

• 43% of fish protein 43% of fish protein currently imported currently imported into the Ukraineinto the Ukraine

• However, However, productivity of productivity of water is great water is great enough to produce enough to produce 2X Ukrainian fish 2X Ukrainian fish protein needsprotein needs

Fisheries in UkraineFisheries in Ukraine

• Today, catches Today, catches of commercial of commercial fish are an order fish are an order of magnitude of magnitude smaller than in smaller than in the 1970’s and the 1970’s and early 1980’searly 1980’s

0100200300400500600700800900

1971 1991 2005

Northern pike(t)

Commercialcatch, total (t)

Northern pike was one from Northern pike was one from the 5 species on the top of the 5 species on the top of commercial catch reports commercial catch reports up to the end of 1990 up to the end of 1990 (about 1000 t per year)(about 1000 t per year)

Now we have only Now we have only about 100 t per about 100 t per yearyear

Why did density of Northern Why did density of Northern pike in Ukrainian reservoirs pike in Ukrainian reservoirs decrease?decrease?

Kakhovskoe reserviorKakhovskoe reservior

Probable reasons of Northern Probable reasons of Northern pike density reduction in pike density reduction in Ukrainian reservoirsUkrainian reservoirs• High pressure on the reproductive core of High pressure on the reproductive core of

northern pike population before spawning northern pike population before spawning because of late fishing closures because of late fishing closures

• Almost closed access to spawning areasAlmost closed access to spawning areas

• Reduced spawning area caused by lower Reduced spawning area caused by lower water level in early Spring resulted in a water level in early Spring resulted in a reduction in the number of recruits reduction in the number of recruits

Most useful gearsMost useful gears

Gear typeGear type LegalitiesLegalities CatchabiliCatchabilityty

SelectivitSelectivityy

Gill netsGill nets legallegal highhigh middlemiddle

Trammel Trammel netsnets

legallegal very highvery high lowlow

Trap netsTrap nets legallegal middlemiddle middlemiddle

Fyke netsFyke nets legallegal middlemiddle middlemiddle

TrollingTrolling legallegal middlemiddle highhigh

ElectrofishinElectrofishingg

illegalillegal highhigh highhigh

Gill nets and trammel netsGill nets and trammel nets

• Mostly hand-madeMostly hand-made• Flexible construction: Flexible construction:

can chang very fast in can chang very fast in depending on object depending on object size, depth of fishing size, depth of fishing area, season etc.area, season etc.

• Cheap ($50-150)Cheap ($50-150)• In Kakhovskoe In Kakhovskoe

reservoir about 280 km reservoir about 280 km of nets set each fishing of nets set each fishing dayday

Trap nets and Fyke nets Trap nets and Fyke nets

• Hand-madeHand-made

• Set on shallow areas Set on shallow areas up to 5 m deepup to 5 m deep

• Various construction Various construction depending on depending on preferable objectpreferable object

• Expensive (500-Expensive (500-1000$), cheap to use 1000$), cheap to use

TrollingTrolling

• From bank or from boatFrom bank or from boat

• Factory Artificial lures or home-made Factory Artificial lures or home-made baitsbaits

• ExpensiveExpensive

ElectroshokingElectroshoking• Home-madeHome-made

• Various construction depending on Various construction depending on preferable objectpreferable object

• Cheap (150-300 $)Cheap (150-300 $)

• Compact (1-3 kg weight)Compact (1-3 kg weight)

• QuietQuiet

By analyze situation in Ukraine By analyze situation in Ukraine we can identify additional we can identify additional methods to catch pike in USAmethods to catch pike in USA

• Remove most of oldest adult pike Remove most of oldest adult pike before spawning before spawning

• Don’t let the pike in to the spawning Don’t let the pike in to the spawning areaarea

• Kill as many pike eggs as possibleKill as many pike eggs as possible

Northern pike in USANorthern pike in USA

• The objective of the The objective of the present research is to present research is to evaluate several evaluate several mechanical techniques mechanical techniques for removing introduced for removing introduced populations of northern populations of northern pike in Rainbow Lake pike in Rainbow Lake and Fools Hollow Lake to and Fools Hollow Lake to test if northern pike can test if northern pike can be effectively suppressed be effectively suppressed in a smaller system. in a smaller system.

The four most effective methods using The four most effective methods using the experience of AGFD, USFWS and the experience of AGFD, USFWS and Ukrainian scientists were chosen. Ukrainian scientists were chosen.

Fyke nettingFyke netting

Gill nettingGill netting

Electrofishing Electrofishing

Angling Angling

MethodsMethods

• We will estimate abundance of northern pike at We will estimate abundance of northern pike at each sampling time using a each sampling time using a Jolly-Seber (POPAN ) Jolly-Seber (POPAN ) open-population model on program MARK (Cooch open-population model on program MARK (Cooch and White 2006) for capture-recapture methodsand White 2006) for capture-recapture methods. .

• Catch per unit effort over time will be divided by Catch per unit effort over time will be divided by the northern pike population size at that time to the northern pike population size at that time to provide a measure of gear efficiency which will provide a measure of gear efficiency which will allow us to compare all data from all tested allow us to compare all data from all tested reservoirs from any period of time (i.e., CPUE at reservoirs from any period of time (i.e., CPUE at time i/abundance at time i = efficiency at time i).time i/abundance at time i = efficiency at time i).

Pilot resultsPilot results

• During our 2005-2006 sampling period we During our 2005-2006 sampling period we spend about 1000 hours on gill netting, spend about 1000 hours on gill netting, 500 hours fyke netting and 30 hours on 500 hours fyke netting and 30 hours on electrofishing electrofishing

• Caught 278 northern pike Caught 278 northern pike

• 186 were marked and returned at lake for 186 were marked and returned at lake for further gears efficiency and population further gears efficiency and population abundance studyabundance study

• All pike caught these season will be killedAll pike caught these season will be killed

Comparison of Northern pike Comparison of Northern pike gill nets catch in dependence gill nets catch in dependence of year seasons (Rainbow lake, of year seasons (Rainbow lake, 2006)2006)

0.135

0.306

0.158

0

0.05

0.1

0.15

0.2

0.25

0.3

0.35

kg/hour

Winter Spring Summer

Northern pike Catchability Northern pike Catchability (Raibow lake, 2005-2006) (Raibow lake, 2005-2006)

0.221

0.005

0.740

0

0.1

0.2

0.3

0.4

0.5

0.6

0.7

0.8

kg/hour

Gill nets Fyke nets Electrofishing

Gear tipe

Northern pike CPUE in Northern pike CPUE in personnel hours personnel hours

2.30

0.10

0.37

0.00

0.50

1.00

1.50

2.00

2.50

kg/pers

onel h

ours

Gill nets Fyke nets Electrofishing

Our plans Our plans

Northern pike in UkraineNorthern pike in UkraineNorthern pike behavior and movement in Northern pike behavior and movement in dependence of water quality and seasons to dependence of water quality and seasons to

protect pikeprotect pikeNorthern pike age structure, recruitment and density Northern pike age structure, recruitment and density

to pattern Sustainable yield model and stock to pattern Sustainable yield model and stock northern pike in Ukrainian reservoirsnorthern pike in Ukrainian reservoirs

Northern Pike in USANorthern Pike in USADevelop chemical and physical attractants for Develop chemical and physical attractants for Northern pike to increase fishing gear efficiencyNorthern pike to increase fishing gear efficiency