LONG-TERM PRAXIS OF FISHERY MANAGEMENT OF LAKE

VÕRTSJÄRV

AIN JÄRVALTCentre for Limnology

Institute of Agriculture and Environmental SciencesEstonian University of Life Sciences

LAKE VÕRTSJÄRV270 km2, shallow (mean depth 2,8 m), eutrophic lake

32 native fish species• Main commercial species: eel, pikeperch, pike,

bream, perch• Total catch 350 t or 13 kg/ha

(2008 - 500 t, 18 kg/ha)• Only passiv gears - trap or fyke net 324, gillnet 360

1 trap net per 83 ha and 1 gill-net per75 ha

Peculiarities of fishery L. Võrtsjärv

• Water level changes• Native fish species• Eel stocking - annual investments 100-130 000 EUROs

• Main problem:• Balance between sustainable catch of native

fish species (pikeperch, pike) and maximal catch of eel (changes according to EMP since 2008)

Fishery management of Lake Võrtsjärv since 1920

Period Owner Users Number of fishermen

Fishing gear

private fishermen

various seines, weirs, traps, gill nets

Ltd-s and unions of fishermen

sailing trawls

1950-65 state collective farms 35-45 Fine-meshed trawls, gill nets, seines

fyke nets, gill nets

seines,

1994-2000 state, 7 municipalities

private fishermen

20-26 fyke nets, gill nets

1920-40 state 50-70

1965-91 state, Ministery of Nature Protection

and Forestry

state farm 25-30

fyke nets, gill nets

2001- state, 7 municipalities

private fishermen

48 fyke nets, gill nets

1992-93 state, Viljandi, Tartu, Valga county

private fishermen

20-23

Management in 2008• State waterbody• Responsible manager - Ministery of Environment and

Ministery of Agriculture • 46 professional fishermen (2008)

– 324 fyke nets (length 150 m), annual tax 300 EUROs per fyke net (100% for restocking of eel)

– 360 gill nets (min mesh size 65 mm), 20 EUROs per net– by the historical right (mean number of gears during last 3 years)

• low recreational fishing• annual state support for restocking of eel

– in 2002-2006 up to 25 000 EUROs per year, since 2007 = 0• Cost of total annual catch – 0,5-0,6 million

EUR (2 EUR/ha)

Total number of professional fishermen in Lake Võrtsjärv

0

10

20

30

40

50

1994

1995

1996

1997

1998

1999

2000

2001

2002

2003

2004

2005

2006

2007

Average annual catch of main fish species in L. Võrtsjärv 1935-2007

010

2030

4050

6070

8090

100

1935-39 1952-59 1960-69 1970-79 1980-89 1990-99 2000-04 2005-07

Cat

ch to

ns

pikeperch pike bream eel total* 10

Species composition and average CPUE of trawl catches in L. Võrtsjärv 1978-2007

0

20000

40000

60000

80000

100000

120000

140000

Sm

elt

Pik

e

Eel

Roa

ch

Ble

ak

Bre

am

Whi

te b

ream

Bur

bot

Per

ch

Pik

eper

ch

Ruf

f

g pe

r tra

wl h

our

1978-801984-871990-932000-07Average

Stocking of eel Anguilla anguilla

annual investments 100-130 000 EUROsglass eels (7 cm, 0,3 g) since 50sfarmed eels (15 cm, 5 g) 1988, 1995, since 2002

The stocking and catch of eel in L. Võrtsjärv 1933-2007

0

1

2

3

4

1933

-39

1958

1961

1964

1967

1970

1973

1976

1979

1982

1985

1988

1991

1994

1997

2000

2003

2006

rest

okci

ng m

illion

0

20

40

60

80

100

120

catc

h t

restocking

catch

Class-eels Klaasangerjad

Restocking of farmed eels into Lake Võrtsjärv in 2006

PIKEPERCH• Legal size 45 cm (SL), 51 cm (TL) >1,3 kg

The commercial catch ( t ) of pikeperch and CPUE (kg per trawl/hour) in Lake Võrtsjärves 1981-2007

0

10

20

30

40

50

60

70

80

90

100

1981

1983

1985

1987

1989

1991

1993

1995

1997

1999

2001

2003

2005

2007

catc

h to

ns; C

PU

E k

g/tra

wl-h

our

catch

CPUE of trawl

The commercial catch ( t ) of pike and CPUE (kg per trawl/hour) in Lake Võrtsjärves 1981-2007

010

203040

506070

8090

1971

1973

1975

1977

1979

1981

1983

1985

1987

1989

1991

1993

1995

1997

1999

2001

2003

2005

2007C

PU

E k

g/tra

wl-h

our;

catc

h to

ns trawl catch

Winter gill net catch - divides activities and incomes of fishermen

• 90 % of total – pikeperch– pike

• second-rate abundant– bream and burbot

Main problems connected of fishery caused by hypoxia in L. Võrtsjärv

• Decrease of moving activity– lower winter catches (pikeperch and pike)

• Fishkill• Disturbing the overwintering of eel

– emigration – easy prey for pike

Foto: A. Tuvikene

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