LONG-TERM PRAXIS OF FISHERY MANAGEMENT OF LAKE VÕRTSJÄRV
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LONG-TERM PRAXIS OF FISHERY MANAGEMENT OF LAKE
VÕRTSJÄRV
AIN JÄRVALTCentre for Limnology
Institute of Agriculture and Environmental SciencesEstonian University of Life Sciences
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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
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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)
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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
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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)
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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
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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
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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
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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
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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
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Class-eels Klaasangerjad
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Restocking of farmed eels into Lake Võrtsjärv in 2006
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PIKEPERCH• Legal size 45 cm (SL), 51 cm (TL) >1,3 kg
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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
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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
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Winter gill net catch - divides activities and incomes of fishermen
• 90 % of total – pikeperch– pike
• second-rate abundant– bream and burbot
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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
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Foto: A. Tuvikene
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