Post on 13-Dec-2015
Fishing practise, science and management, a French case study
Cédric Briand
ÅLSEMINARIUM i Stockholm den 20 oktober 2005
I. Status of fisheries and current management practises in France
II. A practical example of management : the Vilaine
III. What consequence will have the setting of management plans on the quantity of glass eel available for transport ?
Landings of the glass eel fisheries in FranceEstimation for 2004
FAO 76 T
T
1999-2001 StatisticsLoss of 40 % 1999-2001> 2004-2005
Export from France
0.0
200.0
400.0
600.0
800.0
1000.0
1200.0
1400.01
97
3
19
75
19
77
19
79
19
81
19
83
19
85
19
87
19
89
19
91
19
93
19
95
19
97
19
99
20
01
20
03
Ex
po
rt (
To
nn
es
)
Spain Japan China + Hong Kong Other Fishery Expertise
Source Ofimer, Castelnaud, Thibault
2004 Export =65 T, FAO expertise > 76 T
Yellow eel catches (T)
Yellow eel fisheries landings 2001
Atlantic 220 T
Mediterranean 900 TMediterranean 300 T
• Management by hydrographical district• Separate management for marine and fluvial areas• Separate management in the Atlantic and the Mediterranean areas• Habitat restoration along with fishery management measures
Eel management in France
The Vilaine10 400 km²
II. A practical example of management : the Vilaine
Exploitation rate 96%
Piège
• Targets– 700 kg glass eel > freshwater– 0.3 eels/m² of riffle
• Measures– Reduction of the fishing season– Fishing trips after closure of the fishery
Management in the Vilaine
0
10
20
30
40
50
60
1980 1985 1990 1995 2000 2005 2010 2015
Tot
al c
atch
(to
ns).
Total annual catch for the Vilaine fishery
0.0
0.5
1.0
1.5
2.0
2.5
3.0
1994 1996 1998 2000 2002 2004 2006
year
Gla
ss e
el n
um
be
r (x
10
00
)
Trapping ladder
0.0
0.5
1.0
1.5
2.0
2.5
1 2 3
Distance (rkm)
Nb
.m-² 1998
19992000200120022003
<50 50-100 >100
Yellow eel density in the basin /electrofishing
0.0
0.5
1.0
1.5
2.0
2.5
3.0
1994 1996 1998 2000 2002 2004 2006
year
Gla
ss e
el n
umbe
r (x
100
0)
Trapping ladder fished
15 trips60 trips
Fishing ladder efficiency = Trapping ladder catches/Stock in the estuary (marking recaptures)
%
The efficiency of the fishing ladder has diminished
5 kg
0.0
0.5
1.0
1.5
2.0
2.5
3.0
1994 1996 1998 2000 2002 2004 2006
year
Gla
ss e
el n
umbe
r (x
100
0)
Trapping ladder fished
700 kg
Target of 700 kg never reached
R² = 0.63
0
50
100
150
200
250
300
01/11/02 01/01/03 01/03/03 01/05/03Gla
ss e
el r
ecru
itmen
t (K
g)
2002-2003 p=0,25 2002-2003 p=0,75 2002-2003 p=0,5
0
0,05
0,1
0,15
0,2
0,25
0,3
0,35
1 3 5 7 9 11 13 15 17 19 20Captures avril/capture totale (%)
Fré
quen
ces
50 %
25 %
10 %
Modelling of glass eel recruitment1996-2000
Modelling of April recruitment1987-1995
0
200
400
600
800
1000
1200
01/11/02 01/12/02 01/01/03 01/02/03 01/03/03 01/04/03 01/05/03
Gla
ss e
el (
Kg)
Standing stock always lower than expected
Cumulated recruitment
Recruitment
Standing Stock
FisheryclosureFishery catch
Models should account for mortality and settlement
Summary
• Glass eels have no chance to die naturally
• Estuarine stock is probably below density-dependent migration
• The Vilaine is an extreme case, also an habitat problem
• How much glass eels are available for transport once French basins achieve the target ?
• What is the target ?
III Consequence of the management plans for the
resource available for transport
Bpa
40 % of pristine production
40 % of potential production at the actual recruitment
Zpa
• How do we implement Bpa?• The following discussion applies to Zpa• What does 40 % SPR means when fishing several stages ? 63 % SPR per stage if fishing of both yellow eel and glass eel 73 % SPR per stage in the Loire where silver eel are also fished
About Targets
Glass eel fisheries : 2005
Fishing limitations -13 T
% SPR marine fishery=70 to 87
Loire
Gironde
Adour
%SPR=4
%SPR=20
Eel repartition is receding in the Gironde and the Loire
0
50 000
100 000
150 000
200 000
250 000
1978 1980 1982 1984 1986 1988 1990 1992 1994 1996 1998 2000 2002
0
2 000
4 000
6 000
8 000
10 000
12 000
14 000
16 000
18 000Garonne (1)
Adour et courant landais (2)
(1) Catch (in Kg) (2) Catch (in Kg)
Decrease of the total catch of yellow eel fisheries in the Gironde and Loire estuaries
Low fishing efficiency also corresponds to large carrying capacity ?
Conclusion About 60 T available after management measures (guess) French basins now seem to be below carrying capacity ? Market problem
Tack