Generic Harvest Control Rules for European Fisheries Rainer Froese, Trevor A. Branch, Alexander...
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Transcript of Generic Harvest Control Rules for European Fisheries Rainer Froese, Trevor A. Branch, Alexander...
Generic Harvest Control Rules for European Fisheries
Rainer Froese, Trevor A. Branch, Alexander Proelß, Martin Quaas, Keith Sainsbury & Christopher
Zimmermann
Accepted in Fish & Fisheries
Acronyms
• Bmsy is the biomass that can produce the maximum sustainable yield (UNCLOS, UNFSA)
• Fmsy is the corresponding fishing mortality• Blim is the biomass below which
recruitment is reduced and collapse possible
• Bpa is a biomass slightly above Blim but far below Bmsy
Cod, Eastern Baltic
0
100
200
300
400
500
600
700
800
900
1000
1965 1970 1975 1980 1985 1990 1995 2000 2005 2010
Year
SS
B a
nd
Lan
din
gs
(100
0 t)
Bmsy
Froese & Proelß Fish & Fisheries 2010
Bpa
Blim
Recruitment of Eastern Baltic Cod
0
100,000
200,000
300,000
400,000
500,000
600,000
700,000
800,000
900,000
0 100,000 200,000 300,000 400,000 500,000 600,000 700,000 800,000
SSB (tons)
Re
cru
its
(th
ou
sa
nd
s)
BpaBlim
European Fisheries are Mismanaged
• 24% are threatened by collapse (B < Blim)• 31% are near threatened (Blim > B < Bpa)• 45% are not threatened (B > Bpa)• But only 3-4 of these stocks have B > Bmsy
and F < Fmsy , i.e., comply with UNCLOS and UNFSA
• ICES since 2010 gives estimates of Fmsy but not MSY or Bmsy
• Less than half of the stocks are assessed
HCR 1: Reference and Trigger Biomass
The reference biomass Bmsy for the subsequent rules and reference points is the biomass that can produce the maximum sustainable yield.
This biomass also acts as a trigger when stocks fall below this level.
HCR 2: Target Biomass
The target biomass, to be achieved on average over approximately 5 years,
is 1.3 Bmsy.
The target biomass can be increased as required by economic, ecosystem or other considerations.
HCR 3: Limit Biomass
The limit biomass Blim, which is to be avoided with a high probability, is 0.5 Bmsy
A higher biomass limit may be set for species with low resilience to exploitation.
HCR 4: Total Allowable Catch
Fisheries are managed by a total allowable catch (TAC).
A maximum TAC is set for each stock so that the respective target biomass is maintained on average.
This maximum TAC may be taken as long as biomass fluctuations remain above Bmsy.
HCR 5: TAC Reductions
If the biomass falls below Bmsy, then the TAC is linearly reduced, as a function of biomass, to reach zero catch at Blim.
HCR 6: Mixed Fisheries
In fisheries where several target species are caught with the same gear, the maximum TACs for the respective stocks will be set such that the most sensitive stocks do not fall below Bmsy on average over five years, with a high probability of not falling below Blim.
HCR 7: Discard
No discard of commercially exploited species will be allowed, except for species with a demonstrated high discard survival rate.
HCR 8: Bycatch
Ecological risk assessment will be conducted on bycatch species and to assess potential damage to the environment caused by fishing, with respective measures to be taken to minimize risk.
HCR 9: Size structure
The mean size and age in the catch will be adjusted to minimize changes in age structure caused by fishing, and to reduce the effects of fisheries-induced unnatural selection.
Proposed Harvest Control Rules
0
0.2
0.4
0.6
0.8
1
0 0.5 1 1.5 2
B /B msy
Y/M
SY
B msy0.5 B msy 1.3 B msy
DepletedZone
OverfishingZone
BufferZone
TargetZone
MSY
0.91 MSY
0.75 MSY
Comparison Schaefer vs Fox
0
0.2
0.4
0.6
0.8
1
0 0.5 1 1.5 2
B /B msy
Y/M
SY
B msy0.5 B msy 1.3 B msy 2 B msy
Fox Schaefer
Status of European Stocks
0
0.2
0.4
0.6
0.8
1
1.2
1.4
1.6
0 0.5 1 1.5 2
B /B msy
Y/M
SY
B msy0.5 B msy 1.3 B msy
Status of European Stocks
0
0.2
0.4
0.6
0.8
1
1.2
1.4
1.6
0 0.5 1 1.5 2
Biomass / B MSY
Lan
din
gs
/ M
SY
B MSY 1.3 B MSY
MSY
0.9 MSY
Move stocks here.Landings may then be 60% higher
Froese et al., accepted in FAF
Test Case North Sea Herring (I)
0
200
400
600
800
1,000
1,200
0 500 1,000 1,500 2,000 2,500 3,000 3,500
Spawner Biomass (1000 t)
Lan
din
gs
(100
0 t)
1960
1960
1962
19621967
1967
1977
1978
1978
1.3 B msy
Test Case North Sea Herring (II)
0
200
400
600
800
1,000
0 500 1,000 1,500 2,000 2,500 3,000 3,500 4,000
Spawner Biomass (1000 t)
Lan
din
gs
(100
0 t)
2008
2008
1985
1985 1987
1983
20032003
1979
1.3 B msy
1987
Test Case Blue Whiting
0
500
1,000
1,500
2,000
2,500
0 2,000 4,000 6,000 8,000 10,000 12,000
Spawner Biomass (1000 t)
Lan
din
gs
(100
0 t)
1.3 B msy
1981
2008
1999
Lowrecruitment
Highrecruitment
2006 Lowrecruitment
1981
20062008
1983
1999
Comparison F-based vs Y-based
0
0.2
0.4
0.6
0.8
1
1.2
1.4
1.6
1.8
2
0 0.2 0.4 0.6 0.8 1 1.2 1.4 1.6 1.8 2
B / B msy
F /
Fm
sy o
r Y
/ M
SY
B msy
Proposed HCR
F -based HCR
How to Get to Bmsy with Least Pain?
Cod, Eastern Baltic
0
100
200
300
400
500
600
700
800
900
1000
1965 1970 1975 1980 1985 1990 1995 2000 2005 2010
Year
SS
B a
nd
Lan
din
gs
(100
0 t)
BMSY
MSY
Froese & Proelß Fish & Fisheries 2010