Transcript Generic Harvest Control Rules for European Fisheries

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
1000
Bmsy
900
SSB and Landings (1000 t)
800
700
600
500
400
300
Bpa
200
Blim
100
0
1965
1970
1975
1980
1985
1990
1995
2000
2005
2010
Year
Froese & Proelß Fish & Fisheries 2010
Recruitment of Eastern Baltic Cod
900,000
Blim
Bpa
800,000
Recruits (thousands)
700,000
600,000
500,000
400,000
300,000
200,000
100,000
0
0
100,000
200,000
300,000
400,000
SSB (tons)
500,000
600,000
700,000
800,000
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
0.5 B msy
B msy
1.3 B msy
MSY
1
0.91 MSY
Depleted
Zone
Y /MSY
0.8
Overfishing
Zone
Buffer
Zone
Target
Zone
0.75 MSY
0.6
0.4
0.2
0
0
0.5
1
B /B msy
1.5
2
Comparison Schaefer vs Fox
0.5 B msy
B msy
1.3 B msy
2 B msy
1
Fox
Y /MSY
0.8
Schaefer
0.6
0.4
0.2
0
0
0.5
1
B /B msy
1.5
2
Status of European Stocks
0.5 B msy
B msy
0.5
1
1.3 B msy
1.6
1.4
1.2
Y /MSY
1
0.8
0.6
0.4
0.2
0
0
B /B msy
1.5
2
Status of European Stocks
B MSY
1.3 B MSY
Move stocks here.
Landings may then
be 60% higher
1.6
1.4
Landings / MSY
1.2
MSY
1
0.9 MSY
0.8
0.6
0.4
0.2
0
0
0.5
1
1.5
2
Biomass / B MSY
Froese et al., accepted in FAF
Test Case North Sea Herring (I)
1,200
1.3 B msy
Landings (1000 t)
1,000
800
1960
1967
600
1962
1960
1962
400
1967
1977
1978
200
1978
0
0
500
1,000
1,500
2,000
2,500
Spawner Biomass (1000 t)
3,000
3,500
Test Case North Sea Herring (II)
1,000
1.3 B msy
1987
Landings (1000 t)
800
1985
600
2003
1985
2003
1987
2008
400
2008
200
1979
0
0
1983
500
1,000
1,500
2,000
2,500
Spawner Biomass (1000 t)
3,000
3,500
4,000
Test Case Blue Whiting
2,500
1.3 B msy
Landings (1000 t)
2,000
2006
High
recruitment
Low
recruitment
1,500
1999
2008
1999
1,000
Low
recruitment
500
2008
2006
1981
1981
1983
0
0
2,000
4,000
6,000
8,000
Spawner Biomass (1000 t)
10,000
12,000
Comparison F-based vs Y-based
B msy
2
1.8
F / Fmsy or Y / MSY
1.6
1.4
1.2
F -based HCR
1
0.8
Proposed HCR
0.6
0.4
0.2
0
0
0.2
0.4
0.6
0.8
1
B / B msy
1.2
1.4
1.6
1.8
2
How to Get to Bmsy
with Least Pain?
Cod, Eastern Baltic
1000
BMSY
900
SSB and Landings (1000 t)
800
700
600
500
400
MSY
300
200
100
0
1965
1970
1975
1980
1985
1990
1995
2000
2005
2010
Year
Froese & Proelß Fish & Fisheries 2010
Thank You
Rainer Froese
IFM-GEOMAR
[email protected]