1 1

Ingolf RøttingenThe establishment and use of the agreed HCR

for Norwegian spring sapawning herringHarvest control rules for sustainable fisheries Management sept 2004

2 2

The depletion of the

Norwegian spring spawning herring • Spawning stock reduced from 10 million t

in the beginning of the 1950s to practically zero twenty years later– To high exploitation rates on all life stages– No firm scientific advice– No international agreements

3 3

Rebuilding (recovery) periodStock managed by Norwegian government

• Rebuilding aim (target level) 2.5 million t– ”Estimated” (few data points!) from stock-

recruitment data based on early (1978) VPA estimates

– Management action to reach the rebuilding aim: Apply lowest possible fishing mortality, in practice F=0.05

– Rebuilding (recovery) time: Approx 20 years

4 4

Norwegian spring spawning herring, mid 1990s

• A rebuilt and straddling stock– Need of international management

agreement (Coastal states)• Main issues (working groups (biologists and

economists) set up by the Coastal states) – Allocation of total TAC– Agreement on long time management

strategy

5 5

Coastal states working group on long time management strategy

• Defined 3 management objectives– High sustainable yield (in tonnes)– Stabilisation of catches – Low risk of stock depletion

• Working tool: Medium term- simulations

6 6

Technical framework for medium-term simulations, as applied by the Northern Pelagic

and Blue Whiting WG (WGNPBW)

• Blim = 2.5 million t (former rebuilding aim and MBAL)

• Bpa = 5.0 million t• Fpa = 0.15• Linear reduction in F from 0.15 at Bpa to 0.05 at

Blim

7 7

Decision table

Strategy Mean TAC Var i catch (max-min) P (SSB < 2.5 m.t.)

F = 0.15 Catch ceiling = 1.5 m.t.

 840.000 t.

 1.120.000 t.

 19%

F = 0.15 Catch ceiling = 1.0 m.t.

 750.000 t.

 620.000 t.

 16%

F = 0.10 Catch ceiling = 1.5 m.t.

 710.000 t.

 990.000 t.

 9%

F = 0.10 Catch ceiling = 1.0 m.t.

 660.000 t.

 660.000 t.

 6%

8 8

HCR rule Agreed by the coastal states in October 1999

• The parties agreed to restrict their fishing on the basis of a TAC consistent with a fishing mortality rate of less than 0.125, unless future scientific advice requires modification of this fishing mortality rate

• Should the SSB fall below a reference point of 5 mill t (Bpa) the fishing mortality rate (0.125) shall be adapted in the light of scientific estimates of the conditions then prevaililing. Such an adoption shall ensure a safe and rapid recovery of the SSB to a level in excess of 5 mill t

9 9

Request from coastal states on recovery strategies for Norwegian spring spawning herring

• ICES should evaluate the strategies that would ensure a probability in the range of 50 to 80% of restoring the SSB to above Bpa within 2 to 5 years

• Response from ICES: – A general rebuilding approach with a time constraint is

not suitable for the NSSH stock due to highly dynamic recruitment properties

– ICES advice in favour of linear reduction as the main element in a restoring (recovery) strategy for the NSSH stock

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Effect of linear reduction in fishing mortality below trigger values 2.5 and 5 million t

STARTING POINT FOR F-REDUCTION :

2.5 MILL T 5.0 MILL T

Probability of falling below Blim in medium term (1999-2008) (WGNPBW 1998)

0.38 0.21

Same (2000-2009) (WGNPBW 1999)

0.38 0.19

Same (2001-2010)

F above Bpa=0.125 (Agreed HCR in 1999)

(WGNPBW 2000)

0.20 0.10

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Norwegian spring spawning herringEffect of linear reduction below the reference value

• Conclusion presented to the Coastal States management agency:

– The probability of SSB falling below 2.5 million t in the medium term (i e 10 years) is almost halved when a linear reduction in F at SSB levels below Bpa= 5.0 million t is applied

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Coastal states agreement on recovery strategy (2001): At least a linear reduction in fishing mortality from 0.125

at Bpa (5.0 mill t) to 0.05 at Blim (2.5 mill t)

13 13

Effects of applying this type of recovery plan

(i e linear reduction in fishing mortality) • Fishery continues at a reduced level after

threshold is crossed, not a total closure

• Small changes in F less contentious and more acceptable than large ones

• More stringent measures are applied as the stock situation worsens

• Errors in estimation of SSB less critical

14 14

Agreed Recovery plan in the Management of Norwegian spring spawning herring

• Result of an interplay between ICES/ Coastal states management agency/ scientists in advisory positions/model makers.

• Probably easier to agree on including an explicit recovery element in the management plan when the spawning stock is above the trigger point for implementing a reduction in the exploitation level

15 15

Use of the agreed HCR

• Spawning stock of NSSH>Bpa since mid 1990s. Recovery or restoring plan has therefore not yet been tested in ”real life” . Stock estimate 2004: 6.9 mill t, proposed increase with recruitment of 2002 year class from 2007

• 2004 estimated fishing mortalities: 2000: 0.23

2001: 0.18

2002: 0.19

2003: 0.13

• Poor year-class in 2001, medium 2000 and 2003, strong in 2002, Stong in 2004(?)

16 16

A complete HCR?

• Catches have varied 1.4 mill t-750 000 t. Should a stabilisation measure be introduced?– Catch ceiling 1.0 mill t?

• Multi-annual TAC (3 years?)?

• This is up to the industry and management authorities to decide