1 1 Ingolf Røttingen The establishment and use of the agreed HCR for Norwegian spring sapawning herring Harvest 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) period Stock 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 StrategyMean TACVar i catch (max-min)P (SSB < 2.5 m.t.) F = 0.15 Catch ceiling = 1.5 m.t t t. 19% F = 0.15 Catch ceiling = 1.0 m.t t t. 16% F = 0.10 Catch ceiling = 1.5 m.t t t. 9% F = 0.10 Catch ceiling = 1.0 m.t t 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

10 Effect of linear reduction in fishing mortality below trigger values 2.5 and 5 million t STARTING POINT FOR F-REDUCTION : 2.5 MILL T5.0 MILL T Probability of falling below Blim in medium term ( ) (WGNPBW 1998) Same ( ) (WGNPBW 1999) Same ( ) F above Bpa=0.125 (Agreed HCR in 1999) (WGNPBW 2000)

11 Norwegian spring spawning herring Effect 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

12 Coastal states agreement on recovery strategy (2001): At least a linear reduction in fishing mortality from at Bpa (5.0 mill t) to 0.05 at Blim (2.5 mill t)

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 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 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 estimated fishing mortalities: 2000: : : :0.13 Poor year-class in 2001, medium 2000 and 2003, strong in 2002, Stong in 2004(?)

16 A complete HCR? Catches have varied 1.4 mill t 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