The Barents sea cod HCR: experience of evaluation

and future task

Yuri KovalevPINRO, Russia

The 30th Session of The Joint Russian-Norwegian Fishery Commission

(November 2001)

• The Parties agreed to compose:  

BASIC DOCUMENT REGARDING THE MAIN PRINCIPLES AND CRITERIA FOR LONG TERM, SUSTAINABLE

MANAGEMENT OF LIVING MARINE RESOURCES IN THE BARENTS AND NORWEGIAN SEAS

Basic Document Working Group has been established to work on it

The 31st Session of The Joint Russian-Norwegian Fishery Commission

(November 2002)

The Parties agreed the management strategies for cod and haddock based on PA referent points and short term forecast (3 years) in order to reduce interannual changes in TAC.

For NEA cod the 10% limit of possible changes in TAC has been proposed.

 

The new rules for setting the annual fishing quota (TAC) for Northeast Arctic cod (NEA cod)

– estimate the average TAC level for the coming 3 years based on Fpa. TAC for the next year will be set to this level as a starting value for the 3 year period.

– the year after, the TAC calculation for the next 3 years is repeated basing on the updated information about the stock development, however the TAC should not be changed by more than +/- 10% compared with the previous year’s TAC.

– if the spawning stock falls below Bpa, the Parties should consider a lower TAC than the decision rules would imply.

BDWG and ICES work on evaluation of proposed management strategy

the first scientific view

– The rule is incomplete. If SSB<Bpa what reduction of F should be done?

– Interannual changes in historical stock biomass and catches are considerably higher than 10% proposed for TAC

– A simulation model is needed to evaluate the effect of applying the rule and to decide: Is it consistent with the precautionary approach?

«Evaluation of the proposed harvest control rule for Northeast Arctic cod»

B. Bogstad, A. Aglen, D. W. Skagen and M.N. Åsnes, IMR, Norway;

Y. Kovalev and N. Yaragina, PINRO, Murmansk, Russia

NEA cod population model and computer program

– PROST ( PROjections Stochastic, IMR )

– Recruitment model - the segmented regression approach taking into account a cyclic term and time trend

– Density-dependent weight at age in stock (weight in catch is a function of weight in stock)

– Density-dependent maturation

NEA cod population model and computer program

Uncertainty

– Recruitment model

– Exploitation pattern

– initial stock size and assessment error as normally distributed with CV 0.25

Arctic Fisheries Working Group(2003-2004)

- Since 2003 the working group makes prognoses and estimates possible catch options both the usual way and in accordance with the request of the JRNFC

- In 2004 the evaluation of the agreed management strategies for cod was done by BDWG and AFWG

ACFM May 2004

“The management plan ... has been evaluated through simulations, taking into account the known population dynamics of this stock...

The simulations indicate that the probability of SSB falling below Bpa or Blim is very low ... ANDthe amended rule is consistent with the precautionary approach.”

Since 2004 the basis of ACFM advice on NEA cod is the proposed by JRNFC HCR

Future work on HCR evaluation

• What is the appropriate level of interannual changes of TAC?

• Is the HCR suitable for rebuilding the stock? ?

•Target F (maximum long term yield)

The 32nd Session of The Joint Russian-Norwegian Fishery Commission

(November 2003)

A scientific work should be initiated to assess the long term yield from important commercial fish stocks in the Barents Sea

Fmax as a proxy of the F corresponding to the maximum long term yield if cannibalism is density dependent

0

0.4

0.8

1.2

1.6

0.0 0.2 0.4 0.6 0.8 1.0

Fbar

YP

R

M=0.2 M=max M=f(SSB)

The maximum long term yield

0

200

400

600

800

1000

0 0.2 0.4 0.6 0.8 1 1.2

Fbar

Ca

tch

, th

us

.t

Mean for 1960-2000 (model)

Mean for 1983-2000 (model)

Mean observed catch for 1960-2000

An assessment of the long term yield

First step

The evaluation of maximum expected long-term yield and corresponding fishing mortality for cod on a single-species basis using the model PROST

 

The effect of Northeast Arctic cod stock size and capelin biomass on cod cannibalism

37794230

2964

860

120

101428

864

5831

7287

5150796

200

193503

911

2056

2776

4273

3630 2210

0

0.2

0.4

0.6

0.8

1

1.2

0 100 200 300 400 500 600 700 800 900 1000

SSB in the beginning of the year, thous. t.

R, m

ln. s

pec.

capelin biomass

An assessment of the long term yield

Next steps

Plan of work will be presented to Commission in 2004 The basis is an analysis of the population dynamics of NEA

cod taking into account this species interaction with other species which influence the yield from the cod

Including other species priority: capelin, herring, harp seal, minke whale, shrimp, haddock ...

 

The long term yield HCR Estimation and Implementation

• A simulation model is needed to answer the request

• The basis is an analysis of the population dynamics in order to make an adequate population model

• Interactions with other species should be taken into account

• A monitoring is needed after implementation of the rule to correct the model and results in accordance with new knowledge