Single-stock exploitation boundaries

Considering the options below, ICES advises on the basis of the agreed management plan. This corresponds to catches weighing no more than 24 420 tonnes in 2010.

Exploitation boundaries in relation to the proposed management plan

Following the agreed management plan implies catches of no more than 24 420 tonnes in 2010, which is expected to lead to an SSB of 94 000 t in 2011. The agreed management plan is consistent with the precautionary approach.

Exploitation boundaries in relation to high long-term yield, low risk of depletion of production potential and considering ecosystem effects

Fishing mortality in the range of the target mortality of the proposed management plan is expected to give a high long-term yield and a low risk of stock depletion.

Exploitation boundaries in relation to precautionary limits

Precautionary reference points for fishing mortality have not been defined for this stock. Any management measures should have a high probability of avoiding B_lim.


Table 5.4.30.1 Herring in Division VIa North. Single stock exploitation boundaries (advice), management, and catches.

Year	ICES Advice	Predicted catch corresp. to advice	Agreed TAC	Disc. slip.	ICES Catch1
1987	Reduce F to F0.1/status quo F	38–55	49.7		44
1988	TAC	46	49.8		36
1989	TAC	58	58	1.6	34
1990	TAC	61	75	1.3	45
1991	TAC	57	62	1.2	29
1992	TAC	62	62	0.2	29
1993	Catch at status quo F	54–58	62	0.8	32
1994	Catch at status quo F	50–60	62	0.7	24
1995	No specific advice	602	77		30
1996	No advice because of misreporting	-	83.57		26
1997	Catch at status quo F		83.57	0.1	333
1998	Catch at status quo F	59	80.37	0.9	33
1999	Average catches, 1991–1996	28	68		30
2000	Average catches, 1991–1996	28	42		184
2001	Average catches, 1991–1999	30	36.36		244
2002	Average catches, 1991–1999	30	36.36		334
2003	Catch at status quo F	30	30		284
2004	F=0.30	41	30	0.1	254
2005	Catch at status quo F	30	30.1		144
2006	Catch at status quo F	34	34		27
2007	Status quo TAC advice	34	34		30
2008	F = 0.2 (proposed management plan)	15	27.2		16
2009	F =0.2 (proposed management plan)	13	21.76
2010	F 0.25 (agreed management plan)	24
Weights in ‘000 t. 1) Adjusted for misreporting. 2) Catch at status quo F. 3) Revised in 1999. 4) Revised in 2007.

The EU adopted a management plan on 18 December 2008 (Council Regulation (EC) 1300/2008) based on the following rule;

SSB in the year of the TAC	Fishing mortality	TAC constraint
SSB > 75 000 t	F = 0.25	20%
SSB < 75 000 t	F = 0.2	20%
SSB < 62 500 t	F = 0.2	25%
SSB < 50 000 t (Blim)	F = 0	-

A similar proposed management plan was evaluated by ICES in 2005 and found to be consistent with the precautionary approach. In 2008 ICES checked that the recent changes in stock dynamics and the changes to the plan had not significantly increased the risks. ICES gives advice based on the management plan.

Management considerations

There has been considerable uncertainty in the amount of landings from this stock in the past. Area misreporting continues to be a problem, with almost all countries taking catches of herring in other areas and reporting it into VIa North. However, routine use of VMS has reduced the problem.

The assessment is noisy, leading to annual revisions of SSB and F. The management plan has been designed to cope with this by applying a constraint on year on year change in TAC. Revisions in SSB can be upwards or downwards, so it is important to maintain the restrictions on change in TAC both when the stock is revised upwards or downwards. Asymmetrical responses have not been tested and may be significantly more risky.

The stock identity of herring west of the British Isles was reviewed by the EU-funded project WESTHER. This identified Division VIaN as an area where catches comprise a mixture of fish from Divisions VIaN, VIaS, and VIIaN. Concerning the management plan for Division VIaN, ICES has advised that herring components should be managed separately to afford maximum protection and optimal yield. If there is an increasing catch on the mixed fishery in Division VIaN, this should be considered in the management of the Division VIaS component, which is in a depleted state. In 2008 ICES began to evaluate management for this Division VIa(south) and VIIa(north). It will be a number of years before ICES can provide a fully operational integrated strategy for these units. In this context ICES recommends that the management plans for Division VIaN should be continued.

Impacts of fisheries on the ecosystems

Herring are an important prey species in the ecosystem and also one of the dominant planktivorous fish.

Herring fisheries tend to be clean with little bycatch of other fish. Scottish discard observer programmes since 1999 indicate that discarding of herring in these directed fisheries are at a low level. These discard observer programmes have recorded occasional catches of seals and zero catches of cetaceans. Herring fisheries rarely disturb the seabed.