Single-stock exploitation boundaries


Exploitation boundaries in relation to existing management plans


Fishing according to the proposed management plan would imply catches up to 15 000 tonnes. The proposal was evaluated and found to be consistent with the precautionary approach.

Exploitation boundaries in relation to precautionary considerations


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

Conclusion on exploitation boundaries


In the absence of exploitation boundaries in relation to precautionary limits ICES recommends to fish according to the proposed management plan.

Management considerations


There has been considerable uncertainty in the level of landings from this area in the past. Recent revisions to catch data have reduced some of this uncertainty. Enforcement has improved since 2005 and catch figures are more accurate. In 2006 the stock was more heavily exploited than it has been since 1999. This recent increased F is associated with increased enforcement and reduction of area misreporting from Area IVa.

The stock identity of herring west of the British Isles was reviewed by the EU-funded project WESTHER. This identified VIaN as an area where catches comprise a mixture of fish from Areas VIaN, VIaS, and VIIaN. Concerning the management plan for VIaN, ICES has advised that herring components should be managed separately to afford maximum protection. If there is an increasing catch on the mixed fishery in VIaN, this should be considered in the management of the VIaS component which is in a depleted state. 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 previously endorsed plans for VIaN should be continued (see Section 5.3.3.1). If the proposed management plan were to be implemented in 2008, the current low status of the stock would imply that the 15% TAC reduction limits would not apply.

Ecosystem considerations


Irregular cycles are shown in the productivity of herring stocks (weights-at-age and recruitment). There are many hypotheses as to the cause of these changes in productivity, but in most cases it is thought that the environment plays an important role (through transport, prey, and predation). Coincident periods of high and low production have been seen in the herring in VIa (N) and Irish Sea herring. Exploitation and management strategies must account for the likelihood of productivity changing. The VIa (N) herring stock has shown a marked decline in productivity during the late 1970s and has remained at a low level since then.

There are no explicit management objectives for this stock. However, a proposed management plan is currently being discussed. This management plan was evaluated by ICES in 2005 and found to be consistent with the precautionary approach.

Catch and TACs
Catch and TACsWeights in ‘000 t.
¹⁾ Adjusted for misreporting.
²⁾ Catch at status quo F.
³⁾ Revised down from 60 in 1999.
⁴⁾ Revised at HAWG 2007.
⁵⁾ F_int is the intermediate F of the suggested management plan.