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North Sea Autumn Spawning herring

Main characteristics and peculiarities
• one of the best-known herring stocks in the world; stock showed enormous fluctuations in the past: rapid decline in the late 1970s due to overfishing and recruitment failure, followed by a 4-yr closure of the fishery, another decline in the mid-1990s mainly due to high bycatches of juveniles in the industrial fishery. This led to the implementation of a recovery plan in 1997.
• exemplary stock for fisheries management within the European Union (click here to read the text of the EU-Norway agreement for North Sea herring management; further reading [a short paper on North Sea herring management])

Assessment Summary
year	2000 (WG 2001)
type	agreed assessment, single species (but M derived from multi-species models): ICA
assessment quality	good
main problems	(1) significant amount of misreporting and little information on discarding (2) difficult separation between NSAS and Western Baltic Spring Spawners in Div IIIa and Sub-Div IVa(East)
fisheries independent information	(1) int'l hydroacoustic summer survey, (2a) int'l bottom trawl survey 1st and 3rd quarter, (2b) MIK index, (3) larval survey(s)
catch	372'000 t (1999: 370'000 t)
spawning stock biomass	771'000 t (1999: 815'000 t - Assessment 2001; 906'000 t - Assessment 2000)
fishing mortality	F(adults [2-6])=0.42, F(juv [0-1])=0.05; (1999: F(adults)=0.46 - Assessment 2001; F(adults)=0.38 - Assessment 2000)
reference points	Blim (MBAL)=800'000 t, Bpa=1'300'000 t, Fpa(adults)=0.25, Fpa(juv)=0.12
state of the stock	outside safe biological limits: SSB below Bpa (in 2000 even below Blim), F(adults) above Fpa
perspective	stock recovering, will be above Bpa within the next few years, if measures are taken to effectively limit catches to TACs

Stock parameters (under construction)

This standard figure can be downloaded as a printable pdf-file (requires Acrobat Reader)

• estimated catch (including discards and unallocated or misreported catch, totals) or commercial landings (official figures, totals)
• distribution of catches
• spawning stock biomass
• recruitment
• fishing mortality
• catch in numbers at age
• mean mass at age in the catch
• mean mass at age in the stock
• natural mortality at age
• proportion mature

If you like to compare with last year's assessment results (for 1999), click here.

Distribution
NSAS are distributed in the North Sea [Area IV], the Eastern Channel [Div VIId], and the Kattegat/Skagerak [Div IIIa]. Spawning takes place along the British East coast and in the Channel. The southern North Sea and Eastern Channel are inhabited by a separate component, the Downs herring. A separate TAC is set for this component, but it is managed within the North Sea stock complex due to the impossibility of differentiating Downs herring from the rest of the stock complex, at least on a commercial scale.

Note that there is a difference between North Sea Autumn Spawning herring (which is Autumn spawners only, caught in the North Sea, the Eastern Channel and Div IIIa) and herring caught in the North Sea (which is a mixture of NSAS, Western Baltic Spring Spawners and some minor coastal spring spawning stocks, but caught only in Area IV and Div VIId). This is important as the catch of NSAS caught outside the North Sea is up to 15% of the total catch, and the assessment is conducted for the NSAS stock and not for the North Sea! Click here for a detailed table on the composition and catches by fleet for NSAS and Western Baltic Spring Spawners, which are mixing in Div IIIa and Sub-Div IVa(E).

Management advice
ICES advises that catches in 2002 should be within the constraints on fishing mortality agreed by the EC and Norway, i.e. F(adults)<0.2 and F(juv)<0.1. There are a number of different options within these limits. Fishing mortality in recent years is well in excess of the specified targets and ICES advises that additional measures to control the catches and ensure accurate reporting will be required to restrict catches.

Note that ICES does not recommend a closure of the fishery in spite of the spawning stock biomass being below Blim. Due to the excellent recruitment (especially the 1998 yearclass), which is indicated by several different indices, it is believed that SSB will be above Blim already in Summer 2001. However, this perspective is optimistic, and there remains some probability that the North Sea stock is not recovering, if fishing mortality is not significantly reduced.

Source
ICES Working Group for the Assessment of Herring South of 62°N 2000, ICES CM 2000/ACFM:10; and 2001, ICES CM 2001/ACFM:12

Data entered/updated by (Date)
Christopher Zimmermann (25-06-00/21-06-01)

Please contact clupea@clupea.de if you like to contribute more information on this or other stocks!