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Irish Sea herring

Main characteristics and peculiarities
• spawning takes place on two distinct grounds (indicating at least 2 sub-stocks): Manx and Mourne (see below)

Assessment Summary
year	2000 (WG 2001)
type	single species: Integrated Catch Analysis
assessment quality	unstable/weak
main problems	(1) no reliable estimates of catches for 1998 and 1999 (2) limited biological information on different sub-stocks available
fisheries independent information	(1) Acoustic survey covering part of the area (2) 2 Larvae surveys (3) Groundfish survey
catch	2'000 t (1999: 4'100 t)
spawning stock biomass	10'000 t (1999: 10'600 t)
fishing mortality	F(adults [2-6])=0.15 (1999: 0.27)
reference points	Bpa=9'500 t, Blim=6'500 t, Fpa under review
state of the stock	probably within safe biological limits, (SSB above Bpa, F low)
perspective	uncertain

Stock parameters (under construction)

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

Distribution
Irish Sea herring is distributed in ICES Area VIIa (North).

Management advice
Total allowable catches for 2002 should not exceed the mean of the last 5 years (4'800 t).

Stock Composition
Traditionally the stock of herring in the Irish Sea was viewed as having two main spawning components, the Manx and Mourne spawners. The Manx component spawned to the east of the Isle of Man and the Mourne component to the east of the Northern Irish coast. Both are dominated by autumn spawning herring, that typically spawn from September to October. In the 1970s the Mourne herring was thought to make up to 35-40% of the spawning biomass in the Irish Sea, based on catch. However by the late 1990s the Mourne component appears to be only 2-4% of the spawning biomass, based on the results from surveys of larvae. Herring in the Irish Sea has been assessed as one stock since 1982.

Fishery
There has been a decline in the number of boats that fish for herring in the Irish Sea since the 1980s. In 1987, over 120 boats fished for herring in the Irish Sea but in 2000 less than 5 boats targeted herring. The stock was thought to have collapsed in the late 1970s and recovered in the early 1980s. Landings have been relatively stable since 1980. There was an industrial fishery in the western Irish Sea that caught juvenile herring and sprat from 1969 to 1978.

Monitoring of the Stock
The commercial catches are monitored and sampled by the relevant fisheries Institutes. No analysis of the amount of discarding or slippage by the fleet is carried out. Trends in abundance of the stock are determined from research surveys and are used in the assessment. The extensive survey programme is carried out by the Department of Agriculture and Rural Development (DARD) based in Belfast and by the University of Liverpool's Port Erin Marine Laboratory (PEML) on the Isle of Man. The surveys include a hydroacoustic survey of the Irish Sea every September, surveys of larvae over the Manx spawning ground and over the whole Irish Sea and two trawl surveys a year.

Sources
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
ICES Study Group on Herring Assessment and Biology in the Irish Sea and Adjacent Waters, ICES CM 1994/H:5, 69 pp.

Data entered/updated by (Date)
Christopher Zimmermann (01-07-00)/Mark Dickey-Collas (11-01-01)/Christopher Zimmermann (27-06-01)

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