Fisheries and Resources Monitoring System

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Clyde herring - West of Scotland
Marine Resource  Fact Sheet
ICES Advice 2009
Clyde herring - West of Scotland
Fact Sheet Citation  
Clyde Herring (Division VIa)
Owned byInternational Council for the Exploration of the Sea (ICES) – More
Related observationsLocate in inventorydisplay tree map
 
Species:
FAO Names: en - Atlantic herring, fr - Hareng de l'Atlantique, es - Arenque del Atlántico, ru - Сельдь атлантическая
Geographic extent of Clyde herring - West of Scotland
Main Descriptors
Considered a single stock: Yes        Spatial Scale: Sub-Regional
Management unit: Yes        Reference year: 2008
 
 
Biological State and Trend
State & Trend Descriptors
PartnerFIRMS
Exploitation rateUndefinedUncertain/Not assessed
Abundance levelUndefinedUncertain/Not assessed


Spawning biomass in relation to precautionary limits Fishing mortality in relation to precautionary limits Fishing mortality in relation to high long-term yield

Fishing mortality in relation to

agreed target

Comment
Undefined Undefined Underfished Below target  



In the absence of precautionary reference points the state of the stock cannot be evaluated. An analytical assessment shows that SSB (in 2009) is 1.8 times Blim. ICES considers that the stock over recent years has been fluctuating at a low level and is being exploited close to Fmsy. Recruitment has been very low since 1998, and the 2001 and 2002 year classes are weak.
Habitat and Biology
Depth zone: Shelf (50 m - 200 m).   Vertical distribution: Pelagic.  

Geographical Distribution
Jurisdictional distribution: National

Water Area Overview
Spatial Scale: Sub-Regional

Geo References
Resource Structure
Considered a single stock: Yes
Exploitation
 

Factors affecting the fisheries and the stock

Changes in fishing technology and fishing patterns

Historically, catches have been taken from this area by three fisheries:

  1. A Scottish domestic pair trawl fleet and the Northern Irish fleet operated in shallower, coastal areas, principally fishing in the Minches and around the Island of Barra in the south; younger herring are found in these areas. This fleet has reduced in recent years.
  2. The Scottish single-boat trawl and purse-seine fleets, with refrigerated seawater tanks, targeting herring mostly in the northern North Sea, but also operating in the northern part of Division VIaN. This fleet now operates mostly with trawls, but many vessels can deploy either gear.
  3. An international freezer-trawler fishery has historically operated in deeper water near the shelf edge where older fish are distributed. These vessels are mainly registered in the Netherlands, Germany, France, and England, but most are Dutch owned.


In recent years the age structure of the catch of these last two fleets has become more similar.

Impacts of the environment on the fish stock

Temperatures in this area have been increasing over recent decades. There are indications that salinity is also increasing. It is considered that this may have implications for herring. It is known that similar environmental changes have affected the North Sea herring. There is evidence that there have been recent changes of the productivity of the Division VIaN stock.

Herring are thought to be a source of food for seals. A recent study of seal diets off western Scotland revealed that grey seals may be an important predator for herring in this area. The numbers of seals in Division VIaN is thought to have increased over the last decades. The seal consumption of herring is estimated with great uncertainty and the impact of increased predation is not known, but there is a possibility that seal predation could influence natural mortality.
Assessment
 
Assessment Model
Methodology

Scientific basis

Data and methods

Analytic assessment using catch data and data from one acoustic survey.

The acoustic survey used to tune the assessment has been re-evaluated and found to provide a useful, but noisy signal for tuning the assessment.

Uncertainties in assessment and forecast

The assessment is considered to be noisy, but unbiased. Medium-term evaluations of the management plan have been carried out assuming the same level of noise as seen in the assessment. Risks of SSB<Blim are expected to be low if the management is followed.

Comparison with previous assessment and advice

This year’s assessment is revised upwards compared to last year’s, with F 37% lower and SSB 49% higher compared to 2008 values. The basis for the advice has changed from last year, a reduction in TAC, to this year’s advice for an increase in catch in line with the agreed management plan.
Overall Assessment Results


Figure 5.4.30.1 Herring in Division VIa North. Landings, fishing mortality, recruitment, and SSB. Estimates are marked in grey


Figure 5.4.30.2 Herring in Division VIa North. Stock and recruitment, yield, and precautionary approach


Figure 5.4.30.3 Herring in Division VIa North. Historical performance of the assessments. Note: assessments prior to 2001 not comparable with recent assessments.


Table 5.4.30.2 Herring in Division VIa North. Catch in tonnes by country, 1985–2008. These figures do not correspond in all cases to the official statistics and cannot be used for management purposes.
Country 1985 1986 1987 1988 1989 1990 1991 1992
Denmark                
Faroes 104 400       326 482  
France 20 18 136 44 1 342 1 287 1 168 119
Germany 5 937 2 188 1 711 1 860 4 290 7 096 6 450 5 640
Ireland   6 000 6 800 6 740 8 000 10 000 8 000 7 985
Netherlands 5 500 5 160 5 212 6 131 5 860 7 693 7 979 8 000
Norway 4 690 4 799 4 300 456   1 607 3 318 2 389
UK 28 065 25 294 26 810 26 894 29 874 38 253 32 628 32 730
Unallocated -502 37 840 18 038 5 229 2 123 2 397 -10 597 -5 485
Discards         1 550 1 300 1 180 200
Total 43 814 81 699 63 007 47 354 53 039 69 959 50 608 51 578
Area-Misreported -4 672 -10 935 -18 647 -11 763 -19 013 -25 266 -22 079 -22 593
WG Estimate 39 142 70 764 44 360 35 591 34 026 44 693 28 529 28 985
Source (WG) 1987 1988 1989 1990 1991 1993 1993 1994
 
Country 1993 1994 1995 1996 1997 1998 1999 2000
Faroes                
France 818 274 3 672 2 297 3 093 1 903 463 870
Germany 4 693 5 087 3 733 7 836 8 873 8 253 6 752 4 615
Ireland 8 236 7 938 3 548 9 721 1 875 11 199 7 915 4 841
Netherlands 6 132 6 093 7 808 9 396 9 873 8 483 7 244 4 647
Norway 7 447 8 183 4 840 6 223 4 962 5 317 2 695  
UK 32 602 30 676 42 661 46 639 44 273 42 302 36 446 22 816
Unallocated -3 753 -4 287 -4 541 -17 753 -8 015 -11 748 -8 155  
Discards   700     62 90  
Total 56 175 54 664 61 271 64 359 64 995 65 799 61 514 37 789
Area-Misreported -24 397 -30 234 -32 146 -38 254 -29 766 -32 446 -23 623 -19 467
WG Estimate 31 778 24 430 29 575 26 105 35 233 33 353 29 736 18 322
Source (WG) 1995 1996 1997 1997 1998 1999 2000 2001
 
Country 2001 2002 2003 2004 2005 2006 2007 2008
Faroes   800 400 228 1 810

570

484 927
France 760 1 340 1 370 625 613 701 703 564
Germany 3 944 3 810 2 935 1 046 2 691 3 152 1 749 2 526
Ireland 4 311 4 239 3 581 1 894 2 880 4 352 5 129 3 103
Netherlands 4 534 4 612 3 609 8 232 5 132 7 008 8 052 4 133
Norway                
UK 21 862 20 604 16 947 17 706 17 494 18 284 17 618 13 963
Unallocated   878 -7          
Discards       123 772 163    
Total 35 411 36 283 28 835 29 854 31 392 34 230 33 735 25 216
Area-Misreported -11 132 -8 735 -3 581 -7 218 -17 263 -6 884 -4 119 -9 162
WG Estimate 24 556 32 914 28 081 25 021 14 129 27 346 29 616 16 054
Source (WG) 2002 2003 2004 2005 2006 2007 2008 2009


Table 5.4.30.3 Herring in Division VIa North. Summary of stock assessment.

Year

Recruitment

Age 1

Thousands

SSB

tonnes

Landings

tonnes

Mean F

Ages 3-6

1957 1085415 184542 43438 0.2833
1958 2129925 200966 59669 0.3315
1959 2124103 214361 65221 0.3043
1960 628969 248252 63759 0.1948
1961 1282671 248296 46353 0.1290
1962 2323456 237651 58195 0.2055
1963 2128325 261562 49030 0.1830
1964 979318 307678 64234 0.1530
1965 7855652 316322 68669 0.1580
1966 1065520 427781 100619 0.1920
1967 2499919 460184 90400 0.1885
1968 4100323 437487 84614 0.1425
1969 2998830 475825 107170 0.2415
1970 3440170 444140 165930 0.3580
1971 9572399 316111 207167 0.7885
1972 2675839 443971 164756 0.3648
1973 1074339 385359 210270 0.6055
1974 1672283 204084 178160 0.9570
1975 2101533 107141 114001 0.9093
1976 608221 73429 93642 1.0677
1977 621969 51907 41341 0.9935
1978 913517 48526 22156 0.6767
1979 1216369 72378 60 0.0008
1980 885405 122146 306 0.0002
1981 1660598 131858 51420 0.3623
1982 770261 109542 92360 0.6750
1983 2977418 81150 63523 0.7137
1984 1132203 120051 56012 0.5182
1985 1199475 147680 39142 0.3157
1986 887707 133119 70764 0.5272
1987 2097344 123340 44360 0.3442
1988 899294 147822 35591 0.2858
1989 844942 163947 34026 0.2480
1990 433443 154485 44693 0.3500
1991 380590 125793 28529 0.2610
1992 792557 102884 28985 0.2858
1993 580372 98509 31778 0.2482
1994 869256 89016 24430 0.2280
1995 631358 71728 29575 0.2660
1996 835046 115212 26105 0.1703
1997 1491824 75352 35233 0.5070
1998 481352 98427 33353 0.4900
1999 305133 81928 29736 0.3025
2000 1636643 69449 18322 0.2367
2001 1090588 113982 24556 0.2410
2002 1143083 134943 32914 0.2667
2003 434105 133947 28081 0.2315
2004 251977 119690 25021 0.1948
2005 299915 98238 14129 0.1202
2006 554435 93270 27346 0.2273
2007 323159 91848 29616 0.2875
2008 145843 91884 16054 0.1555
2009 629205* 91933    
Average 1542709 179267 59900 0.3556
* geometric mean 1989-2006

Reference Point
 


  Type Value Technical basis
Precautionary approach Blim 50 000 t Lowest reliable estimate of SSB
  Bpa Not defined  
  Flim Not defined  
  Fpa Not defined  
Targets Fmgt 0.25 HCR Simulations Fmsy HAWG 2005
Unchanged since 2005


Yield and spawning biomass per Recruit F-reference points:
 

Fish Mort

Ages 3-6

Yield/R

SSB/R

Average last 3 years 0.22 0.04 0.17
F0.1 0.17 0.04 0.20
Fmed 0.27 0.04 0.15


Projection



Basis: F (2009) = F (TAC 2009) = 0.23; SSB (2009) 1 = 92 t; landings (2009) = 21.76; R(09-11) = (GM89-06) = 629.2 million


Outlook for 2010
Rationale Catches (2010) SSB (2010)1 Basis

F

(2010)

SSB

(2011)

% TAC change2
Zero catch 0 108 F=0 0 130 -100%
Management plan F=0.25 24.42 94 Fsq*1.08 0.25 96 +12%
Status quo options 17.63 98 Fsq*0.74 0.17 110 -20%
  21.76 96 Fsq*0.95 0.22 99 0%
  26.15 93 Fsq*1.17 0.27 93 +20%
  28.69 91 Fsq*1.52 0.35 90 +32%
  32.83 89 Fsq*1.74 0.40 85 +51%

Weights in ‘000 tonnes.

Shaded scenarios are not considered consistent with the management plan.

1) For autumn spawning stocks, the SSB is determined at spawning time and is influenced by fisheries between 1 January and spawning.

2) TAC 2010 relative to TAC 2009



Scientific Advice

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 Blim.


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.



Management
Management unit: Yes

Management Objectives

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 Advice

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.
Source of information
 
ICES.2009.Report of the ICES Advisory Committee, 2009. ICES Advice, 2009.
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