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Spring Spawing herring - Norwegian Sea, 2008
Marine Resource  Fact Sheet
ICES Advice 2009
Spring Spawing herring - Norwegian Sea, 2008
Fact Sheet Citation  
Norwegian spring-spawning herring
Owned byInternational Council for the Exploration of the Sea (ICES) – More
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Species:
FAO Names: en - Atlantic herring, fr - Hareng de l'Atlantique, es - Arenque del Atlántico, ru - Сельдь атлантическая
Geographic extent of Spring Spawing herring - Norwegian Sea
Main Descriptors
Considered a single stock: Yes        Spatial Scale: Sub-Regional
Management unit: Yes
 
 
Habitat and Biology
Depth zone: Shelf (50 m - 200 m).   Vertical distribution: Pelagic.  

Geographical Distribution
Jurisdictional distribution: Straddling between High Seas and EEZ

Water Area Overview
Spatial Scale: Sub-Regional

Geo References
Resource Structure
Considered a single stock: Yes
Exploitation
 

Factors affecting the fisheries and the stock

Regulations and their effects

In the rebuilding phase of the stock in the 1980s and early 1990s (SSB < MBAL = 2.5 million tonnes), the management objective was to keep fishing mortality below 0.05. With the exception of a few years, this objective was achieved. A minimum landing size regulation of 25 cm is in force in EU and Norway waters. This has prevented the exploitation of young herring. These regulations have contributed to rebuilding of the stock to levels well above precautionary limits. When the fishery expanded in the mid-1990s, a long-term management plan was agreed.

For the 2006 fishery, the parties exploiting the resource (European Union, Faroe Islands, Iceland, Norway, and Russia) did not reach agreement regarding the allocation of the quota and no TAC was agreed. However, the fishing mortality in 2006 did not exceeded Fpa. From 2007 onwards, the parties have reached agreement on annual TACs and allocation of the quotas in accord with the management plan.

Changes in fishing technology and fishing patterns

In general, the fishery follows the migration of the stock as it moves from the wintering and spawning grounds along the Norwegian coast to the summer feeding grounds in the Faroese, Icelandic, Jan Mayen, Svalbard, and international areas. Due to limitations for some countries to enter the EEZs of other countries in 2008, the fisheries do not necessarily depict the distribution of herring in the Norwegian Sea. A special feature of the summer fishery in 2005 and 2006 was the prolonged fishery in the Faroese and Icelandic zone up to late August, where the oldest age groups were present in the second and third quarter. In 2007 and 2008 a clean herring fishery was hampered by mixture of mackerel schools in the area. This was especially the case for the Faroese fleet, which usually targets mackerel later in the year (October–November).

Impacts of the environment on the fish stock

The stock undergoes extensive migrations in the Northeast Atlantic, which have been linked to changes in ocean climate and changes in zooplankton distribution.

During 1995–2005, a weak relationship existed between zooplankton biomass in May and herring condition in the autumn. The March–April North Atlantic Oscillation (NAO) index in 2004 and 2005 was successfully used to predict the herring condition index in the winters of 2005 and 2006. Although no such analyses are available for the most recent years, the average biomass of zooplankton in the Norwegian Sea in May has been decreasing since 2002 and, in 2009, reached a record low level since the measurements started in 1997.

The Arctic front is a central feeding area for the herring stock. During periods when the Arctic front is shifted westwards, part of the stock feeding in the western Norwegian Sea also moves westward. The position of the Arctic front is correlated with large-scale environmental events.
Assessment
 
Assessment Model
Methodology

Scientific basis

Data and methods

In 2008, a benchmark procedure was applied to the stock assessment.

The advice is based on an analytical assessment, which takes into consideration catch data and eight surveys (acoustic surveys of adults and juveniles, larval survey, and 0-group survey), of which five surveys are continuing. The assessment is conducted using a VPA based model from the TASACS package. As agreed at the benchmark, the VPA analysis is restricted to the years 1988–2009, which is regarded as the period representative of the present production and exploitation regimes. For the period before 1988, the results are derived from the 2006 assessment, which are consistent with this year’s assessment.

The present assessment is an updated assessment, using the models, configurations and procedures agreed at the benchmark. The benchmark also examined cases where individual survey points might be excluded from the assessment model. Based on the agreed examination procedures, the 2009 value from the Norwegian herring larval survey on the Norwegian shelf (survey 8) was excluded from the assessment. This data point was excluded as the abundance estimate was anomalously low and the average size of the larvae was large suggesting that the survey was late relative to spawning. A similar rationale was used in the past to exclude the 2003 data point from the Norwegian larval survey.

Uncertainties in assessment and forecast

There is uncertainty about recent recruitment estimates. A source of uncertainty is caused by the lack of coherence in some of the survey information for the youngest ages. In addition, the catch in 2008 from a few directed fisheries by Norway and Russia in the 3rd and 4th quarter contained relatively high numbers of 1 and 2 year olds (year classes 2007 and 2006). The available surveys, however, indicate that these year classes are not strong.

There is uncertainty in the estimate of SSB and fishing mortality related to the exclusion of the 2009 survey point of the Norwegian herring larvae survey on the Norwegian shelf. Including the 2009 survey point would have resulted in the estimate of SSB being about 10% lower.

The international ecosystem survey in the Nordic Seas in May is the most important survey in the assessment and will remain so in future assessments. It is important that this survey is maintained and that the vessels participating in this survey have access to the survey grounds. As well it is essential to maintain good geographical survey coverage to avoid increases in assessment uncertainty and maintain the integrity of the assessment.

While discarding of this stock is estimated to be low, an un-quantified amount of slippage is known to occur, thus it has not been possible to account for slippage in the assessment.

Comparison with previous assessment and advice

The perception of the state of the stock and its exploitation has not changed markedly. Compared to last year, the SSB for 2008 is estimated to be about 5% higher and the fishing mortality in 2007 to be about 3% lower (see Figure 9.4.5.3).

The basis for the advice is the same as last year.
Overall Assessment Results


Figure 9.4.5.1. Herring in the Northeast Atlantic (Norwegian spring-spawning herring). Summary of stock assessment: landings, fishing mortality, recruitment, and SSB. Data prior to 1988 are from the 2006 assessment year.


Figure 9.4.5.2. Herring in the Northeast Atlantic (Norwegian spring-spawning herring). Stock–recruitment and PA plot. Data prior to 1988 are from the 2006 assessment year.


Figure 9.5.4.3. Herring in the Northeast Atlantic (Norwegian spring-spawning herring). Comparison of current assessment with previous assessments.

Table 9.4.5.2.
Table 9.4.5.3. Herring in the Northeast Atlantic (Norwegian spring-spawning herring). Summary of the stock assessment. Data prior to 1988 are from the 2006 assessment year.
Year Recruitment SSB Landings F weighted
  Age 0     Ages 5–14
  thousands tonnes tonnes  
1950 751000000 14200000 826000 0.0584
1951 146000000 12500000 1280000 0.0697
1952 96600000 10900000 1250000 0.0728
1953 86100000 9350000 1070000 0.0663
1954 42100000 8660000 1640000 0.1130
1955 25000000 9270000 1360000 0.0783
1956 29900000 10900000 1660000 0.1100
1957 25400000 9650000 1320000 0.1030
1958 23100000 8690000 986000 0.0787
1959 412000000 7180000 1110000 0.1130
1960 198000000 5850000 1100000 0.1360
1961 76100000 4390000 830000 0.1040
1962 19000000 3440000 849000 0.1460
1963 169000000 2670000 985000 0.2530
1964 93900000 2530000 1280000 0.2260
1965 8490000 3060000 1550000 0.2780
1966 51400000 2800000 1960000 0.6960
1967 3950000 1470000 1680000 1.5200
1968 5190000 344000 712000 3.4900
1969 9780000 145000 67800 0.5900
1970 661000 71000 62300 1.3200
1971 236000 32000 21100 1.5300
1972 957000 16000 13200 1.5000
1973 12900000 85000 7020 1.1700
1974 8630000 91000 7620 0.1140
1975 2970000 79000 13700 0.1900
1976 10100000 138000 10400 0.1060
1977 5100000 286000 22700 0.1110
1978 6200000 358000 19800 0.0434
1979 12500000 388000 12900 0.0238
1980 1470000 471000 18600 0.0341
1981 1100000 504000 13700 0.0215
1982 2340000 503000 16700 0.0200
1983 343000000 575000 23100 0.0291
1984 11500000 602000 53500 0.0903
1985 36600000 515000 170000 0.3790
1986 6040000 437000 225000 1.0700
1987 9090000 926000 127000 0.4040
1988 25724000 2768000 135301 0.045
1989 73988400 3409000 103830 0.029
1990 109705800 3702000 86411 0.022
1991 320875600 3877000 84683 0.023
1992 383921700 3767000 104448 0.027
1993 121890400 3641000 232457 0.064
1994 42242100 4122000 479228 0.129
1995 18643900 4976000 905501 0.229
1996 57789400 6545000 1220283 0.192
1997 50575900 7887000 1426507 0.180
1998 282407700 7290000 1223131 0.153
1999 227356600 6852000 1235433 0.186
2000 54030800 5837000 1207201 0.213
2001 35695300 4794000 766136 0.180
2002 568142000 4928000 807795 0.184
2003 185261300 6298000 789510 0.114
2004 344513300 7149000 794066 0.094
2005 53536700 7715000 1003243 0.128
2006* 90770000 11580000 968958 0.131
2007* 30990000 11836000 1266993 0.098
2008** 103000000 12437000 1545656 0.125
2009** 103000000 13300000    
Average 100457748 4646433 690524 0.3220
* Recruitment value has been replaced in the forecast by RCT estimate.** GM mean 1989–2005.

Reference Point
 


  Type Value Technical basis
Precautionary approach Blim 2.5 million t MBAL
  Bpa 5.0 million t Blim * exp(0.4*1.645).
  Flim not defined -
  Fpa 0.15 based on medium-term simulations.
Targets Fmgt <0.125 Management Plan.
PA points unchanged since 1998.


Projection


Outlook for 2010 Basis: Landings (2009) = 1643 (=TAC); Fw(2009)1) = 0.119; SSB(2009) = 13.3 million t.; SSB(2010)= 12.2 million t. The fishing mortality applied according to the agreed management plan (F(management plan)) is 0.125.
Rationale Landings(2010) Basis F(2010) SSB(2011) % SSB change 2) % TAC change 3)
Zero catch 0 F=0 0.000 12.2 0% -100%
Status quo 1483 F(2008) 0.125 10.8 -11% -10%
Agreed management plan 157 F(management plan)*0.1 0.013 12.0 -2% -90%
  389 F(management plan)*0.25 0.031 11.8 -3% -76%
  770 F(management plan)*0.50 0.063 11.5 -6% -53%
  1132 F(management plan)*0.75 0.094 11.1 -9% -31%
  1353 F(management plan)*0.90 0.113 10.9 -11% -18%
  1483 F(management plan) 0.125 10.8 -11% -10%
  1628 F(management plan)*1.1 0.138 10.7 -12% -1%
  1822 F(management plan)*1.25 0.156 10.5 -14% 11%
Precautionary limits 1755 Fpa 0.150 10.5 -14% 7%
Landings weights in thousand tonnes, stock biomass weights in million tonnes. The scenario in italics is not considered consistent with the precautionary approach.1) Fw = Fishing mortality weighted by population numbers (age groups 5–14).2) SSB 2011 relative to SSB 20103) Catch/landings 2010 relative to TAC 2009.


Scientific Advice

Single-stock exploitation boundaries

Considering the options below, ICES advises on the basis of the exploitation target in the existing management plan that catches in 2010 should not exceed 1483000 t.

Exploitation boundaries in relation to existing management plans

The management plan implies maximum catches of 1483000 t in 2010, which is expected to leave a spawning stock of 10.8 million tonnes in 2011.

Exploitation boundaries in relation to precautionary limits

The long-term management plan is considered to be consistent with the precautionary approach.


Table 9.4.5.1. Herring in the Northeast Atlantic (Norwegian spring-spawning herring). Single-stock exploitation boundaries (advice), management, and catch.


Year
ICESAdvice Predicted catchcorresp. to advice Agreed TAC ICESCatch
1987 TAC 150 115 127
1988 TAC 120–150 120 135
1989 TAC 100 100 104
1990 TAC 80 80 86
1991 No fishing from a biological point of view 0 76 85
1992 No fishing from a biological point of view 0 98 104
1993 No increase in F 119 200 232
1994 Gradual increase in F towards F0.1; TAC suggested 334 450 479
1995 No increase in F 513 None1 906
1996 Keep SSB above 2.5 million t - None2 1 217
1997 Keep SSB above 2.5 million t - 1 500 1 420
1998 Do not exceed the harvest control rule - 1 300 1 223
1999 Do not exceed the harvest control rule 1 263 1 300 1 235
2000 Do not exceed the harvest control rule Max 1 500 1 250 1 207
2001 Do not exceed the harvest control rule 753 850 770
2002 Do not exceed the harvest control rule 853 850 809
2003 Do not exceed the harvest control rule 710 7113 773
2004 Do not exceed the harvest control rule 825 8253 794
2005 Do not exceed the harvest control rule 890 1 0003 1 003
2006 Do not exceed the harvest control rule 732 9673 969
2007 Do not exceed the harvest control rule 1 280 1 280 1267
2008 Do not exceed the harvest control rule 1 518 1518 1546
2009 Do not exceed the harvest control rule 1 643 1 642  
2010 Do not exceed the harvest control rule 1 483    
Weights in ‘000 t. 1Autonomous TACs totaling 900 000 t. 2Autonomous TACs totaling 1 425 000 t were set by April 1996. 3 There was no agreement on the TAC, the number is the sum of autonomous quotas from the individual Parties.


Management
Management unit: Yes

Management Objectives

The EU, Faroe Islands, Iceland, Norway, and agreed in 1999 on a long-term management plan. This plan consists of the following elements:

  1. Every effort shall be made to maintain a level of Spawning Stock Biomass (SSB) greater than the critical level (Blim) of 2 500 000 t.
  2. For the year 2001 and subsequent years, the Parties agreed to restrict their fishing on the basis of a TAC consistent with a fishing mortality rate of less than 0.125 for appropriate age groups as defined by ICES, unless future scientific advice requires modification of this fishing mortality rate.
  3. Should the SSB fall below a reference point of 5 000 000 t (Bpa), the fishing mortality rate referred to under paragraph 2, shall be adapted in the light of scientific estimates of the conditions to ensure a safe and rapid recovery of the SSB to a level in excess of 5 000 000 t. The basis for such an adaptation should be at least a linear reduction in the fishing mortality rate from 0.125 at Bpa (5 000 000 t) to 0.05 at Blim (2 500 000 t).
  4. The Parties shall, as appropriate, review and revise these management measures and strategies on the basis of any new advice provided by ICES.


ICES considers that this agreement is consistent with the precautionary approach.
Management Advice

Management considerations

Historically, the size of the stock has shown large variations and dependency on the irregular occurrence of very strong year classes. In 2009, SSB is estimated to be at its highest level in the last 60 years. In recent years, catches have also increased but fishing mortality has remained low and close to that agreed in the management plan. The management plan is considered precautionary.

In the absence of strong year classes after 2004, the stock is expected to decline in the near future even when fished according to the management plan. This is normal behaviour of stocks which show spasmodic recruitment dynamics. The decline of the stock will result in a reduction in the projected catches in incoming years.

Impacts of fisheries in the ecosystem

The herring in the Northeast Atlantic stock is a straddling stock. Juveniles and adults of this stock form an important part of the ecosystem in the Barents Sea, the Norwegian Sea, and the Norwegian coast. Herring is an important food resource for higher trophic level predators (e.g. large fish, seabirds, and marine mammals), and also a consumer of zooplankton in the Norwegian Sea and capelin larvae in the Barents Sea.

Little information is available on the impact of the herring fishery on the ecosystem. The fishery is entirely pelagic. There is little quantitative information on the bycatches in the fisheries for herring, but these are thought to be small. Therefore, unintended effects of the fishery on the ecosystem are probably small.
Biological State and Trend
Exploitation rate: Harvested sustainably
Abundance level: Full reproductive capacity


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 F Comment
Full reproductive capacity Harvested sustainably Unknown At target MSY estimate not available



Based on the most recent estimates of SSB (in 2009) ICES classifies the stock as having full reproductive capacity. Based on the most recent estimate of fishing mortality (in 2008) ICES classifies the stock as being harvested sustainably.

SSB in 2009 is well above Bpa and is estimated as one of the highest in the time-series. The stock contains a number of good year classes. In the last 10 years, four large year classes have been produced (1998, 1999, 2002 and 2004). However, the available information indicates that year classes after 2004 have been of low abundance.
Source of information
 
ICES. 2009. Report of the ICES Advisory Committee, 2009. ICES Advice, 2009.
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