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| Marine Resource Fact Sheet |
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 | Herring in Subdivision 30 (Bothnian Sea) |
| | Data Ownership | | This document provided, maintained and owned by International Council for the Exploration of the Sea (ICES) , is part of ICES Advice data collection. |
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| Related observations | Locate in inventory | | | | Species: | | FAO Names: en - Atlantic herring, fr - Hareng de l'Atlantique, es - Arenque del Atlántico, ru - Сельдь атлантическая |
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| Geographic extent of Herring - Bothnian Sea Map tips - Click on
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| FAO Fishing Statistical Subdivision Areas |
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| 27.3.d.30 | Bothnian Sea (Subdivision 27.3.d.30) |
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| Main Descriptors | Considered a single stock: Yes Spatial Scale: Sub-Regional
Management unit: No Reference year: 2012
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| Considered a single stock: A group of individuals in a species occupying a well defined spatial range independent of other stocks of the same species. It can be affected by random dispersal movements and directed migrations due to seasonal or reproductive activity. |
| Spatial Scale: Spatial scale contains a standard term such as Global, Regional (e.g. for the whole Atlantic), sub-regional (e.g. for a part of the Atlantic), national, local (for sub-national levels). |
| Considered a management unit: An aquatic resource or fishery is declared as [Fishery] Management Unit if it is effectively the focus for the application of selected management methods and measures, within the broader framework of a management system. According to the FAO Glossary for Responsible Fishing, "a Fishery Management Unit (FMU) is a fishery or a portion of a fishery identified in a Fishery Management Plan (FMP) relevant to the FMP's management objectives." FMU's may be organised around fisheries biological, geographic, economic, technical, social or ecological dimensions , and the makeup and attribute of a fishery management unit depends mainly on the FMP's management objectives. |
| Jurisdictional distribution: Jurisdictional qualifier (e.g. "shared", "shared - highly migratory") of the aquatic resource related with its spatial distribution. |
| Environmental group: Classification of the aquatic resource according to the environmental group (e.g. pelagic invertebrate, or demersal fish) to which the species belong. |
| Reference Year: The Reference Year is the last year considered in the stock assessment and/or fishery status. |
| | | | | | Biological State and Trend  | Figure 8.4.6.2  |
The spawning-stock biomass tripled between the mid-1980s and mid-1990s and thereafter decreased by 40% until 1999. In the 2000s SSB remained high and has increased further after 2008. There is, however, great uncertainty around the estimates. Since the beginning of the time-series, the most likely estimates of fishing mortality have been below F MSY and have exceeded F MSY only in 1997 and 1999. Prior to 1994, recruitment was stable and low and has continued to remain stable over the past 20 years, but at a slightly higher average value than previously. The three year classes 2002, 2006, and 2008 are the most abundant in recent years. Landings in 2011 were the highest recorded over the time-series. Habitat and Biology Depth zone: Shelf (50 m - 200 m). Vertical distribution: Pelagic. The growing grey seal population in the Bothnian Sea has resulted in increased predation on herring. Environmental influence on the stockThe body weight of herring in the Bothnian Sea has declined over the last 20 years. The decrease in weight-at-age may be the result of a combination of density-dependent effects and a decrease in zooplankton prey. Geographical Distribution Jurisdictional distribution: Shared between nations Water Area Overview Spatial Scale: Sub-Regional Baltic Sea Geo References  | | Geographic extent of Herring - Bothnian Sea
| FAO Fishing Statistical Subdivision Areas | 27.3.d.30: Bothnian Sea (Subdivision 27.3.d.30) |
| | | | | | Intersecting Major FAO areas and LME areas |
The following area codes have been found as intersecting the distribution of Herring - Bothnian Sea Resource Structure Considered a single stock: Yes Exploitation The fisheriesOn average, 95% of the total catch is taken by the trawl fishery; the trapnet fishery is of minor importance. The small-scale herring gillnet fishery has a declining importance in coastal areas in Sweden. In the trawl fishery, larger and more effective trawls have been introduced in the 1990s. Sprat bycatches in herring fisheries are low in ICES Subdivision 30. | Catch distribution | Total landings (2011) are 78.5 kt (4% trapnets, 95% trawls, and 1% gillnets). Discards are negligible. | Effects of the fisheries on the ecosystemWith a low fishing mortality and high stock size, the effect of the fisheries on the ecosystem is probably not significant from a trophic point of view. Assessment Scientific Advice ICES advises on the basis of the MSY framework that catches in 2013 should be no more than 97 000 tonnes. Overall Assessment Results  | | Figure 8.4.6.2 Herring in Subdivision 30, Bothnian Sea. Historical performance of the assessment. A new assessment model and revision of input data was considered in 2012. |
Assessment Model Quality considerationIn contrast to the XSA model used previously, the retrospective patterns on SSB and F from the state–space model (SAM) do not show any trends. It is anticipated that extending the acoustic survey time-series and reconstructing commercial tuning fleets will improve the quality of the assessment.  | | Figure 8.4.6.2 Herring in Subdivision 30, Bothnian Sea. Historical performance of the assessment. A new assessment model and revision of input data was considered in 2012. |
Scientific basis | Assessment type | State–space model (SAM). | | Input data | Acoustic survey indices from 2007 to 2011, and one commercial cpue series, Finnish trapnet fleet. | | Discards and bycatch | Negligible discards. Small bycatches of sprat/mixed landings of herring and sprat, mainly from southern parts of the Bothnian Sea. | | Indicator | The trends in acoustic abundance and biomass estimates support the assessment results. | | Other information | Benchmark for the Subdivision 30 herring stock was carried out in 2012. | | Working group report | WGBFAS | Management Management unit: No Management plansNo specific management objectives are known to ICES. Source of information The above excerpts are from the first two pages of the ICES advice, the supporting information to this advice can be read in full at the following reference: ICES. Herring in Subdivision 30 (Bothnian Sea). Report of the ICES Advisory Committee, 2012. ICES Advice, May 2012.  http://www.ices.dk/committe/acom/comwork/report/2012/2012/Her-30.pdf |
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