Indicator Specification

Status of marine fish stocks

Indicator Specification

Indicator codes: CSI 032 , MAR 007

Published 03 Mar 2015 Last modified 04 Dec 2019

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Topics: Water and marine environment

This page was archived on 03 Apr 2018 with reason: Other (New version data-and-maps/indicators/status-of-marine-fish-stocks-3 was published)

The indicator assesses both the status of the commercial fish stocks in Europe´s regional seas and the level of pressure exerted by fisheries on those stocks against their sustainable reference levels. It also provides an overview of the availability of information to provide such analysis. To that end it reports on: The availability of information for assessing the status of the level of exploitation and the reproductive capacity. This is reflected by the proportion of the total landings (as a proxy of catch) from commercial fisheries per regional sea covered by quantitative stock assessments (i.e. providing information on the 2 indicators fishing mortality and spawning stock biomass and their sustainable reference levels). The status of the assessed marine fish and shellfish stocks based on the current level of exploitation and the reproductive capacity (i.e. the status of fishing mortality and spawning stock biomass compared to their sustainable reference levels)

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Assessment versions

Published (reviewed and quality assured)

No published assessments

Rationale

Justification for indicator selection

Commercial fish and shellfish stocks from European waters are crucial sources of seafood and their sustainable use has been at the core of EU policy for more than a decade. Historically, many stocks have been over exploited sometimes to the point that it may affect their reproductive capacity and, thus, their potential for recovery from exploitation. In addition, many commercially exploited stocks do not have enough information to be assessed against sustainable reference levels. Assessing the availability of information and the status of the assessed fish stocks is therefore key for understanding if their use is sustainable. In addition, this analysis also allows progress towards the EU policy objectives of fishing at sustainable levels i.e. at Maximum Sustainable Yield, to be tracked, in particular for the Common Fisheries Policy and the Marine Strategy Framework Directive.

Scientific references

A Census of Marine Biodiversity Knowledge, Resources, and Future Challenges Costello MJ, Coll M, Danovaro R, Halpin P, Ojaveer H, et al. (2010) . PLoS ONE 5(8): e12110.
Marine Strategy Framework Directive - Descriptor 3+ ICES, 2012. ICES CM2012/ACOM:62. 173 pp.
Green Paper- Reform of the Common Fisheries Policy EC, 2009. COM(2009) 163 final

Indicator definition

The availability of information for assessing the status of the level of exploitation and the reproductive capacity. This is reflected by the proportion of the total landings (as a proxy of catch) from commercial fisheries per regional sea covered by quantitative stock assessments (i.e. providing information on the 2 indicators fishing mortality and spawning stock biomass and their sustainable reference levels).
The status of the assessed marine fish and shellfish stocks based on the current level of exploitation and the reproductive capacity (i.e. the status of fishing mortality and spawning stock biomass compared to their sustainable reference levels)

Units

Fish landings are expressed in tonnes. Stocks are expressed in number of stocks.

Policy context and targets

Context description

The scope of the Common Fisheries Policy (CFP) includes the conservation of marine biological resources and the management of fisheries targeting them. To that end, the CFP should adapt exploitation rates so as to ensure that, within a reasonable timeframe, the exploitation of marine biological resources restores and maintains populations of harvested stocks above levels that can produce the Maximum Sustainable Yield (MSY). This should be achieved by 2015, or no later than 2020.

This also translates the international commitment, subscribed to by EU Member States at the World Summit on Sustainable Development in Johannesburg (September 2002), to maintain or restore fish stocks to levels that can produce the Maximum Sustainable Yield (MSY), with the aim of achieving these goals for depleted stocks on an urgent basis, and where possible not later than 2015.

The EU Marine Strategy Framework Directive (MSFD) requires “Good Environmental Status” (GES) by 2020. Three criteria for GES have been identified for commercial fish and shellfish:

Level of exploitation
Reproductive capacity
Healthy age- and size-distribution

The requirements of GES, according to the MSFD, are aligned to the requirement of MSY for both the “level of exploitation” and the “reproductive capacity”. The “Healthy age- and size-distribution” is not sufficiently developed yet.

Targets

The new CFP (2014) environmental objectives and targets are:

the populations of fish stocks are progressively restored and maintained above biomass levels that can produce the Maximum Sustainable Yield (MSY), while applying the precautionary approach. This sustainable biomass objective has been further translated into a management target, which is, to ensure all fish stocks are exploited (i.e. the level of fishing pressure) at MSY rates by 2015 where possible, and by 2020 at the latest.
to implement the ecosystem-based approach to fisheries management

The MSFD (2008) overall objective is to reach Good Environmental Status (GES) of the marine environment by 2020. For its descriptor D3 on commercial fish stocks, this means "Populations of all commercially exploited fish and shellfish are within safe biological limits, exhibiting a population age and size distribution that is indicative of a healthy stock". Concretely this means:

Sustainable exploitation: fishing mortality (F) is at or below levels that deliver Maximum Sustainable Yield (MSY), i.e. F ≤ F_MSY.
Reproductive capacity intact: (or its proxy) spawning stock biomass (SSB) is above the reference level, i.e. SSB ≥ SSBmsy (or above its proxy).

Key policy question

Is the use of commercial fish stocks sustainable?

Methodology

Methodology for indicator calculation

This indicator consists of three parts:

Total landings in Europe´s regional seas divided into proportions of landings of assessed and non-assessed stocks, as analysed by the International Council for Exploration of the Sea (ICES), the General Fisheries Commission for the Mediterranean (GFCM) and the International Commission for the Conservation of Atlantic Tunas (ICCAT).
Proportion of assessed fish stocks that are in Good Environmental Status (GES) per regional sea, based on stock assessments by ICES, GFCM and ICCAT.
Overview of the status of assessed fish stocks and its trend over time in the North East Atlantic and Baltic seas based, on two criteria and their respective indicators: Sustainable level of exploitation (fishing mortality, F) and reproductive capacity (Spawning stock biomass, SSB).

Stocks

Fish species rarely reproduce randomly with conspecies throughout their geographical range, but form a series of stocks that are reproductively isolated in space and time. Cod, for instance, is currently considered to form eight different stocks covering the Baltic Sea, North Sea, Celtic Sea, Barents Sea and the Icelandic waters, between which mixing is negligible. European eel is an example of another extreme situation where there is only one stock as all mature eel migrate to the Sargasso Sea to spawn in random mixture with each other. The stocks used are those assessed by ICES (Baltic sea, Northeast Atlantic), GFCM (Mediterranean and Black sea) and ICCAT (tunas). In the Northeast Atlantic area, stocks are generally defined based on biological criteria and knowledge of population migration, mixing and spawning areas. In the Mediterranean and Black seas, due to lack of biological knowledge, stocks are defined largely by area and not, in general, on the basis of well-established biological knowledge on population units.

Geographical attribution of stocks

Because stocks are based on a specific geographic area, most can be attributed to a specific regional sea. In order to report the status per regional sea, the landings data per FAO major fishing area (which, in turn, is matched to both ICES and GFCM areas - see http://www.fao.org/fishery/area/Area27/en#str or http://www.fao.org/fishery/area/Area37/en for the GFCM areas) was matched to the regional seas surrounding Europe. The stocks were attributed to each regional sea based on the overlap between their geographical range (ICES area) or the geographical area for which the assessment is conducted (GFCM area) and the regional sea.

For both the ICES and GFCM/ICCAT stocks, we introduced one category of widely distributed stocks (both for those in the Northeast Atlantic ocean and in the Mediterranean) that could not be attributed to any of the regions as they cover multiple regions.

The attribution of stocks to one region that exist, and thus are caught, in more than one region remains however an arbitrary decision. The adopted methodology allocates a stock to a regional sea and only considers the catches for the assessment on availability of information for the same regional sea. This means, if the same stock is being caught in a different regional sea and those landings have assessment information, it is not included in the analysis.

For example “Saithe in Subarea IV (North Sea), Division IIIa (Skagerrak), and Subarea VI (West of Scotland and Rockall)” is attributed (by the ICES WKD3R which we adopted) to the North Sea, while catches come both from the North Sea as well as the Celtic Sea. So, when showing the percentage catch (in practice landings) covered by assessed stocks, the Celtic sea saithe catches that are covered by an assessment are not included, since this stock is now only attributed to the North Sea.

Allocating a stock to a regional sea without moving the catch therefore results in a bias (an assessed catch appearing to be unassessed), while moving the catch to the regional sea, to which the stock is attributed, would also distort the regional catches. The other alternative, i.e. counting a stock twice through allocating it to two regional seas, would generate double counting and thus not be an optimal solution either. A more adequate solution to attributing stocks and catch data will be implemented in future assessments as work on the policy implementation progresses.

Temporal coverage

Landings data for the Mediterranean and Black Sea were only available until 2010, therefore we based the landings information for all regional seas in this year.

For the status assessment, the stock assessment information was based on ICES, ICCAT or GFCM assessments. From the stocks covered by ICES we used the estimates of fishing mortality (F) and reproductive capacity (SSB) from 2012, as available from ICES advice for 2013. From the stocks covered by GFCM/ICCAT we used the latest assessment available, which varied between 2008 and 2012, and the most recent year for which estimates were reported.

Landings and stock assessment data

Landings are used as proxy of catches. For the Northeast Atlantic Ocean and Baltic Sea, landings data is based on the ICES FISHSTAT database. Mediterranean and Black Sea catch data and information are from the FAO. Data refers to fish, crustaceans, molluscs and other aquatic organisms and is reported in whole tonnes live weight (TLW). The statistics comprise reported national data from commercial, industrial and small-scale fisheries, carried out in inland, coastal and high seas fishing areas, but not recreational fisheries. Only part of these species/taxa consist of one or more commercial stocks, of which only part are covered by quantitative stock assessments such that their status can be assessed based on the set of indicators used .

Assessed versus non-assessed

Stocks for which ICES provides advice are categorised depending on the availability of data and stock assessment, where e.g. for data-rich stocks, full analytical stock assessments are in place, while the data-poor stocks are without quantitative assessments and forecasts (see ICES 2012). However, information on fishing mortality (F) and reproductive capacity (SSB) was not consistently available for all stocks considered data-rich by ICES. Therefore, stocks were classified in four categories, depending on the availability of information to calculate the status of F and SSB against the policy objectives of the MSFD. These are:

Not assessed: there was not sufficient information available to assess the status of F and/or SSB as described below
Assessed F: information available to assess status based on Fishing mortality (F) and F_MSY
Assessed SSB: information available to assess status based on Spawning Stock Biomass (SSB) and SSB_MSY (or some proxy i.e. MSY B_trigger)
Assessed both F & SSB: information available to assess status based on both the F and SSB criteria as described above.

The information from the stock assessments was then matched to the landings data through a match between the commercial stocks and their equivalent species or, if needed, higher taxonomic groups. This then allowed a division of the landings per regional sea into the four data availability categories.

Status of marine fish stocks compared to Good Environmental Status (GES)

According to the MSFD (Descriptor 3), three criteria apply to determine if a stock is in GES:

Sustainable exploitation: Sustainably exploited stocks are stocks for which fishing mortality (F) is at or below levels that deliver Maximum Sustainable Yield (MSY), i.e. F ≤ F_MSY. Thus only if a value of F and F_MSY were available we considered the stock assessed against this criterion and only if F ≤ F_MSY was this stock considered to be in GES.
Reproductive capacity intact: Stocks with reproductive capacity intact are those for which the spawning stock biomass (SSB) is above levels that can deliver MSY. In the ICES area, this criterion for reproductive capacity (SSB > SSB_MSY) was modified into SSB > MSY B_trigger for practical reasons. It should be noted that currently MSY Btrigger is only a proxy but a process is underway within the MSFD implementation process working on D3 to adequately update SSB_MSY proxies. This will be considered in future assessments of this indicator. In addition, SSB is consistently provided as part of the ICES stock assessments, i.e. Northeast Atlantic and Baltic Sea, but mostly not by GFCM or ICCAT, i.e. involving the Mediterranean Sea, Black Sea and tuna stocks. This will determine against which criteria the status can be assessed in each regional sea.

Methodology for gap filling

Not applicable

Methodology references

No methodology references available.

Data specifications

EEA data references

No datasets have been specified here.

External data references

Data sources in latest figures

Uncertainties

Methodology uncertainty

Regional distribution of data

The matching of catch areas (ICES, GFCM; ICCAT) and stocks to Europe´s regional seas needs further agreement.

Information availability

Here we used the availability of the indicator and boundary value for each MSFD criterion to reflect the information availability.

Data sets uncertainty

Catch and stock assessment data

We used the most recent year for which data is available. This resulted in a mismatch in the timing of the catch data (2010) and stock assessment data (2012 for ICES stocks, 2008-2012 for GFCM/ICCAT stocks).

Rationale uncertainty

Status of commercial species

The status of the commercial species is now expressed as the proportion of the stocks that fulfils one or more of the GES criteria. This is the most straightforward method that does not require any additional information. However, this can also be expressed as the proportion of the catches or of the biomass depending on data availability. Each method will give markedly different results.

Similarly, the status of the European marine (shell)fish over time is shown as the deviation of the annual value of the two selected indicators in relation to their boundary values, but can also be expressed as a ratio.