Latest Version, 2018 Assessment

Reproductive capacity of commercially exploited stocks of UK interest

To maintain the reproductive capacity of stocks, each stock’s spawning biomass should be at or above the level capable of producing maximum sustainable yield. The proportion of marine fish stocks (including Nephrops) subject to quota management and achieving this goal increased from 28% in 1990 to 56% in 2016.

Background

Europe has a long history of commercially exploiting marine fisheries resources. Historically, the overexploitation of finfish and shellfish stocks led to the depletion of stock abundances. In response, a range of national and international management measures to protect and conserve marine fisheries resources were implemented. Measures that help to protect the Spawning Stock Biomass (referred to as ‘SSB’) include Minimum Conservation Reference Sizes and technical regulations on fishing gears to ensure that stocks are exploited sustainably at full reproductive capacity with a stable population structure. Achieving Good Environmental Status and maintaining stocks within safe biological limits requires that the spawning stock biomass of each stock is at or above the level capable of producing Maximum Sustainable Yield, this level is denoted ‘MSY B_trigger’.

Stocks are aggregated within UK waters of the North East Atlantic Ocean to assess the overall proportion of stocks with spawning stock biomass estimates above or equal to MSY B_trigger. Since marine fish (including Nephrops) are subject to international quota and national shellfish stocks (crab, lobster, and scallop) are not, these two groups are considered separately. However, since there are currently no accepted reference points for national shellfish stocks, this indicator assessment can only evaluate temporal trends in the spawning stock biomass estimates of marine fish stocks with respect to MSY B_trigger. The objective is to increase the proportion of stocks with spawning stock biomass at or above MSY B_trigger and reduce to zero the number of stocks that have unknown status relative to maximum sustainable yield reference points.

Further information

Political commitments to achieve the sustainable exploitation of marine fisheries resources have been specified in two major pieces of European environmental legislation. Firstly, the European Union’s Common Fisheries Policy was launched in 1970 with the objective of ensuring that fishing is environmentally, economically, and socially sustainable (European Commission, 2013). An important component of the Common Fisheries Policy is that stocks should be exploited sustainably to provide the maximum sustainable yield, defined the maximum catch that can be taken annually without reducing stock productivity, by 2020. Secondly, the European Union’s Marine Strategy Framework Directive was established in 2008 to protect the marine environment and ensure the sustainable use of marine goods and services by achieving Good Environmental Status of marine waters by 2020 (EU Commission, 2008). Fulfilling the Marine Strategy Framework Directive’s objective of achieving Good Environmental Status is consistent with the Common Fisheries Policy requirement that spawning stock biomass levels are at or above the level capable of generating maximum sustainable yield. The Marine Strategy Framework Directive requires that “populations of all commercially exploited finfish and shellfish are within safe biological limits, exhibiting a population age and size distribution that is indicative of a healthy stock” (EU Commission, 2008).

Most commercially exploited fish and Nephrops (Norway lobster) stocks in Europe are monitored and assessed by the International Council for the Exploration of the Sea (ICES) and are subject to internationally agreed quotas. In UK waters, national assessments are undertaken for crab and lobster stocks (Cefas 2015a; 2015b; Mesquita and others, 2016) and scallops (Dobby and others, 2012; ICES 2015). Fisheries management advice for assessed stocks is based on estimates of fishing mortality and biomass relative to reference points for long-term sustainability (ICES, 2016). Reference points include the spawning stock biomass trigger point (MSY B_trigger), which is considered the lower bound in the natural fluctuation of spawning stock biomass around the level that results from fishing at maximum sustainable yield for a long time. Assessment methods vary among stocks according to the quantity and quality of the available data. All available data for UK stocks are considered equally in the indicator assessment.

Marine Fish (Quota) Stocks

Stocks considered here are given in Table 1. Assessed stocks have been classified by the International Council for the Exploration of the Sea into one of six data categories depending on the availability of data collected under the European Union Data Collection Framework (ICES, 2012). The categorisation of the stocks reflects the decreasing availability of data, and conclusions on fishing mortality and stock biomass are typically less certain as the category increases.

Table 1. Marine fish (quota) stocks of UK interest.

Stock Description	Data type	Assessment method	Method description
Nephrops in Divisions IVb and IVc Botney Gut/Silver Pit (FU5)	Data-Limited	Data-limited method for Nephrops	Potential harvest rates given habitat
North Sea Megrim in Divisions IVa and VIa	Data-rich	Bayesian state-space biomass dynamic model	Fully quantitative
Whiting in Division VIb (Rockall)	Data-Limited	NA	NA
Cod in VIb Rockall Plateau	Data-Limited	NA	NA
Pollack (Pollachius pollachius) in Subareas VI-VII (Celtic Seas and the English Channel)	Data-Limited	DCAC (Depletion-Corrected Average Catch)	Commercial landings trend
Sprat in Subarea VI and Divisions VIIa-c and f-k (Celtic Sea and West of Scotland)	Data-Limited	NA	NA
Black-bellied anglerfish in Divisions VIIb,k, and VIIIa,b,d	Data-Limited	Survey CPUE and landings	Trends based
Anglerfish in Subareas IV and VI and Division IIIa	Data-Limited	Survey CPUE and landings	Trends based
White anglerfish in Divisions VIIb,k, and VIIIa, b, d	Data-Limited	Survey CPUE and landings	Trends based
Ling in Subareas VI-IX, XII, and XIV, and in Divisions IIIa and IVa	Data-Limited	Commercial CPUE and landings	Trends based
Megrim in Division VIb	Data-Limited	Survey CPUE and landings	Trends based
Megrim in Divisions VIIb,k and VIIIa, b, d	Data-Limited	Statistical catch at age model	Trends based
Plaice in Divisions VIIf,g	Data-Limited	Survey-based assessment	Survey-based trends
Whiting in Division VIIa	Data-Limited	Survey-based assessment (SurbaR)	Survey-based trends
Cod (Gadus morhua) in Subarea IV and Divisions VIId and IIIa West (North Sea. Eastern English Channel. Skagerrak)	Data-rich	Age-based analytical assessment (SAM)	Fully quantitative
Cod (Gadus morhua) in Divisions VIIe-k (Western English Channel and Southern Celtic Seas)	Data-rich	Age-based analytical assessment (XSA)	Fully quantitative
Cod (Gadus morhua) in Division VIIa (Irish Sea)	Data-rich	Analytical assessment (SAM)	Fully quantitative
Cod (Gadus morhua) in Division VIa (West of Scotland)	Data-rich	Analytical age-based assessment (TSA)	Fully quantitative
Spurdog in the Northeast Atlantic	Data-rich	Age-length and sex-structured model (De Oliveira et al., 2013)	Fully quantitative
Haddock in Subarea IV and Divisions IIIa West and VIa (North Sea. Skagerrak and West of Scotland)	Data-rich	Age-based analytical assessment (TSA)	Fully quantitative
Haddock in Divisions VIIb.c.e-k	Data-rich	Age-Structured Assessment Programme (ASAP)	Fully quantitative
Haddock in Division VIIa (Irish Sea)	Data-Limited	SURBA analysis based on survey information	Survey-based trends
Haddock in Division VIb (Rockall)	Data-rich	Analytical age-based assessment (XSA)	Fully quantitative
Herring in Subarea IV and Divisions IIIa and VIId (North Sea autumn spawners)	Data-rich	Age-based analytical assessment (SAM)	Fully quantitative
Herring (Clupea harengus) in Divisions VIa and VIIb.c (West of Scotland. West of Ireland)	Data-rich	Age-based analytical assessment (SAM)	Fully quantitative
Herring in the Celtic Sea and South of Ireland	Data-rich	Age-based analytical assessment (ASAP)	Fully quantitative
Herring in Division VIIa North of 52° 30N (Irish Sea)	Data-rich	Age-based analytical assessment (FLSAM)	Fully quantitative
Herring in Subareas I. II. V and Divisions IVa and XIVa (Norwegian spring-spawning herring)	Data-rich	Statistical assessment model (XSAM)	Fully quantitative
Hake in Division IIIa. Subareas IV. VI and VII and Divisions VIIIa.b.d (Northern stock)	Data-rich	Length-based model (SS3)	Fully quantitative
Horse mackerel (Trachurus trachurus) in Divisions IIa. IVa. Vb. VIa. VIIa-c. e-k. VIII (Western stock)	Data-rich	Age-based analytical assessment (Linked Separable Adapt VPA)	Fully quantitative
Mackerel in the Northeast Atlantic (combined Southern. Western and North Sea spawning components)	Data-rich	Age-based analytical model (SAM)	Fully quantitative
Nephrops in Division VIa (North Minch. FU 11)	Data-rich	Underwater TV survey combined with yield-per-recruit analysis from length data	Fully quantitative
Nephrops in Division VIa (South Minch. FU 12)	Data-rich	Underwater TV survey combined with yield-per-recruit analysis from length data	Fully quantitative
Nephrops in the Firth of Clyde + Sound of Jura (FU 13)	Data-rich	Underwater TV survey combined with yield-per-recruit analysis from length data	Fully quantitative
Nephrops in Division VIIa (Irish Sea East. FU 14)	Data-rich	Underwater TV survey combined with yield-per-recruit analysis from length data	Fully quantitative
Nephrops in Division VIIa (Irish Sea West. FU 15)	Data-rich	Underwater TV survey combined with yield-per-recruit analysis from length data	Fully quantitative
Nephrops in Division VIIb.c.j.k (Porcupine Bank. FU 16)	Data-rich	Underwater TV survey combined with yield-per-recruit analysis from length data	Fully quantitative
Nephrops in Division IVb (Farn Deeps. FU 6)	Data-rich	Underwater TV survey combined with yield-per-recruit analysis from length data	Fully quantitative
Nephrops in Division IVa (Fladen Ground. FU 7)	Data-rich	Underwater TV survey combined with yield-per-recruit analysis from length data	Fully quantitative
Nephrops in Division IVb (Firth of Forth. FU 8)	Data-rich	Underwater TV survey combined with yield-per-recruit analysis from length data	Fully quantitative
Nephrops in Division IVa (Moray Firth. FU 9)	Data-rich	Underwater TV survey combined with yield-per-recruit analysis from length data	Fully quantitative
Plaice in Division VIId (Eastern Channel)	Data-rich	Age-based analytical assessment (Aarts and Poos, 2009)	Fully quantitative
Plaice in Division VIIe (Western Channel)	Data-Limited	Age-based analytical assessment (XSA)	Survey-based trends
Plaice in Division VIIa (Irish Sea)	Data-Limited	Age-based assessment model (Aarts and Poos, 2009)	Survey-based trends
Plaice Subarea IV (North Sea)	Data-rich	Age-based analytical assessment (XSA)	Fully quantitative
Roundnose grenadier (Coryphaenoides rupestris) in Subareas VI and VII, and Divisons Vb and XIIb	Data-rich	Bayesian surplus production model covering only Division 5.b and subareas 6 and 7	Fully quantitative
Saithe in Subarea IV (North Sea) Division IIIa West (Skagerrak) and Subarea VI (West of Scotland and Rockall)	Data-rich	Age-based analytical assessment (SAM)	Fully quantitative
Sole in Divisions VIIf. g (Celtic Sea)	Data-rich	Age-based analytical assessment (XSA)	Fully quantitative
Sole in Division VIId (Eastern Channel)	Data-rich	Age-based analytical assessment (XSA)	Fully quantitative
Sole in Division VIIe (Western Channel)	Data-rich	Age-based analytical assessment (XSA)	Fully quantitative
Sole in Division VIIa (Irish Sea)	Data-rich	Age-based analytical assessment (XSA)	Fully quantitative
Sole in Subarea IV (North Sea)	Data-rich	Statistical catch-at-age model with flexible selectivity functions	Fully quantitative
Sprat in Subarea IV (North Sea)	Data-rich	Age-based analytical assessment (SMS)	Fully quantitative
Blue whiting in Subareas I-IX. XII and XIV (Combined stock)	Data-rich	Age-based analytical assessment (SAM)	Fully quantitative
Whiting Subarea IV (North Sea) and Division VIId (Eastern Channel)	Data-rich	Age-based analytical assessment (XSA)	Fully quantitative
Whiting in ICES Division VIIb. c. e-k	Data-rich	Age-based analytical assessment (XSA)	Fully quantitative
Whiting in Division VIa (West of Scotland)	Data-rich	Age-based analytical assessment (TSA)	Fully quantitative

National Shellfish Stocks:

Stocks considered here are given in Table 2. National assessments are completed every three years. Currently, biomass reference points are not available (Cefas 2015a, 2015b; Dobby and others, 2012; Mesquita and others, 2016; ICES 2015).

Table 2. National shellfish stocks of UK interest. The King scallops stocks (*) are proposed stock units (ICES, 2016).

Species	Stock	Species	Stock
Velvet crab Necora puber	Clyde	Lobster Homarus gammarus; Palinurus elephas	East Anglia
	East Coast		Northumberland and Durham
	Hebrides		Southwest
	Mallaig		Yorkshire and Humber coast
	North Coast		Clyde
	Orkney		East Coast
	Papa Bank		Hebrides
	Shetland		Mallaig
	South East		North Coast
	South Minch		Orkney
	Sule		Papa Bank
	Ullapool		Shetland
Brown crab Cancer pagarus	Clyde		South East
	East Coast		South Minch
	Hebrides		Sule
	Mallaig		Ullapool
	North Coast	King scallops Pecten maximus*	Irish Sea
	Orkney		Cardigan Bay
	Papa Bank		Celtic Sea
	Shetland		Western Channel N
	South East		Western Channel S
	South Minch		Eastern Channel N
	Sule		Central North Sea
	Ullapool		West of Kintyre
	Celtic Sea		Northwest
	Central North Sea		Northeast
	Southern North Sea		Shetland
	Western Channel		Orkney
Queen Scallops Aequipecten opercularis	West of Scotland and Irish Sea (VIa and VIIa)		Clyde
			East Coast

Assessment method

A total of 57 marine fish stocks (including Nephrops) and 59 national shellfish stocks of UK interest in the North East Atlantic Ocean were included in the assessment of spawning stock biomass indicators.

Fishing pressure metrics were estimated since 1990 because there were great changes prior to this in fisheries management aims and objectives (Lassen and others, 2014). A new advisory framework was adopted in 1976, precautionary approach reference points were not formally adopted until the 1990s, and maximum sustainable yield much later (Lassen and others, 2014). Following an initial analysis, national shellfish and marine fish (including Nephrops) communities were separated given the differing management regimes for national stocks and those with internationally agreed quotas, contrasting temporal patterns in the metrics and differing levels of maturity in the stock assessment procedures.

Data were lacking for the reference point for national shellfish stocks, so trends in this indicator could be assessed only through the spawning stock biomass of marine fish stocks.

Marine fish (quota) stocks

Stocks ranged from ICES Data Categories 1 to 6 and were located in the Celtic Seas and Greater North Sea. Category 1 is considered data-rich, and all other categories are data-limited. The stocks comprise a very large proportion of the total landings by UK vessels (> 90%).

ICES has developed maximum sustainable yield and precautionary approaches to provide fisheries management advice based on data availability and the current state of knowledge (ICES, 2016a). Stocks in ICES Data Categories 1 and 2 have full analytical assessments that provide estimates of spawning stock biomass that can be compared to spawning stock biomass trigger points consistent with ICES maximum sustainable yield advice (for example, ICES, 2016b). Spawning stock biomass trigger point estimates, however, require a relatively high level of data and knowledge of stock dynamics. Assessments for Category 3 and Category 4 stocks provide estimates of spawning stock biomass from survey indices or catch time-series that can be related to proxies of Maximum Sustainable Yield or precautionary reference points (ICES, 2016c). Data-limited stocks in Categories 5 and 6 have insufficient information to estimate spawning stock biomass with a high degree of certainty and management advice is based on the precautionary approach (ICES, 2013).

The preliminary analysis focused on estimating stock size relative to spawning stock biomass trigger points for stocks of UK interest. Reference points (Maximum Sustainable Yield B_trigger) and time-series of annual spawning stock biomass estimates were extracted from the ICES Standard Graphs database and an online interface for stock assessment . An annual stock size metric for each stock was estimated by dividing annual spawning stock biomass estimates by the time-series invariant MSY B_trigger. For the remaining data-limited stocks of UK interest, without time-series of annual spawning stock biomass estimates and/or MSY B_trigger points, assessments could not be made, and stocks were classified as unknown.

National shellfish stocks

Crab and lobster assessments are the most developed of the shellfish assessments and provide data on spawning stock biomass by sex using Length Cohort Analysis (Cefas 2015a, 2015b; Mesquita and others, 2016). Stock assessments for scallops are still in development, but great progress has been made in recent years with well-defined stock units in Scottish waters and preliminary stock units for English and Welsh waters under discussion (Dobby and others, 2012; ICES 2015).

Indicator

The indicator is estimated annually by dividing the total number of stocks with spawning stock biomass greater than MSY B_trigger by the number of unique stocks present in the dataset (irrespective of whether reference points and time series are available for each stock). In this way, the number of stocks over time is kept constant despite changes in assessment procedures. The community-specific indicator is thus the annual proportion of marine fish stocks of UK interest or national shellfish stocks with spawning stock biomass above MSY B_trigger.

Results

Findings in the UK Initial Assessment in 2012

Previously assessments were made by subregion (Greater North Sea, Celtic Seas) for those stocks for which ICES provided full assessments (including reference points) and for which the UK contributed to through the Data Collection Framework. These assessments considered the precautionary approach reference point (known as ‘Bpa’) as the target for spawning stock biomass in line with ICES advice at the time. For national shellfish stocks, an indicator assessment could not be reported due to data limitations. Thus Nephrops (Norway lobster) was the only shellfish species that contributed quantitatively to the initial assessment.

For the Greater North Sea, 91% of analytically assessed fish stocks (excluding data-limited stocks) were considered at Good Environmental Status in terms of reproductive capacity (HM Government, 2012). Four of the nine Nephrops functional units in the North Sea were assessed and of these 75% met Good Environmental Status for the reproductive capacity of stocks.

For the Celtic Seas, 72% of analytically assessed fish stocks (excluding data-limited stocks) met Good Environmental Status for the reproductive capacity of stocks (HM Government, 2012). All four of the eight Nephrops functional units assessed met Good Environmental Status in relation to reproductive capacity.

Latest findings

The indicator has been altered and now includes more stocks than before, including those of unknown status. All national shellfish stocks were unknown relative to maximum sustainable yield reference points. A steady increase in the proportion of marine fish stocks with spawning stock biomass above or equal to the level capable of producing Maximum Sustainable Yield (MSY B_trigger) was evident since 1990 (Figure 1). Of the 57 marine fish (quota) stocks, 28% achieved spawning stock biomass above or equal to MSY B_trigger in 1990, and this proportion gradually increased to reach 56% in 2016. The proportion of marine fish stocks with spawning stock biomass estimates below MSY B_trigger remained relatively stable over time, peaking at 40% in 2000 and again in 2007 then subsequently declining to 26% in 2015 and 23% in 2016. Data-limited marine fish stocks without annual spawning stock biomass estimates and/or MSY B_trigger points decreased from 42% in 1990 to 14% between 2005 and 2014, then rose slightly to 21% in 2016. This rise in recent years is due to the scheduling of assessment updates and acknowledgements by working groups that assessment methods required reassessment (known as benchmarking).

Overall, the assessment illustrates a transition towards achieving all populations of commercial fish within safe biological limits by 2020. Since 2012, on average 59% of the internationally managed marine fish (quota) stocks were sustained at full reproductive capacity indicative of healthy stocks. However, of the combined set of shellfish and marine fish stocks, 61% remained unknown in 2015.

Figure 1. The proportion of marine fish (quota) stocks of UK interest exploited with respect to MSY B_trigger (the spawning stock biomass level capable of producing Maximum Sustainable Yield).

Further information

Progress towards achieving populations of commercial fish within safe biological limits by 2020

The stocks considered here are fished not only by UK vessels but also by fleets from other countries. The proportion of the total international landings that arises from fish stocks that are sustained at or above MSY B_trigger has increased to > 90% since 2009 (Figure 2). This demonstrates that the majority of landings are taken from fish stocks that are in a healthy state.

Figure 2. The proportion of total international catch of stocks of UK interest partitioned among assessment status with respect to MSY B_trigger (the spawning stock biomass level capable of producing Maximum Sustainable Yield).

A high degree of confidence exists in the assessment of spawning stock biomass for many marine fish stocks of UK interest. The proportion of marine fish stocks with unknown status decreased gradually to 14% in 2005 and remained around this level thereafter. Fluctuations are evident in the final two years of the assessment (16% in 2015 and 21% in 2016) due to the scheduling of assessment updates and acknowledgements by working groups that assessment methods required reassessment (known as benchmarking). The proportion of data-limited stocks classified as unknown in the assessment should decline as data availability increases and assessment methods improve in the future. The status of each stock in 2015 and 2016 is given in Tables 3 and 4 respectively.

Table 3. Marine fish (quota) stocks of UK interest spawning stock biomass indicators evaluated in 2015. Indicator values below 1 show spawning stock biomass levels below those capable of producing maximum sustainable yield.

Stock description	Stock code	Indicator	Biomass sustainability
Nephrops in Division VIIa (Irish Sea East. FU 14)	nep-14	5.2	Sustainably Fished
Haddock in Division VIIa (Irish Sea)	had-iris	3.875	Sustainably Fished
Haddock in Divisions VIIb.c.e-k	had-7b-k	3.823	Sustainably Fished
Plaice in Divisions VIIf,g	ple-celt	3.385	Sustainably Fished
Nephrops in the Firth of Clyde + Sound of Jura (FU 13)	nep-13	3.138	Sustainably Fished
Nephrops in Division VIa (North Minch. FU 11)	nep-11	2.676	Sustainably Fished
Whiting in ICES Division VIIb. c. e-k	whg-7e-k	2.383	Sustainably Fished
Nephrops in Division VIa (South Minch. FU 12)	nep-12	1.959	Sustainably Fished
Herring in the Celtic Sea and South of Ireland	her-irls	1.877	Sustainably Fished
Megrim in Division VIb	meg-rock	1.783	Sustainably Fished
Haddock in Division VIb (Rockall)	had-rock	1.722	Sustainably Fished
Herring in Division VIIa North of 52° 30N (Irish Sea)	her-nirs	1.394	Sustainably Fished
Sole in Division VIIe (Western Channel)	sol-echw	1.371	Sustainably Fished
Nephrops in Division VIIa (Irish Sea West. FU 15)	nep-15	1.333	Sustainably Fished
Roundnose grenadier (Coryphaenoides rupestris) in Subareas VI and VII, and Divisons Vb and XIIb	rng-5b67	1.16	Sustainably Fished
White anglerfish in Divisions VIIb,k, and VIIIa, b, d	anp-78ab	1.159	Sustainably Fished
Sole in Divisions VIIf. g (Celtic Sea)	sol-celt	1.131	Sustainably Fished
Megrim in Divisions VIIb,k and VIIIa, b, d	mgw-78	1.123	Sustainably Fished
Plaice Subarea IV (North Sea)	ple-nsea	3.282	Sustainably Fished
Nephrops in Division IVb (Firth of Forth. FU 8)	nep-8	2.274	Sustainably Fished
Plaice in Division VIId (Eastern Channel)	ple-eche	2.106	Sustainably Fished
Saithe in Subarea IV (North Sea) Division IIIa West (Skagerrak) and Subarea VI (West of Scotland and Rockall)	sai-3a46	1.662	Sustainably Fished
Sole in Subarea IV (North Sea)	sol-nsea	1.328	Sustainably Fished
Nephrops in Division IVa (Moray Firth. FU 9)	nep-9	1.324	Sustainably Fished
Herring in Subarea IV and Divisions IIIa and VIId (North Sea autumn spawners)	her-47d3	1.202	Sustainably Fished
Haddock in Subarea IV and Divisions IIIa West and VIa (North Sea. Skagerrak and West of Scotland)	had-346a	1.106	Sustainably Fished
Anglerfish in Subareas IV and VI and Division IIIa	ang-ivvi	1.053	Sustainably Fished
Herring in Subareas I. II. V and Divisions IVa and XIVa (Norwegian spring-spawning herring)	her-noss	1.053	Sustainably Fished
Whiting Subarea IV (North Sea) and Division VIId (Eastern Channel)	whg-47d	1.02	Sustainably Fished
Hake in Division IIIa. Subareas IV. VI and VII and Divisions VIIIa.b.d (Northern stock)	hke-nrtn	6.814	Sustainably Fished
Blue whiting in Subareas I-IX. XII and XIV (Combined stock)	whb-comb	1.908	Sustainably Fished
Mackerel in the Northeast Atlantic (combined Southern. Western and North Sea spawning components)	mac-nea	1.629	Sustainably Fished
Ling in Subareas VI-IX, XII, and XIV, and in Divisions IIIa and IVa	lin-oth	1.523	Sustainably Fished
Black-bellied anglerfish in Divisions VIIb,k and VIIIa,b,d	anb-78ab	0.872	SSB < MSY Btrigger
Herring (Clupea harengus) in Divisions VIa and VIIb.c (West of Scotland. West of Ireland)	her-67bc	0.61	SSB < MSY Btrigger
Whiting in Division VIIa	whg-iris	0.594	SSB < MSY Btrigger
Cod (Gadus morhua) in Divisions VIIe-k (Western English Channel and Southern Celtic Seas)	cod-7e-k	0.57	SSB < MSY Btrigger
Cod (Gadus morhua) in Division VIIa (Irish Sea)	cod-iris	0.496	SSB < MSY Btrigger
Sole in Division VIIa (Irish Sea)	sol-iris	0.382	SSB < MSY Btrigger
Whiting in Division VIa (West of Scotland)	whg-scow	0.225	SSB < MSY Btrigger
Cod (Gadus morhua) in Division VIa (West of Scotland)	cod-scow	0.13	SSB < MSY Btrigger
Plaice in Division VIIe (Western Channel)	ple-echw	0.001	SSB < MSY Btrigger
Sole in Division VIId (Eastern Channel)	sol-eche	0.987	SSB < MSY Btrigger
Cod (Gadus morhua) in Subarea IV and Divisions VIId and IIIa West (North Sea. Eastern English Channel. Skagerrak)	cod-347d	0.931	SSB < MSY Btrigger
Nephrops in Division IVa (Fladen Ground. FU 7)	nep-7	0.928	SSB < MSY Btrigger
Nephrops in Division IVb (Farn Deeps. FU 6)	nep-6	0.659	SSB < MSY Btrigger
Sprat in Subarea IV (North Sea)	spr-nsea	0.346	SSB < MSY Btrigger
Horse mackerel (Trachurus trachurus) in Divisions IIa. IVa. Vb. VIa. VIIa-c. e-k. VIII (Western stock)	hom-west	0.852	SSB < MSY Btrigger
Nephrops in Division VIIb.c.j.k (Porcupine Bank. FU 16)	nep-16		Unknown
Plaice in Division VIIa (Irish Sea)	ple-iris		Unknown
Spurdog in the Northeast Atlantic	dgs-nea		Unknown
Nephrops in Divisions IVb and IVc Botney Gut/Silver Pit (FU5)	nep-5		Unknown
North Sea Megrim in Divisions IVa and Via	meg-4a6a		Unknown
Whiting in Division VIb (Rockall)	whg-rock		Unknown
Cod in VIb Rockall Plateau	cod-rock		Unknown
Pollack (Pollachius pollachius) in Subareas VI-VII (Celtic Seas and the English Channel)	pol-celt		Unknown
Sprat in Subarea VI and Divisions VIIa-c and f-k (Celtic Sea and West of Scotland)	spr-celt		Unknown

 

Table 4: Marine fish (quota) stocks of UK interest spawning stock biomass indicators evaluated in 2016 based on preliminary data. Indicator values below 1 show spawning stock biomass levels below those capable of producing maximum sustainable yield.

Stock description	Stock code	Indicator	Biomass sustainability
Nephrops in Division VIIa (Irish Sea East. FU 14)	nep-14	5.56	Sustainably Fished
Haddock in Division VIIa (Irish Sea)	had-iris	4.885	Sustainably Fished
Nephrops in the Firth of Clyde + Sound of Jura (FU 13)	nep-13	3.355	Sustainably Fished
Plaice in Divisions VIIf,g	ple-celt	3.285	Sustainably Fished
Nephrops in Division VIa (North Minch. FU 11)	nep-11	2.633	Sustainably Fished
Haddock in Divisions VIIb.c.e-k	had-7b-k	2.608	Sustainably Fished
Haddock in Division VIb (Rockall)	had-rock	2.314	Sustainably Fished
Nephrops in Division VIa (South Minch. FU 12)	nep-12	2.076	Sustainably Fished
Whiting in ICES Division VIIb. c. e-k	whg-7e-k	1.826	Sustainably Fished
Megrim in Division VIb	meg-rock	1.688	Sustainably Fished
Nephrops in Division VIIa (Irish Sea West. FU 15)	nep-15	1.667	Sustainably Fished
Herring in the Celtic Sea and South of Ireland	her-irls	1.573	Sustainably Fished
Herring in Division VIIa North of 52° 30N (Irish Sea)	her-nirs	1.393	Sustainably Fished
Sole in Division VIIe (Western Channel)	sol-echw	1.39	Sustainably Fished
Megrim in Divisions VIIb,k and VIIIa, b, d	mgw-78	1.145	Sustainably Fished
White anglerfish in Divisions VIIb,k, and VIIIa, b, d	anp-78ab	1.123	Sustainably Fished
Sole in Divisions VIIf. g (Celtic Sea)	sol-celt	1.081	Sustainably Fished
Cod (Gadus morhua) in Subarea IV and Divisions VIId and IIIa West (North Sea. Eastern English Channel. Skagerrak)	cod-347d	16.364	Sustainably Fished
Plaice Subarea IV (North Sea)	ple-nsea	4.112	Sustainably Fished
Nephrops in Division IVb (Firth of Forth. FU 8)	nep-8	2.729	Sustainably Fished
Plaice in Division VIId (Eastern Channel)	ple-eche	2.46	Sustainably Fished
Saithe in Subarea IV (North Sea) Division IIIa West (Skagerrak) and Subarea VI (West of Scotland and Rockall)	sai-3a46	1.845	Sustainably Fished
Sole in Subarea IV (North Sea)	sol-nsea	1.738	Sustainably Fished
Nephrops in Division IVa (Fladen Ground. FU 7)	nep-7	1.608	Sustainably Fished
Herring in Subarea IV and Divisions IIIa and VIId (North Sea autumn spawners)	her-47d3	1.339	Sustainably Fished
Anglerfish in Subareas IV and VI and Division IIIa	ang-ivvi	1.112	Sustainably Fished
Whiting Subarea IV (North Sea) and Division VIId (Eastern Channel)	whg-47d	1.103	Sustainably Fished
Herring in Subareas I. II. V and Divisions IVa and XIVa (Norwegian spring-spawning herring)	her-noss	1.005	Sustainably Fished
Hake in Division IIIa. Subareas IV. VI and VII and Divisions VIIIa.b.d (Northern stock)	hke-nrtn	7.326	Sustainably Fished
Blue whiting in Subareas I-IX. XII and XIV (Combined stock)	whb-comb	2.236	Sustainably Fished
Mackerel in the Northeast Atlantic (combined Southern. Western and North Sea spawning components)	mac-nea	1.529	Sustainably Fished
Ling in Subareas VI-IX, XII, and XIV, and in Divisions IIIa and IVa	lin-oth	1.522	Sustainably Fished
Black-bellied anglerfish in Divisions VIIb,k and VIIIa,b,d	anb-78ab	0.857	SSB < MSY Btrigger
Cod (Gadus morhua) in Divisions VIIe-k (Western English Channel and Southern Celtic Seas)	cod-7e-k	0.78	SSB < MSY Btrigger
Whiting in Division VIIa	whg-iris	0.603	SSB < MSY Btrigger
Cod (Gadus morhua) in Division VIIa (Irish Sea)	cod-iris	0.527	SSB < MSY Btrigger
Herring (Clupea harengus) in Divisions VIa and VIIb.c (West of Scotland. West of Ireland)	her-67bc	0.522	SSB < MSY Btrigger
Sole in Division VIIa (Irish Sea)	sol-iris	0.413	SSB < MSY Btrigger
Whiting in Division VIa (West of Scotland)	whg-scow	0.364	SSB < MSY Btrigger
Cod (Gadus morhua) in Division VIa (West of Scotland)	cod-scow	0.122	SSB < MSY Btrigger
Sole in Division VIId (Eastern Channel)	sol-eche	0.885	SSB < MSY Btrigger
Haddock in Subarea IV and Divisions IIIa West and VIa (North Sea. Skagerrak and West of Scotland)	had-346a	0.814	SSB < MSY Btrigger
Nephrops in Division IVb (Farn Deeps. FU 6)	nep-6	0.812	SSB < MSY Btrigger
Sprat in Subarea IV (North Sea)	spr-nsea	0.453	SSB < MSY Btrigger
Horse mackerel (Trachurus trachurus) in Divisions IIa. IVa. Vb. VIa. VIIa-c. e-k. VIII (Western stock)	hom-west	0.767	SSB < MSY Btrigger
Nephrops in Division VIIb.c.j.k (Porcupine Bank. FU 16)	nep-16		Unknown
Spurdog in the Northeast Atlantic	dgs-nea		Unknown
Plaice in Division VIIa (Irish Sea)	ple-iris		Unknown
Plaice in Division VIIe (Western Channel)	ple-7e		Unknown
Roundnose grenadier (Coryphaenoides rupestris) in Subareas VI and VII, and Divisons Vb and XIIb	rng-5b67		Unknown
Nephrops in Division IVa (Moray Firth. FU 9)	nep-9		Unknown
Nephrops in Divisions IVb and IVc Botney Gut/Silver Pit (FU5)	nep-5		Unknown
North Sea Megrim in Divisions IVa and Via	meg-4a6a		Unknown
Whiting in Division VIb (Rockall)	whg-rock		Unknown
Cod in VIb Rockall Plateau	cod-rock		Unknown
Pollack (Pollachius pollachius) in Subareas VI-VII (Celtic Seas and the English Channel)	pol-celt		Unknown
Sprat in Subarea VI and Divisions VIIa-c and f-k (Celtic Sea and West of Scotland)	spr-celt		Unknown

Species that are present in the area, but not of commercial importance to UK fisheries (including many elasmobranch stocks) were excluded from this assessment. These stocks are more appropriately considered within the indicators developed for the Marine Strategy Framework Directive on Biological Diversity Descriptor. Historically herring fishing in the Clyde area was important nationally, but there is no current assessment, and uncertainty in the stock identity and its distinctness from herring in the wider and adjacent regions. Therefore, a separate ‘unknown’ entry for Clyde herring has not been made in the indicator. Cod in the north-east Arctic sustains an important level of landings by UK trawlers (approximately 12,000 tonnes in 2015), but given that this is only 1% of the international landings by fisheries targeting the stock and also that the stock is not within European Union waters it was not included in the indicator assessment (the stock is in good status with spawning stock biomass > MSY B_trigger).

Conclusions

The UK Marine Strategy Framework Directive target for reproductive capacity of stock (HM Government, 2015) is that:

• The reproductive capacity of the stock shall be maintained at, or above levels that will support the long-term exploitation of stocks at F_MSY, as indicated by spawning stock biomass of all stocks being above Maximum Sustainable Yield B_trigger.

Since 2012, an average of 59% of marine fish stocks (including Nephrops) with international quota have been exploited sustainably at full reproductive capacity, with spawning stock biomass greater than or equal to MSY B_trigger, and on average 25% of stocks have been over-exploited (spawning stock biomass less than MSY B_trigger). The remaining proportion of marine fish stocks and all national shellfish stocks are currently unknown relative to maximum sustainable yield reference points.

Fisheries management measures have likely contributed to the increase in the proportion of marine fish stocks within safe biological limits. While progress has been made, further improvements are required and are expected given the current implementation of the landing obligation.

Further information

A great proportion of international landings are taken from fish stocks that are in a healthy state (> 90% since 2009) indicating that fisheries are generally targeting healthy marine fish stocks. The indicator assessment demonstrates progression toward Good Environmental Status of UK waters.

Knowledge gaps

Spawning stock biomass estimates for 21% of marine fish stocks remained of unknown status with respect to the level capable of producing Maximum Sustainable Yield in 2016 due to a lack of spawning stock biomass and reference point estimates required to evaluate the performance of the maximum sustainable yield management strategy. All national shellfish stocks were ‘unknown’ relative to reference points. This proportion will continue to decline as information becomes available and assessment methods improve. For some shellfish stocks, current data collection methods are insufficient to support assessments of spawning stock biomass with respect to MSY B_trigger. However, scallop stock assessments, in particular, are improving rapidly (ICES 2015).

Further information

Stock assessments are limited by current data collection, and without expansion of monitoring, some stocks (particularly shellfish) may remain of unknown status.

Some stock units cover a large spatial area, and migrations of fish between national waters occur. Assessments of national waters are related to those of countries. The proportion of each stock that is attributable to national waters is unclear given seasonal and temporal changes in spatial distributions of stocks. The relative impact of differing countries management measures on shared stocks is similarly unclear.

Any changes in the productivity of marine ecosystems, linked to changes in prevailing environmental conditions, will likely impact on the population growth rates of stocks and thus the spawning stock biomass obtainable when exploited at maximum sustainable yield. In light of such changes, MSY B_trigger targets may require an adjustment in future.

Current maximum sustainable yield targets do not explicitly include multi-species interactions between predators and prey. As predator populations increase, prey species may decrease, and further work is required to improve stock level targets (MSY B_trigger) to incorporate information on such interactions.

References

Cefas (2015a) ‘Lobster (Homarus gammarus)’ Stock Status Report 2014 24 September 2015 (viewed on 23 November 2018)

Cefas (2015b) ‘Edible crab (Cancer pagurus)’ Stock Status Report 2014 24 September 2015 (viewed on 23 November 2018)

Dobby H, Millar S, Blackadder L, Turriff J, McLay A (2012) ‘Scottish Scallop Stocks: Results of 2011 Stock Assessments’ Scottish Marine and Freshwater Science Volume 3 No 10. Marine Scotland Science (viewed on 23 November 2018)

European Commission (2013) ‘Regulation (EU) No 1380/2013 of the European Parliament and of the Council of 11 December 2013 on the Common Fisheries Policy (CFP), amending Council Regulations (EC) No 1954/20003 and (EC) No 1224/2009 and repealing Council Regulations (EC) No 2371/2002’ Official Journal of the European Union 354, 22-61 (viewed on 22 November 2018)

European Commission (2008) ‘Directive 2008/56/EC of the European Parliament and of the Council of 17 June 2008 establishing a framework for community action in the field of marine environmental policy (Marine Strategy Framework Directive; MSFD)’ European Parliament and Council of the European Union Official Journal of the European Union 164, 19-40 (viewed on 21 September 2018)

HM Government (2012) ‘Marine Strategy Part One: UK Initial Assessment and Good Environmental Status’ (viewed on 5 July 2018)

HM Government (2015) ‘Marine Strategy Part Three: UK Programme of Measures’ (viewed on 5 July 2018)

ICES (2012) ‘ICES Implementation of Advice for Data-limited Stocks in 2012 in its 2012 Advice’ ICES CM 2012/ACOM:68, 42 pages (viewed on 22 November 2018)

ICES (2013) ‘Report of the Workshop to Finalize the ICES Data-limited Stock (DLS) Methodologies Documentation in an Operational Form for the 2013 Advice Season and to make Recommendations on Target Categories for Data-limited Stocks (WKLIFE II), 20–22 November 2012, Copenhagen, Denmark’ ICES CM 2012/ACOM:79, 46 pages (viewed on 22 November 2018)

ICES (2015) ‘Report of the Scallop Assessment Working Group (WGScallop), 6-10 October 2014, Nantes, France’ ICES CM 2014\ACOM:24, 35 pages (viewed on 22 November 2018)

ICES (2016) ‘Report of the Scallop Assessment Working Group (WGScallop)’ ICES CM 2015/ACOM:23, 40 pages (viewed on 23 November 2018)

ICES (2016a) ‘General context of ICES advice’ ICES Advice 2016, Book 1, Section 1.2 pages 1-15 (viewed on 22 November 2018)

ICES (2016b) ‘Report of the Workshop to consider F_MSY ranges for stocks in ICES categories 1 and 2 in Western Waters (WKMSYREF4), 13–16 October 2015, Brest, France’ ICES CM 2015/ACOM:58, 187 pages (viewed on 22 November 2018)

ICES (2016c) ‘Report of the Workshop to consider MSY proxies for stocks in ICES category 3 and 4 stocks in Western Waters (WKProxy), 3–6 November 2015, ICES Headquarters, Copenhagen’ ICES CM 2015/ACOM:61, 183 pages (viewed on 22 November 2018)

Lassen H, Kelly C and Sissenwine M (2014) ‘ICES advisory framework 1977-2012: from Fmax to precautionary approach and beyond’ ICES Journal of Marine Science 71: 166–172 (viewed on 23 November 2018)

Mesquita C, Dobby H, McLay A (2016) ‘Crab and Lobster Fisheries in Scotland: Results of Stock Assessments 2009 – 2012’ Scottish Marine and Freshwater Science Volume 7 No 9. Marine Scotland Science (viewed on 22 November 2018)

Acknowledgements

Assessment metadata

Assessment Type	UK MSFD Indicator Assessment
	D3.2 Reproductive capacity of commercially exploited stocks of UK interest
Point of contact email	marinestrategy@defra.gov.uk
Metadata date	Thursday, August 1, 2019
Title	Reproductive capacity of commercially exploited stocks of UK interest
Resource abstract	This indicator measures progress towards the objective that 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
Linkage	This dataset summarises stock assessment advice for quota fish stocks and national shellfish stocks. These files contain data quantifying annual recruitment, biomass, stock size, landings, catches, discards, industrial bycatch, fishing pressure (fishing pressure mean, ranges, and estimated pressure accountable to landings, discards and bycatch) and stock indicators (Flim fisheries mortality that if exceeded would result in the stock falling below Blim, Blim spawning stock Biomass at the limit reference point, Fpa level of catches that if exceeded would result in the stock falling below Bpa, Bpa spawning stock Biomass in relation to the precautionary approach, Fpa, FMSY Maximum sustainable yield, BMSY Maximum sustainable yield biomass trigger) for various fish stocks (fish species in given ICES regions).
Conditions applying to access and use	© Crown 2018 copyright Defra, licenced under the Open Government Licence (OGL).
Assessment Lineage	These data are used to determine the indicator D3.1 Commercial fishing pressure for stocks of UK interest and D3.2 Reproductive capacity of commercially exploited stocks of UK interest. Data processing is carried out by landmark on the CEFMAT interface, as per an r script created collaboratively between Christopher Lynam, Zachary Radford and Joseph Ribeiro (Cefas).
Dataset metadata	This indicator summarises stock assessment advice for quota fish stocks and national shellfish stocks. The input data for quota fish stocks arise from the ICES stock assessment database http://standardgraphs.ices.dk/stockList.aspx, while the data for national shellfish stocks arise from Marine Scotland and Cefas assessments (see links in References). The UK_ICES_fish_stock_and_shellfish_stock_assessment_data_2017.csv is modified from the ICES stock assessment database. Appended to this is the UK national shellfish stocks data, which were taken from assessment reports provided by Cefas and Marine Scotland. In the dataset, the first column “ICES” identifies those stocks that originate from the ICES stock assessment database with the entry “Y”. The SPiCT_Stock data2_281117.csv contains ICES stock assessment model outputs. SPiCT refers to 'Stochastic Production model in Continuous Time', the model used to produce outputs for data limited stocks. These data were not released online by ICES when this data were collated (12/09/2017), but instead downloaded directly by www.stockassessment.org (Casper Berg, DTU-Aqua) to Cefas on 08 June 2016. The SPiCT_Stock data2_281117.csv contains ICES stock assessment model outputs. SPiCT refers to 'Stochastic Production model in Continuous Time', the model used to produce outputs for data limited stocks. These data were not released online by ICES when this data were collated (12/09/2017), but instead downloaded directly by www.stockassessment.org (Casper Berg, DTU-Aqua) to Cefas on 08 June 2016.
Links to datasets identifiers	Please, see doi below
Dataset DOI	https://doi.org/10.14466/CefasDataHub.74

The Metadata are “data about the content, quality, condition, and other characteristics of data” (FGDC Content Standard for Digital Geospatial Metadata Workbook, Ver 2.0, May 1, 2000).

Metadata definitions

Assessment Lineage - description of data sets and method used to obtain the results of the assessment

Dataset – The datasets included in the assessment should be accessible, and reflect the exact copies or versions of the data used in the assessment. This means that if extracts from existing data were modified, filtered, or otherwise altered, then the modified data should be separately accessible, and described by metadata (acknowledging the originators of the raw data).

Dataset metadata – information on the data sources and characteristics of data sets used in the assessment (MEDIN and INSPIRE compliance).

Digital Object Identifier (DOI) – a persistent identifier to provide a link to a dataset (or other resource) on digital networks. Please note that persistent identifiers can be created/minted, even if a dataset is not directly available online.

Indicator assessment metadata – data and information about the content, quality, condition, and other characteristics of an indicator assessment.

MEDIN discovery metadata - a list of standardized information that accompanies a marine dataset and allows other people to find out what the dataset contains, where it was collected and how they can get hold of it.

Recommended reference for this indicator assessment

Lynam, C.P.¹, Radford, Z.¹, Ribeiro, J.¹, Engelhard, G.¹, Firmin, C¹, Dobby, H.², Mesquita, C.², Bluemel, J.¹, Bell, E.¹, & O'Brien, C.¹ 2018. Reproductive capacity of commercially exploited stocks of UK interest. UK Marine Online Assessment Tool, available at: https://moat.cefas.co.uk/pressures-from-human-activities/commercial-fish-and-shellfish/reproductive-capacity/

¹Centre for Environment, Fisheries and Aquaculture Science

²Marine Scotland