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Abundance indices for norwegian coastal cod north of 62°N

Summary

In connection with the benchmark processes within ICES on Norwegian Coastal Cod north of 62°N during autumn 2020-spring 2021, new abundance index series based on bottom trawl stations and acoustics at the autumn coastal survey were made. The acoustic index covers the period 1995-2019 while the trawl index covers the period 2003-2019. This report describes the methods used and briefly presents the results.

1 - Introduction

New abundance index series for Norwegian coastal cod north of 62° were produced using the software StoX (Johnsen et al. 2019). Indices were calculated by applying trawl swept area and acoustic methods, using data collected during the Norwegian annual coastal survey in autumn NOcoast-Aco-4Q.

Time series of indices for the period 1995 to 2019 in numbers and biomass (2003-2019 for the swept-area index), their coefficient of variation, length- and weight-at-age are tabulated for three subareas and the total area in Appendix A (acoustic indices) and Appendix B (swept-area trawl indices).

2 - Biology, stock structure, and management of coastal cod

Coastal cod occurs in fjords and coastal areas along the entire coast of Norway. The management area for this species is divided into two areas south and north of 62 ° N. Genetic studies indicate a genetic cline along the coast from eastern Finnmark to inner Skagerrak (Dahle et al., 2018). Coastal cod north of 62 ° N is somewhat related to Northeast Arctic (NEA) cod, while coastal cod south of 62 ° N showing some similarities to North Sea and Skagerrak cod.

Compared to NEA cod the immature coastal cod has faster individual growth and earlier age of maturation (Berg and Albert, 2003). Since individual growth is reduced after the age of first maturation, the weight at age for old fish is somewhat lower for coastal cod than for Northeast Arctic cod at the same age.

Spawning areas for coastal cod have been mapped by egg sampling and classified according to their relative value (Gytefelt Torsk MB at www.fiskeridirektoratet.no ). See also Figures 18-23 in Aglen et al. (2020). Some of these coastal cod spawning areas are close to spawning areas for NEA cod. Probably due to rather small-scale differences in currents and egg buoyancy, the coastal cod eggs and larvae tend to be retained near the spawning areas, while NEA cod eggs and larvae are transported by currents northward into the Barents Sea.

Annual total allowable catches (TAC) were set for coastal cod at 40 kt in the years 1987-2003, 20 kt in 2004, and 21kt in later years. A large proportion of the annual landings of coastal cod is by-catches in the fishery for NEA cod. A rebuilding plan was established 2011 and several technical regulations were introduced to reduce “bycatches” of coastal cod, including gear restrictions and restrictions on vessel size, and closures of spawning areas in the spawning season (Henningsværstraumen and Inner Lofoten).

3 - The autumn coastal survey

3.1 - The history of the survey and how it has developed over the years

The Institute of Marine Research (IMR) has since 1985 conducted an annual acoustic survey of coastal areas and offshore banks north of 62°N with the objective of obtaining abundance indices of commercially important fish species (Skants, 2019). The annual coverage (in October and November) of coastal areas and fjords, as well as open ocean banks, between Stad (62°N) and Varanger (71.3 °N) has since 1995 included measurements of coastal cod ( Gadus morhua ).

The trawl gear used during the first years was a Campelen 1800 standard shrimp trawl with rock hopper gear and 35 mm mesh size in the cod end. Scanmar sensors provided information about the trawl opening (height in meters), door spread and bottom contact. Since 2003 a Campelen 1800 standard shrimp trawl with rock hopper gear, 20 mm mesh size in the cod end and 80mm (stretched) in the front part is the standard fishing gear, combined with Scanmar trawl and door sensors (Aglen et al., 2005). Additional stations were added in 2017, which was done as it was considered necessary to gather more information on deep water shrimps and redfish (Mehl et al., 2018a). Standard trawl duration is 30 minutes at a speed of 3 knots, with preferred doorspread of 49-52m and trawl opening of 3.5-4.5m. Data were collected with several vessels, which are listed in Table 1.

The survey consists of a stratified grid for acoustic measurements, with fixed bottom trawl stations and additional bottom and pelagic stations on acoustic registrations within each of the strata.

During the surveys hydrographic stations were sampled semi-regularly. CTD-measurements were taken at some of the fixed bottom trawl stations or with a set distance of 30 nautical miles between each station (Staby et al., 2020).

The surveyed area was initially divided into 23 strata, and these were grouped into three subareas: North of 67°N (Area “A”), 65°-67°N (Area “B”), and 62°-65°N (Area “C”) (Figure 1). The stratum “Vestfjorden East” was, however, removed from all years, since this stratum had no acoustic coverage and no trawl hauls in most years.

Acoustic transects and bottom trawl hauls are standardized since 2003. In 2017 additional acoustic transects were added to selected strata in order to improve the accuracy of saithe biomass estimates in those strata that contributed a significantly to the total estimate. Figure 2 shows the acoustic transects and trawl hauls made during the coastal survey in 2019.

Trawl catches are sorted and weighed by species according to standard procedures (Mjanger et al., 2020). Length measurements (e.g. total length; from snout to end of the caudal fin) are done for most species, either of all sorted individuals or of a subsample from large catches. Additional information such as age and type from otoliths, sex and gonad maturity stage are collected from cod.

 

Figure 1. Map showing the 23 strata (lower panel) and the three subareas (upper panel) used for coastal cod index calculations.

 

 

Figure 2. Acoustic transects and trawl hauls made during the cruise in 2019. These are standard transects and trawl hauls that are made during this survey.

 

3.2 - Previous attempts to extract abundance indices from the survey data

As described in chapter 1.2, the autumn coastal survey has a long history and has undergone various changes over the years. It started out as an acoustic survey primarily targeting coastal cod in the Troms and Finnmark counties in the 1980s. These surveys were conducted by the former “Fiskeriforskning” marine research institute in Tromsø. IMR in Bergen started a survey at approximately the same time of the year, but targeting mainly saithe in the outer coastal areas, partly overlapping the areas of the former survey. A third survey, covering overwintering herring in the fjords was aslo conducted by IMR. “Fiskeriforskning” was discontinued and the department responsible for resource surveys was included in IMR. From 2003 these surveys were combined and standardized to be a combined acoustic and trawl survey mainly targeting coastal cod and saithe. When the surveys were merged and standardized in 2003, attempts were made to construct an acoustic index for coastal cod based on the original coastal cod survey and the saithe survey, covering also more southern parts of the coast north of 62 ° N. Due to partly different procedures, working protocols, and data format at the two responsible institutes, and since the surveys partly overlapped in space and time, this combination was difficult. The series was started in 1995, but for the years prior to 2003, only some of the acoustic transects, mostly those that had been standardized during the “Fiskeriforskning” survey, were used in index calculations.

3.3 - Description of the survey data

Table 1 lists the surveys from 1995-2019, which vessels took part, the number of stations taken etc.

Year Vessel Cruise ID For swept area index For acoustic index
      N BT N aged N length N BT (with cod) N aged N length N miles scrutinized
Total With cod Total With cod
1995 Michael Sars 1995111           2515 497 3869 3575
  Johan Hjort 1995211           80 1845 3952 2158
  Volstad 1995810           0 54 0 0
1996 Johan Hjort 1996214           171 2727 3285 1905
  Michael Sars 4-1996           2393 5376 6186 1552
1997 Johan Hjort 1997213           432 3656 3687 2650
  Michael Sars 4-1997           1670 4653 4180 0
1998 G.O.Sars 1998016           493 2237 3030 1808
  Jan Mayen 4-1998           2476 4060 3175 0
1999 Johan Hjort 1999215           399 1083 3813 1653
  Jan Mayen 4-1999           2780 4444 3420 0
2000 Johan Hjort 2000214           414 1202 3766 1816
  Jan Mayen 4-2000           4240 5276 3090 0
2001 Johan Hjort 2001213           267 844 4523 1229
  Jan Mayen 4-2001           3181 3815 2614 0
2002 Johan Hjort 2002214           362 1173 4655 2128
  Jan Mayen 4-2002           2048 2511 3164 0
2003 Johan Hjort 2003211 58 50 1381 2520 72 1580 2808 3695 2012
  Jan Mayen 2003706 78 68 1367 1734 109 1635 2077 4007 3130
2004 Johan Hjort 2004212 50 41 981 1714 67 1159 2010 3502 1989
  Jan Mayen 2004704 81 69 1270 1814 88 1345 1942 3469 2824
2005 Johan Hjort 2005212 42 36 759 1345 51 949 1625 3013 1768
  Jan Mayen 2005704 82 66 695 863 80 689 870 3794 3180
2006 Johan Hjort 2006213 51 42 543 821 48 677 1047 3851 2165
  Håkon Mosby 2006623 0 0 0 0 7 33 51 4479 34
  Jan Mayen 2006705 90 71 865 995 87 886 1021 4013 3260
2007 Johan Hjort 2007212 39 25 179 296 39 327 489 3550 1042
  Håkon Mosby 2007623 0 0 0 0 8 0 103 3778 0
  Jan Mayen 2007703 107 87 834 1040 85 829 1036 4670 3860
2008 Johan Hjort 2008210 86 81 1197 1773 103 1381 2012 6275 5831
  Håkon Mosby 2008623 31 16 233 329 24 308 439 1875 0
  Jan Mayen 2008705 4 4 73 127 10 73 192 214 193
2009 Johan Hjort 2009209 49 41 760 1240 46 818 1306 2860 1696
  Håkon Mosby 2009629 17 6 11 11 5 29 29 1127 180
  Jan Mayen 2009703 66 57 1263 2345 75 1299 2466 2819 2680
  Jan Mayen 2009704 4 4 140 382 14 166 544 524 524
2010 Johan Hjort 2010211 114 90 1957 3847 120 2284 4841 6175 4284
  Jan Mayen 2010704 6 6 149 489 12 168 518 380 380
2011 Johan Hjort 2011214 38 32 536 839 31 561 880 2450 1796
  Helmer Hanssen 2011722 81 71 1246 2075 80 1292 2158 4074 2875
  Helmer Hanssen 2011723 6 6 114 177 18 184 290 240 222
2012 Johan Hjort 2012210 64 55 834 1496 64 974 1701 3760 2552
  Håkon Mosby 2012620 65 51 1129 1878 50 1202 2123 2663 1402
2013 Johan Hjort 2013210 54 51 932 1638 72 1020 1836 3018 1602
  Håkon Mosby 2013623 59 50 1160 2288 65 1249 2451 2339 1227
  Helmer Hanssen 2013851 8 8 124 317 21 124 492 436 432
2014 Helmer Hanssen 2014011 8 8 209 717 21 222 736 455 449
  Johan Hjort 2014213 61 54 928 1601 81 1046 1767 4036 2680
  Håkon Mosby 2014621 74 61 1292 2555 94 1344 2623 2718 1837
2015 Johan Hjort 2015211 64 53 901 1272 65 992 1797 3880 2289
  Håkon Mosby 2015621 74 58 1180 1798 59 1183 2580 2447 1578
  Helmer Hanssen 2015854 8 7 181 566 21 229 613 395 390
2016 Johan Hjort 2016210 70 61 1451 2336 91 1545 2580 4594 4429
  Håkon Mosby 2016620 69 53 976 1463 59 1012 1522 2978 1567
2017 Johan Hjort 2017210 99 89 1616 2822 94 1656 2887 4696 2322
  Kristine Bonnevie 2017620 87 70 917 1854 97 957 1931 3760 1567
2018 Johan Hjort 2018210 110 90 1713 3282 134 1747 3316 4141 1527
  Kristine Bonnevie 2018623 86 66 1301 2365 94 1389 2523 3983 2146
2019 Johan Hjort 2019210 128 100 1516 2059 108 1598 2164 4832 2411
  Kristine Bonnevie 2019629 87 70 1191 2409 117 1196 2499 3345 2371
Table 1. Description of survey data. The number of bottom trawl (BT) stations for swept area and acoustic indices differ because different data filters are applied (see sections 4.1.3 and 4.2.6).

4 - Software used

StoX is a software developed by the Institute of Marine Research for survey analysis and index calculation. StoX is freely available (ftp://ftp.imr.no/StoX/Download/ ) and is relatively well documented (Johnsen et al., 2019). StoX is currently used for the calculation of bottom trawl indices from the Barents Sea winter survey (Mehl et al., 2018b) and from the Barents Sea ecosystem survey in the autumn (BESS) (Johannesen et al., 2019).

The data was mainly downloaded from: https://datasetexplorer.hi.no/apps/datasetexplorer/v2/navigation and the folder “Varanger Stad NOR coastal cruise in autumn». However, for some research vessels, especially in the early part of the period, data was lacking in the relevant folders and had to be retrieved from the original data files and reformatted to the current xml format used by StoX (https://www.hi.no/hi/forskning/prosjekter/stox). Steps have been taken to have these data stored in the “Varanger Stad NOR coastal cruise in autumn” folder structure and quality assure for later use.

5 - Acoustic indices

A stock abundance index series based on acoustic data from the annual autumn coastal survey ( NOcoast-Aco-4Q ) was calculated using the StoX software (Johnsen et al., 2019). Acoustic data covering the coastline from 62°N to the Russian border are available back to 1995, although the coverage in various parts of this area varied somewhat due to various reasons, see chapter 3.1 and 3.2 for details. For some early years in the series, acoustic data was only available from parts of the survey area. The area was split into 23 strata (see above) and the stock abundance index was calculated for each stratum separately. For various reasons, it was decided to split the total area into three subareas: The coast north of 67°N (A, consisting of 18 strata), between 65° and 67°N (B, consisting of 2 strata), and between 62°N and 65°N (C, consisting of 2 strata) (Fig 1). The spatial coverage during most of the time series is much better in subarea A than in B and C.

To estimate the uncertainty, 500 bootstrap runs were performed, and the indices are the average index from these runs.

5.1 - Acoustic indices by length

The conversion of mean nautical area scattering coefficient (NASC, m 2 nmi −2 ) to fish density was carried out using a standard procedure, where trawl stations (with a catch of more than 1 cod individual) were assigned to each PSU. As a rule, all stations within a stratum were assigned to the PSUs in the same stratum. However, if less than three trawl stations were carried out in a stratum, stations in neighbouring strata were assigned to the PSUs so that at least three stations were assigned to each PSU.

The combined length distribution (d), calculated for each transect (PSU, j), is given by

, (eqn 1)

where d l,s,j is fish density (number by 1 nmi tow distance) by station (s) and length group (l, cm), and n is the total number of stations.

The fish density (ρ, individuals nmi -2 ) by length group and transect was calculated using

(eqn 2)

where NASC j,l is the mean nautical area scattering coefficient by transect and length group and σ bs,l (m2) is the acoustic backscattering cross-section for a fish of length l.

NASC j,l is given by

(eqn 3)

where σ bs,l is the acoustic backscattering cross-section for a fish of length l multiplied by the proportion (p) of a fish of length l in d l,j , and NASC j is the mean nautical area scattering coefficient over a given transect.

The acoustic backscattering cross-section for a fish of length l is calculated using

, (eqn 4)

where the target strength, TS (dB re 1m 2 ), for a fish of length l is calculated using

, (eqn 5)

where m and a are constants, set at 20 and -68.0 respectively.

The abundance (N, inds) of cod by length group l and stratum k is given by

, (eqn 6)

where A (nmi 2 ) is the stratum area, and the mean density of cod by l and k is given by

(eqn 7)

where is the transect weight,  is the total number of sample transects and  and are the distance of each transect by stratum and the mean transect distance over each stratum respectively.

5.2 - Acoustic indices by age

Only a subsample of the length-measured individuals (j) is aged. A two-stage conversion process is used to convert the abundance of fish by length group to abundance of fish by age group.

First, the abundance ( N k,l ) by l and k is distributed the length-measured individuals to generate so-called super-individuals, each representing an abundance estimated as:

, (eqn 8)

where

, (eqn 9)

and m is the number of length-measured individuals.

Second, in instances where a super-individual is not aged, the missing age is filled in by a random data imputation. The imputation of missing age is principally carried out at the station level, randomly selecting the value from aged super-individuals within the same length group. If no aged super-individual is available at station level, the imputation is attempted at strata level, or lastly on survey level. In instances, where no age information is available at any level for a specific length group, the abundance estimate is presented with unknown age. As the imputation of missing age values in both examples also imputes associated biological parameters, abundance can be estimated for any combination of classifications assigned to the super-individuals e.g. sex, maturity, age etc. In our case the otolith type was used to classify the super-individuals, see below.

5.3 - Length and weight at age

Length and weight at age was calculated using the weighting factors defined in eqn 8 (the “super -individuals”).

5.4 - Uncertainty of abundance indices

Uncertainty was estimated as the coefficient of variation (ratio of standard deviation to the mean, CV). StoX calculates CV using bootstrap runs by stratum, treating each trawl station as the primary sampling unit. Here we used 500 bootstrap runs.

5.5 - Extracting coastal cod from total cod

Since the discrimination of coastal cod and other cod caught at the coastal survey is based on otolith types (see above), this poses a special challenge to producing abundance index series with uncertainty for coastal cod. Running a StoX project on the acoustical and biological data to produce an acoustic index series will primarily produce indices for all cod present in these data sources. However, when running the bootstrap process in StoX, it is possible to group the superindividuals by several categories, for instance age and otolith type. There is no facility inside StoX to present those “two-dimensional” bootstrap data but using an R-script manipulating the bootstrap files generated by StoX it is possible to extract relevant data. Thus, this was done after the whole time series was made by ordinary StoX-runs, by selecting only those entries in the bootstrap data that contained superindividuals with otolith types “1” and “2”. All tables and figures in the appendices were produced with this R-script. The R-script itself is documented in appendix C. Since the growth pattern can only be distinguished with certainty in otoliths from two-year old and older fish (although an otolith type is in some cases noted also for younger fish), the indices of age 0 and age 1 were excluded from the index series suggested for use in stock assessment.

5.6 - Acoustic indices - settings in StoX

The processes included and the settings of parameters when running StoX for acoustic indices are given in Tables 2-5:

Table 2. Baseline processes:

Process Parameters Values
ReadProcessData    
ReadAcousticXML FileName1, FileName2, … Relevant data files
FilterAcoustic AcousticData ReadAcousticXML
  DistanceExpr N/A
  FreqExpr N/A
  NASCExpr acocat == 31
NASC LayerType WaterColumn
ReadBioticXML FileName1, FileName2, … Relevant file names
FilterBiotic FishStationExpr fs.getLengthSampleCount(‘TORSK’)>1
  CatchExpr species == ‘164712’
  SampleExpr N/A
  IndExpr N/A
StationLengthDist LengthDistType NormLengthDist
RegroupLenghDist LengthInverval 1.0
Catchability CatchabilityMethod LengthDependentSweepWidth
  LengthDist RegroupLengthDist
  ParLenfthDependentSweepWidth SpecCat=;Alpha=5.91;Beta=0.43;LMin=15.0;LMax=62.0
RelLengthDist LengthDist Catchability
DefineStrata UseProcessData True”
StratumArea AreaMethod Accurate
DefineAcousticTransect DefinitionMethod UseProcessData
MeanNASC NASC NASC
  SampleUnitType PSU
BioStationAssignment BioticData FilterBiotic
  AssignmentMethod Stratum (first time, then UseProcessData)
  EstLayers 1~PELBOT
BioStationWeigting WeightingMethod SumWeightCount
TotalLengthDist LengthDist RelLengthDist
AcousticDensity LengthDist TotalLengthDist
  NASC MeanNASC
  m 20
  a -68
MeanDensity_Stratum Density AcousticDensity
  SampleUnitType Stratum
SumDensity_Stratum Density MeanDensity_Stratum
Abundance Density SumDensity_Stratum
  PolygonArea StratumArea
IndividualDataStations Abundance Abundance
IndividualData IndividualDataStations IndividualDataStations
SuperIndAbundance Abundance Abundance
  IndividualData IndividualData
  AbundWeightMethod StationDensity
  LengthDist RegroupLengthDist

Table 3. Baseline report processes:

Process Parameters Values
FillMissingData Superindividuals SuperIndAbundance
  FillVariables ImputeByAge
  Seed 1
  FillWeight Mean
EstimateByPopulationCategory Superindividuals FillMissingData
  Lengthinterval 5.0
  Scale 1000
  Dim1 olotithtype
  Dim2 age
  Dim3 SpecCat

Table 4. R processes:

Process Parameters Values
runBootstrap bootstrapMethod AcousticTrawl
  acousticMethod PSU~Stratum
  bioticMethod PSU~Stratum
  startProcess TotalLengtDist
  endProcess SuperIndAbundance
  nboot 500
  seed 1
  cores 4
imputeByAge seed 1
  cores 4
SaveProjectData   Enabled”

Table 5 R report processes:

Process Parameters Values
getReports out all
  options grp1=”age”, grp2=”otolithtype”
getPlots out all
  options grp1=”age”, grp2=”otolithtype”

5.7 - Resulting time series

The annual abundance indices and biomass indices by age groups and for age group 2+, their coefficient of variation, and mean length and weight by age groups are shown in Appendix A for the total area and for the subareas A, B and C.

The abundance indices for age 2+ are depicted in Figures 3 to 6. The series for the total area (Fig 3) is characterized by high indices at the beginning of the time series, but rapidly decreasing from 1997 to a level of 10-20 million, without any clear trends. In general, the uncertainties are larger during the first part of the time series compared to more recent years.

 

Figure 3. Acoustic index series for coastal cod age 2+ in the total area. Error bars represent +/- two standard deviations.

 

The series for subarea A (the northern part of the survey area, Figure 4) resembles that for the total area, because this area contains most of the coastal cod.

 

Figure 4. Acoustic index series for coastal cod age 2+ in subarea A (north of 67 ° N). Error bars represent +/- two standard deviations.

 

The indices for subareas B (Figure 5) and C (Figure 6) are lower than for subarea A. The uncertainties are also more variable from year to year.

 

Figure 5. Acoustic index series for coastal cod age 2+ in subarea B (between 65 ° N and 67 ° N). Error bars represent +/- two standard deviations.

 

 

Figure 6. Acoustic index series for coastal cod age 2+ in subarea C (between 62 ° N and 65 ° N). Error bars represent +/- two standard deviations.

 

To assess whether the indices can describe the stock dynamics over time, plots on how year classes (cohorts) could be traced from year to year were constructed (Figure 7-10). The progression of year classes through the stock is reasonably well described for the total area and for subarea A (Figures 7-8). A year effect is visible for instance in 1998, when all age groups where recorded lower than expected. In other years, single age groups, in particular among older fish, show unexpected patterns. This seems to be a problem for age groups above 10 years. As expected, the plot for Subarea A (Figure 8) resembles that for the total area, while those for Subarea B (Figure 9) and Subarea C (Figure 10) show a much less consistent picture, where strong year effects are visible .

 

Figure 7. Abundance (log scale) over time for the year classes 1995 to 2014 for age 1 and older in the acoustic index series for the total area. The age is shown for each data point.

 

 

Figure 8. Abundance (log scale) over time for the year classes 1995 to 2014 for age 1 and older in the acoustic index series for Subarea A. The age is shown for each data point.

 

 

Figure 9. Abundance (log scale) over time for the year classes 1995 to 2014 for age 1 and older in the acoustic index series for Subarea B. The age is shown for each data point.

 

 

Figure 10. Abundance (log scale) over time for the year classes 1995 to 2014 for age 1 and older in the acoustic index series for Subarea C. The age is shown for each data point.

 

5.8 - Internal consistency in the acoustic series for subarea A

The internal consistency plots (number at age n in year n plotted versus number at age n+1 in year y+1) for age groups 1-6 are shown in Figure 11 and for age groups 7-12 in Figure 12. In most cases the fit is rather poor. Exceptions are age 1-2 and age 2-3, with rather high correlation, but the regressions are highly affected by the large indices during the first part of the period.

 

Figure 11. Consistency plots for the acoustic index for area A. Age groups 1-6.

 

 

Figure 12. Consistency plots for the acoustic index for area A. Age groups 7-12.

 

5.9 - Comparison with acoustic index series calculated with previous methods

An acoustic index has been calculated for this stock since 1995 (see chapter 1.3). Because this approach used a somewhat more detailed strata system and a method based on the SAS software platform, it is difficult to compare that series with the new acoustic index developed in StoX. Nonetheless, a comparison made for the sum over ages 2+ (Figure 13) shows that there are large differences between the series before 2002. For the period after 2002 the indices are much more similar, with the new series estimates being somewhat lower in most years. A part of the large discrepancies found in the early years of the series can be explained by poor data quality of the acoustic data. When the series was rerun in StoX and the acoustic data checked in detail, some few enormous NASC values were detected, indicating that parts of the bottom signal had been integrated. In small strata containing few transects and few values, such erroneous values may have a big impact on the total index. For instance, in 2000, taking out a NASC value of 4718 from a small stratum (Sørøya Indre) made the index in that stratum change from 46 000 tonnes to 1400 tonnes. In 1996, 1999 and in 2000 six extremely high values were found and removed from the transects, which had profound effects on the index values from these years. It is unknown whether these erroneous values were in fact included in the old acoustic series or not. In the remaining years before 2002, no extreme values could be found and also in these years the new index is substantially lower than the old index, indicating that there are other reasons for the differences. Despite this we argue that the new indices should be accepted on the grounds that they are developed in one go, using a more quality assured software with identical settings from year to year, and with a more thorough quality assurance of the acoustic data.

 

Figure 13. Comparison of the old and new acoustic abundance index series for sum over ages 2+ for the total area.

 

6 - Swept area indices

A stock abundance index series based on bottom trawl hauls at the annual autumn coastal survey ( NOcoast-Aco-4Q ) was calculated using the StoX software. Trawl data covering the coastline from 62°N to the Russian border were available back to 1995, although the coverage in various parts of this area varied somewhat due to ship availability, weather conditions etc. However, the survey was designed as an acoustic survey before 2003, and trawls were done on acoustic registrations in order to supply biological data for the acoustic observations. Consequently, we did use trawl data prior to 2003 when calculating the swept-area indices for coastal cod. The area is split into 22 strata (Figure 1) and the stock abundance index is calculated for each stratum separately. It was decided to split the total area into three subareas: The coast north of 67°N (A, consisting of 18 strata), between 65° and 67°N (B, consisting of 2 strata), and between 62°N and 65°N (C, consisting of 2 strata). The coverage during most of the time series is much better in subarea A than in B and C.

The coastal cod was split from the NEA cod using the same methods as described for the acoustic index, see above.

To estimate the uncertainty of the estimate, 500 bootstrap runs were performed, and the indices are the average index from these runs.

6.1 - Swept area indices by length

The following description is taken from Johannesen et al. (2019):

The swept area density ( ρ , individuals per square nautical mile, inds nmi -2 ) by stratum (k), station (s) and length group l (1 cm), is given by

, (eqn 10)

where f k,s,l is the number of individuals standardized over a towing distance of 1 nmi by k, s and l, and sw l is the adjusted swept width in nmi’s by length group calculated using

, (eqn 11)

where EW l is the length dependent effective swept width. The length dependency of swept width is taken from (Dickson, 1993)

The abundance ( N , inds) by l and k is calculated using

, (eqn 12)

where A is stratum area (nmi 2 ), and ρ k,l is the average swept area density by l and k, given by

, (eqn 13)

where n is number of stations.

6.2 - Swept area indices by age

The sampling protocol for the survey is to sample one individual from each 5 cm length group at each trawl station for aging and individual weights. A two-stage conversion process is used to convert the abundance of fish by length group to abundance of fish by age group.

Firstly, the abundance ( N k,l ) by length group l (5 cm) and stratum k is distributed by the length-measured individuals (j) to generate so-called “Super-individuals” (super-individuals represent fractions of a total, our use corresponds to a probability based design where is the inverse of the inclusion probability for a single fish sample), each representing an abundance estimated as:

, (eqn 14)

where

, (eqn 15)

and m is the number of length-measured individuals

Secondly, in instances where a super-individual is not aged, the missing age is filled in by a random data imputation. The imputation of missing age is principally carried out at the station level, randomly selecting the value from aged super-individuals within the same length group. If no aged super-individual is available at the station level, the imputation is attempted at strata level, or lastly on survey level. In instances where no age information is available at any level for a specific length group, the abundance estimate is presented with unknown age (Johnsen et al., 2019).

6.3 - Length and weight at age

Length and weight at age was calculated using the weighting factors defined in eqn 15 (the “super -individuals”).

6.4 - Uncertainty of abundance indices

Uncertainty was estimated as the coefficient of variation (ratio of standard deviation to the mean, CV). StoX calculates CV using bootstrap runs by stratum, treating each trawl station as the primary sampling unit. Here we used 500 bootstrap runs.

6.5 - Extracting coastal cod from total cod

Since the discrimination of coastal cod and other cod caught at the coastal survey is based on otolith types (see above) this poses a special challenge to producing abundance index series with uncertainty for coastal cod. Running a StoX project on the biological data to produce a swept-area index series will primarily produce indices for all cod present in this data source. However, when running the bootstrap process in StoX, it is possible to group the superindividuals by several categories, for instance age and otolith type. There is no facility inside StoX to present those “two-dimensional” bootstrap data but using an R-script manipulating the bootstrap files generated by StoX it is possible to extract relevant data. Thus, this was done after the whole time series were made by ordinary StoX-runs, by selecting only those entries in the bootstrap data that contained superindividuals with otolith types “1” and “2”. Alle tables and figures in the appendices to this document were produced by this R-script. The R-script itself is documented in appendix “C”.

6.6 - Swept area indices – settings in StoX

The processes included and the settings of parameters when running StoX for swept area indices are given in tables 6-9:

Table 6. Baseline processes:

Process Parameters Values
ReadProcessData    
ReadBioticXML FileName1, FileName2, … Relevant file names
FilterBiotic FishStationExpr* gear =~[‘3270’,’3271’] and
    gearcondition < 3 and
    tawlquality =~[‘1’,’3’] and
    fishstationtype !=[‘2’] and
  CatchExpr species == ‘164712’
  SampleExpr N/A
  IndExpr N/A
DefineSweptAreaPSU Method Station
StationLengthDist LengthDistType NormLengthDist
RegroupLenghDist LengthInverval 5.0
Catchability CatchabilityMethod LengthDependentSweepWidth
  LengthDist RegroupLengthDist
  ParLenfthDependentSweepWidth SpecCat=;Alpha=5.91;Beta=0.43;LMin=15.0;LMax=62.0
RelLengthDist LengthDist Catchability
DefineStrata UseProcessData True”
StratumArea AreaMethod Accurate
TotalLengthDist LengthDist RegroupLengthDist
SweptAreaDensity SweptAreaMethod LengthDependent
  BioticData FilterBiotic
  LengthDist TotalLengthDist
  DistanceMethod FullDistance
  SweepwidthMethod Predetermined
MeanDensity_Stratum Density SweptAreaDensity
  SampleUnitType Stratum
  PolygonArea StratumArea
AbundanceByLength Density MeanDensity_Stratum
IndividualDataStations Abundance AbundanceByLength
IndividualData IndividualDataStations IndividualDataStations
SuperIndAbundance Abundance AbundanceByLength
  IndividualData IndividualData
  AbundWeightMethod StationDensity
  LengthDist RegroupLengthDist

* In the period 2017-2019 this filter was changed to allow for inclusion of stations coded with StationType = C and trawlQuality = 2

Table 7. Baseline report processes:

Process Parameters Values
FillMissingData Superindividuals SuperIndAbundance
  FillVariables ImputeByAge
  Seed 1
  FillWeight Mean
EstimateByPopulationCategory Superindividuals FillMissingData
  Lengthinterval 5.0
  Scale 1000
  Dim1 otolithtype
  Dim2 age
  Dim3 SpecCat

Table 8. R processes:

Process Parameters Values
runBootstrap bootstrapMethod AcousticTrawl
  acousticMethod PSU~Stratum
  bioticMethod PSU~Stratum
  startProcess TotalLengtDist
  endProcess SuperIndAbundance
  nboot 500
  seed 1
  cores 4
imputeByAge seed 1
  cores 4
SaveRImage   Enabled”

Table 9. R report processes:

Process Parameters Values
getReports out all
  options grp1=”age”, grp2=”otolithtype”
getPlots out all
  options grp1=”age”, grp2=”otolithtype”

6.7 - Resulting time series

Index series for the total area (Figure 14) and for the three subareas A (Figure 15), B (Figure 16) and C (Figure 17) are shown below. The abundance indices for the total area is rather flat but one year, 1997, stands out from the rest having a three times as high index and much wider confidence limits than the rest of the years in the series.

The amount of coastal cod in subarea A (Figure 15) is much higher than in the more southern subareas B and C, and the index series in subarea A therefore resembles the total index to a high degree. While the index for subarea A (and therefore also the total area) shows peaks in 2003 and in 2014-2015, the series for subareas B and C are without conspicuous trends. The relative uncertainty is much higher for the two southern subareas than for the northern (subarea A). The uncertainty in the last four years is smaller than for the earlier part of the index series, for all subareas.

 

Figure 14. Trawl index series for coastal cod age 2+ in the total area. Error bars represent +/- two standard deviations.

 

 

Figure 15. Trawl index series for coastal cod age 2+ in subarea A (north of 67 ° N). Error bars represent +/- two standard deviations.

 

 

Figure 16. Trawl index series for coastal cod age 2+ in subarea B, (between 65 ° N and 67 ° N). Error bars represent +/- two standard deviations.

 

 

Figure 17. Trawl index series for coastal cod age 2+ in subarea C, (between 62 ° N and 65 ° N). Error bars represent +/- two standard deviations.

 

Consistency among cohorts are illustrated on Figures 18-21. The cohorts can be followed in subarea A (and in the total area) without conspicuous year effects, except in 2005 and 2007. For the two subareas B (Figure 20) and C (Figure 21) it is not possible to follow the year classes except for short periods, indicating that the indices for these subareas do not reflect the total abundance of coastal cod during the period 2002 to 2019.

 

Figure 18. Abundance (log scale) over time for the year classes 2002 to 2014 for age 1 and older in the trawl index series for the total area. The age is shown for each data point.

 

 

Figure 19. Abundance (log scale) over time for the year classes 2002 to 2014 for age 1 and older in the trawl index series for Subarea A. The age is shown for each data point.

 

 

Figure 20. Abundance (log scale) over time for the year classes 1995 to 2014 for age 1 and older in the trawl index series for Subarea B. The age is shown for each data point.

 

 

Figure 21. Abundance (log scale) over time for the year classes 2002 to 2014 for age 1 and older in the trawl index series for Subarea C. The age is shown for each data point.

 

6.8 - Consistency within the trawl index series for area A

The internal consistency plots (number at age n in year n plotted versus number at age n+1 in year y+1) for age groups 1-6 are shown in Figure 22 and for age groups 7-12 in Figure 23. In most cases the fit is poor.

 

Figure 22. Consistency plots of the trawl index for area A. Age groups 1-6.

 

 

Figure 23. Consistency plots of the trawl index for area A. Age groups 7-11.

 

7 - Comparison of the trawl and acoustic index series

The acoustic index series and the trawl index series give a partly independent view of the stock situation over time. They are not totally independent, since the length information used to translate the acoustic backscatter into fish abundance comes by and large from the same trawl hauls that are used for calculation of swept area indices, and the age information used to break the acoustic index down to age groups partly comes from the same trawl hauls that are used to calculate the swept area indices. However, the total backscatter, mainly determining the acoustic index, is totally independent of the catch rates in the trawl hauls, so in this respect the two series give independent information about the amount of fish. There are numerous reasons that these indices differ. Trawling on the bottom is only possible were the bottom is trawlable, that is soft and smooth and not to steep. In many areas of the coast it is not possible to trawl, and consequently the trawl hauls may not be representative of areas with hard and/or steep bottom. On the other hand, even though the acoustic method will cover all navigable waters, the acoustic backscatter signal is difficult to interpret where the bottom is steep, and in all areas the dead zone near the bottom will not be covered. Also, the allocation of acoustic backscattering by species can be challenging, and in particular in areas where it is not possible to trawl.

In Figure 24 the new acoustic index series and the swept-area series are compared, and also the landings statistics are included on the figure for comparison.

 

Figure 24. New acoustic series (2+), trawl index series (2+) and landings (taken from table 2.1a in ICES (2020).

 

The acoustic series, going back to 1995, shows a decrease in the last part of the 1990s with a simultaneous decrease in catches during that period, from a record high catch in 1995 to a level at about half of that total during the next decades. The acoustic index and the trawl index fluctuate without clear trends after 2003, in some years the acoustic index is higher than the trawl index and vice versa. These index series are compared on age-group basis in figure 25 and 26. The consistency is quite good for many of the age groups, with r 2 in the range 0.2-0.6. However, for some age groups (mainly 3-6) the fit is poorer, with r 2 in the range 0.0-0.1.

 

Figure 25. Comparison of acoustic index and trawl index for area A in the period 2003 to 2009, age groups 1-6.

 

 

Figure 26. Comparison of acoustic index and trawl index for area A in the period 2003 to 2009, age groups 7-12.

 

8 - Conclusions by the data evaluation workshop regarding inclusion of these time series in the assessment of Norwegian Coastal Cod north of 62°N

Based on an evaluation of what is presented in this document concerning data quality, survey coverage, and year-to-year consistency, the data evaluation workshop held in December 2020 concluded that

  1. The acoustic abundance index series from 1995 to 2019, for age groups 2-10+, may be used as input data in analytical assessment models for coastal cod in subarea A. The corresponding estimates of length- and weight-at-age may be used as estimates of length- and weight-at-age in the stock.

  2. For subareas B and C, the acoustic indices for biomass of age 2+ may be used in biomass models or to assess changes in stock abundance from year to year, using methods for data-limited stocks.

  3. The trawl index series from 2003 to 2019, for age groups 2-10, may be used as input data in analytical assessment models for coastal cod in subarea A. The corresponding estimates of length- and weight-at-age may be used as estimates of length- and weight-at-age in the stock.

  4. For subareas B and C, the trawl indices of biomass of age 2+ may be used in biomass models or to assess changes in stock abundance from year to year, using methods for data-poor stocks.

9 - References

Aglen, A., Berg, E., Mehl, S., and Sunnanå, K. 2005. Acoustic abundance of saithe, coastal cod and juvenile herring Finnmark – Møre Autumn 2005. Toktrapport/Havforskningsinstituttet, 2005/23.

Aglen, A., Nedreaas, K., Knutsen, J. A., and Huse, G. 2020. Kysttorsk nord for 62 grader nord. Vurdering av status og forslag til forvaltningstiltak og ny gjenoppbyggingsplan. Fisken og Havet, 2020/2: 1-64.

Berg, E., and Albert, O. T. 2003. Cod in fjords and coastal waters of North Norway: distribution and variation in length and maturity at age. ICES Journal of Marine Science, 60: 787-797.

Dahle, G., Quintela, M., Johansen, T., Westgaard, J. I., Besnier, F., Aglen, A., Jorstad, K. E., et al. 2018. Analysis of coastal cod (Gadus morhua L.) sampled on spawning sites reveals a genetic gradient throughout Norway's coastline. BMC Genet, 19: 42.

Dickson, W. 1993. Estimation of the capture efficiency of trawl gear. 1:Development of a theoretical model. Fisheries Research, 16: 239-253.

ICES 2020. Arctic Fisheries Working Group (AFWG). ICES Scientific Reports., 2:52. : 577

Johannesen, E., Johnsen, E., Johansen, G. O., and Korsbrekke, K. 2019. StoX applied to cod and haddock data from the Barents Sea NOR-RUS ecosystem cruise in autumn. Swept area abundance, length and weight at age 2004-2017. Fisken og Havet, 2019-6: 1-40.

Johnsen, E., Totland, A., Skålevik, Å., Holmin, A. J., Dingsør, G. E., Fuglebakk, E., Handegard, N. O., et al. 2019. StoX: An open source software for marine survey analyses. Methods in Ecology and Evolution, 10: 1523-1528.

Mehl, S., Aglen, A., Berg, E., Dingsor, G. E., and Korsbrekke, K. 2018a. Akustisk mengdemåling av sei, kysttorsk og hhyse Finnmark-Møre hausten 2017. Toktrapport/Havforskningsinstituttet, Nr. 2–2018.

Mehl, S., Aglen, A., Johnsen, E., and Skålevik, Å. 2018b. Estimation of acoustic indices with CVs for cod and haddock in the Barents Sea winter survey 1994 – 2017 applying the Sea2Data StoX software. Fisken og Havet, 5-2018.

Mjanger, H., Svendsen, B. V., Senneset, H., Fuglebakk, E., Skage, M. L., Diaz, J., Johansen, G. O., et al. 2020. Handbook for sampling fish, crustaceans and other invertebrates. pp. 1-157. Institute of Marine Research, Bergen.

Skants, K. D. 2019. Species composition, distribution and ecology of the demersal fish community along the Norwegian coast north of Stad under varying environmental conditions. In Department of Biological Sciences - Marine Biology. University of Bergen, Norway.

Staby, A., Mehl, S., Berg, E., Aglen, A., and Korsbrekke, K. 2020. Acoustic abundance of saithe and coastal cod Finnmark – Møre Autumn 2018. Toktrapport/Havforskningsinstituttet, Nr. 5–2020.

10 - Appendix A. Acoustic abundance indices

10.1 - Total area

  Age 0 Age 1 Age 2 Age 3 Age 4 Age 5 Age 6 Age 7 Age 8 Age 9 Age 10 Age 11 Age 12 Age 13 Age 14 Age 15 Age 16 Age 17
1995 0.050 26.961 11.015 7.254 7.207 7.023 4.618 1.561 0.678 0.341 0.042   0.134          
1996 23.006 17.763 10.743 12.628 6.669 7.434 3.386 1.269 0.213 0.035 0.123              
1997 0.030 17.724 17.907 20.326 9.288 5.243 2.652 0.919 0.393 0.091 0.016 0.029            
1998 1.445 8.713 10.675 10.731 9.626 4.238 1.806 0.951 0.141 0.123 0.038   0.013   0.026 0.026    
1999   2.562 3.990 4.112 3.283 2.794 0.941 0.214 0.030 0.067 0.023   0.007          
2000 2.175 5.264 8.468 7.426 4.935 4.320 3.106 0.712 0.307 0.087 0.029 0.026   0.015        
2001 0.298 2.725 4.847 4.734 4.343 2.516 1.637 1.018 0.219 0.031 0.040 0.029 0.010 0.020        
2002 0.518 1.822 2.894 3.842 4.809 3.659 3.273 1.154 0.459 0.126 0.105 0.005   0.051        
2003 4.819 3.324 2.401 3.516 3.757 2.245 1.743 0.749 0.423 0.207 0.024 0.005   0.027     0.024  
2004 4.822 3.297 3.038 3.454 3.633 2.398 1.521 0.587 0.316 0.126 0.108 0.005     0.004      
2005 0.044 1.451 1.799 3.303 2.867 2.178 1.390 0.495 0.263 0.156 0.032 0.067            
2006 6.949 5.377 2.439 4.039 3.274 2.394 2.178 1.246 0.206 0.186 0.017 0.033 0.006          
2007 26.132 2.578 3.742 3.234 4.091 2.597 1.728 1.276 0.464 0.125 0.028 0.020   0.006        
2008 13.880 2.399 1.815 1.733 1.573 1.015 0.763 0.425 0.230 0.099 0.026 0.023 0.025 0.000 0.000      
2009 1.929 3.973 1.930 2.833 3.263 1.728 0.812 0.468 0.556 0.200 0.033 0.061 0.002   0.001 0.002    
2010 1.293 5.708 2.689 3.141 2.527 1.981 0.679 0.364 0.467 0.248 0.120 0.052 0.023 0.006 0.002 0.004    
2011 0.518 3.795 3.527 2.746 3.011 2.018 1.544 0.421 0.355 0.149 0.094 0.019 0.060 0.014        
2012 0.098 3.649 2.309 3.651 2.025 1.348 0.894 0.530 0.256 0.111 0.122 0.049 0.019 0.023 0.007   0.004  
2013 0.585 5.142 3.306 1.857 1.960 1.510 0.952 0.695 0.451 0.216 0.088 0.089 0.062 0.006 0.006 0.003 0.006  
2014 15.684 6.133 4.296 3.148 2.205 2.951 1.647 1.154 0.695 0.490 0.091 0.084 0.084 0.008 0.010 0.028 0.017 0.024
2015 0.248 5.389 4.024 2.486 2.678 1.418 1.413 0.641 0.476 0.424 0.166 0.049 0.061 0.003 0.008   0.001  
2016 1.524 2.719 2.790 2.837 2.795 2.628 0.770 0.580 0.525 0.157 0.152 0.104 0.062 0.005 0.006   0.004  
2017 6.355 1.250 3.441 3.312 2.643 1.891 1.207 0.484 0.291 0.172 0.053 0.094 0.022 0.016        
2018 0.338 5.069 2.751 2.181 2.550 1.711 1.210 0.456 0.387 0.228 0.096 0.052 0.021 0.012   0.005 0.003  
2019 0.925 3.464 3.443 4.787 3.112 3.160 1.942 1.222 0.317 0.384 0.158 0.059 0.094 0.013 0.004 0.010 0.008  
Table A.1.1. Abundance indices (millions)
  Age 0 Age 1 Age 2 Age 3 Age 4 Age 5 Age 6 Age 7 Age 8 Age 9 Age 10 Age 11 Age 12 Age 13 Age 14 Age 15 Age 16 Age 17
1995 0.522 0.165 0.103 0.063 0.112 0.125 0.200 0.163 0.308 0.472 0.408   0.221          
1996 0.641 0.197 0.093 0.105 0.118 0.105 0.217 0.437 0.393 0.501 0.301              
1997 0.424 0.228 0.214 0.134 0.134 0.127 0.229 0.218 0.412 0.427 0.656 0.634            
1998 0.722 0.249 0.118 0.094 0.139 0.142 0.266 0.509 0.313 0.862 0.992   0.509   0.000 0.000    
1999   0.237 0.092 0.093 0.169 0.154 0.184 0.157 0.459 0.132 0.455   0.509          
2000 0.781 0.136 0.145 0.097 0.076 0.080 0.094 0.133 0.244 0.399 0.393 0.333   0.480        
2001 0.683 0.178 0.294 0.163 0.139 0.161 0.163 0.201 0.286 0.701 0.587 0.470 0.639 0.740        
2002 0.632 0.162 0.126 0.136 0.101 0.088 0.062 0.149 0.253 0.555 0.563 0.552   0.400        
2003 0.310 0.262 0.238 0.122 0.120 0.113 0.142 0.160 0.188 0.245 0.344 0.671   1.652     0.596  
2004 0.251 0.177 0.118 0.092 0.072 0.115 0.109 0.132 0.167 0.715 0.260 0.543     0.485      
2005 0.872 0.114 0.153 0.121 0.064 0.092 0.124 0.112 0.263 0.327 0.285 0.788            
2006 0.498 0.999 0.509 0.100 0.100 0.077 0.206 0.184 0.149 0.148 0.000 0.392 0.496          
2007 0.645 0.200 0.170 0.168 0.140 0.152 0.150 0.199 0.291 0.429 0.804 0.846   0.920        
2008 0.343 0.238 0.182 0.138 0.129 0.114 0.136 0.187 0.231 0.379 0.373 0.476 0.501 0.357 0.357      
2009 1.051 0.215 0.153 0.108 0.096 0.137 0.107 0.158 0.129 0.229 0.307 0.204 0.523   0.672 0.514    
2010 0.501 0.394 0.166 0.147 0.115 0.101 0.183 0.189 0.208 0.199 0.200 0.206 0.558 0.242 0.406 0.537    
2011 0.827 0.125 0.126 0.110 0.119 0.108 0.125 0.252 0.163 0.192 0.277 0.517 0.338 0.767        
2012 0.599 0.211 0.233 0.122 0.123 0.119 0.090 0.159 0.160 0.227 0.185 0.423 0.466 0.492 0.402   0.315  
2013 0.538 0.129 0.149 0.120 0.133 0.119 0.118 0.165 0.195 0.312 0.345 0.357 0.485 0.649 0.550 0.390 0.557  
2014 0.815 0.158 0.178 0.087 0.115 0.123 0.118 0.134 0.089 0.204 0.416 0.336 0.312 0.831 0.170 0.522 0.687 0.31
2015 0.784 0.115 0.090 0.096 0.068 0.094 0.094 0.116 0.159 0.178 0.260 0.353 0.309 0.258 0.717   0.600  
2016 0.598 0.304 0.132 0.084 0.072 0.088 0.156 0.164 0.177 0.265 0.194 0.228 0.528 0.426 0.341   0.297  
2017 0.644 0.463 0.177 0.168 0.163 0.108 0.155 0.218 0.264 0.425 0.286 0.336 0.509 0.606        
2018 0.911 0.403 0.146 0.147 0.166 0.146 0.114 0.191 0.355 0.297 0.138 0.275 0.325 0.667   0.225 0.260  
2019 0.232 0.137 0.172 0.117 0.093 0.083 0.101 0.100 0.194 0.232 0.235 0.207 0.631 0.500 0.601 0.769 0.663  
Table A.1.2. CV on abundance indices
  Age 0 Age 1 Age 2 Age 3 Age 4 Age 5 Age 6 Age 7 Age 8 Age 9 Age 10 Age 11 Age 12 Age 13 Age 14 Age 15 Age 16 Age 17
1995 0.000 1.595 3.414 5.298 10.124 14.865 12.579 7.364 4.352 2.470 0.144   2.387          
1996 0.157 0.716 2.459 9.286 9.228 14.394 9.253 5.554 1.402 0.388 2.020              
1997 0.000 0.742 4.335 13.470 12.866 10.135 7.839 2.911 1.564 0.874 0.176 0.148            
1998 0.014 0.459 3.533 9.317 13.530 9.495 5.873 4.444 0.832 0.676 0.615   0.157   0.525 0.690    
1999   0.163 1.110 3.412 5.253 5.734 2.634 0.974 0.225 0.768 0.050   0.121          
2000 0.025 0.368 2.708 5.928 7.447 10.068 8.850 3.148 2.040 0.714 0.343 0.322   0.062        
2001 0.001 0.202 1.940 4.520 7.163 5.798 5.105 3.435 1.292 0.213 0.497 0.518 0.086 0.311        
2002 0.004 0.207 1.324 4.145 10.772 12.037 15.280 7.214 2.094 0.372 0.688 0.108   0.629        
2003 0.044 0.232 0.878 2.892 5.256 4.996 5.326 2.982 2.183 1.278 0.216 0.011   0.297     0.602  
2004 0.032 0.294 1.069 3.050 6.188 5.196 4.794 2.187 1.267 0.530 1.069 0.053     0.031      
2005 0.001 0.158 0.766 3.133 6.391 5.533 4.219 2.099 0.909 0.747 0.456 1.119            
2006 0.056 0.418 0.991 4.012 5.343 5.421 7.007 4.649 1.058 1.169 0.109 0.837 0.027          
2007 0.170 0.273 1.925 3.470 7.754 6.811 5.634 5.958 3.044 1.401 0.463 0.056   0.136        
2008 0.086 0.236 0.820 1.990 3.216 3.378 2.586 1.968 1.111 0.416 0.105 0.272 0.125 0.005 0.004      
2009 0.017 0.295 0.766 3.172 6.214 4.608 2.897 2.052 2.655 1.152 0.153 0.244 0.007   0.003 0.017    
2010 0.013 0.349 1.379 3.545 4.865 5.500 2.392 1.708 2.664 1.538 0.755 0.340 0.187 0.013 0.030 0.036    
2011 0.004 0.263 1.323 3.126 6.611 6.104 6.308 2.243 2.143 0.960 0.491 0.070 0.498 0.066        
2012 0.001 0.268 0.828 4.271 4.190 4.127 3.332 2.484 1.427 0.699 0.847 0.233 0.120 0.128 0.049   0.018  
2013 0.007 0.423 1.246 1.662 3.477 4.405 3.267 2.707 2.361 1.239 0.363 0.805 0.768 0.019 0.050 0.051 0.099  
2014 0.107 0.476 1.707 3.558 4.234 8.651 6.267 5.510 3.663 2.927 0.869 0.585 0.606 0.033 0.076 0.282 0.144 0.601
2015 0.001 0.379 1.439 2.677 5.755 4.118 5.073 3.024 2.108 2.650 0.923 0.412 0.314 0.032 0.075   0.009  
2016 0.011 0.201 0.896 3.477 6.475 9.308 2.905 2.686 3.419 1.131 0.794 1.011 0.321 0.022 0.057   0.033  
2017 0.023 0.090 1.794 3.567 5.254 5.651 4.860 2.213 2.042 1.108 0.334 0.912 0.111 0.237        
2018 0.002 0.232 1.411 2.578 5.404 5.587 4.468 2.509 2.330 1.632 0.713 0.190 0.107 0.111   0.100 0.023  
2019 0.008 0.230 1.264 5.626 6.381 9.351 7.683 5.747 1.634 2.419 1.091 0.477 1.047 0.129 0.041 0.121 0.056  
Table A.1.3. Biomass indices (kilotonnes)
  Age 0 Age 1 Age 2 Age 3 Age 4 Age 5 Age 6 Age 7 Age 8 Age 9 Age 10 Age 11 Age 12 Age 13 Age 14 Age 15 Age 16 Age 17
1995 10.32 18.93 32.17 42.33 51.98 59.07 64.26 77.92 84.99 87.89 66.98   121.24          
1996 9.36 16.66 28.83 42.12 52.28 58.17 64.66 75.70 86.68 99.18 117.56              
1997 9.01 16.70 29.27 40.89 51.93 58.40 66.89 68.71 71.67 102.00 104.42 83.00            
1998 10.62 18.05 32.04 44.30 52.03 60.09 68.11 75.99 85.28 83.72 108.43   105.00   121.00 135.00    
1999   19.52 31.19 44.18 54.57 59.18 65.77 75.68 89.32 101.33 59.00   118.00          
2000 10.84 20.08 32.38 43.35 53.30 61.11 64.79 74.55 84.79 86.55 107.35 102.13   79.00        
2001 8.09 19.99 33.90 45.84 55.13 60.77 65.76 67.88 81.74 87.23 107.06 114.32 99.84 112.68        
2002 10.48 22.97 35.07 47.29 59.65 67.22 75.42 81.62 76.42 67.24 85.16 115.00   108.00        
2003 9.71 19.33 33.45 43.70 52.16 60.48 67.16 72.87 77.01 80.32 92.80 61.00   106.31     143.00  
2004 8.97 21.14 33.03 44.26 54.96 59.27 67.27 69.90 71.79 75.35 94.15 91.37     89.00      
2005 11.42 22.30 34.93 45.12 58.67 62.84 65.37 72.60 71.13 75.09 108.25 108.92            
2006 9.50 20.87 34.69 46.11 54.54 59.96 67.03 70.13 77.68 82.59 86.00 125.00 76.00          
2007 9.20 21.59 36.48 47.12 56.97 63.04 67.82 74.34 84.51 100.75 113.52 63.01   123.00        
2008 9.28 22.26 35.87 48.72 58.44 68.49 69.09 76.16 75.58 72.09 71.91 100.25 75.56 100.00 89.00      
2009 9.74 19.82 33.58 47.80 57.19 64.24 69.97 75.08 75.45 81.76 75.15 69.59 69.00   73.00 94.94    
2010 10.64 18.92 37.05 48.19 57.32 64.37 70.59 76.38 77.19 82.08 83.16 80.20 88.28 61.59 104.00 89.97    
2011 9.48 20.10 33.60 48.36 60.20 66.93 72.32 78.96 80.93 81.32 77.59 74.36 93.14 75.21        
2012 9.99 20.39 33.07 48.58 59.74 66.44 71.89 76.67 80.60 82.69 84.96 78.38 84.87 83.30 90.72   79.00  
2013 11.56 20.96 34.05 45.15 56.49 66.80 70.65 72.89 78.61 82.37 74.51 90.29 100.75 69.54 88.38 113.00 125.00  
2014 9.23 20.92 34.57 48.76 58.05 66.80 73.31 77.93 79.82 82.24 98.26 85.29 84.24 81.05 85.00 91.57 93.45 132.00
2015 9.27 19.72 32.67 47.60 60.07 66.99 70.91 76.65 75.76 83.48 82.52 89.27 77.38 95.00 97.44   101.00  
2016 9.44 20.37 32.47 49.21 61.22 71.39 72.88 75.49 84.37 87.80 78.17 94.49 81.43 75.84 98.37   96.00  
2017 8.18 19.84 37.35 47.86 58.89 66.84 74.01 78.35 86.43 84.31 84.70 97.13 82.55 112.60        
2018 9.83 16.24 37.40 48.86 60.06 68.90 71.09 81.46 87.41 86.52 88.92 72.67 80.98 93.55   121.66 93.00  
2019 10.11 19.89 33.35 49.27 59.27 67.46 73.53 77.35 79.47 82.90 85.52 91.33 96.75 99.46 96.00 109.00 96.00  
Table A.1.4. Length at age (cm)
  Age 0 Age 1 Age 2 Age 3 Age 4 Age 5 Age 6 Age 7 Age 8 Age 9 Age 10 Age 11 Age 12 Age 13 Age 14 Age 15 Age 16 Age 17
1995 9 59 310 730 1405 2118 2754 4733 6494 7359 3297   17869          
1996 8 41 229 736 1385 1940 2702 4269 6627 10964 16213              
1997 8 42 240 665 1384 1932 2947 3175 4264 9600 11387 5140            
1998 10 53 332 869 1405 2229 3251 4432 5987 5884 16233   12260   19880 26100    
1999   64 278 828 1602 2059 2811 4567 7363 11535 2190   18340          
2000 12 70 320 798 1508 2329 2848 4424 6726 8851 12330 12873   4220        
2001 5 74 390 953 1648 2300 3116 3386 5983 7187 11653 17035 8460 15001        
2002 9 114 460 1077 2248 3295 4674 6289 4656 3785 7783 21980   12350        
2003 9 68 366 821 1397 2225 3056 3965 5110 6049 8878 2030   12562     25600  
2004 7 89 352 884 1705 2173 3152 3729 3976 4459 10347 9093     7130      
2005 16 109 425 952 2231 2542 3047 4245 3467 4716 14816 15482            
2006 8 87 423 993 1632 2265 3214 3767 5173 6240 6530 25080 4220          
2007 7 106 516 1074 1901 2631 3269 4690 6565 11169 15781 2984   21100        
2008 6 100 453 1148 2046 3321 3392 4648 4869 4344 4077 10683 4730 9250 8520      
2009 10 75 397 1120 1904 2664 3561 4368 4756 5743 4817 3886 3084   3122 9672    
2010 10 64 508 1128 1926 2779 3540 4692 5740 6199 6336 6553 7983 2058 12154 7475    
2011 8 69 374 1136 2195 3020 4096 5365 6040 6395 5275 3933 8509 4558        
2012 8 74 359 1165 2073 3068 3728 4666 5524 6269 6948 5022 7201 6460 7052   4630  
2013 12 83 377 893 1773 2915 3432 3911 5284 5662 4216 8854 12081 4092 7780 16220 16300  
2014 7 78 399 1130 1919 2931 3806 4775 5268 5980 9081 6864 7090 4752 7920 9733 8282 24950
2015 6 70 358 1076 2149 2906 3589 4725 4436 6305 5666 8150 5273 10170 9617   11240  
2016 7 75 322 1226 2317 3540 3774 4609 6533 7303 5138 9556 5174 4215 10057   8325  
2017 4 78 522 1079 1995 2985 4014 4531 7036 6375 6323 9637 5013 14338        
2018 5 50 513 1196 2112 3257 3696 5545 6065 7157 7429 3669 5306 9401   19356 7350  
2019 9 67 367 1176 2049 2959 3958 4696 5085 6396 6804 8025 10306 9786 9585 12345 7040  
Table A.1.5. Weight at age (gram)
  Index_2plus SD_2plus CV_2plus
1995 40.034 2.670 0.067
1996 42.500 2.417 0.057
1997 56.823 5.676 0.100
1998 38.388 2.848 0.074
1999 15.451 1.184 0.077
2000 29.426 2.112 0.072
2001 19.437 2.667 0.137
2002 20.341 1.462 0.072
2003 15.111 1.527 0.101
2004 15.189 0.951 0.063
2005 12.547 0.774 0.062
2006 16.004 1.348 0.084
2007 17.304 1.438 0.083
2008 7.728 0.770 0.100
2009 11.887 0.888 0.075
2010 12.303 0.906 0.074
2011 13.958 0.921 0.066
2012 11.346 0.884 0.078
2013 11.204 0.992 0.089
2014 16.921 1.184 0.070
2015 13.845 0.818 0.059
2016 13.414 0.687 0.051
2017 13.624 1.318 0.097
2018 11.660 0.862 0.074
2019 18.706 1.279 0.068
Table A.1.6. Abundance index, standard deviation (SD) and Coefficient of variation (CV) for sum of age 2+ fish

10.2 - Subarea A: North of 67°N

  Age 0 Age 1 Age 2 Age 3 Age 4 Age 5 Age 6 Age 7 Age 8 Age 9 Age 10 Age 11 Age 12 Age 13 Age 14 Age 15 Age 16 Age 17
1995 0.050 26.495 8.774 4.974 6.382 6.440 4.373 1.309 0.532 0.321 0.041   0.090          
1996 22.399 17.580 9.025 8.592 4.576 5.306 2.723 1.022 0.213 0.033 0.036              
1997 0.030 16.567 15.358 16.930 7.710 4.484 2.316 0.716 0.328 0.091 0.016 0.029            
1998 1.435 8.360 6.757 8.524 8.261 3.717 1.530 0.700 0.102 0.122 0.038   0.013          
1999   2.494 3.486 3.387 2.788 2.498 0.751 0.172 0.030 0.022 0.023   0.007          
2000 2.175 5.028 7.439 5.831 3.939 3.853 2.825 0.622 0.258 0.071 0.018 0.014   0.015        
2001 0.298 2.711 4.551 4.246 3.776 2.184 1.499 0.974 0.149 0.029 0.040 0.029 0.010 0.020        
2002 0.518 1.188 2.071 2.532 2.926 2.075 0.970 0.596 0.293 0.121 0.091 0.005   0.051        
2003 4.798 3.276 2.168 3.026 3.303 1.838 1.519 0.651 0.364 0.190 0.024 0.004   0.027     0.024  
2004 4.532 3.113 2.657 2.795 2.553 1.680 1.097 0.370 0.210 0.118 0.063 0.005     0.004      
2005 0.023 0.903 1.201 2.229 1.814 1.492 0.842 0.233 0.233 0.127 0.015 0.067            
2006 6.266 4.974 1.822 2.618 2.230 1.374 1.603 1.037 0.130 0.089   0.033 0.006          
2007 26.132 2.457 3.033 2.780 3.800 2.432 1.629 1.215 0.441 0.120 0.032 0.020   0.006        
2008 13.853 2.344 1.739 1.684 1.511 0.985 0.761 0.399 0.225 0.097 0.026 0.023 0.026 0.000 0.000      
2009 1.706 3.910 1.502 2.083 2.596 1.374 0.605 0.386 0.378 0.140 0.031 0.028 0.002   0.001 0.002    
2010 1.159 5.514 2.502 2.852 2.244 1.680 0.582 0.309 0.432 0.229 0.113 0.052 0.023 0.002 0.002 0.004    
2011 0.364 2.104 2.542 1.869 2.372 1.469 1.215 0.394 0.278 0.137 0.074 0.018 0.046 0.014        
2012 0.097 3.560 2.163 3.470 1.829 1.157 0.768 0.492 0.254 0.109 0.122 0.049 0.019 0.023 0.007   0.004  
2013 0.422 4.694 3.084 1.597 1.770 1.287 0.838 0.657 0.430 0.216 0.083 0.089 0.062 0.006 0.006 0.003 0.006  
2014 14.500 5.687 3.969 2.889 2.005 2.721 1.542 1.103 0.426 0.443 0.082 0.084 0.084 0.008 0.010 0.028 0.017 0.024
2015 0.248 3.264 2.903 1.976 1.652 0.977 1.072 0.480 0.387 0.311 0.159 0.049 0.059 0.003 0.008   0.001  
2016 1.513 2.675 2.572 2.433 1.883 1.976 0.726 0.536 0.393 0.142 0.103 0.080 0.062 0.003 0.006   0.004  
2017 6.355 1.205 3.290 3.217 2.454 1.771 1.120 0.436 0.266 0.168 0.053 0.094 0.022 0.016        
2018 0.336 5.013 2.615 2.008 2.321 1.375 1.002 0.427 0.366 0.167 0.096 0.052 0.021 0.012   0.005 0.003  
2019 0.310 2.607 2.992 3.724 2.221 2.149 1.272 0.656 0.212 0.262 0.106 0.040 0.092 0.013 0.004 0.010 0.008  
Table A.2.1. Abundance indices (millions)
  Age 0 Age 1 Age 2 Age 3 Age 4 Age 5 Age 6 Age 7 Age 8 Age 9 Age 10 Age 11 Age 12 Age 13 Age 14 Age 15 Age 16 Age 17
1995 0.522 0.168 0.130 0.090 0.124 0.136 0.211 0.194 0.395 0.500 0.412   0.324          
1996 0.654 0.198 0.111 0.154 0.168 0.141 0.259 0.538 0.394 0.483 1.133              
1997 0.424 0.239 0.246 0.160 0.156 0.142 0.250 0.259 0.470 0.427 0.656 0.634            
1998 0.726 0.259 0.186 0.117 0.161 0.161 0.311 0.690 0.401 0.865 0.992   0.509          
1999   0.243 0.105 0.114 0.198 0.173 0.229 0.193 0.469 0.399 0.455   0.509          
2000 0.781 0.143 0.164 0.124 0.095 0.090 0.103 0.151 0.291 0.489 0.540 0.504   0.480        
2001 0.683 0.179 0.313 0.182 0.159 0.186 0.176 0.209 0.406 0.717 0.588 0.470 0.639 0.740        
2002 0.632 0.248 0.174 0.205 0.160 0.136 0.147 0.228 0.363 0.575 0.632 0.552   0.400        
2003 0.311 0.266 0.263 0.140 0.137 0.137 0.161 0.182 0.218 0.262 0.346 0.200   1.652     0.596  
2004 0.265 0.187 0.134 0.112 0.102 0.157 0.143 0.190 0.252 0.763 0.371 0.543     0.485      
2005 0.988 0.181 0.228 0.177 0.100 0.135 0.203 0.228 0.297 0.400 0.590 0.788            
2006 0.552 1.081 0.682 0.154 0.146 0.131 0.279 0.218 0.228 0.311   0.392 0.496          
2007 0.645 0.209 0.203 0.192 0.150 0.161 0.158 0.208 0.307 0.440 0.629 0.846   0.920        
2008 0.343 0.244 0.189 0.142 0.134 0.118 0.136 0.198 0.236 0.386 0.373 0.481 0.450 0.357 0.357      
2009 1.189 0.218 0.197 0.145 0.120 0.169 0.139 0.185 0.189 0.315 0.246 0.424 0.523   0.672 0.514    
2010 0.558 0.408 0.178 0.162 0.130 0.119 0.214 0.222 0.225 0.215 0.212 0.207 0.558 0.661 0.406 0.537    
2011 1.073 0.218 0.170 0.159 0.146 0.147 0.155 0.268 0.205 0.195 0.347 0.510 0.443 0.767        
2012 0.601 0.217 0.249 0.129 0.136 0.138 0.104 0.172 0.162 0.232 0.186 0.423 0.466 0.492 0.402   0.315  
2013 0.677 0.140 0.160 0.140 0.147 0.139 0.134 0.174 0.204 0.312 0.365 0.357 0.485 0.649 0.550 0.390 0.557  
2014 0.880 0.170 0.192 0.094 0.126 0.133 0.126 0.141 0.144 0.226 0.463 0.336 0.312 0.831 0.170 0.522 0.687 0.312
2015 0.784 0.178 0.121 0.118 0.105 0.134 0.116 0.143 0.183 0.236 0.255 0.353 0.298 0.258 0.717   0.600  
2016 0.602 0.309 0.144 0.098 0.107 0.117 0.165 0.178 0.237 0.292 0.287 0.295 0.528 0.686 0.341   0.297  
2017 0.644 0.481 0.185 0.173 0.176 0.116 0.167 0.242 0.289 0.436 0.286 0.336 0.509 0.606        
2018 0.909 0.409 0.152 0.159 0.182 0.182 0.137 0.204 0.376 0.406 0.138 0.278 0.325 0.667   0.225 0.260  
2019 0.660 0.180 0.198 0.147 0.127 0.120 0.151 0.176 0.283 0.333 0.348 0.275 0.636 0.500 0.601 0.769 0.663  
Table A.2.2. CV on abundance indices
  Age 0 Age 1 Age 2 Age 3 Age 4 Age 5 Age 6 Age 7 Age 8 Age 9 Age 10 Age 11 Age 12 Age 13 Age 14 Age 15 Age 16 Age 17
1995 0.000 1.541 2.472 3.574 8.904 13.457 11.950 6.114 3.126 2.279 0.143   1.580          
1996 0.152 0.709 1.947 5.779 6.165 10.249 7.685 4.485 1.401 0.378 0.715              
1997 0.000 0.677 3.790 11.041 10.756 8.589 6.793 2.140 1.152 0.874 0.176 0.148            
1998 0.014 0.410 1.751 7.160 11.622 8.458 4.866 3.312 0.527 0.676 0.615   0.157          
1999   0.155 0.947 2.695 4.204 4.894 2.062 0.733 0.218 0.144 0.050   0.121          
2000 0.025 0.347 2.398 4.816 6.154 9.109 7.947 2.654 1.529 0.406 0.155 0.128   0.062        
2001 0.001 0.199 1.778 3.973 6.276 5.075 4.503 3.240 0.679 0.206 0.497 0.518 0.086 0.311        
2002 0.004 0.105 0.737 2.351 4.653 4.935 3.358 2.646 1.109 0.330 0.570 0.108   0.629        
2003 0.044 0.228 0.783 2.488 4.716 4.167 4.746 2.687 2.016 1.232 0.216 0.009   0.297     0.602  
2004 0.029 0.276 0.896 2.449 4.212 3.600 3.513 1.412 0.993 0.464 0.322 0.053     0.031      
2005 0.000 0.089 0.526 1.947 3.129 3.294 2.134 0.857 0.813 0.706 0.131 1.119            
2006 0.050 0.367 0.691 2.624 3.674 3.129 5.589 4.035 0.575 0.714   0.837 0.027          
2007 0.170 0.239 1.465 2.959 7.066 6.257 5.154 5.472 2.811 1.352 0.556 0.056   0.136        
2008 0.086 0.225 0.742 1.869 2.978 3.285 2.581 1.807 1.097 0.402 0.105 0.272 0.130 0.005 0.004      
2009 0.014 0.288 0.538 2.152 4.876 3.708 2.309 1.786 1.958 0.763 0.150 0.163 0.007   0.003 0.017    
2010 0.013 0.329 1.271 3.109 4.196 4.604 2.072 1.448 2.196 1.432 0.722 0.340 0.187 0.006 0.030 0.036    
2011 0.003 0.125 1.024 2.183 5.403 4.579 4.488 2.024 1.561 0.855 0.388 0.067 0.360 0.066        
2012 0.001 0.259 0.768 3.956 3.675 3.333 2.816 2.292 1.421 0.668 0.847 0.233 0.120 0.128 0.049   0.018  
2013 0.005 0.399 1.184 1.469 3.215 3.913 2.883 2.593 2.101 1.239 0.350 0.805 0.768 0.019 0.050 0.051 0.099  
2014 0.095 0.442 1.415 3.201 3.762 7.909 5.684 5.150 2.363 2.482 0.801 0.585 0.605 0.033 0.076 0.282 0.144 0.601
2015 0.001 0.228 1.068 2.143 3.604 2.897 4.120 2.284 1.801 1.743 0.901 0.412 0.310 0.032 0.075   0.009  
2016 0.011 0.197 0.823 2.555 3.643 6.702 2.776 2.567 2.266 0.980 0.626 0.768 0.321 0.015 0.057   0.033  
2017 0.023 0.086 1.667 3.416 4.788 5.220 4.523 2.068 1.855 1.072 0.334 0.912 0.111 0.237        
2018 0.002 0.231 1.366 2.266 4.909 4.355 3.679 2.334 2.179 1.388 0.713 0.188 0.107 0.111   0.100 0.023  
2019 0.002 0.163 1.112 4.212 4.414 6.413 4.854 3.382 1.272 1.623 0.840 0.392 1.042 0.129 0.041 0.121 0.056  
Table A.2.3. Biomass indices (kilotonnes)
  Age 0 Age 1 Age 2 Age 3 Age 4 Age 5 Age 6 Age 7 Age 8 Age 9 Age 10 Age 11 Age 12 Age 13 Age 14 Age 15 Age 16 Age 17
1995 10.32 18.86 31.39 42.05 51.83 58.77 64.27 77.55 82.36 87.08 67.02   123.50          
1996 9.35 16.68 28.32 41.25 51.87 58.06 65.16 74.80 86.75 99.57 115.00              
1997 9.01 16.61 29.56 40.75 51.99 58.11 66.89 66.80 68.62 102.00 104.42 83.00            
1998 10.62 17.76 30.26 44.04 51.99 60.31 67.81 74.93 82.22 83.81 108.43   105.00          
1999   19.41 31.17 44.06 54.06 58.69 65.44 74.00 88.95 88.21 59.00   118.00          
2000 10.84 20.01 32.55 43.97 53.96 61.39 64.53 73.81 81.94 80.31 95.00 95.83   79.00        
2001 8.09 19.97 33.70 45.70 55.37 61.09 65.17 67.64 76.07 87.23 107.08 114.32 99.84 112.68        
2002 10.48 21.64 32.65 45.02 54.46 62.01 68.83 72.35 70.52 66.73 85.06 115.00   108.00        
2003 9.71 19.30 33.32 43.76 52.60 60.94 67.73 73.67 78.79 81.86 92.81 61.00   106.31     143.00  
2004 8.95 21.13 32.67 44.05 54.52 59.26 67.72 70.47 75.66 73.91 78.59 91.37     89.00      
2005 10.81 21.56 35.73 44.68 55.44 60.55 62.62 71.48 71.73 80.28 93.23 108.92            
2006 9.38 20.54 34.11 46.36 54.97 60.44 68.74 71.20 74.57 89.01   125.00 76.00          
2007 9.20 21.18 35.88 47.14 56.79 62.75 67.34 73.72 83.42 100.55 116.00 63.01   123.00        
2008 9.28 22.14 35.38 48.30 57.91 68.55 69.09 75.83 75.85 71.71 71.91 100.50 76.19 100.00 89.00      
2009 9.32 19.78 32.92 46.75 57.07 64.71 71.37 76.56 76.92 81.19 75.56 77.65 69.00   73.00 94.94    
2010 10.96 18.85 36.95 47.84 56.91 64.12 71.24 76.42 75.45 82.04 83.12 80.27 88.28 60.00 104.00 89.97    
2011 9.48 19.13 34.62 48.69 61.02 67.55 71.22 78.14 80.80 80.53 78.30 74.68 91.37 75.21        
2012 9.99 20.33 32.92 48.14 59.16 65.29 71.21 76.19 80.69 82.10 84.99 78.38 84.87 83.30 90.72   79.00  
2013 11.52 21.22 34.28 45.56 56.92 67.73 70.94 73.28 77.28 82.37 75.33 90.29 100.75 69.54 88.38 113.00 125.00  
2014 9.10 20.91 33.72 48.61 57.78 66.75 72.83 77.50 81.58 80.84 98.65 85.29 84.26 81.05 85.00 91.57 93.45 132.00
2015 9.27 19.53 33.54 47.67 60.74 67.79 72.91 77.37 77.14 81.76 83.06 89.27 77.53 95.00 97.44   101.00  
2016 9.43 20.35 32.47 47.38 58.18 69.76 73.27 76.41 81.13 86.63 80.74 90.52 81.43 80.85 98.37   96.00  
2017 8.18 19.80 37.05 47.69 58.55 66.73 74.09 79.55 85.97 84.07 84.70 97.13 82.55 112.60        
2018 9.83 16.29 37.64 48.45 60.08 68.36 71.05 81.20 87.30 92.19 88.92 72.72 80.98 93.55   121.66 93.00  
2019 9.51 19.64 33.67 49.05 59.01 68.22 73.51 80.38 84.43 84.10 91.63 97.77 97.12 99.46 96.00 109.00 96.00  
Table A.2.4. Length by age (cm)
  Age 0 Age 1 Age 2 Age 3 Age 4 Age 5 Age 6 Age 7 Age 8 Age 9 Age 10 Age 11 Age 12 Age 13 Age 14 Age 15 Age 16 Age 17
1995 9 58 282 719 1395 2091 2767 4693 5905 7211 3300   17490          
1996 8 41 216 672 1349 1939 2779 4223 6638 11146 20000              
1997 8 41 244 655 1393 1914 2921 2988 3768 9600 11387 5140            
1998 10 49 259 840 1406 2261 3173 4320 5275 5896 16233   12260          
1999   63 272 793 1508 1964 2759 4257 7262 6561 2190   18340          
2000 12 69 322 826 1561 2363 2811 4260 5977 6061 8736 9458   4220        
2001 5 74 377 933 1660 2320 2998 3338 4478 7193 11658 17035 8460 15001        
2002 9 88 357 918 1595 2377 3468 4415 3868 3588 8921 21980   12350        
2003 9 68 361 820 1427 2269 3127 4114 5493 6350 8881 2030   12562     25600  
2004 6 88 337 877 1652 2154 3198 3816 4696 4092 5206 9093     7130      
2005 14 99 436 878 1725 2205 2545 3674 3521 5562 8817 15482            
2006 8 82 401 1002 1648 2277 3500 3948 4445 8003   25080 4220          
2007 7 97 485 1065 1864 2581 3170 4520 6363 11113 17480 2984   21100        
2008 6 97 427 1109 1971 3327 3393 4543 4921 4270 4077 10741 4962 9250 8520      
2009 8 74 357 1032 1877 2694 3804 4600 5147 5349 4887 5518 3084   3122 9672    
2010 11 63 502 1089 1871 2743 3587 4682 5095 6261 6449 6565 7983 2635 12154 7475    
2011 8 59 401 1165 2279 3109 3702 5163 5593 6174 5325 3982 8151 4558        
2012 8 73 355 1134 2014 2886 3663 4633 5548 6099 6953 5022 7201 6460 7052   4630  
2013 12 85 384 918 1817 3041 3438 3963 4926 5662 4340 8854 12081 4092 7780 16220 16300  
2014 7 78 357 1108 1874 2906 3686 4668 5541 5585 9243 6864 7094 4752 7920 9733 8282 24950
2015 6 69 369 1083 2181 2969 3842 4763 4675 5648 5767 8150 5309 10170 9617   11240  
2016 7 74 321 1050 1932 3385 3832 4767 5755 6972 6003 9218 5174 5537 10057   8325  
2017 4 78 507 1063 1959 2944 4023 4695 7003 6312 6323 9637 5013 14338        
2018 5 50 523 1143 2107 3151 3676 5510 5992 8487 7429 3678 5306 9401   19356 7350  
2019 8 62 372 1131 1984 2983 3815 5141 5908 6420 7801 9778 10405 9786 9585 12345 7040  
Table A.2.5. Weight by age (gram)
  Index_2plus SD_2plus CV_2plus
1995 33.395 2.667 0.080
1996 31.513 2.386 0.076
1997 47.938 5.599 0.117
1998 29.757 2.844 0.096
1999 13.154 1.183 0.090
2000 24.871 2.111 0.085
2001 17.500 2.666 0.152
2002 11.695 1.446 0.124
2003 13.128 1.526 0.116
2004 11.551 0.946 0.082
2005 8.250 0.773 0.094
2006 10.931 1.348 0.123
2007 15.491 1.424 0.092
2008 7.476 0.770 0.103
2009 9.127 0.886 0.097
2010 11.024 0.905 0.082
2011 10.425 0.917 0.088
2012 10.463 0.884 0.084
2013 10.131 0.993 0.098
2014 15.424 1.184 0.077
2015 10.035 0.807 0.080
2016 10.917 0.687 0.063
2017 12.905 1.319 0.102
2018 10.468 0.860 0.082
2019 13.753 1.271 0.092
Table A.2.6. Abundance index, standard deviation (SD) and Coefficient of variation (CV) for sum of age 2+ fish

10.3 - Subarea B: Between 65° and 67°N

  Age 0 Age 1 Age 2 Age 3 Age 4 Age 5 Age 6 Age 7 Age 8 Age 9 Age 10 Age 11 Age 12 Age 13 Age 14 Age 15 Age 16
1995   0.319 1.494 1.205 0.390 0.219 0.204 0.155 0.117 0.040 0.015   0.044        
1996 0.612 0.084 1.390 3.276 1.178 1.406 0.425 0.134     0.099            
1997   0.934 1.928 2.312 1.023 0.383 0.094 0.036 0.035                
1998   0.264 1.216 0.903 0.846 0.406 0.070 0.053 0.039 0.027         0.026 0.026  
1999   0.036 0.360 0.466 0.260 0.202 0.127 0.023 0.001 0.045              
2000   0.236 0.976 1.511 0.814 0.350 0.244 0.089 0.049 0.016 0.016 0.016          
2001   0.110 0.315 0.358 0.382 0.399 0.162 0.064 0.065 0.007     0.006        
2002 0.039 0.203 0.422 0.342 0.375 0.119 0.116 0.048 0.032   0.016            
2003 0.027 0.085 0.293 0.764 0.518 0.436 0.237 0.116 0.085 0.023   0.005          
2004 0.064 0.174 0.526 0.750 1.015 0.686 0.390 0.185 0.120 0.015 0.041            
2005 0.054 0.130 0.488 0.769 0.485 0.464 0.261 0.196 0.036 0.029 0.019            
2006 0.166 0.411 0.557 1.325 0.810 0.771 0.520 0.195 0.033 0.080              
2007 0.075 0.100 0.682 0.412 0.204 0.145 0.177 0.056 0.015     0.017          
2008 0.323 0.140 0.098 0.028 0.028 0.020 0.006 0.014 0.013 0.002   0.004 0.001        
2009 0.223 0.116 0.533 0.481 0.616 0.283 0.197 0.066 0.165 0.062 0.018 0.013          
2010 0.014 0.488 0.343 0.282 0.211 0.258 0.113 0.064 0.010 0.021 0.022 0.005 0.004 0.005      
2011 0.170 1.784 1.046 0.828 0.553 0.425 0.178 0.028 0.069 0.015 0.016 0.013 0.012        
2012 0.002 0.219 0.573 0.323 0.084 0.086 0.044 0.052 0.018 0.009 0.014 0.020 0.006 0.012     0.004
2013 0.171 0.620 0.618 0.509 0.340 0.303 0.164 0.075 0.044 0.021 0.015 0.013 0.016        
2014 1.113 0.357 0.392 0.159 0.062 0.080 0.052 0.065 0.235 0.114 0.010   0.018 0.007      
2015   2.151 1.048 0.429 0.620 0.356 0.229 0.114 0.050 0.078 0.066 0.007 0.016   0.006    
2016 0.057 0.477 0.387 0.131 0.144 0.228 0.164 0.134 0.076 0.032 0.023 0.025 0.028 0.002      
2017   0.052 0.202 0.116 0.052 0.122 0.052 0.055 0.022 0.012 0.013 0.010 0.005 0.003      
2018 0.006 0.283 0.146 0.167 0.088 0.096 0.119 0.060 0.046 0.027 0.014 0.006 0.003 0.007      
2019 0.631 0.874 0.616 1.017 0.850 0.681 0.191 0.237 0.066 0.087 0.054 0.027 0.005        
Table A.3.1. Abundance indices (millions)
  Age 0 Age 1 Age 2 Age 3 Age 4 Age 5 Age 6 Age 7 Age 8 Age 9 Age 10 Age 11 Age 12 Age 13 Age 14 Age 15 Age 16
1995   0.027 0.008 0.023 0.074 0.081 0.055 0.036 0.167 0.104              
1996 0.280 0.298 0.011 0.010 0.054 0.055 0.115 0.174                  
1997   0.234 0.174 0.060 0.092 0.137 0.353 0.501 0.485                
1998   0.145 0.075 0.100 0.080 0.104 0.464 0.240 0.443                
1999   0.010 0.002 0.001 0.001 0.001   0.000 0.019                
2000   0.038 0.013 0.012 0.027 0.075 0.101 0.080 0.038 0.103              
2001   0.682 0.384 0.257 0.110 0.156 0.164 0.255 0.176 0.619     0.727        
2002 0.937 0.263 0.394 0.096 0.048 0.298 0.564 0.924 0.662                
2003 0.000 0.324 0.099 0.061 0.092 0.074 0.090 0.129 0.156 0.284   0.671          
2004 0.351 0.051 0.069 0.078 0.055 0.101 0.117 0.151 0.106 0.743 0.289            
2005 0.487 0.251 0.045 0.032 0.027 0.032 0.038 0.080 0.265   0.118            
2006 0.000 0.027 0.036 0.023 0.042 0.035 0.033 0.093 0.199                
2007 0.644 0.313 0.144 0.144 0.143 0.145 0.201 0.201 0.616     0.487          
2008 0.723 0.555 0.336 0.708 0.471 0.101 0.856 0.584 0.695 0.201   0.685 0.040        
2009 0.000 0.376 0.179 0.079 0.109 0.086 0.092 0.291 0.081 0.178 0.543 0.267          
2010 0.212 0.366 0.167 0.147 0.079 0.076 0.073 0.059 0.362 0.713 0.248 0.000 0.427 0.000      
2011 0.606 0.078 0.098 0.087 0.103 0.080 0.144 0.736 0.111 0.496 1.063 0.230 0.000        
2012 0.369 0.213 0.506 0.527 0.318 0.304 0.467 0.434 0.410 0.444 0.353 0.599 0.286 0.349     0.315
2013 0.548 0.160 0.191 0.092 0.067 0.057 0.160 0.271 0.254 0.528 0.633 0.651 0.590        
2014 0.112 0.150 0.159 0.173 0.107 0.230 0.272 0.416 0.039 0.335 0.644   0.114 0.866      
2015   0.052 0.064 0.105 0.084 0.083 0.161 0.203 0.442 0.265 0.688 0.754 0.615   0.930    
2016 0.872 0.621 0.256 0.158 0.134 0.243 0.198 0.204 0.169 0.326 0.385 0.291 1.181 0.000      
2017   0.679 0.351 0.274 0.219 0.306 0.359 0.405 0.574 0.387 0.736 0.668 1.067 0.612      
2018 0.729 0.733 0.276 0.189 0.209 0.347 0.508 0.501 0.527 0.041 0.375 0.450 0.707 0.558      
2019 0.056 0.097 0.145 0.075 0.077 0.076 0.192 0.108 0.183 0.117 0.097 0.195 1.231        
Table A.3.2. CV on abundance indices
  Age 0 Age 1 Age 2 Age 3 Age 4 Age 5 Age 6 Age 7 Age 8 Age 9 Age 10 Age 11 Age 12 Age 13 Age 14 Age 15 Age 16
1995   0.029 0.528 0.814 0.573 0.469 0.517 0.822 1.037 0.377 0.036   0.811        
1996 0.005 0.001 0.404 2.548 1.454 2.479 0.939 0.622     1.546            
1997   0.053 0.377 1.398 1.149 0.663 0.257 0.113 0.054                
1998   0.034 0.375 0.753 1.019 0.735 0.197 0.242 0.305 0.045         0.525 0.690  
1999   0.004 0.088 0.302 0.306 0.384 0.325 0.107 0.008 0.624              
2000   0.022 0.290 1.016 0.966 0.688 0.779 0.495 0.511 0.308 0.232 0.233          
2001   0.010 0.097 0.234 0.421 0.519 0.577 0.190 0.499 0.052     0.077        
2002 0.000 0.019 0.117 0.437 0.880 0.217 0.194 0.080 0.088   0.135            
2003 0.000 0.006 0.104 0.466 0.540 0.775 0.590 0.321 0.283 0.054   0.011          
2004 0.000 0.017 0.180 0.552 1.501 1.205 1.039 0.538 0.304 0.047 0.734            
2005 0.001 0.009 0.167 0.511 0.777 1.091 0.732 0.587 0.104 0.042 0.356            
2006 0.002 0.052 0.252 1.211 1.089 1.385 1.205 0.462 0.144 0.371              
2007 0.001 0.013 0.328 0.328 0.293 0.306 0.444 0.176 0.099     0.028          
2008 0.003 0.018 0.044 0.040 0.066 0.053 0.021 0.056 0.072 0.015   0.026 0.003        
2009 0.003 0.009 0.190 0.570 1.034 0.697 0.533 0.170 0.602 0.395 0.037 0.027          
2010 0.000 0.030 0.121 0.229 0.388 0.607 0.308 0.289 0.026 0.059 0.109 0.011 0.009 0.009      
2011 0.001 0.146 0.298 0.783 0.895 1.020 0.541 0.093 0.560 0.035 0.053 0.032 0.119        
2012 0.000 0.021 0.192 0.181 0.104 0.183 0.106 0.165 0.078 0.057 0.057 0.101 0.023 0.053     0.018
2013 0.002 0.037 0.147 0.321 0.393 0.675 0.400 0.231 0.199 0.089 0.038 0.045 0.063        
2014 0.011 0.030 0.231 0.114 0.062 0.157 0.173 0.251 1.117 0.437 0.043   0.066 0.022      
2015   0.153 0.229 0.455 1.060 0.976 0.550 0.373 0.167 0.814 0.245 0.030 0.068   0.044    
2016 0.001 0.041 0.102 0.083 0.187 0.601 0.501 0.470 0.345 0.311 0.108 0.147 0.153 0.008      
2017   0.004 0.072 0.101 0.102 0.307 0.164 0.180 0.084 0.074 0.057 0.041 0.022 0.033      
2018 0.000 0.014 0.044 0.266 0.145 0.262 0.381 0.239 0.237 0.127 0.071 0.021 0.023 0.044      
2019 0.006 0.069 0.184 1.140 1.734 1.720 0.582 0.841 0.199 0.370 0.251 0.143 0.021        
Table A.3.3. Biomass indices (kilotonnes)
  Age 0 Age 1 Age 2 Age 3 Age 4 Age 5 Age 6 Age 7 Age 8 Age 9 Age 10 Age 11 Age 12 Age 13 Age 14 Age 15 Age 16
1995   21.94 33.66 41.58 52.72 60.33 64.29 80.92 94.71 99.01 60.00   117.00        
1996 9.77 13.00 31.63 42.75 51.16 57.11 61.34 80.03     118.00            
1997   18.27 27.13 39.84 49.63 57.20 64.53 75.17 54.90                
1998   24.38 31.97 43.56 49.98 57.23 65.97 77.02 93.29 57.00         121.00 135.00  
1999   23.93 29.19 40.33 49.29 57.53 64.02 79.87 97.41 107.50              
2000   21.57 31.06 40.66 49.45 58.17 67.45 79.64 98.84 109.64 114.00 105.00          
2001   21.77 31.73 41.09 48.33 51.45 67.05 65.76 90.48 89.36     117.00        
2002 10.00 21.90 30.75 48.87 60.98 55.74 53.59 54.19 64.97   97.00            
2003 10.00 19.94 32.96 39.46 47.12 56.05 62.67 65.60 69.22 62.20   61.00          
2004 8.78 21.77 32.31 42.25 52.07 55.61 63.78 65.68 64.11 72.33 119.74            
2005 14.00 20.18 31.72 40.21 52.84 60.99 64.04 65.15 65.77 55.00 118.60            
2006 11.67 23.80 35.49 45.03 51.23 55.95 61.56 63.11 77.31 75.96              
2007 9.93 23.80 35.85 43.51 51.89 58.93 62.27 68.55 89.30     57.00          
2008 10.73 25.27 36.20 53.57 62.11 63.98 69.17 71.80 79.42 88.53   88.78 69.99        
2009 12.06 20.77 32.24 48.29 54.11 61.31 64.81 63.53 70.97 81.89 59.00 59.21          
2010 12.07 19.16 32.56 42.26 55.80 60.52 64.49 74.90 61.80 66.77 81.14 58.00 60.00 62.00      
2011 9.38 21.22 30.50 45.76 54.64 62.29 66.89 72.58 83.47 61.36 69.07 64.00 102.00        
2012 10.08 22.09 32.87 39.25 50.99 59.63 63.30 67.45 74.09 83.90 74.29 78.35 73.00 75.00     79.00
2013 11.77 19.05 30.12 40.89 49.69 62.10 64.29 68.26 76.04 76.13 64.04 69.00 74.35        
2014 10.68 21.23 38.25 42.25 47.41 58.78 70.43 73.83 76.04 74.19 81.08   73.00 75.00      
2015   19.98 28.38 46.96 56.02 64.47 61.88 69.70 70.49 97.01 74.19 77.00 75.97   95.00    
2016 10.17 21.51 30.89 39.64 50.72 62.92 66.87 69.58 76.89 94.71 75.77 83.81 82.33 73.00      
2017   22.41 33.81 44.66 57.33 63.23 69.02 68.73 73.62 85.84 77.96 76.14 81.37 99.00      
2018 10.00 17.57 32.27 51.22 54.42 63.85 66.85 73.31 77.17 77.83 79.02 73.70 93.65 81.74      
2019 10.55 20.66 30.44 48.03 58.75 62.90 66.59 71.27 67.22 73.38 73.15 82.61 76.59        
Table A.3.4. Mean length (cm)
  Age 0 Age 1 Age 2 Age 3 Age 4 Age 5 Age 6 Age 7 Age 8 Age 9 Age 10 Age 11 Age 12 Age 13 Age 14 Age 15 Age 16
1995   91 354 676 1470 2148 2538 5295 8844 9406 2400   18580        
1996 8 17 291 778 1233 1763 2214 4688     15560            
1997   57 198 604 1124 1733 2787 3282 1506                
1998   128 309 835 1204 1809 2823 4634 7894 1655         19880 26100  
1999   115 245 648 1175 1906 2556 4722 9728 13870              
2000   92 297 672 1186 1962 3185 5549 10436 18769 14266 14380          
2001   96 316 670 1106 1305 3618 2991 7694 7230     12000        
2002 8 93 281 1286 2350 1887 1755 1800 2999   8358            
2003 9 67 354 610 1045 1780 2491 2787 3325 2370   2030          
2004 6 100 343 738 1479 1758 2669 2925 2549 3406 18680            
2005 25 76 342 664 1601 2352 2804 3001 2954 1456 18544            
2006 13 127 453 914 1343 1798 2317 2363 4449 4608              
2007 7 140 483 801 1442 2115 2557 3154 6675     1648          
2008 10 165 456 1543 2445 2691 3419 4277 5767 7574   6239 2733        
2009 16 75 361 1190 1687 2469 2704 2580 3664 6423 2096 2033          
2010 14 62 355 821 1851 2355 2731 4543 2399 2843 4951 2128 2285 1910      
2011 8 82 286 947 1620 2404 3064 4232 8231 2328 3590 2440 10116        
2012 8 96 338 581 1286 2207 2533 3215 4211 7063 4248 4862 3745 4325     4630
2013 13 60 241 631 1160 2225 2436 3071 4535 4334 2569 3425 4214        
2014 10 85 601 723 992 2003 3273 4023 4751 3973 4632   3634 3340      
2015   71 218 1058 1709 2748 2397 3311 3329 10905 3492 4310 4381   7785    
2016 9 88 266 637 1299 2644 3007 3441 4570 9507 4613 5960 5345 3425      
2017   91 367 878 1938 2496 3208 3272 3821 6200 4275 4325 4387 10610      
2018 5 47 302 1623 1627 2653 3092 4115 4976 4771 4989 3209 7866 6455      
2019 10 79 299 1121 2042 2529 3058 3557 3014 4284 4647 5383 4261        
Table A.3.5. Mean weight (gram)
  Index_2plus SD_2plus CV_2plus
1995 3.848 0.030 0.008
1996 7.908 0.072 0.009
1997 5.782 0.365 0.063
1998 3.587 0.104 0.029
1999 1.483 0.001 0.000
2000 4.082 0.033 0.008
2001 1.753 0.309 0.176
2002 1.467 0.289 0.197
2003 2.474 0.049 0.020
2004 3.724 0.076 0.020
2005 2.746 0.026 0.009
2006 4.291 0.037 0.009
2007 1.687 0.104 0.061
2008 0.214 0.060 0.279
2009 2.417 0.195 0.081
2010 1.331 0.107 0.081
2011 3.157 0.150 0.048
2012 1.238 0.565 0.457
2013 2.113 0.138 0.065
2014 1.184 0.068 0.057
2015 3.014 0.149 0.049
2016 1.363 0.042 0.031
2017 0.664 0.197 0.296
2018 0.770 0.252 0.327
2019 3.830 0.106 0.028
Table A.3.6. Abundance index, standard deviation (SD) and Coefficient of variation (CV) for sum of age 2+ fish

10.4 - Subarea C: Between 62°N and 65°N

  Age 0 Age 1 Age 2 Age 3 Age 4 Age 5 Age 6 Age 7 Age 8 Age 9 Age 10 Age 11 Age 12 Age 13 Age 14 Age 15 Age 16
1995   0.147 0.748 1.075 0.435 0.364 0.050 0.097 0.029 0.021              
1996 0.008 0.118 0.333 0.816 0.966 0.761 0.249 0.113 0.015 0.014              
1997   0.223 0.621 1.083 0.556 0.376 0.242 0.167 0.059                
1998 0.015 0.089 2.701 1.303 0.520 0.115 0.206 0.198                  
1999   0.031 0.145 0.259 0.235 0.094 0.062 0.019                  
2000     0.053 0.085 0.182 0.117 0.036                    
2001   0.102 0.350 0.462 0.379 0.288 0.137 0.052 0.030 0.005 0.002   0.006        
2002 0.039 0.604 0.930 0.969 1.552 1.570 2.387 0.604 0.167 0.010              
2003   0.040 0.063 0.314 0.146 0.096 0.044 0.027 0.031 0.010 0.000 0.004          
2004 0.226 0.040 0.209 0.270 0.391 0.234 0.075 0.051 0.014 0.015 0.010            
2005   0.417 0.143 0.356 0.618 0.293 0.302 0.076 0.007   0.004            
2006 0.517 0.009 0.080 0.095 0.264 0.296 0.080 0.029 0.043 0.017 0.017            
2007 0.075 0.103 0.190 0.125 0.140 0.122 0.179 0.080 0.032 0.005 0.005 0.017          
2008 0.350 0.129 0.124 0.053 0.054 0.011 0.007 0.025 0.010     0.005          
2009   0.063 0.230 0.386 0.233 0.080 0.016 0.036 0.028 0.006 0.006 0.020          
2010 0.123 0.399 0.181 0.222 0.154 0.162 0.026 0.009 0.044 0.025 0.015   0.004        
2011 0.000 0.094 0.102 0.131 0.120 0.134 0.164 0.036 0.008 0.008 0.032 0.000 0.002 0.000      
2012   0.130 0.441 0.385 0.189 0.182 0.155 0.083 0.021 0.007 0.013 0.020 0.006 0.012     0.004
2013 0.023 0.172 0.396 0.249 0.150 0.095 0.108 0.052 0.065 0.021 0.013 0.013 0.016        
2014 0.119 0.427 0.203 0.180 0.174 0.250 0.151 0.101 0.106 0.161 0.019   0.018 0.007      
2015   0.027 0.099 0.125 0.487 0.095 0.179 0.064 0.082 0.087 0.059 0.007 0.014   0.006    
2016 0.053 0.433 0.219 0.428 0.927 0.744 0.137 0.118 0.188 0.023 0.071 0.047 0.028        
2017   0.095 0.202 0.082 0.175 0.145 0.110 0.082 0.042 0.008 0.013 0.010 0.005 0.003      
2018   0.283 0.084 0.091 0.177 0.332 0.272 0.064 0.059 0.081 0.014 0.007 0.003 0.007      
2019 0.017 0.039 0.166 0.136 0.083 0.372 0.489 0.393 0.067 0.055 0.013 0.012 0.004        
Table A.4.1. Abundance index (millions)
  Age 0 Age 1 Age 2 Age 3 Age 4 Age 5 Age 6 Age 7 Age 8 Age 9 Age 10 Age 11 Age 12 Age 13 Age 14 Age 15 Age 16
1995   0.139 0.050 0.040 0.094 0.103 0.510 0.112 0.455 0.105              
1996 0.253 0.313 0.202 0.129 0.116 0.160 0.440 0.349                  
1997   0.342 0.143 0.052 0.122 0.151 0.287 0.258 0.502                
1998 0.394 0.073                              
1999   0.289 0.080 0.052 0.057 0.122 0.154 0.294                  
2000                                  
2001   0.737 0.345 0.200 0.116 0.222 0.244 0.418 0.494 0.903     0.727        
2002 0.937 0.083 0.172 0.009 0.053 0.109 0.069 0.185 0.315                
2003   0.675 0.325 0.108 0.205 0.188 0.222 0.273 0.370 0.452   0.200          
2004 0.149 0.221 0.152 0.200 0.086 0.197 0.147 0.172 0.453 0.550 0.319            
2005     0.019 0.020 0.010 0.034 0.011 0.047 0.334   0.488            
2006   0.578 0.035   0.029 0.015 0.049 0.077                  
2007 0.644 0.311 0.334 0.173 0.088 0.112 0.188 0.123 0.315     0.487          
2008 0.668 0.600 0.267 0.373 0.247 0.124 0.734 0.318 0.896     0.108          
2009   0.698 0.415 0.090 0.253 0.068 0.252 0.292 0.169 0.671              
2010 0.137 0.448 0.317 0.187 0.099 0.115 0.297 0.319 0.081 0.577 0.368   0.427        
2011 0.669 0.833 0.603 0.270 0.148 0.069 0.064 0.527 0.142 0.012 0.487 0.427 0.004        
2012   0.358 0.658 0.443 0.139 0.143 0.133 0.275 0.364 0.515 0.357 0.599 0.286 0.349     0.315
2013 0.542 0.524 0.296 0.192 0.150 0.182 0.240 0.388 0.172 0.528 0.624 0.651 0.590        
2014 0.647 0.150 0.348 0.151 0.046 0.076 0.096 0.270 0.089 0.239 0.366   0.147 0.866      
2015   0.662 0.105 0.159 0.047 0.066 0.096 0.110 0.140 0.160 0.722 0.754 0.502   0.930    
2016 0.906 0.684 0.451 0.049 0.021 0.074 0.238 0.232 0.068 0.455 0.143 0.195 1.181        
2017   0.371 0.352 0.387 0.065 0.257 0.170 0.273 0.294 0.583 0.736 0.668 1.067 0.612      
2018   0.628 0.462 0.348 0.097 0.102 0.221 0.473 0.406 0.146 0.375 0.307 0.707 0.558      
2019 0.453 0.532 0.426 0.161 0.185 0.052 0.035 0.039 0.130 0.134 0.516 0.490 0.573        
Table A.4.2. CV on abundance indices
  Age 0 Age 1 Age 2 Age 3 Age 4 Age 5 Age 6 Age 7 Age 8 Age 9 Age 10 Age 11 Age 12 Age 13 Age 14 Age 15 Age 16
1995   0.025 0.414 0.910 0.647 0.940 0.133 0.428 0.189 0.063              
1996 0.000 0.006 0.110 0.982 1.667 1.735 0.652 0.447 0.045 0.074              
1997   0.012 0.168 1.030 0.961 0.883 0.790 0.658 0.403                
1998 0.000 0.015 1.406 1.404 0.889 0.302 0.809 0.890                  
1999   0.004 0.075 0.415 0.743 0.455 0.247 0.134                  
2000     0.020 0.096 0.328 0.270 0.125                    
2001   0.009 0.167 0.455 0.595 0.593 0.305 0.158 0.250 0.036 0.004   0.077        
2002 0.000 0.094 0.602 1.357 5.275 7.009 12.038 4.644 0.964 0.083              
2003   0.002 0.011 0.136 0.141 0.170 0.110 0.070 0.143 0.036 0.003 0.009          
2004 0.002 0.002 0.055 0.203 0.697 0.556 0.301 0.266 0.031 0.091 0.036            
2005   0.059 0.081 0.693 2.536 1.236 1.372 0.680 0.011   0.045            
2006 0.004 0.001 0.053 0.177 0.609 0.964 0.274 0.178 0.339 0.084 0.109            
2007 0.001 0.025 0.157 0.231 0.441 0.429 0.619 0.500 0.295 0.055 0.063 0.028          
2008 0.003 0.012 0.097 0.115 0.201 0.042 0.024 0.152 0.074     0.039          
2009   0.004 0.105 0.497 0.420 0.215 0.072 0.155 0.136 0.016 0.016 0.054          
2010 0.001 0.028 0.046 0.285 0.346 0.461 0.103 0.030 0.490 0.122 0.076   0.009        
2011 0.000 <