HADDOCK

Melanogrammus aeglefinus


Assessment report
Published by

Marine and Freshwater Research Institute, Iceland

Published

7 June 2024

General information

Icelandic haddock (Melanogrammus aeglefinus) is fairly abundant in the coastal waters around Iceland and is mostly limited to the Icelandic continental shelf, while 0-group and juveniles from the stock are occasionally found in East Greenland waters (ICES area 14). Apart from this, larval drifts links with other regions have not been found. In addition, minimal catches have been reported in area 14 (maximum of less than 10 tons in 2016). The nearest area to Iceland where haddock is found in reasonable abundance are in shallow Faroese waters, which constitutes as a separate stock. The two regions are separated by a wide and relatively deep ridge, an area where reporting of haddock catches is nonexistent, both commercially and scientifically. Tagging studies (Jónsson 1996) conducted between 1953 and 1965 showed no migrations of juvenile and mature fish outside of Icelandic waters, as most recaptures took place in the area of tagging (or adjacent areas) and on the spawning grounds south of Iceland. Information about stock structure (metapopulation) of haddock in Icelandic waters is limited.

The species is found all around the Icelandic coast, principally in the relatively warm waters off the west and south coast, in shallow waters (10-200 m depth). Spawning has historically been limited to the southern waters. Haddock is also found off the north coast and in warm periods a large part of the immature fish have been found north of Iceland. In recent years a larger part of the fishable stock has been found off the north coast of Iceland than in the last two decades of the 20th century.

Fishery

The fishery for haddock in 5a has not changed substantially in recent years, but the total number of boats that account for 95% of the fishery has been declining steadily (Figure 1 and table 1). Around 250 longliners annually report catches of haddock, around 60 trawlers and 40 demersal seine boats. Most of Haddock in 5a is caught by trawlers and the proportion caught by that gear has decreased since 1995 from around 70% to 45% in 2017. However, for the last two years this proportion has increased slightly and is now around 60%. At the same time the proportion caught by longlines has increased from around 15% in 1995 - 2000 to 40 % in 2011–2023. Catches in demersal seine have varied less and have been at around 15% of Icelandic catches of Haddock in 5a. Currently less than 2% of catches are taken by other vessel types, but historically up to 10 % of total catches were by gillnetters, but since 2000 these catches have been low (Figure 2). Most of the haddock caught in 5a by Icelandic vessels is caught at depths less than 200 m (Figure 3). The main fishing grounds for Haddock in 5a, as observed from logbooks, are in the south, southwestern and western part of the Icelandic shelf (Figure 4 and Figure 5). The main trend in the spatial distribution of haddock catches in 5a according to logbook entries is the increased proportion of catches caught in the north and northeast.

Figure 1: Haddock in 5a. Number of vessels (all gear types) accounting for 95% of the total catch annually since 1994. Left: Plotted against year. Right: Plotted against total catch. Data from the Directorate of Fisheries.

Figure 2: Haddock in 5a. Landings in tons and percent of total by gear and year

Table 1: Haddock in 5a. Number of Icelandic vessels landing haddock, and all landed catch divided by gear type.
Year Nr. Bottom Trawl Nr. Other Nr. Danish Seine Nr. Long Line Bottom Trawl Other Danish Seine Long Line Total catch
2000 164 504 117 479 23300 1740 3101 13089 41230
2001 146 631 91 447 22034 2050 3036 11982 39102
2002 144 548 91 417 30377 1990 3596 13638 49601
2003 136 550 96 435 36239 1664 4804 17284 59991
2004 131 656 95 449 50722 1787 8095 23198 83802
2005 126 488 90 449 53046 1573 10493 30767 95879
2006 116 416 93 436 45968 1217 12709 36237 96131
2007 109 345 94 407 57033 1080 12869 37199 108181
2008 102 311 91 362 51228 944 16457 33051 101680
2009 98 448 81 335 39078 608 15182 26571 81439
2010 94 623 67 279 29341 475 10138 23916 63870
2011 95 630 54 278 20718 473 6866 21175 49232
2012 98 699 56 289 20469 473 6048 18722 45712
2013 95 702 65 282 18829 398 4955 19197 43379
2014 84 654 47 283 13438 329 3776 15598 33141
2015 83 607 50 257 17337 360 4327 16432 38456
2016 82 580 53 237 17045 321 4456 14927 36749
2017 80 531 53 210 16456 343 4539 14447 35785
2018 71 494 58 194 26639 336 5585 15190 47750
2019 69 493 43 183 35947 302 6237 14650 57136
2020 73 536 42 149 32005 278 5079 16189 53551
2021 82 532 46 141 35961 264 5338 14411 55974
2022 73 513 57 114 39003 243 3929 13640 56815
2023 76 607 60 96 44514 311 6560 17427 68812

Figure 3: Haddock in 5a. Depth distribution of haddock catches from bottom trawls, longlines, trawls and demersal seine from Icelandic logbooks

Figure 4: Haddock in 5a. Changes in spatial distribution of haddock catches as recorded in Icelandic logbooks.

Figure 5: Haddock in 5a. Spatial distribution of catches by all gears for selected years.

Data available

In general sampling is considered good from commercial catches from the main gears (demersal seines, longlines and trawls). The sampling does seem to cover the spatial and seasonal distribution of catches (see Figure 7 and Figure 8). In 2020 sampling effort was reduced substantially, on-board sampling in particular, due to the COVID-19 pandemic. However the reduced sampling during this period is considered to be sufficiently representative of the fishing operations and thus not considered to substantially affect the stock assessment. The sampling effort has since increased to near pre-pandemic levels.

Figure 7: Haddock in 5a. Ratio of samples by month (bars) compared with proportion landings by month (solid black line) split by year and main gear types. Numbers of above the bars indicate number of samples by year, month and gear.

Figure 8: Haddock in 5a. Fishing grounds last year as reported in logbooks (contours) and positions of samples taken from landings (crosses) by main gear types.

Landings and discards

All landings in 5a before 1982 are derived from the STATLANT database, and also all foreign landings in 5a to 2005. The years between 1982 and 1993 landings by Icelandic vessels were collected by the Fisheries Association of Iceland (Fiskifélagið). Landings after 1994 by Icelandic vessels are given by the Icelandic Directorate of Fisheries. Landings of foreign vessels (mainly Norwegian and Faroese vessels) are given by the Icelandic Coast Guard prior to 2014 but after 2014 this are also recorded by the Directorate. Discarding is banned by law in the Icelandic demersal fishery. Based on annual discards estimates since 2001, discard rates in the Icelandic fishery for haddock due to highgrading are estimated very low in recent years (<3% in either numbers or weight, see MRI (2016) for further details) while historically discards may have been substantial in the early 1990s. Measures in the management system such as converting quota share from one species to another are used by the fleet to a large extent and this is thought to discourage discarding in mixed fisheries. In addition to prevent high grading and quota mismatch the fisheries are allowed to land fish that will not be accounted for in the allotted quota, provided that the proceedings when the landed catch is sold will go to the Fisheries Project Fund (Verkefnasjóður sjávarútvegsins).

Figure 9: Haddock in 5a. Estimates of annual discards by gear (point estimate and 95% confidence interval). No estimates are available since 2018.

Length compositions

The bulk of the length measurements is from the three main fleet segments, i.e. trawls, longlines and demersal seine (Table 2). The number of available length measurements by gear has fluctuated in recent years in relation to the changes in the fleet composition.

Length distributions from the main fleet segments are shown in Figure 10. The sizes caught by the main gear types (bottom trawl and longlines) appear to be fairly stable, primarily catching haddock in the size range between 40 and 70 cm. Gillnets tend to catch slightly larger fish and modes of the length distribution vary more depending on the availability of large haddock.

Figure 10: Haddock in 5a. Commercial length distributions by gear and year

Table 2: Haddock in 5a. Number of samples and length measurements from landed catch.
Year Bottom Trawl Num. samples Bottom Trawl Num. lengths Danish Seine Num. samples Danish Seine Num. lengths Long Line Num. samples Long Line Num. lengths
2000 344 66143 21 3114 88 14393
2001 359 71914 26 4098 168 30110
2002 467 85869 47 7644 212 32425
2003 422 71509 75 7094 210 31239
2004 503 82474 75 10416 252 35405
2005 514 94529 102 14880 375 53472
2006 500 74627 241 29862 747 75392
2007 837 102155 515 34922 531 87737
2008 813 83284 389 29477 572 88920
2009 630 56466 349 35176 406 63817
2010 470 59477 265 19727 344 56681
2011 357 53462 204 8494 237 43200
2012 349 41424 191 10270 306 60842
2013 267 34357 92 2597 237 43132
2014 155 13731 51 3157 217 37035
2015 187 26101 92 2816 222 41594
2016 163 21500 132 2540 202 37492
2017 200 23387 151 6417 232 42360
2018 134 21780 94 5611 231 35621
2019 295 50698 42 3266 187 25692
2020 109 17640 15 1552 64 8929
2021 139 22264 20 2112 38 4669
2022 124 18937 16 1942 34 3941
2023 129 23280 22 1933 28 3382

Age compositions

An overview of the sampled ototliths is shown in Table 3. Catch in numbers-at-age is shown in Figure 11. The catches in 2023 are mainly of the 2014 to 2017 year classes. The number of year classes contributing to the catches has increased in recent years; the result of low fishing mortality in recent years and the last year class contributing with more than 1% of total is 11 years old (Figure 12).

Table 3: Haddock in 5a. Number of samples and otoliths collected from landed catch.
Year Bottom Trawl Num. samples Bottom Trawl Num. otoliths Danish Seine Num. samples Danish Seine Num. otoliths Long Line Num. samples Long Line Num. otoliths
2000 344 6773 21 800 88 2848
2001 359 5208 26 359 168 2755
2002 467 6510 47 750 212 2848
2003 422 7237 75 878 210 3499
2004 503 6786 75 698 252 2855
2005 514 6478 102 823 375 3520
2006 500 6447 241 1219 747 4806
2007 837 6602 515 1969 531 4451
2008 813 7637 389 2163 572 4464
2009 630 5449 349 1822 406 2800
2010 470 5458 265 1473 344 3199
2011 357 3522 204 1140 237 2675
2012 349 4448 191 1436 306 3204
2013 267 3039 92 750 237 2751
2014 155 1421 51 329 217 1550
2015 187 1924 92 324 222 1151
2016 163 1769 132 440 202 975
2017 200 1363 151 337 232 945
2018 134 1385 94 291 231 845
2019 295 1740 42 362 187 925
2020 109 1322 15 276 64 625
2021 139 1820 20 300 38 775
2022 124 1100 16 120 34 265
2023 129 1462 22 220 28 440

Figure 11: Haddock in 5a. Catch at age from the commercial fishery in Iceland waters. Bar size is indicative of the catch in numbers and bars are colored by cohort. Note different scales on y-axis

Figure 12: Haddock in 5a. Catch at age from the commercial fishery in Iceland waters. Biomass caught by year and age, bars are colored by cohort.

Weight at age in the catch

Mean weight at age in the catch is shown in Figure 13. Catch weights of the older year classes have been increasing in recent years, after being very low when the stock was large between 2005 and 2009. Higher mean weight at age is most apparent for the younger haddock from the small cohorts (2008–2013), which has resulted in a mean weight of the old fish above average. Mean weight of younger year classes in the catches has decreased but is still above average.

Figure 13: Haddock in 5a. Mean weight at age in the catch from the commercial fishery in Icelandic waters. Bars are coloured by cohort.

Natural mortality

No information is available on natural mortality. For assessment and advisory purpose the natural mortality is set to 0.2 for all age groups.

Catch, effort and research vessel data

Catch per unit of effort from commercial fisheries

Catch per unit of effort data (Figure 14) shows that for hauls where the catch is composed of more than 50 % haddock the CPUE has been steadily increasing since 1990 for the main gear types. The CPUE from all catches from bottom trawls and demersal seine is amongst the highest recorded while for longlines it is relatively low. This is in-line with fishermen’s perception that it is easy to catch haddock. This gives a different picture of the development of the stock than what is observed in surveys and assessment, much less increase after 2000 and much less decrease in recent years. However it is worth noting that there is also a considerable change in the size composition of the stock, where the biomass of 60 cm and above is at the highest observed in the time series, while the total biomass is close to it average value, suggesting that the CPUE may be more representative of larger fish.

There are also considerable differences in the CPUE by area, where the area north of Iceland has seen a continuous increase while the southern regions are more consistent with the total biomass index from the spring survey. Bycatch is of little concern as the haddock is commonly targeted in specific catch mixtures.

The catch per unit effort could not be estimated for 2022 as the effort data from that year were not available at the time of assessment.

Figure 14: Haddock in 5a. Catch per unit of effort in the most important gear types. The dashed lines are based on locations where more than 50% of the catch is haddock and solid lines on all records where haddock is caught. A change occurred in the longline fleet starting September 1999. Earlier only vessels larger than 10 BRT were required to return logbooks but later all vessels were required to return logbooks. Effort data is not available for 2022.

Icelandic survey data

Information on abundance and biological parameters from Haddock in 5a is available from two surveys, the Icelandic groundfish survey in the spring and the Icelandic autumn survey.

The Icelandic groundfish survey in the spring, which has been conducted annually since 1985, covers the most important distribution area of the haddock fishery. The autumn survey commenced in 1996 and expanded in 2000 to include deep water stations. It provides additional information on the development of the stock. The autumn survey has been conducted annually with the exception of 2011 when a full autumn survey could not be conducted due to a fisherman strike. Although both surveys were originally designed to monitor the Icelandic cod stock, the surveys are considered to give a good indication of the haddock stock, both the juvenile population and the fishable biomass. A detailed description of the Icelandic spring and autumn groundfish surveys is given in the Stock Annex. Figure 15 shows both a recruitment index (abundance < 25 cm) and the trends in various biomass indices (total biomass, biomass > 60 cm and biomass > 45 cm). Changes in spatial distribution observed in the spring survey are shown in Figure 16). The shows that a larger proportion of the observed biomass now resides in the north (areas NW and NE). Survey length distributions are shown in Figure 18 (abundance) and changes in spatial distribution in Figure 17.

Both surveys show an high increase total biomass between 2002 and 2005 but considerable decrease from 2007–2010. The difference in perception of the stock between the surveys is that the autumn survey shows less contrast between periods of large and small stock. The 2015 estimate from the autumn survey exhibited substantially lower biomass compared to adjacent years. The contrast between the surveys appears to be stronger when looking at the biomass of 60 cm and larger, but both surveys show that the 60 cm\(^+\) is at its maximum in recent years. A marked increase in total survey biomass was observed in the autumn of 2022 and spring 2023.

Age disaggregated indices from the March survey are shown in Figure 19. Similar to the biomass of 60cm\(^+\) the index of age \(11^+\) higher than seen before in March survey. This is assumed to be related to lower fishing mortality after the establishment of a management plan for haddock in 5a. After a period of low recruitment the biomass for other age groups is near the geometric mean in both surveys.

Figure 15: Haddock in 5a. Indices (total biomass, biomass> 45 cm, biomass> 60 cm and abundance <25 cm) in the Spring Survey (March) 1985 and onwards (line shaded area) and the autumn survey (point ranges).

Figure 16: Haddock in 5a. Changes in geographical distribution of the survey biomass.

Figure 17: Haddock in 5a. Location of haddock in the most recent March (SMB) and the Autumn (SMH) surveys, bubble sizes are relative to catch sizes, and crosses indicate stations where no haddock was observed.

Figure 18: Haddock in 5a. Length disaggregated abundance indices from the March survey 1985 and onwards.

Figure 19: Haddock in 5a. Age disaggregated indices in the Spring Survey (left) and the autumn survey (rights). Bars indicated the deviation from the log mean index, fill colors indicate cohorts. Note different scales on y-axes.

Stock weight at age

Mean weight at age in the catch is shown in Figure 13. Stock weights are obtained from the groundfish survey in March and are also used as mean weight at age in the spawning stock. Both stock and catch weights of the older year classes have been increasing in recent years, after being very low when the stock was large between 2005 and 2009. Higher mean weight at age is most apparent for the younger haddock from the small cohorts (2008–2013), which has resulted in a mean weight of the old fish above average. Mean weight of younger year classes has decreased but is still above average.

Figure 20: Haddock in 5a. Stock weights from the March survey in Icelandic waters. Bars are coloured by cohort.

Stock maturity at age

Maturity-at-age data are shown in Figure 21. Those data are obtained from the groundfish survey in March. Maturity-at-age of the youngest age groups has been decreasing in recent years which is likely to be related to the distributional shift towards the north. Maturity by size has been decreasing and the most likely explanation is a large proportion of those age groups north of Iceland where the proportion of mature has always been low, as illustrated in Figure 22.

Figure 21: Haddock in division 5a. Maturity at age in the survey. Bars are coloured by cohort. The values are used to calculate the spawning stock.

Figure 22: Haddock in 5a. Geographical differences in proportion mature by year and age (top), and stock weights (below).

Data analyses

Analytical assessment

This stock was last benchmarked in 2019 as a part of a harvest control rule evaluation (WKICEMSE 2019), but the current assessment model had been run in parallel to the previous assessment since 2013. The management plan for haddock in 5a based on this assessment was tested at the same meeting and subsequently implemented by the government of Iceland in the same year.

The assessment model used is a statistical catch–at-age model described in Björnsson, Hjörleifsson, and Elvarsson (2019). The model runs from 1979 onwards and ages 1 to 10 are tracked by the model, where the age of 10 is a plus group. Natural mortality is set to 0.2 for all age groups. Selection pattern of the commercial fleet is defined in terms of mean stock weights at age, rather than age, based on a logit selection function: \[ S_{a,y} = \frac{1}{1+e^{-\alpha( \log(sW_{a,y})-\log(W_{50}))}} \] The rationale for this choice, compared to a more traditional age-based selection, is to account for observed changes in growth between year classes. Larger year classes tend to have have lower mean weight compared to smaller year classes, as observed in Figure 13. As fishery selection is mainly size based, the assessment model using a size based selection only requires two parameters to estimate the selection pattern. In contrast an age-based selection pattern would require parameter based on multiple selection time periods.

The weights to the survey data are based on a common multiplier to the variance estimates of each age group and survey obtained from a backwards calculation model (described in Björnsson, Hjörleifsson, and Elvarsson 2019), shown in Figure 23.

The ratio of fishing and natural mortality before spawning was set at 0.4 and 0.3 respectively as haddock is known to spawn in the period between April till the end of May.

Figure 23: Haddock in 5a. Estimated selection by weight, CV pattern, stock recruitment relationship and survey catchability.

Data used by the assessment

The assessment relies on four sources of data, that are described above. These are the two surveys, commercial samples and landings. The commercial data is used to compile catch at age data that enter the likelihood along with the survey at age from both surveys. Stock weights and catch weights at age are derived from the spring survey and catches respectively. The maturity data is similarly collected in the spring survey. Prior to 1985, when the spring survey started, stock weights and maturity at age were assumed constant at the 1985 values. A full description of the preparation of the data used for tuning and as input is given in the stock annex (see ICES (2019)).

Diagnostics

The fit to data is illustrated in Figure 25) where no concerning residual patterns are observed. When looking at the combined fit (Figure 24) the figure shows the observed vs. predicted biomass from the surveys and it indicates that historically the autumn survey biomass has been closer to the prediction than corresponding values from the March survey, where the contrast in observed biomass is more than predicted from the assessment. The model accounts for this by estimating a stronger residual correlation for the spring survey (0.527) compared with the autumn survey (0.193). When contrasting the biomass levels before and after the mid 2000’s peak the autumn survey suggests that the biomass level after the peak biomass is higher while the spring survey is at similar levels. Thus the model appears to fall in a region between the two surveys. Related to this Figure 23) shows the estimated “catchability” and CV as a function of age for the surveys, showing that estimated CV is lower is generally lower for ages 2–6, whereas the CV increases faster by age for the autumn survey compared with the spring survey.

Figure 24: Haddock in division 5a. Aggregated model fit to the total biomass indices. Note that residual correlation is estimated (see text for further details).

Figure 25: Haddock in division 5a. Residuals from the model fit to survey and catch data based on the both the surveys. Red circles indicate negative residuals (observed < modelled), while blue postive. Residuals are proportional to the area of the circles.

Model results

The results of the assessment indicate that the stock decreased from 2008–2011 when large year classes disappeared from the stock and were replaced by smaller year classes (Figure 26). From 2011 to 2017 the stock stabilized as a results of lower fishing mortality and since 2017 the stock biomass has increased rapidly as strong year classes have entered into the fishery. Fishing mortality is now estimated to be above the overall goal of the currently implemented HCR, whilst historically low. The baseline assessment does indicate that the stock size high and will remain in the coming years. The analytical retrospective (Figure 28) indicates an upwards revision in the most recent years. As this related to strong incoming recruitment to the fishable biomass the assessment is considered stable even though the estimated 5 year Mohns’s \(\rho\) fall slightly outside the acceptable range as illustrated in Figure 28.

Assessment in recent years has shown some difference between model runs where either or both of the two different tuning series, i.e. March and the October surveys, are omitted from the estimation, but currently this difference is mostly within the estimated uncertainty (Figure 27) but that has not always been the case. When the model is only fitted with catch data the reference biomass shows an opposite trend from the baseline assessment which is estimated to be decreasing. Last years catch only assessment however indicated that biomass was increasing at a faster rate suggesting that the uncertainty of the estimate of the current state of the stock when the surveys are omitted increases substantially.

Estimated selection is illustrated in Figure 29, where substantial variations in selection at age is estimated by the model. Haddock in Icelandic waters has exhibited substantial density dependence in growth, as illustrated in Figure 32.

Figure 26: Haddock in division 5a. Summary from assessment. Dashed vertical line indicates the assessment year and yellow shaded region the uncertainty as estimated by the model.

Figure 27: Haddock in 5a. Comparision of assessment results where either the spring survey or the autumn survey is omitted from the estimation.

Figure 28: Haddock in division 5a. Analytical retrospective analysis of the assessment of haddock with a 5 year peel.

Figure 29: Haddock in 5a. Estimated selection at age.

Short term projections

Following the management plan the advice for the coming fishing year (2024/2025) is based in the biomass of 45 cm\(^+\) at the beginning the next calendar year (2025). To arrive at this prediction a deterministic projection of the growth in weight and changes in maturity in the coming calendar year is needed. Growth in 2025 is predicted by the equation:

\[log(\frac{W_{a+1,y+1}}{W_{a,y}}) = \alpha + \beta log(W_{a,y0}) + \delta_y\]

where according to the stock annex the factor \(\delta_y\) for the assessment year (Figure 32) is the average of the points estimates of the growth factor in the two preceding years. Growth has been high but variable in recent years but was much less in when the stock was larger in the early 2000s. Maturity, selection, catch weights at age and proportion of the biomass above 45cm\(^+\) are then predicted from stock weights in 2024, see Figure 32 and Figure 33. When those values have been estimated the prediction is done by the same model as used in the assessment. The model works iteratively as the estimated TAC for the fishing year 2024/2025 has some effect of the biomass at the beginning of 2025, which the TAC is based on. This procedure is described in detail in the stock annex. A comparison of the predicted variables and observed/estimated values from the current assessment and last years projection are shown in Figure 30 and Figure 31. This difference shown in Figure 30 is not considered to be related to the weight predictions for the advisory year as the assessment has consistently been revised upwards is the last years (Figure 28).

The projection this year assumes that the remainder of the TAC for the fishing year that ends on August 30. is caught. The projected stock status for the interim year is shown in Table 4 and the output from the projection in Table 5.

Table 4: Haddock in 5a. The input data used for the advisory year prognosis of the Icelandic haddock in the assessment: the predicted weights, the selection pattern, M, proportion of M before spawning, and the number-at-age derived from Muppet run.
Age Catch At Age Stock Maturity Catch Weights Stock Weights Numbers At Age Selection
1 0.000 0.000 170.437 30.3677 69305.40 0.000
2 160.671 0.018 483.312 155.8590 52144.80 0.008
3 1312.870 0.157 944.663 446.1150 36656.80 0.077
4 9559.850 0.348 1279.900 718.4930 77495.10 0.199
5 14309.200 0.626 1780.300 1205.9100 68668.10 0.446
6 11737.900 0.781 2215.410 1699.5400 44866.60 0.638
7 775.187 0.892 2823.860 2487.1700 2710.72 0.807
8 2350.340 0.911 2995.720 2728.7700 7681.77 0.838
9 536.962 0.924 3152.320 2955.9300 1746.52 0.861
10 637.018 0.939 3369.100 3281.0800 2026.87 0.887

Figure 30: Haddock in 5a. Comparison of the short term prediction of reference biomass to the realised value a year later.

Figure 31: Haddock in 5a. Comparison of some of the results of last years assessment assessment based on different tuning data and current assessment tuned with both the surveys

Figure 32: Haddock in 5a. Input data to the prediction model, where the exponent of the yearfactor (growth multiplier) is estimated to derive the reference biomass in the advisory year, as described in the text.

Figure 33: Haddock in 5a. Maturity at weight as used in the projections.

Table 5: Haddock in 5.a. Results of the short term projections when a target harvest rate of 0.35 is applied.
Year Calendar Year Catch Fishing Year Catch SSB B45+ HR Recruitment (age 2)
2024 73783 76774 127009 187073 0.394 44940.6
2025 78101 80756 143086 219356 0.356 52144.8
2026 78175 73013 151298 230722 0.339 56742.4
2027 70240 64695 142000 208635 0.337 56742.4

Management

The Icelandic Ministry of Food, Agriculture and Fisheries is responsible for management of the Icelandic fisheries and implementation of legislation. The Ministry issues regulations for commercial fishing for each fishing year (1 September–31 August), including an allocation of the TAC for each stock subject to such limitations. Haddock in 5a has been managed by TAC since the 1987. Landings have roughly followed the advice given by MFRI and the set TAC in all fishing years (Figure 34)) . Since the 2001/2002 the catches have exceeded more that 5% the set TAC in twelve fishing years. The largest overshoot in landings in relation to the advice/TAC was observed in the fishing year 2020/2021 when the landings of haddock exceeded the advice by 33%. The reasons for the implementation errors are related to the management system that allows for transfers of quota share between fishing years and conversion of TAC from one species to another (species transformation).

The TAC system does not include catches taken by Norway and the Faroe Islands by bilateral agreement. The level of those catches is known in advance but has until recently not been taken into consideration by the Ministry when allocating TAC to Icelandic vessels. There is no minimum landing size for Haddock in 5a. There are agreements between Iceland, Norway and the Faroe Islands relating to a fishery of vessels in restricted areas within the Icelandic EEZ. Faroese vessels are allowed to fish 5600 t of demersal fish species in Icelandic waters which includes maximum 1200 tonnes of cod and 40 t of Atlantic halibut.

The effect of these species transformations and quota transfers is illustrated in Figure 35. The illustrates that when the biomass of haddock was high in the years between 2002 to 2007 the net transfers to haddock from other species increased. This may in part be explained by shifts in distribution of haddock, as illustrated in Figure 5, as the fisheries that traditionally target the northern area had lower amounts of haddock in their quota portfolio. However looking over longer period quota transfer towards/from haddock has on the average been close to zero. With the establishment a management plan in 2013 the transfers between quota years have decreased substantially, while at the same time transfers from other species have increased. This is likely due to the fact that haddock is easy to catch, as demonstrated by high CPUE in recent years. The haddock quota may also be limiting in some mixed fisheries and that haddock may have been underestimated in last years could also contribute to transfer towards haddock. These effects were considered when the management plan was tested.

Figure 34 illustrates the difference between national TAC and landed catch in 5a. The difference can be attributed to species transformation (in both directions), while for the 1999/2000 and 2020/2021 fishing years the government of Iceland increased TAC mid-season. Similarly the TAC for the 2020/2021 fishing year was increased by 8 000 t and reduced by the same amount the following fishing year.

In 2023 the Ministry of Food, Agriculture and Fisheries initiated the process of reviewing the the management plan for haddock in Icelandic waters and it expected that it will be reviewed before the 2025/2026 fishing year.

Figure 34: Haddock in 5a. Comparison of the realised catches and the set TAC for the fishing operations in Icelandic waters. Note that in the 1999/2000 fishing year the government of Iceland increased TAC mid-season

Figure 35: Haddock in 5a. An overview of the net transfers of quota between years and species transformations in the fishery in 5a.

Table 6: Haddock in 5a. ICES advice and official landings. All weights are in tonnes.
Year ICES advice Predicted catch corresp. to advice Agreed TAC ICES landings for the fishing year ICES landings for the calendar year
1984* National advice < 55000 60000 — 48000
1985* National advice < 45000 60000 — 51000
1986* National advice < 50000 60000 — 48000
1987* National advice < 50000 60000 — 40760
1988* National advice < 60000 65000 — 54204
1989* National advice < 60000 65000 — 62885
1990* National advice < 60000 65000 — 67198
1991** National advice < 38000 48000 — 54692
1991/1992 National advice < 50000 50000 48123 47121
1992/1993 National advice < 60000 65000 47255 48123
1993/1994 National advice < 65000 65000 58443 59502
1994/1995 National advice < 65000 65000 60829 60884
1995/1996 National advice < 55000 60000 53972 56890
1996/1997 National advice < 40000 45000 49764 43764
1997/1998 National advice < 40000 45000 37811 41192
1998/1999 National advice < 35000 35000 45146 45411
1999/2000 F reduced below Fmed < 35000 35000 41150 42105
2000/2001 F reduced below provisional Fpa < 31000 30000 39143 39654
2001/2002 F reduced below provisional Fpa < 30000 41000 41069 50498
2002/2003 F reduced below provisional Fpa < 55000 55000 55269 60883
2003/2004 F reduced below provisional Fpa < 75000 75000 77916 84828
2004/2005 F reduced below provisional Fpa < 97000 90000 96617 97225
2005/2006 F reduced below provisional Fpa < 110000 105000 99926 97614
2006/2007 F reduced below provisional Fpa < 112000 105000 99763 109966
2007/2008 F reduced below provisional Fpa < 120000 100000 109810 102872
2008/2009 F reduced below 0.35 < 83000 93000 88617 82045
2009/2010 F reduced below 0.35 < 57000 63000 67579 64169
2010/2011 F reduced below 0.35 < 51000 50000 50042 49433
2011/2012 F reduced below 0.35 < 42000 45000 49179 46208
2012/2013 F reduced below 0.35 < 32000 36000 40512 44097
2013/2014 TAC 0.4 × B45+cm,2014 < 38000 38000 39628 33900
2014/2015 TAC 0.4 × B45+cm,2015 < 30400 30400 36656 39646
2015/2016 TAC 0.4 × B45+cm,2016 < 36400 36400 40117 38109
2016/2017 TAC 0.4 × B45+cm,2017 < 34600 34600 36340 37062
2017/2018 TAC 0.4 × B45+cm,2018 < 41390 41390 43700 49993
2018/2019 TAC 0.4 × B45+cm,2019 < 57982 57982 59382 58850
2019/2020 TAC 0.35 x B45+cm,2020 < 41823 41823 48991 54781
2020/2021 TAC 0.35 x B45+cm,2021 < 45389 45389 60672 57599
2021/2022 TAC 0.35 x B45+cm,2022 < 50429 41929 51986 58770
2022/2023 TAC 0.35 x B45+cm,2023 < 62219 62219 68881 70595
2023/2024 TAC 0.35 x B45+cm,2024 < 76415 76415 — —

Management considerations

All the signs from commercial catch data and surveys indicate that Haddock in 5a is at present in a good state. This is confirmed in the assessment. At WKICEMSE 2019 the harvest rate target applied by the HCR in the period between 2013 and 2018 was estimated to be no longer precautionary while a rate of 0.35 was in-line with both the precautionary and ICES’s MSY approach. In 2024 the stock is estimated to have increased substantially and it is projected to remain at this level in the coming years due to above average year classes that have now entered the fishable biomass. Analytical retrospective analysis of the assessment revealed a negative bias in the estimate of the SSB. While this is bordering on acceptable limits the robustness of the HCR was tested against model uncertainty of this magnitude.

References

Björnsson, Höskuldur, Einar Hjörleifsson, and Bjarki ór Elvarsson. 2019. “Muppet: Program for Simulating Harvest Control Rules.” Reykjavik: Marine; Freshwater Researh Institute. http://www.github.com/hoski/Muppet-HCR.
ICES. 2019. “Stock Annex: Haddock (Melanogrammus aeglefinus ) in Division 5.a (Iceland grounds).” International Council for the Exploration of the Seas; ICES publishing.
Jónsson, Jón. 1996. Tagging of Cod (Gadus Morhua) in Icelandic Waters 1948-1986;: Tagging of Haddock (Gadus Aeglefinus) in Icelandic Waters 1953-1965. Hafrannsóknastofnunin.
MRI. 2016. “Mælingar á brottkasti þorsks og ýsu (e. Measurments of discards of Cod and Haddock), 2014–2016, Reykjavik, Iceland.” Vol. 3. Marine; Freshwater Research Institute, Iceland; Marine Research Institute, Iceland. https://www.hafogvatn.is/static/research/files/fjolrit-183pdf.