13 Haddock in Subarea IV and Division IIIa (N)

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1 610 ICES WGNSSK REPORT Haddock in Subarea IV and Division IIIa (N) The assessment of haddock presented in this section is an update assessment. No changes have been made to the run settings and model configurations used in last year s assessment. Recommendations for issues to be considered at the forthcoming benchmark meetings are given in Section General Ecosystem aspects Ecosystem aspects are summarised in the Stock Annex Fisheries A general description of the fishery (along with its historical development) is presented in the Stock Annex. Most of the information presented below and in the Stock Annex pertains to the Scottish fleet, which takes the largest proportion of the haddock stock. This fleet is not just confined to the North Sea, as vessels will sometimes operate in Divisions VIa (off the west coast of Scotland) and VIb (Rockall). C hanges in fleet dynam ics There have been no decommissioning schemes affecting haddock fisheries since the major rounds in 2002 and Scottish vessels have been taking up opportunities for oil support work during with a view to saving quota and days at sea. With the reduced cod quota in recent years, many vessels have tended to concentrate more on the haddock fishery, with others taking the opportunity to move between the Nephrops and demersal fisheries (particularly during 2006 and 2007 there may have been fewer boats changing focus in this way in 2008 and 2009). Accompanying the change in emphasis towards the haddock fishery, there has also been a tendency to target smaller fish in response to market demand. Some trawlers operating in the east of the North Sea are using 130 mm mesh (to ensure they meet regulations), and this is likely to improve selectivity for haddock. Fish from the moderate 2005 yearclass now form the bulk of haddock catches, and discarding rates for these fish declined during 2008 as they grew beyond the minimum landings size. A more complete history of the North Sea haddock fishery is given in the Stock Annex. It is difficult to conclude what will be the likely effect of the recent fishery changes on haddock mortality. Changes in gear that are required to qualify for the Scottish Conservation Credits Scheme (CCS; see Section ) are likely to reduce bycatch (and therefore) discards of haddock in the Nephrops fishery in particular. In 2008, Scottish vessels w ere included in the CCS unless they opt outed of it, and as only one or two vessels chose to do so, compliance was close to 100%. Cod avoidance under the real-time closures scheme (which is a component of the CCS) could also have moved vessels away from haddock concentrations, but the extent of this depends on how closely cod and haddock distributions are linked, and on how successful the avoidance strategies have been. On the other hand, vessels catching fewer cod may increase their exploitation of haddock in order to maintain economic viability. In 2009, the CCS is the only option available to Scottish skippers.

2 ICES WGNSSK REPORT Additional information provided by the fishing industry Haddock are still the mainstay of the Scottish whitefish fleet. Quota uptake for 2008 was around 61%, in line with recent years (range 53% to 76% since 1999). However, the projected UK quota uptake for 2009 is thought to be higher, partly because whiting quota are likely to be exhausted rapidly. UK uptake (as of 6 th May) was 21.2% in 2008, and 27.4% in ICES advice ICES advice for 2008 In June 2007, ICES concluded the following: Based on the most recent estimate of SSB and fishing mortality, ICES classifies the stock as having full reproductive capacity and being harvested sustainably. SSB in 2006 is estimated at t. SSB is above the Bpa. The stock is still dominated by the strong 1999 year class and the 2005 year class is also estimated to be above average. Fishing mortality in 2006 is estimated at 0.49, which is below Fpa. The Q3 North Sea surveys for haddock (EngGFS and ScoGFS) did not change the perception of recruitment significantly compared to the estimates available in June. Therefore, ICES did not change its advice in October ICES advice for 2009 In June 2008, ICES concluded the following: Based on the most recent estimate of SSB (in 2008) and fishing mortality (in 2007), ICES classifies the stock as having full reproductive capacity and being harvested sustainably. SSB in 2008 is estimated to be above Bpa. Fishing mortality in 2007 is estimated to be below Fpa, but above the target FHCR (0.3) specified in the EU Norway management plan. The influence of the strong 1999 year class on the stock is diminishing. The 2005 year class is estimated to be above average. As in 2007, the 2008 Q3 North Sea surveys for haddock (EngGFS and ScoGFS) did not change the perception of recruitment significantly compared to the estimates available in June. Therefore, ICES did not change its advice in October Management North Sea haddock are jointly managed by the EU and Norway under an agreed management plan, the details of which are given in the Stock Annex. The plan was modified during 2008 to allow for limited interannual quota flexibility, following the meeting in June of the Norway-EC Working Group on Interannual Quota Flexibility and subsequent simulation analysis (Needle 2008a). The review and potential revision planned for 2009 has been postponed until Annual management of the fishery operates through TACs for two discrete areas. The first is Subarea IV and Division IIIa (EC waters), which are considered jointly. The 2008 and 2009 TACs for haddock in this area were t and t respectively. At most t of the 2009 TAC was to be taken in Norwegian waters of Subarea IV by EC vessels. The second area is Divisions IIIa-d, for which the TACs for 2008 and 2009 were t and t respectively. During 2008, 15 real-time closures (RTCs) w ere implemented under the Scottish Conservation Credits Scheme (CCS). At the time of writing in 2009, 46 further RTCs have

3 612 ICES WGNSSK REPORT 2009 been implemented (w ith a target of 150 for the year), and the CCS been adopted by 439 Scottish and around 30 English and Welsh vessels. It has two central themes aimed at reducing the capture of cod through: 1 ) avoiding areas with elevated abundances of cod through the use of compulsory Real Time Closures (RTCs) and voluntary amber zones ; and 2 ) the use of more species selective gears. Within the scheme, efforts are also being made to reduce discards generally. Although the scheme is intended to reduce mortality on cod, it will undoubtedly have an effect on the mortality of associated species such as haddock. Whether this effect is positive (e.g. moving vessels away for areas inhabited by both cod and haddock) or negative (e.g. increasing targeting on haddock to compensate for forgone cod catches) remains to be seen (see also Section ). How ever, early indications suggest that improved gear selectivity is likely to contribute to reductions in fishing mortality and discard levels, particularly of haddock and whiting, and there is evidence that the exploitation patterns for haddock and whiting across all participating vessels have improved since the introduction of the CCS scheme (see, for example, Section 13.4 below). In early 2008, a one-net rule was introduced in Scotland as part of the CCS. This is likely to have improved the accuracy of reporting of landings to the correct mesh size range. How ever, Scottish seiners w ere granted a derogation from the one-net rule until the end of January 2009, and were allowed to carry two nets (e.g mm as well as 120+ mm). They were required to record landings from each net on a separate logsheet and to carry observers when requested (ICES-WGFTFB 2008). The remaining technical conservation measures in place for the haddock fisheries are summarised in the Stock Annex. New EU effort regulations for 2009 are listed in Section Data available Collation issues for c atc h data Due to problems in InterCatch with the raising of discard estimates from unsampled fleets (see Section 1.XXX), the international catch data for haddock have been aggregated using a spreadsheet approach (as has been the case for the previous two years). Some brief notes are provided here which are intended to clarify issues that have arisen with this process. Further information on the data collation method used can be found in the Stock Annex. Discard data from UK (England and Wales) Discards data (total tonnes discarded for the years , numbers at age and mean weights at age) w ere provided by UK (E&W). These data had not been available at the time of data collation for previous WGs. Previously, UK(E&W) have provided their discard data for Subarea IV and Division VIId aggregated as a single area. Since there are very few haddock caught in Division VIId this means that the E&W discards for haddock were effectively for Subarea IV. In order to improve the situation for whiting in Division VIId, the data submitter was asked whether discard data could be provided separately for ICES Subarea IV and Division VIId. These data were available for cod, haddock and whiting. The received UK (E&W) discards data were for 2002 onwards.

4 ICES WGNSSK REPORT The earlier data could be incorporated as part of a benchmark assessment workshop for North Sea haddock. The 2007 spreadsheet for aggregation of international catch data was updated with the E&W discards data, and these data were also used in the 2008 data collation for raising purposes. Revisions to catch data for 2007 UK (England & Wales) There was a small reduction (2.089 tonnes) in the UK (E&W) landings of haddock from Subarea IV. Norway Norwegian data revisions for 2007 landings were received for human consumption only. No industrial bycatch data revisions were received. Norwegian data revisions were provided for Division IIIa (including both IIIaN and IIIaS). The 2007 spreadsheet has been updated with these most recent data revisions from Norway. Sw eden Contrary to what was reported to the 2008 WG, there was no industrial bycatch (i.e. a zero observation) of haddock by Sweden in Catch data for 2008 The approach to the raising of discards was essentially the same as for 2007, since the data that were provided by respective nations were broadly of the same format in terms of the fishing areas for which age distributions were available. Some minor changes to the data available were noted for 2008, as follows. Denmar k Age distributions for industrial bycatch in Subarea IV and Division IIIa(N) (numbers at age and mean weights at age) were provided by Denmark. Concerns were raised about these data, as the mean weights-at-age seemed implausible for Subarea IV. The available age distribution for industrial bycatch in Division IIIa(N) also seemed incongruous when compared with those for the human consumption and discarded components of the catch. No other age distributions are available for the industrial catch. Danish discard age compositions were used as a proxy for the missing industrial bycatch age compositions. Norway Norwegian landings were provided covering the fishery for human consumption only. In addition, it appears that the Norwegian data for Division IIIa may include both IIIa(N) and IIIa(S). The data were requested for just Division IIIa(N) but a clear resolution to this had not been reached by the time of the WG meeting. Due to these data issues, it has not been possible to estimate industrial bycatch for Division IIIa and these data are missing from the current assessment. Faroes Preliminary Faroese landings of haddock for Subarea IV were provided. These data are not yet available from the official statistics.

5 614 ICES WGNSSK REPORT 2009 G er many The sum of products of landings numbers at age and mean weights at age gave an SOP check of 0.67 for German landings data. Although the data for discards were incorporated into the spreadsheet, German discards and landings data were not used for raising because of this SOP discrepancy. Sw eden Swedish discards sampling is carried out in the fisheries that discard the most. The data submitted for Sweden noted that the shrimp fishery is not well covered by sampling and that this may present a problem. The Swedish haddock discards data Division IIIa(N) have been included in the collation, but not used for raising purposes this follows the same procedure as last year C atc h Official landings data for each country participating in the fishery are presented in Table , together with the corresponding WG estimates and Total Allowable Catch (TAC). The full time series of landings, discards and industrial by-catch (IBC) is presented in Table These data are illustrated further in Figure The total landed yield of the international fishery changed little between 2007 and The WG estimates (Table ) suggest that discarding decreased substantially during 2008, which may be due in part to the growth beyond the minimum landing size of the moderate 2005 year-class. Subarea IV discard estimates are derived from data submitted by several countries. As Scotland is the principal haddock fishery in that area, Scottish discard practices dominate the overall estimates. Industrial bycatch (IBC) has declined considerably from the high levels observed until the late 1990s Age compositions Total catch-at-age data are given in Table , while catch-at-age data for each catch component are given in Tables The fishery in 2008 (landings for human consumption) was strongly reliant on the moderate 2005 year-class, although the strong 1999 year-class is still present in the plus-group. It is interesting to note that the plus-group in 2007 and 2008 is larger than at any time since the mid-1970s: this is the result of the combination of the large 1999 year-class and low fishing mortality in recent years. Discards predominantly consist of medium-sized fish aged 2 and 3 (from the 2006 and 2005 year-classes respectively). Vessels seldom exhaust their quota in this fishery, and discarding behaviour is thought to be driven by a complicated mix of economic and other market-driven factors Weight at age Weight-at-age for the total catch in the North Sea is given in Table Weight-atage in the total catch is a number-w eighted average of weight-at-age in the human consumption landings, discards and industrial bycatch components. Weight-at-age in the stock is assumed to be the same as weight-at-age in the total catch. The mean weights-at-age for the separate catch components are given in Tables and are illustrated in Figure : this shows the declining trend in weights-at age for older ages, as well as evidence for reduced growth rates for large year classes.

6 ICES WGNSSK REPORT Maturity and natural mortality Maturity and natural mortality are assumed to be fixed over time and are given below. The basis for these estimates is described in the Stock Annex. Ag e Natural mortality Proportion mature C atc h, effort and research vessel data Survey distribution and annual density at age for recent years is given in Figure for the IBTS Q1 survey. Figure gives the equivalent survey distribution for the ScoGFS Q3 survey alone. All plots show a north to north-westerly distribution of haddock. The strong 1999 year class and (to a lesser extent) the moderate 2000 and 2005 year classes can also be identified and tracked through time. Data available for calibration of the assessment are presented in Table , including commercial data from Scottish fleets which are not currently used in the assessment (see below ). The IBTS Q1 data are shown as collated, including the plusgroup (ages 6 and older) which cannot be used in standard XSA tuning. XSA also cannot use data from the current year (2009). For this reason, the IBTS Q1 data are backshifted before being used in XSA that is, all ages and years are reduced by one, and the survey is considered to have taken place at the very end of the previous year. Trends in survey indices are shown in Figure These indicate reasonably good consistency in stock signals from different surveys. Commercial data on landings per unit effort (LPUE) from two Scottish fleets are summarised in Figure , from which the influence of the strong 1999 year-class is again apparent. Figure shows recorded (nominal) effort for these fleets. However, it must be remembered that effort recording is not mandatory in the EU, and these data must be viewed with caution (see also ICES-WGNSSK, 2000). The data available are summarised in the following table: data used in the final assessment are highlighted in bold. Country Fleet Qua rte r Code Yea r ra nge Scotla nd Se ine All ScoSe i Light trawl All ScoLTR Groundfish Q3 ScoGFS_ABDN s urve y 1997 England Inte rna tiona l Groundfish s urve y Groundfish s urve y Groundfish s urve y Groundfish s urve y Groundfish s urve y Q3 ScoGFS_GOV Q3 EngGFS_GRT Q3 EngGFS_GOV Q1 IBTS Q1 IBTS (backshifte d) Age ra nge available Age ra nge use d

7 616 ICES WGNSSK REPORT Data analyses The intention for this year was to perform an update assessment; that is, to carry out the same procedure as last year. This has been done using FLXSA (the FLR implementation of XSA) as the main assessment method. Separable VPA results are presented along with catch curves and intra-series correlations to check for data consistency and validity. The results of a SURBA analysis are also shown, to corroborate the update assessment Reviews of last year s ass es sm ent At its meeting in May 2008, RGNSSK raised a number of issues. These are listed below, along with the WG response and actions taken (if applicable). 3 ) It seems that a reduction of effort has been produced in recent years. If an effective reduction of effort occurred, this could be help in order to obtain some external information to elucidate the differences obtained in recent trends of Fs estimates from different models applied A full analysis of effort trends in the relevant fisheries has not yet been undertaken by the WG. 4 ) One of the main concerns of the RG is still the mean weight at age as it was pointed out by the RG in This in combination with plus group problems (mainly for large year-classes) and doubts on goodness of fit affecting to SSB estimates can be producing certain instability to the system in terms of perception of the stock and forecasts. The EG is conscious about this problems and propose alternatives, as it was done last year (in coherence with update status), to reduce the possible impact in terms of assessment and advice. However, it seems that is accepted by the EG the influence of dependent effects of large year-classes on growth and maturity (e.g YCs) when in fact is just a plausible possibility. It also happens the same for the moderate 2000 YC. This is not so clear for the highest 1967 and high 1974 YCs. It should be preferable first to check if this growth pattern is more a sampling effect than a population effect. It should be desirable to screen the length and/or weight distributions at age in AL(W)K and/or AL(W)Ds mainly for years effects observed in older ages for 1999 and 2007 (and adjacent years) considering weight at age as a quality control tool about: reading problems, weights parameters used, sampling coverage, raising procedures etc. The WG welcomes these comments and suggestions, and is similarly keen to improve growth modelling for haddock and other stocks. One of several initiatives in this area is a PhD studentship at the University of Aberdeen in Scotland, co-supervised by the WG member responsible for the haddock assessment. How ever, suitable methods are not yet available to allow the WG to build such growth modeling into forecast considerations. The points which have not been addressed here need to be considered during the forthcoming benchmark meeting for North Sea haddock, a date for which has not yet been set (see Section 13.9) Exploratory catch-at-age-based analyses The catch-at-age data, in the form of log-catch curves linked by cohort (Figure ), indicates partial recruitment to the fishery up to age 2. Gradients between consecutive values within a cohort from ages 2 to 7 have reduced for recent cohorts,

8 ICES WGNSSK REPORT reflecting a reduction in fishing mortality. Recent catch curves have also lost much of the regularity of more historical catch curves, which may reflect the lower sample size available from reduced landings. Figure plots the negative gradient of straight lines fitted to each cohort over the age range 2 4, which can be viewed as a rough proxy for average total mortality for ages 2 4 in the cohort. These negative gradients are also lower in recent cohorts except for an apparent rise in the 2004 cohort. Cohort correlations in the catch-at-age matrix (plotted as log-numbers) are shown in Figure These correlations show good consistency within cohorts up to the plus-group, verifying the ability of the catch-at-age data to track relative cohort strengths (although data for ages 0 and 1 are slightly more variable). Residuals from a separable VPA carried out on the catch data (Figure ) show very few outliers, and none greater than ±3. This supports the conclusion that catch data are reasonably consistent. Single-fleet XSAs for the final assessment were produced to investigate the sensitivity of XSA to the effects of tuning by individual fleets. Results are shown in Figure for the latter halves of the EngGFS Q3 and ScoGFS Q3 series, as w ell as for the IBTS Q1 series, w ith corresponding log-catchability residual plots shown in Figure Overall trends are similar for the three tuning fleets, but absolute levels differ towards the end of the time series with the ScoGFS series producing higher estimates of F and lower estimates of SSB Exploratory survey-bas ed analyses A SURBA run was carried out using the same combination of tuning indices as in the update XSA assessments, except that the IBTS Q1 survey was not backshifted. The summary plot from this run is given is Figure The stock trends are in broad agreement with those from the XSA assessment. The main exceptions are total mortality, which is estimated to have risen much more quickly during before falling in 2007 (the rise in the very last year is an artefact of the model); and SSB which appears to have recovered considerably in 2007 and 2008 with the growth of the moderate 2005 year-class. The SURBA estimates of recruitment confirm that yearclasses since 2005 have been poor. The IBTS Q1 indices from 2009 are available, but cannot be used directly to indicate recruitment for the 2009 year-class as the survey takes place too early for these juveniles to be caught. Log catch curves for the survey indices are given in Figure Overall, these show good tracking of cohort strength, although there is a tendency for reduced survey catchability on younger ages (shown by the hooks at the start of many of the curves). Cohort correlations in the index-at-age matrices (plotted as log-numbers) are shown in Figure These correlations show good consistency for nearly all of the cohorts and ages used in the final assessment (with a few minor exceptions) C onc lusions drawn from exploratory analyses Exploratory analyses using survey and catch data do not indicate any serious problems with these data for North Sea haddock. One main methodological issue remains which has not yet been addressed. The update assessment sets the maximum iterations for the FLXSA algorithm to a high value (200), so that the iteration process continues until the algorithm has converged. However, doing this also increases the final-year SSB considerably (see, for example, Figure ). FLXSA (and XSA) has no goodness-of-fit criteria, and it is not clear what the correct approach should be in

9 618 ICES WGNSSK REPORT 2009 this situation. In this year s assessment the previous method has been retained, but the WG has concerns about its validity which need to be addressed in any subsequent benchmark (Section 13.9) Final assessment The final XSA assessment uses the following settings, which are the same as those used last year (except for the addition of another year of data). XSA settings from a number of recent years are compared in the Stock Annex. Assessm ent year 2009 q plateau 6 Tuning fleet EngGFS Q ; year ranges ScoGFS Q ; IBTS Q1* Tuning fleet EngGFS Q3 0-7 age ranges ScoGFS Q3 0-7 IBTS Q1* 0-4 *Bac kshifted The final XSA assessment tuning diagnostics are presented in Table , with logcatchability residuals given in Figure , and a comparison of fleet-based contributions to survivors in Figure Fishing mortality estimates for the final XSA assessment are presented in Table , the stock numbers in Table , and the assessment summary in Table and Figure A retrospective analysis, shown in Figure , indicates little retrospective bias in the assessment Historical Stock Trends The historical stock and fishery trends are presented in Figure Landings yield has stabilised since 2000, partly due (in the most recent years) to the limitation of inter-annual TAC variation to ±15% in the EU-Norway management plan. Discards have fluctuated considerably in the same period due to the appearance and subsequent growth of the 1999 and 2005 year-classes, while industrial bycatch (IBC) is now at a very low level for haddock (see also Figure ). The estimated fishing mortality for 2008 has continued the reduction seen in 2007, and is now estimated to be below the management plan target of 0.3. Fluctuations around the target F rate of the management plan are an expected consequence of the lag betw een data collection and management action, and should not be taken to indicate that the plan is not working. The year-classes have been weak, and the fishery is likely to be sustained (over the short term at least) by the 2005 year-class. The final XSA assessment indicates a reduction in the rate of decline of SSB as the 2005 year-class starts to make an impact on spawning biomass Recruitment estimates There are no indications of incoming year-class strength available to the WG. The ScoGFS and EngGFS Q3 survey indices are not yet available. The IBTS Q1 indices are available, but do not include age-0 recruiting fish as these are too small to be caught (or are not yet hatched) when the survey takes place. For this reason, recruitment estimates of the 2009 year-class are based on a mean of previous recruitment.

10 ICES WGNSSK REPORT In the past, a strong year-class has generally been followed by a sequence of low recruitments (Figure ). In order to take this feature into account, the geometric mean of the five lowest recruitment values over the period (4067 million) has been assumed for recruitment in Recruitment estimates for 2007 and 2008 are not included in this calculation, because the two most recent XSA estimates of recruitment are thought to be relatively uncertain. The following table summarises the recruitment, age 1 and age 2 assumptions for the short term forecast. Year cl ass Age in 2009 XS A estimat e (millions) Geom etr ic mean o f 5 lowest recruitments Age 0 in Age 0 in Short-term forecasts Weights-at-age The perceived slow growth of the above-average 1999 and 2000 year-classes continues to pose a problem for the short-term forecast. Mean stock weights for these year classes were calculated using proportional increments. That is: growth from age a to a+1 for these year-classes was estimated using the mean proportional increment (a+1)/a calculated over all other year classes for which this information is available. This method was approved by RGNSSK in 2006 as being appropriate to project weights at age, although alternatives are being explored and the issue needs to be considered at a forthcoming benchmark. Mean stock weights for other ages (except the plus-group) in the forecast where taken as a 5-year average ( ), omitting the 1999 and 2000 year classes from the calculation where appropriate. For the plusgroup weights, an alternative XSA assessment was run using a plus-group at age 13. The abundances and fishing mortality estimates from this were then used as the basis for a simple deterministic 3-year forecast to give abundances from ages for These were then used in turn in weighted-average calculations to generate the required forecast mean weights for the plus-group at age 8. The outcome is summarized in Figure The human consumption mean weights at age were derived in the same manner as for the stock weights-at-age (see Figure ). However, mean weights at age for the 1999 and 2000 year classes did not show unusual growth in the discard and industrial bycatch components, so future mean weights-at-age w ere set to the average for the years for these components. Fishing mortality The 2007 and 2008 WG reports contained extensive analyses and discussion on the exploitation pattern to be used in the forecasts, exploring the hypothesis that moderate-to-large cohorts would experience a different pattern to small cohorts. In both reports, the WG concluded that there was only weak evidence for using anything other than the exploitation pattern from the final historical year in the assessment. In the spirit of the update process, the 2008 fishing mortality-at-age pattern is used for all years in the forecast in the current report. However, this conclusion may not hold

11 620 ICES WGNSSK REPORT 2009 for future cohorts, and the WG recommends that a forthcoming benchmark process explores this issue further. Status quo F is assumed to be the mean F(2 4) for 2008 only. Given the choice of fishing-mortality rates discussed above, partial fishing mortality values were obtained for each catch component (human consumption, discards and bycatch) by using the relative contribution (averaged over ) of each component to the total catch. Forecast results The inputs to the short-term forecast are presented in Table Results for the short-term forecasts are presented in Table The forecast has been run subject to a TAC constraint in 2009 (so that landings yield is restricted to the agreed quota of t). Running the forecast assuming status quo F in the intermediate year leads to landings in 2009 that are greater than the quota. Recent experience (see Table ), and reports from the fishing industry, indicate that full uptake of the quota in 2009 is unlikely. While it is difficult to predict the extent of the undershoot, it would certainly be an error to forecast an overshoot, so a TAC-constrained forecast is a compromise. Assuming a TAC constraint in 2009 and status quo F in 2010, SSB is expected to fall to 171 kt in 2010, and again in 2011 to 167 kt. In this case, human consumption yield will be around 27 kt in 2010, with associated discards of 6 kt. The continued decline in SSB, which will occur despite a fall in 2008 in both F and discard rates, is the result of low recruitment in recent years the 2005 year-class is the only reasonably strong cohort out of the last eight. Tw o alternative options have been highlighted in Table : a forecast allowing for a 15% decrease in the 2009 TAC (which is the maximum decrease allowed under the management plan when SSB > Bpa), and a forecast with total fishing mortality fixed to the level specified in the EU-Norway management plan (F = 0.3). Under the first of these options, 2010 landings yield of 38 kt and discards of 9 kt lead to SSB in 2011 of 154 kt. Under the second, 2010 landings yield of around 32 kt and discards of 7 kt lead to SSB in 2011 of 161 kt. All of these SSB forecasts for 2011 are above Bpa (140 kt), but the trend in SSB is downwards and this will continue unless a strong year-class appears. The following table compares the intermediate-year (2008) forecast from the 2008 WG with the 2008 observations and assessment results from the 2009 WG: WG Landings 2008 F(landings) 2008 Discards 2008 F(dis car ds) 2008 SSB forecast assessment All these values have been assessed to be less than previously predicted. SSB in 2009 could be less because a) the mean w eight-at-age of fish in the forecast was greater than subsequently observed, or b) the numbers of fish in the forecast were overestimated. Figure shows that forecast weights were actually less than subsequently observed weights. Therefore the forecast numbers must have been too high. While the difference is relatively small, the reason for it is presently unclear, and will need to be addressed at a forthcoming benchmark.

12 ICES WGNSSK REPORT Medium-term forecasts and yield-per-recruit analyses No medium-term forecasts have been carried out for this stock. However, management simulations over the medium-term period have been performed for haddock (most recently by Needle 2008a,b), as discussed briefly in Section above. The results of a yield-per-recruit analysis (run using MFYPR) are shown in Figure and Table There is no maximum in the yield-per-recruit curve over the specified range of mean F2-4, so Fmax is undefined. An equilibrium analysis such an yield-per-recruit can be difficult to interpret for a stock like haddock with sporadic large recruitments Biological reference points Biological reference points for this stock are given in the Stock Annex Quality of the assessment Survey data are consistent both within and between surveys, and the catch data are internally consistent. Trends in mortality from catch data and survey indices are quite similar, although surveys do indicate higher mortality in recent years. Only minor changes were made to the data collation or assessment methodology from last year s assessment. There is very little retrospective bias. The stock estimates from the current and previous assessments are compared in Figure Several issues remain of some concern with the assessment, and will need to be addressed during the forthcoming benchmark process:- 1 ) Haddock growth appears to vary by cohort, with large cohorts in particular growing more slowly than small cohorts. The pragmatic solution of applying proportional increments as a basis for predicting the weight at age for the 1999 and 2000 year classes incorporates the history of growth in the stock, while recognising the slow growth rate of these cohorts. However, intersessional work (not presented here) has suggested that alternative growth models may be more appropriate, and these need to be explored further. 2 ) In a similar vein, the proportion of mature individuals in each age-class is likely to vary by year and cohort. The effect of using year specific maturity data obtained from surveys should be considered, as well as methods by which this can be modeled in forecasts. The same consideration applies to estimates of natural mortality (M); biannually-updated values of M are now used in the assessment for North Sea cod, for example (see Section 14). 3 ) Exploitation rates also vary by cohort. The implications of this for forecasting should be addressed. 4 ) It is likely that haddock will continue to experience sporadic large yearclasses. The problem of how to accommodate these year-classes in the plus-group structure of the assessment will therefore not go away, and a robust approach is needed that will remove the requirement to change the plus-group whenever a large year-class enters it. 5 ) The SSB estimates generated by the XSA/FLXSA model is strongly dependent (for haddock) on the number of algorithm iterations permitted. Interim results suggest that changes of ±40% or more are possible. There is no

13 622 ICES WGNSSK REPORT 2009 goodness-of-fit statistic in XSA which would help in the determination of the most suitable number of iterations, so the choice becomes essentially ad hoc. This is not a satisfactory situation and will have to be remedied. Alternative models should be explored. 6 ) Survey indices from the IBTS Q1 series have traditionally been supplied by ICES using a 6+ age group. Information on large year-classes at ages older than 5 is therefore lost from the tuning process. The WG recommends that ICES supply these data for a greater true age range, and that the implications of this be explored in the benchmark assessment. 7 ) The haddock assessment uses separate Scottish and English Q3 groundfish survey series, rather than the combined IBTS Q3 series. The former are longer, but the latter has more sample points and should there be less variable. This choice should be considered in detail. 8 ) The relationship betw een forecasts produced by the WG in one year and assessments generated in the next year needs to be checked. The brief analysis carried out above suggests that there may be a degree of inconsistency, and this issue needs to be explored. 9 ) A longer time-series of discard data from UK(E&W) was made available this year (see Section 13.2). Its inclusion in the overall discard estimation procedure is a question that should be resolved Status of the Stock The historical perception of the haddock stock remains unchanged from last year s assessment. Fishing mortality is now estimated to have fallen further (from 0.41 in 2007 to 0.25 in 2008) and is now close to the historical minimum. This is well below Fpa (0.7), and is also lower than the mortality rate recommended in the management plan (0.3). Discards have also decreased in 2008, possibly due to the growth past the MLS of fish of the 2005 year-class. Spawning stock biomass (203 kt in 2008) is predicted to have continued in its decline from its peak in , but remains above Bpa (140 kt). SSB is forecast to fall further to 195 kt in 2009 despite low F and reduced discards: this is due to the appearance of only one moderate year-class in the last eight years. At current levels of fishing mortality, SSB is likely to continue to decline from 2010 onwards unless a moderate-to-strong year-class appears. The yearclasses are estimated to be w eak, and there is no information yet on the 2009 yearclass. Figure gives the results of the North Sea stock survey from The industry perception of haddock abundance in the main haddock fishing areas (1 and 2) is of stabilization, which concurs with the indications from the assessment of a temporary slowing of the rate of decline in SSB with the growth of the 2005 year-class Management Considerations In 2006 the EU and Norway agreed a revised management plan for this stock, which states that every effort will be made to maintain a minimum level of SSB greater than t (Blim). Furthermore, fishing will be restricted on the basis of a TAC consistent with a fishing mortality rate of no more than 0.30 for appropriate age groups, along with a limitation on interannual TAC variability of ±15%. Following a minor revision in 2008, interannual quota flexibility ( banking and borrowing ) of up to ±10% is permitted (although this facility has not yet been used).

14 ICES WGNSSK REPORT The stipulations of the management plan have been adhered to by the EU and Norway since its implementation in Fishing mortality fell while the 1999 year-class dominated the fishery, and this year-class was allowed to contribute to the fishery and the stock for much longer than if the plan had not been in place. SSB has declined as the 1999 year-class has passed out of the stock, although the rate of the decline has been slowed by low fishing mortality rates and the appearance of the moderate 2005 year-class. F now appears to fluctuating around the target level (0.3) as predicted by management evaluations. Adherence to the EU Norway management plan has contributed to increased yield and greatly improved stability of yield, along with a much lower average fishing mortality level. The decline in SSB has been slowed temporarily by the growth of the moderatelysized 2005 year class, but this year-class is smaller than the 1999 year-class and is unlikely to contribute very strongly to SSB for many years to come. Short-term forecasts indicate a continued decline in SSB in the future until the next significant recruitment event. Keeping fishing mortality close to the target level would be preferable to encourage the sustainable exploitation of the 2005 year-class. As this year-class entered the fishery, discards were fairly substantial in 2006 and 2007, although they were considerably lower in Further improvements to gear selectivity measures, allowing for the release of small fish, would be highly beneficial not only for the haddock stock, but also for the survival of juveniles of other species that occur in mixed fisheries along with haddock. Similar considerations also apply to spatial management approaches (such as real-time closures), and other measures intended to reduce unwanted bycatch and discarding of various species (such as the Scottish Conservation Credits scheme). Short-term forecasts indicate a continued decline in SSB in the future until the next significant recruitment event. How ever, SSB is predicted to remain above Bpa until 2011 at fishing mortality levels below Fpa, and for even longer under the agreed management plan. Haddock is a specific target for some fleets, but is also caught as part of a mixed fishery catching cod, whiting and Nephrops. It is important to consider both the speciesspecific assessments of these species for effective management, as well as the latest developments in the mixed fisheries approach. This is not straightforward when stocks are managed via a series of single-species management plans that do not incorporate mixed-stocks considerations. How ever, a reduction in effort on one stock may lead to a reduction or an increase in effort on another, and the implications of any change need to be considered carefully. Estimates of the catch of haddock as a bycatch in the industrial fisheries have been included in the short-term forecast option table. They indicate that industrial bycatch will be negligible. These estimates are more unreliable than would have been the case in the past and it is likely that they underestimate the likely level in 2009 and 20q0. This is because they are based on average exploitation over the previous three years. During this period industrial fisheries with bycatches of haddock have been either closed or operating at a much reduced level, and this may no longer be the case. References ICES-WGFTFB, Report of the ICES -FAO Wo rking Group on Fishing Technology and Fish Behaviour. ICES CM 2006/FTC:06.

15 624 ICES WGNSSK REPORT 2009 ICES-WGFTFB, Report of the ICES -FAO Wo rking Group on Fishing Technology and Fish Behaviour. ICES CM 2007/FTC:06. ICES-WGFTFB, Report of the ICES-FAO Wo rking Group on Fishing Technology and Fish Behaviour. ICES CM 2008/FTC:02. ICES -WGNSSK, Report of the ICES Working Group for the Assessment of Demersal S tocks in the North S ea and S kagerrak. ICES CM 2000/ACFM:XXXX. Needle, C. L., 2008a. Evaluation of interannual quota flexibility for North Sea haddock: Final report. Wo rking paper for the ICES Advisory Committee (ACOM), S eptember Needle, C. L., 2008b. Management strategy evaluation for North Sea haddock. Fisheries Research, 94(2):

16 ICES WGNSSK REPORT Table Haddock in Subarea IV and Division IIIa. Nominal landings (000 t) during , as officially reported to, and estimated by, ICES, along with WG estimates of catch components, and TACs. Landings estimates for 2008 are preliminary. Sum of Landings Year ICES area Country Division IIIa Belgium Denmark Faeroe Islands Germany Netherlands Norway Portugal Sweden UK - Eng+Wales+N.Irl UK - Scotland Division IIIa Total WG Division IIIa WG estimates of discards WG estimates of IBC WG estimates of landings WG estimates of total catch WG Division IIIa Total Subarea IV Belgium Denmark Faeroe Islands France Germany Greenland Ireland Netherlands Norway Poland Portugal Sweden UK - Eng+Wales+N.Irl UK - Scotland UK - all Subarea IV Total WG Subarea IV WG estimates of discards WG estimates of IBC WG estimates of landings WG estimates of total catch WG Subarea IV Total TAC TAC IIIa TAC IV TAC Total

17 626 ICES WGNSSK REPORT 2009 Table Haddock in Subarea IV and Division IIIa. Working Group estimates of catch components by weight (000 tonnes). Subarea IV Division IIIa(N) Combined Year Landings Discards IBC Total Landings Discards IBC Total Landings Discards IBC Total Min Mean Max denotes missing data.

18 ICES WGNSSK REPORT Table Haddock in Subarea IV and Division IIIa. Numbers at age data (thousands) for total catch. Data used in the assessment are highlighted in bold

19 628 ICES WGNSSK REPORT 2009 Table Haddock in Subarea IV and Division IIIa. Numbers at age data (thousands) for landings. Data used in the assessment are highlight ed in bold

20 ICES WGNSSK REPORT Table Haddock in Subarea IV and Division IIIa. Numbers-at-age data (thousands) for discards. Data used in the assessment are highlighted in bold

21 630 ICES WGNSSK REPORT 2009 Table Haddock in Subarea IV and Division IIIa. Numbers-at-age data (thousands) for IBC. Data used in the assessment are highlighted in bold

22 ICES WGNSSK REPORT Table Haddock in Subarea IV and Division IIIa. Mean weight at age data (kg) for total catch. Data used in the assessment are highlighted in bold

23 632 ICES WGNSSK REPORT 2009 Table Haddock in Subarea IV and Division IIIa. Mean weight at age data (kg) for landings. Data used in the assessment are highlighted in bold

24 ICES WGNSSK REPORT Table Haddock in Subarea IV and Division IIIa. Mean weight at age data (kg) for discards. Data used in the assessment are highlighted in bold

25 634 ICES WGNSSK REPORT 2009 Table Haddock in Subarea IV and Division IIIa. Mean weight at age data (kg) for IBC. Data used in the assessment are highlighted in bold

26 ICES WGNSSK REPORT Table Haddock in Subarea IV and Division IIIa. Data available for calibration of the assessment. Data used in the final assessment are highlighted in bold. EngGFS Q3 GRT. Period: Effort EngGFS Q3 GOV. Period: Effort

27 636 ICES WGNSSK REPORT 2009 Table Haddock in Subarea IV and Division IIIa. Data available for calibration of the assessment. Data used in the final assessment are highlighted in bold. ScoGFS Aberdeen Q3. Period: Effort ScoGFS Q3 GOV. Period: Effort IBTS Q1. Period Effort

28 ICES WGNSSK REPORT Table Haddock in Subarea IV and Division IIIa. Data available for calibration of the assessment. Data used in the final assessment are highlighted in bold. ScoLTR_IV. Period: 0-1 Effort

29 638 ICES WGNSSK REPORT 2009 Table Haddock in Subarea IV and Division IIIa. Data available for calibration of the assessment. Data used in the final assessment are highlighted in bold. ScoSEI_IV. Period: 0-1 Effort

30 ICES WGNSSK REPORT Haddock in Subarea IV and Divis ion IIIa. XSA final assessment: Tuning di- Table agnostics. FLR XSA Diagnostics :11:25 CPUE data from x.idx Catch data for 46 years to Ages 0 to 8. fleet first age last age first year last year alpha beta 1 EngGFS Q3 GRT EngGFS Q3 GOV ScoGFS Aberdeen Q ScoGFS Q3 GOV IBTS Q1 (backshifted) Time series weights : Tapered time weighting not applied Catchability analysis : Catchability independent of size for ages > 0 Catchability independent of age for ages > 6 Terminal population estimation : Survivor estimates shrunk towards the mean F of the final 5 years or the 3 oldest ages. S.E. of the mean to which the estimates are shrunk = 2 Minimum standard error for population estimates derived from each fleet = 0.3 prior weighting not applied Regression weights year age all Fishing mortalities year age XSA population number ( thousands ) age year

31 640 Table cont. Tuning diagnostics. Haddock in Subarea IV and Division IIIa. XSA final assessment: Estimated population abundance at 1st Jan 2009 age year Fleet: EngGFS Q3 GRT Log catchability residuals. year age year age Mean log catchability and standard error of ages with catchability independent of year class strength and constant w.r.t. time Mean_Logq S.E_Logq Regression statistics Ages with q dependent on year class strength slope intercept Age Fleet: EngGFS Q3 GOV Log catchability residuals. year age NA year age

32 ICES WGNSSK REPORT Table cont. Tuning diagnostics. Haddock in Subarea IV and Division IIIa. XSA final assessment: Mean log catchability and standard error of ages with catchability independent of year class strength and constant w.r.t. time Mean_Logq S.E_Logq Regression statistics Ages with q dependent on year class strength slope intercept Age Fleet: ScoGFS Aberdeen Q3 Log catchability residuals. year age year age NA Mean log catchability and standard error of ages with catchability independent of year class strength and constant w.r.t. time Mean_Logq S.E_Logq Regression statistics Ages with q dependent on year class strength slope intercept Age Fleet: ScoGFS Q3 GOV Log catchability residuals. year age year age

33 642 Table cont. Tuning diagnostics. Haddock in Subarea IV and Division IIIa. XSA final assessment: Mean log catchability and standard error of ages with catchability independent of year class strength and constant w.r.t. time Mean_Logq S.E_Logq Regression statistics Ages with q dependent on year class strength slope intercept Age Fleet: IBTS Q1 (backshifted) Log catchability residuals. year age year age year age Mean log catchability and standard error of ages with catchability independent of year class strength and constant w.r.t. time Mean_Logq S.E_Logq Regression statistics Ages with q dependent on year class strength slope intercept Age Terminal year survivor and F summaries: Age 0 Year class = 2008 source survivors N scaledwts EngGFS Q3 GOV ScoGFS Q3 GOV IBTS Q1 (backshifted) fshk nshk

34 ICES WGNSSK REPORT Table cont. Tuning diagnostics. Haddock in Subarea IV and Division IIIa. XSA final assessment: Age 1 Year class = 2007 source survivors N scaledwts EngGFS Q3 GOV ScoGFS Q3 GOV IBTS Q1 (backshifted) fshk Age 2 Year class = 2006 source survivors N scaledwts EngGFS Q3 GOV ScoGFS Q3 GOV IBTS Q1 (backshifted) fshk Age 3 Year class = 2005 source survivors N scaledwts EngGFS Q3 GOV ScoGFS Q3 GOV IBTS Q1 (backshifted) fshk Age 4 Year class = 2004 source survivors N scaledwts EngGFS Q3 GOV ScoGFS Q3 GOV IBTS Q1 (backshifted) fshk Age 5 Year class = 2003 source survivors N scaledwts EngGFS Q3 GOV ScoGFS Q3 GOV IBTS Q1 (backshifted) fshk Age 6 Year class = 2002 source survivors N scaledwts EngGFS Q3 GOV ScoGFS Q3 GOV IBTS Q1 (backshifted) fshk Age 7 Year class = 2001 source survivors N scaledwts EngGFS Q3 GOV ScoGFS Q3 GOV IBTS Q1 (backshifted) fshk

35 644 Table Haddock in Subarea IV and Division IIIa. Estimates of fishing mortalit y at age from the final XSA assessment. Estimates refer to the full year (January December) except for age 0, for which the mortality rate given refers to the second half-year only (July December). AGE YEA R

36 ICES WGNSSK REPORT Table Haddock in Subarea IV and Divis ion IIIa. Estimates of stock numbers at age from the final XSA assessment. Estimates refer to January 1 st, except for age 0 for estimates refer to July 1 st. *Estimated survivors. AGE Y E AR E E E *

37 646 Table Haddock in Subarea IV and Division IIIa. Stock summary table. REC RUI TM EN T TSB SSB CATC H LA NDINGS DIS CARDS IBC YIEL D/SSB MEA N F(2-4) Units Thousands Tonnes Tonnes Tonnes Tonnes Tonnes Tonnes

38 ICES WGNSSK REPORT Table Haddock in Subarea IV and Division IIIa. Short-term forecast input. MFDP version 1a Run: had01 Time and date: 13:14 10/05/2009 Fbar age range (Total) : 2-4 Fbar age range Fleet 1 : 2-4 Fbar age range Fleet 2 : Age N M Mat PF PM SWt Catch Age Sel CWt DSel DCWt IBC Age Sel CWt Age N M Mat PF PM SWt Age N M Mat PF PM SWt Catch Catch Age Sel CWt DSel DCWt Age Sel CWt DSel DCWt IBC IBC Age Sel CWt Age Sel CWt Input units are thousands and kg - output in tonnes

39 648 ICES WGNSSK REPORT 2009 Table highlighted. Haddock in Subarea IV and Division IIIa. Short-term forecast output. The MP target F, a 15% TAC decrease, and the status quo F forecast are MFDP version 1a Run: had01 Time and date: 13:14 10/05/2009 Fbar age range (Total) : 2-4 Fbar age range Fleet 1 : 2-4 Fbar age range Fleet 2 : Catch Landings Discards IBC Landings Biomass SSB FMult Fbar FBar Yield FBar Yield FMult FBar Yield Catch Landings Discards IBC Landings Biomass SSB FMult Fbar FBar Yield FBar Yield FMult FBar Yield Biomass SSB (status quo) (plan target) (15% quota decrease) Input units are thousands and kg - output in tonnes

40 ICES WGNSSK REPORT Table analysis. Haddock in Subarea IV and Division IIIa. Summary of yield-per-recruit MFYPR version 2a Run: had01 Time and date: 14:34 10/05/2009 Yield per results FMult Fbar CatchNos Yield StockNos Biomass SpwnNosJan SSBJan pwnnosspwn SSBSpwn Reference point F multiplier Absolute F Fbar(2-4) FMax >= F F35%SPR Weights in kilograms

41 650 ICES WGNSSK REPORT 2009 Yield (000 tonnes) Landings Discards IBC Figure Haddock in Subarea IV and Division IIIa. Yield by catch component.

42 ICES WGNSSK REPORT Figure Haddock in Subarea IV and Division IIIa. Me an weights-at-age (kg) by catch component. Catch mean weights are also used as stock mean weights. Red dotted line give loess smoothers through each time-series of mean weights-at-age.

43 652 ICES WGNSSK REPORT 2009 Figure Haddock in Subarea IV and Division IIIa. Spatial distribut ion from the IBTS Q1 survey. Contour scale (given in the bar to the right) is the square root of survey CP UE, rescaled to lie between 0 and 1.

44 ICES WGNSSK REPORT Haddock, North Sea Groundfish Survey Q age 6 age 5 age 4 age 3 age 2 age 1 age 0 Numbers per 30 min Figure Haddock in Subarea IV and Division IIIa. Spatial distribution from the ScoGFS Q3 survey.

45 654 ICES WGNSSK REPORT 2009 Haddock, North Sea Groundfish Survey Q age 6 age 5 age 4 age 3 age 2 age 1 age 0 Numbers per 30 min Figure Haddock in Subarea IV and Division IIIa. Spatial distribution from the ScoGFS Q3 survey. (cont.)

46 ICES WGNSSK REPORT Figure effort) at age. Haddock in Subarea IV and Division IIIa. Survey log CP UE (catch per unit

47 656 ICES WGNSSK REPORT 2009 Figure Haddock in Subarea IV and Division IIIa. Commercial log LPUE (landings per unit effort) at age. Red lines: Scottish light trawl. Green lines: Scottish seine.

48 ICES WGNSSK REPORT Nominal hours fished by availa Scottish Light Trawl Scottish Seine 500 hours fished (000,s) Figure Haddock in Subarea IV and Division IIIa. Nominal hours fis hed by Scottish fleets, as provided to the WG. Recording of hours fis hed is not mandatory in European logbooks and is not considered to be a reliable indicator of deployed fis hing effort.

49 658 ICES WGNSSK REPORT 2009 Commercial Catch Data log-catch Figure catches. Haddock in Subarea IV and Division IIIa. Log catch curves by cohort for total

50 ICES WGNSSK REPORT Commercial Catch Data Ages 2 to negative gradient Figure Haddock in Subarea IV and Division IIIa. Negative gradients of log catches per cohort, averaged over ages 2-4. The x-axis represents spawning year of cohort.

51 660 ICES WGNSSK REPORT 2009 Figure Haddock in Subarea IV and Division IIIa. Correlations in the catch-at-age matrix (inc luding the plus-group for ages 8 and older), comparing estimates at different ages for the same year-classes (cohorts). In each plot, the straight line is a normal linear model fit: a thick line represents a significant (p < 0.05) regression, while a thin line is not significant. Approximate 95% confidence intervals for each fit are also shown.

52 ICES WGNSSK REPORT / 1 1/ 2 2/ 3 3/ 4 4/ 5 5/ 6 6/ Figure Haddock in Subarea IV and Division IIIa. Residuals from separable VPA analysis. The x-axis labels give the first year only of the actual year ratio used (so 1970 denotes 1970/1971). The y-axis labels for the lower plot give the first age only of the actual age ratio used (so 1 denotes 1/2). The area of the bubbles in the lower plot is proportional to the size of the residual.

53 662 ICES WGNSSK REPORT 2009 F(2-4) F(2-4) F(2-4) EngGFS ScoGFS IBTS SSB ('000 tonnes) SSB (000 tonnes) SSB Recruits at age 0 (million Recruitment Figure Haddock in Subarea IV and Division IIIa. Stock summary plots for singlefleet XSA runs. Only the more recent segments of the EngGFS and ScoGFS surveys have been used here. Final year (2008) values of SSB and mean F(2-4) are plotted against each other in the upper right plot.

54 ICES WGNSSK REPORT Figure Haddock in Subarea IV and Division IIIa. Log catchability residuals from single-fleet XSA runs. Only the more recent segments of the EngGFS and ScoGFS surveys have been used here.

55 664 ICES WGNSSK REPORT 2009 Mean total mortality Spawning stock biomass Mean Z ( 2-4) Mean-standardised SSB Year Year Total stock biomass Recruitment Mean-standardised TSB Mean-standardised recruitment at age Year Year Figure Haddock in Subarea IV and Division IIIa. Summary plots from an exploratory SURBA assessment, using all available surveys (EngGFS Q3, ScoGFS Q3, IBTS Q1). Solid lines give median estimates, dotted lines give approximate 95% confidence bounds for mean Z and recruitment.

56 ICES WGNSSK REPORT EngGFS Q3 GRT: log cohort abundance Log index Year EngGFS Q3 GOV: log cohort abundance 2 0 Log index Year Figure Haddock in Subarea IV and Division IIIa. Log abundance indices by cohort for each of the five survey indices.

57 666 ICES WGNSSK REPORT 2009 ScoGFS Aberdeen Q3: log cohort abundance Log index Year ScoGFS Q3 GOV: log cohort abundance Log index Year Figure Haddock in Subarea IV and Division IIIa. Log abundance indices by cohort for each of the five survey indices (cont.)

58 ICES WGNSSK REPORT IBTS Q1: log cohort abundance Log index Year Figure Haddock in Subarea IV and Division IIIa. Log abundance indices by cohort for each of the five survey indices (cont.).

59 668 ICES WGNSSK REPORT 2009 Figure Haddock in Subarea IV and Divis ion IIIa. Within-surve y correlations for the EngGFS (GRT) survey series, comparing index values at different ages for the same year-classes (cohorts). In each plot, the straight line is a normal linear model fit: a thick line represents a significant (p < 0.05) regression, while a thin line is not significant. Approximate 95% confidence intervals for each fit are also shown.

60 ICES WGNSSK REPORT Figure cont. Haddock in Subarea IV and Division IIIa. Within-survey correlations for the EngGFS (GOV) survey series, comparing index values at different ages for the same yearclasses (cohorts). In each plot, the straight line is a normal linear model fit: a thick line represents a significant (p < 0.05) regression, while a thin line is not significant. Approximate 95% confidence intervals for each fit are also shown.

61 670 ICES WGNSSK REPORT 2009 Figure cont. Haddock in Subarea IV and Division IIIa. Within-survey correlations for the ScoGFS (Aberdeen) survey series, comparing index values at different ages for the same year-classes (cohorts). In each plot, the straight line is a normal linear model fit: a thick line represents a significant (p < 0.05) regression, while a thin line is not significant. Approximate 95% confidence intervals for each fit are also shown.

62 ICES WGNSSK REPORT Figure cont. Haddock in Subarea IV and Division IIIa. Within-survey correlations for the ScoGFS (GOV) survey series, comparing index values at different ages for the same yearclasses (cohorts). In each plot, the straight line is a normal linear model fit: a thick line represents a significant (p < 0.05) regression, while a thin line is not significant. Approximate 95% confidence intervals for each fit are also shown.

63 672 ICES WGNSSK REPORT 2009 Figure cont. Haddock in Subarea IV and Division IIIa. Within-survey correlations for the IBTS Q1 survey series, comparing index values at different ages for the same year-classes (cohorts). In each plot, the straight line is a normal linear model fit: a thick line represents a significant (p < 0.05) regression, while a thin line is not significant. Approximate 95% confidence intervals for each fit are also shown.

64 ICES WGNSSK REPORT Figure Haddock in Subarea IV and Division IIIa. The effect of the number of XSA iterations carried out on final year population estimates (left-hand plots). The solid lines show results from FLXSA, while the red dots give results from a series of comparative XSA runs. The point of convergence is shown by blue dashed lines, while the red dashed lines show 30 iterations (which for many years was the standard stopping point for this assessment). The legends give equivalent estimates from SURBA, Laurec-Shepherd and separable VPA models. The righthand contour plots show differences over the full assessment time-series in biomass (db), fishing mortality (df) and recruitment (dr) between subsequent iterations. For this example, all the differences occur towards the end of the time-series. Note that this analysis has been carried out using the assessment from the 2008 WG report.

65 674 ICES WGNSSK REPORT 2009 Figure Haddock in Subarea IV and Division IIIa. Log catchability residuals for final XSA assessment. Both EngGFS and ScoGFS are split when used as tuning indices, and this split is shown by vertical lines on the relevant plots.

66 ICES WGNSSK REPORT n shrinkage F shrinkage ibts scogfs enggfs Figure Haddock in Subarea IV and Division IIIa. Contribution to survivors estimates in final XSA assessment.

67 676 ICES WGNSSK REPORT 2009 Figure Haddock in Subarea IV and Division IIIa. Summary plots for final XSA assessment. Dotted horizontal lines indicate Fpa (top right plot) and B pa (bottom left plot), while solid horizontal lines indicate Flim and B lim in the same plots.

68 ICES WGNSSK REPORT SSB (000 tonnnes) Mean F(2-4) Rec. at age 0 (millio 0e+00 2e+05 4e Figure Haddock in Subarea IV and Division IIIa. Eight-year retrospective plots for final XSA assessment.

69 678 ICES WGNSSK REPORT E YC = 1.36e8 5.00E+07 Recruitment at age 0 (000s) 4.00E E E E E Figure Haddock in Subarea IV and Divis ion IIIa. Estimated recruitment from the final XSA assessment for (black line), with 5 lowest values (pink dots) and geometric mean of these (red line).

70 ICES WGNSSK REPORT Total catch (stock) weight (kg) Mean forecast 2000 forecast Age Figure Haddock in Subarea IV and Division IIIa. Results of growth modelling for total catch weights (also used as stock weights) using proportional increments. Black line: arithmetic mean weight-at-age of cohorts (error bars give ±2 standard deviations). Red and purple lines: weights-at-age for the 1999 and 2000 cohorts respectively (solid = observed, dotted = forecast). Large red symbols indicate forecast weight for the 8+ group in 2009 (diamond), 2010 (triangle) and 2011 (circle).

71 680 ICES WGNSSK REPORT 2009 Landings weight (kg) Mean forecast 2000 forecast Age Figure Haddock in Subarea IV and Division IIIa. Results of growth modelling for human consumption landings using proportional increments. Black line: arithmetic mean weight-at-age of cohorts (error bars give ±2 standard deviations). Red and purple lines: weights-at-age for the 1999 and 2000 cohorts respectively (solid = observed, dotted = forecast). Large red symbols indicate forecast weight for the 8+ group in 2009 (diamond), 2010 (triangle) and 2011 (circle).

72 ICES WGNSSK REPORT Mean stock wts-at-age (kg) Mean stock wts-at-age (kg) Age Age 2008 WG forecast 2009 WG observation 2008 WG forecast 2009 WG forecast Mean stock wts-at-age (kg) Age 2008 WG forecast 2009 WG forecast Figure Haddock in Subarea IV and Division IIIa. Comparison of weights-at-age for from the 2008 WG, with the weights-at-age for from the 2009 WG. SSB-per-recruit Yield-per-recruit Mean F(2-4) Yield-per-recruit SSB-per-recruit Figure analysis. Haddock in Subarea IV and Division IIIa. Summary of yield-per-recruit

73 682 ICES WGNSSK REPORT 2009 Figure Haddock in Subarea IV and Division IIIa. Historical assessment quality plot.

74 ICES WGNSSK REPORT Figure Survey. Haddock in Subarea IV and Division IIIa. Results of 2008 North Sea Stock