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ICES CM 2004/ACFM:07 Advisory Committee on Fishery Management

Report of the

Working Group on the Assessment of Demersal Stocks in the North Sea and Skagerrak

9–18 September 2003

Boulogne-sur-Mer, France

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This report is not to be quoted without prior consultation with the General Secretary. The document is a report of an Expert Group under the auspices of the International Council for the Exploration of the Sea and does not necessarily represent the views of the Council.

Draft/Part 1

International Council for the Exploration of the Sea

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TECHNICAL MINUTES

Working Group on the Assessment of Demersal Stocks in the North Sea and Skagerrak (WGNSSK) ACFM October 2003

For the most part, comment has been made only on the benchmark assessments, although this is not exclusively so.

WGNSSK is commended on the thorough approach that it has taken with the benchmark assessments.

General Comments

1. There is a need to move many of the “standard” assessments undertaken by this working group to a more probabilistic approach, specifically towards more appropriate statistical methods with goodness-of-fit diagnostics, to permit a better understanding of the overall quality of the assessment;

2. SURBA is considered to be over-parameterised for use as a mainstream assessment method, but is considered to be useful for exploratory analyses;

3. The non-inclusion of discard data where large-scale discarding exists is problematic. The exploratory analyses that considered the sensitivity of the assessments to the exclusion of discard data is very valuable, but mainly points to the need to measure and include discard data in the assessments;

4. For the update assessments, the review group would have liked more information to be presented on the quality and consistency of the assessment in order to make an informed judgement on it. This does not require a complete evaluation of the data or model settings, just the straightforward presentation of graphical or tabular information.

However, the review group recognises that it is for ICES to give clear guidance of its expectations in this respect.

5. Please note the comments on age range truncations under each section. Especially read that for cod and sole.

Cod 347d

There was a lot of discussion relating to the reduction of the age range used in the assessment, particularly with regard to the cascade effects of having to revise biological reference points. It was accepted that a benchmark assessment is the appropriate time to address such issues, but the following points were made:

•

The change in age range made no substantive difference to the current or historical perception of the stock development;

•

Recent WGNSSK meetings have suggested that mean F should be quantified over ages 4-8 rather than the

“traditional” age range of 2-8. This was in part due to the inclusion of partially recruited ages in the estimate of mean F. Truncating the age range in the assessment at this year’s meeting has forced WGNSSK to adopt a truncated age range of 2-4. This contradicts the previous view of WGNSSK and gives greater relative weight to the partially recruited ages in the estimate of mean F. WGNSSK is requested to look more closely at the age range included in the assessment and over which mean F is calculated, specifically as it may be used to define the mean F that is taken forward into forecasts, including those used to estimate reference points based on long-term yield – a likely future requirement within ICES. Collapsing the age range in a highly truncated manner may distort the estimates of long-term yields and stock size that contribute to this estimation. Explicitly regarding the use of XSA, a trade-off may be possible in this respect if there is scope to live with shrinkage contributing to the calculation of survivors at the oldest age, as the influence of shrinkage on the stock estimates does not appear to be substantial;

•

Calculating mean F over ages 2-4 also means that it is being calculated over a juvenile age range of predominantly

immature fish. It would be useful to distinguish whether this is necessitated by the state of the stock and the

reduction in age-groups present in the stock, and is therefore an additional diagnostic regarding the state of the

stock, or whether it is only a side effect of the exclusion of commercial CPUE data in the calibration of the

assessment.

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•

The reason for not taking the analysis forward into forecast was queried, as the review group felt that the estimate of stock in the last year was more driven by the surveys than the 2002 catch-at-age data. Greater unease about the wisdom of going forward into a forecast was expressed with regard to uncertainties in the “middle” year of the assessment, 2003, when there were substantially greater grounds for uncertainty over the true level of catches and the appropriate fishing mortality rate and exploitation pattern to use as the basis for forecasting (given direct effort control in 2003 and the scale of “drop-down” of vessels from whitefish gear to Nephrops gear that resulted as a consequence of the more generous “Nephrops” days at sea allocations).

Haddock 34

•

A Working Document for ACFM, October 2003 by Coby Needle, FRS Marine Laboratory, about The effects of technical measures and assumptions about exploitation on short-term forecasts for North Sea haddock (Annex 1), was considered in addition to the WGNSSK report;

•

The earlier part of the English groundfish survey series was removed from the assessments of some stocks (due to a perceived step change in Z when the GOV trawl was adopted) but not from this one. WGNSSK is asked to confirm whether such consideration was given to the use of the earlier EGFS data for haddock, and if not, to give it such consideration;

•

The age range used in the assessment and calculation of mean F was addressed for haddock as for cod in 347d.

Similar considerations apply;

•

The trends and patterns in the XSA Ln(q) residuals imply this is not a very good assessment. This may be due to conflicts between the indices used, although this is recognised to be an issues of scale rather than direction (ie the relative magnitude of strong year classes as indicated by surveys rather than their qualitative indications of above average year classes). WGNSSK’s consideration of a similar inconsistency in scale between the surveys and the catch-at-age data is acknowledged. Although the residual plots imply a poor assessment, this does not seem to be a major problem in terms of the consistency of the assessment from last year to this – it was suggested that an assessment method that gives greater weight minimising the residuals of strong year classes (eg AMCI) could be explored for this stock;

•

Unlike the cod assessment, the F

lim

and F

pa

reference points were not updated in line with the new age-range used to calculate mean F.

Whiting 47d

•

A Working Document for ACFM, October 2003 by Coby Needle, FRS Marine Laboratory, about The effects of technical measures and assumptions about exploitation on short-term forecasts for North Sea whiting (Annex 2), was considered in addition to the WGNSSK report;

•

This assessment was rejected by ACFM. ICES has previously considered this assessment to be very uncertain due to inconsistent trends in the development of the stock as indicated (i) by conflicts between stock indices, and (ii) the high sensitivity of the catch-at-age analysis to annual updates. In recent years WGNSSK has tried to address this problem by presenting the results of a probabilistic assessment whose error bounds were considered to best encapsulate the overall uncertainty of the assessment. However, even this approach has failed this year to deal adequately with the high sensitivity of the catch-at-age analysis to the addition of a single year’s data. As the assessment is very sensitive both to the choice of model (and its specific formulation) and to the data included in the model, it suggests that the fundamental problem is data related and this will initially requires more exploration and evaluation of the data than of the model;

•

The same general concerns regarding age ranges to be used in the analysis were made for whiting as for cod in 347d. Similar considerations apply;

Sole Nsea

1. A Working document, ACFM October 2003 on Sole North Sea recruitment update by Sieto Verver, Loes Bolle, Olvin van Keeken, Martin Pastoors, 7/10/2003, Netherlands Institute for Fisheries Research, Ijmuiden, (Annex 3) was considered in addition to the WGNSSK report.

2. When changes are made to the catch-at-age model configuration, it is helpful to provide a clear indication of the

impact of that measure on the time-series, for example removing the “power” model on age 2 – although there is

an indication of its effect on terminal estimates, there is no indication of its effect on the time-series – if there is no

effect on the longer series (and there may not be) then it is helpful to make that clear;

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5. The age range truncation caused real problems in the re-evaluation of reference points for this stock in particular.

The mechanical repetition of what went before meant that the algorithm for re-estimating F

pa

was consistent with the original event, but the biomass values against which simulation outcomes were compared had not been changed (ie if a new B

lim

corresponding to current B

loss

(21kt) was selected as the reference biomass, then it is unlikely that F

pa

would have been revised downwards). Consequently the revision was not accepted, and this meant that none of the F reference value revisions were accepted.

Plaice Nsea

1. A Working document, ACFM October 2003 on Plaice North Sea recruitment update by Sieto Verver, Loes Bolle, Olvin van Keeken, Martin Pastoors, 7/10/2003, Netherlands Institute for Fisheries Research, Ijmuiden, (Annex 4) was considered in addition to the WGNSSK report.

2. Reviewers were unable to follow clearly the discussion of the likely reasons behind the change in perception of the state of this stock and the evaluation of the discard scenario simulations in particular. This required a lot of clarification by the Chair of WGNSSK. This was very important as the ACFM decisions on this stock were based on these aspects of the assessment;

3. The age range used in the assessment and calculation of mean F was addressed for plaice as it was for cod in 347d.

Similar considerations apply, and in the case of plaice were it has a dramatic effect on the scaling of historical stock size, it is clearly an insufficient age range to forecast into the medium to long-term future at low fishing mortality without explicit account being taken of the survival and growth into the individual ages comprising the plus-group.

Mixed Fisheries

The review group recognises that WGNSSK is well aware of the problems that it faces in providing mixed fisheries advice. However, it seeks to highlight two of those problems for attention.

•

Experience of fisheries-based advice in other parts of the world indicate that such provision is possible, but that it requires well-defined fisheries that are based on complete and reliable catch data. In the ICES case, model development has outstripped the provision of appropriate data both for defining fisheries and providing mixed fishery advice. Specifically, the lack of data on discards for most species is a principal concern. Although this is a weakness of many single-stock forecasts it is accentuated in a mixed fisheries context and may lead to inappropriate advice being given to the extent of mis-informing managers;

•

It will not always be possible to provide a framework of analytical forecasts for input into mixed fishery evaluation models such as MTAC. This provides a stimulus for the development of complementary processes that do not require an analytical short-term forecast to proceed.

Sandeel in IV

The WG is asked to evaluate possible in-season indicators of recruiting (1-group) sandeel abundance. The very poor

2003 fishery indicated extremely low abundance of 1-year-olds in 2002 and hence very low SSB in 2004. ACFM

struggled greatly to provide appropriate management advice given that the 2004 fishery will be dominated by 1-year-

olds from the 2003 year class. Given the likely low SSB in 2004 it was necessary to be adaptive in regard to the 2004

fishery and it advised low exploitation until the strength of the 2004 year class was evaluated. Salmon fisheries in many

areas are managed according to escapement policies based on in-season indicators of recruitment. The potential

development of this kind of approach should be explored by the WG. However, a pre-requisite to such an approach is a

reliable (early) in-season indicator of abundance.

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ANNEX 1

Working Document for ACFM, October 2003

The effects of technical measures and assumptions about exploitation on short-term forecasts for North Sea haddock

Coby Needle, FRS Marine Laboratory Introduction

This document continues the work outlined in the haddock section of the 2003 report of the ICES Working Group on the Assessment of Demersal Stocks in the North Sea and Skagerrak (in preparation). During the Working Group, time did not permit a full evaluation of the potential effect of recent technical measures and uncertainty regarding forecast exploitation patterns on haddock forecasts, and an undertaking was made to present appropriate results to ACFM at their October 2003 meeting. These results are given below, along with a resumé of the forecast methodology used.

Methods

The salient points for a short-term projection for haddock in this year’s assessment are as follows:

1. Mean F

2–4

is estimated to have declined during 2000–2002, so that F

sq

(the mean of the last three years) is likely to be an overestimate of F in 2003 and beyond if the trend persists. However, the estimate in the assessment of the strength of the 1999 year class is very uncertain, and terminal F is consequently also very uncertain. Hence F may not have declined in recent years as much as indicated by the assessment.

2. The large 1999 year class has been observed to be small for its age in the human consumption catch component, indicating density-dependent growth retardation. The use of a standard three-year mean for the weight of age-4 fish in 2003 is likely to bias SSB estimates upwards.

3. Several technical measures have been implemented for the mixed demersal fishery in the North Sea (see the WG report, section 4). These include square-mesh panels, restrictions on lifting bags, mesh-size changes and days-at- sea regulations. There have also been a significant number of vessels decommissioned in 2002 and 2003. These measures will have had (and continue to have) effects on both the exploitation pattern and effort exerted by the international fishery, which need to be accounted for in short-term projections and catch forecasts.

4. The 2003 TAC for North Sea haddock (55 kt) was intended to be restrictive, and have the effect of reducing fishing effort to a level commensurate with measures taken to protect the North Sea cod stock.

The standard forecasts methodology was modified in several ways to address these issues.

1. To allow for uncertainty in terminal-year F, three different bases for F in forecasts were explored:

• F(scaled), the mean exploitation pattern over the period 2000–2002, scaled to the level of estimated mean F2–4

in 2002.

• F(2002), the estimated exploitation pattern in 2002

• F(sq), the mean exploitation pattern over the period 2000–2002 (the status quo estimate).

2. The growth of the 1999 year class was modelled by fitting a logistic curve to observed weights for that year class for ages 1–3, and then projecting forward on the basis of the fitted model. This was done separately for each catch component (human consumption, discards, industrial by-catch). Fitting was done using the Solver package in Excel, and the model formulation used was

( )

1 1 exp

W

=

a bA

+ - (1.1)

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4. In the forecast presented in the Working Group report, the uptake of the derogation for 110 mm during 2002 (Commission Regulation EC 2056/2001) was taken to be 0%, so that all vessels in the fishery were assumed to have switched to a 120 mm mesh at the start of 2002. This would mean that the exploitation pattern estimated for 2002 in the historical assessment could be carried forward into the forecasts unchanged. However, if (for example) 100% of vessels had taken up the derogation and remained at 110 mm during 2002, then the exploitation pattern for forecasts would have to be altered to reflect the change at the start of 2003 for all vessels from 110 mm to 120 mm. The extent of the change in selectivity that would have to be incorporated depends on the derogation uptake, which is unknown but which clearly lies on a sliding scale between these two extremes. Modifications also have to be made to account for the likely effects of decommissioning and days-at-sea.

Hence, in the following analyses a wider range of alternatives were explored. The following selectivity parameters for haddock were supplied by FRS:

Selectivity Regulation L

50 L25 S1 S2

Sel1 EU 2000 24.8 22.6 12.384357 0.4993692

Sel2 EU 110 mm 28.7 26 11.677842 0.4068934

Sel3 EU 120 mm 32.1 29.05 11.562444 0.3602008

For each catch component, mean weights-at-age were converted to mean lengths-at-age using

1

W b

L rf a

æ ÷

= çççè ´ ÷÷ö

ø

(1.2)

where

b

and the raising factor (gutted to live weight conversion) rf . Selectivity vectors (Sel1, Sel2, Sel3) relevant to each of the pertinent regulations were calculated using mean lengths-at-age, the selectivity parameters given above, and the following model:

0.0157,

a

= = 2.8268, = 1.16

1 2

1 .

1 exp( )

S

=

S S L

+ - (1.3)

For each catch component and each F-forecast basis (2002, scaled 2002, or status quo), three forecast exploitation patterns were calculated. The first assumed 0% derogation uptake, so that the forecast F was unchanged. The second assumed 100% derogation uptake, so that the forecast exploitation pattern was multiplied by the ratio of Sel3 (120 mm) to Sel2 (110 mm). The third assumed 50% derogation uptake, and thus used the mean of the forecast

Fs from the first and second patterns. The forecast F-at-age in year y

was modified by the difference between the selection in 2002 (S

2002

) and that in year y (S

y

), using

Fy =F2002Sy S2002

. These F vectors were then used in short-term forecast runs, generated using the WGFRANSW program.

The final scenario modification concerned the potential effect of days-at-sea and decommissioning regulations.

The days-at-sea regulation of February 2003 limited fishing to 16 effective fishing days per month, implying a

~50% reduction in fishing mortality. In addition, Kunzlik (2003) estimated that 18% of effective fishing mortality

on haddock would have been removed during 2002 by decommissioning. If these measures had had the full

desired effect, the result would have been a 68% reduction in effective effort. The analyses described above were

therefore repeated assuming an effort multiplier of 0.32. This should probably be viewed as an upper limit on the

likely effect of the days-at-sea regulation and decommissioning: the actual impact of these measures is still to be

evaluated.

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derogation uptake gives lower SSB and landings than 100%. Finally, the effort multiplier of 0.32 greatly increases SSB and reduces landings.

All these conclusions would have been expected, given the exploitation patterns in Table 3. The interesting point is the relation between the forecast human consumption landings and the TAC, which is around 55 kt. The forecast presented in the WG report (run 1) indicates landings of 159 kt in 2003, just under three times the TAC. We should reiterate that the TAC was intended to be restrictive, so we would expect landings at the usual forecast Fs to be higher than the quota.

The extent to which predicted landings exceed the TAC is surprising, however. If this was the true level of landings, then the fleets would have exhausted their quotas during the spring. However, there have been no reports (anecdotal or otherwise) to indicate that this has happened: the latest data on the Scottish commercial fleets show that reported quota uptake as of September 2003 was around 70%. There are several possible reasons for this anomaly. For example:

1. The 1999 year class has been overestimated in the assessment, meaning that the starting point for abundance in the forecast is too high.

2. The fish are being caught, but discards have been underestimated and/or landings have been misreported.

3. Recent technical measures have had an effect, so that the basis for the forecast F being used (F(scaled), F(2002) or

F(sq)) is no longer appropriate.

The WG were unable to determine definitively which of these (or which combination of these) is leading to the apparent overestimation of landings. However, the forecast runs (see Table 2) with F(scaled) as a basis and an effort multiplier of 0.32 (thus assuming the full possible impact of decommissioning and days-at-sea regulations) give forecast landings in 2003 of between 49.2 kt and to 58.8 kt, which would be consistent with the agreed TAC. It is unlikely that the effort reduction due to the days-at-sea regulation would be as high as 50%, certainly not in 2003 given that the regulation only commenced in a piecemeal fashion in February, so the effort multiplier used here (0.32) is probably too low. However, the fact that the landings are consistent with the TAC, combined with the perception that the industry have not yet exhausted their haddock quota, implies that the reported effort reduction is of this approximate magnitude. If this is not all due to technical measures, as appears likely, then it is probably due to a combination of the three points listed above.

In conclusion: a standard forecast, making no allowances for recent regulations, results in forecast landings for 2003 that are three times the TAC. The industry have not reported exhausation of quota, so this standard forecast does not appear to be appropriate. Assuming that the regulations have had their full possible effect results in forecast landings for 2003 that are roughly equal to the TAC. However, it is overly optimistic to expect that the regulations have been able to have their full effect yet. Therefore, the estimated landings in 2003 will probably be somewhat higher than the TAC. This could be because of under-reporting, or because the historical estimate of the strength of the 1999 year class was too high, or a combination of both. Given this, it would be inappropriate to present any one of these forecasts as a reliable short-term prognosis of the haddock stock, the future development of which must remain uncertain.

References

Kunzlik, P. (2003) Calculation of potential reduction in fishing mortality of North Sea and west of Scotland cod, haddock and whiting due to decommissioning of UK vessels in 2002. Working Document 6 to the ICES Working Group on the Assessment of Northern Shelf Demersal Stocks.

Table 1

Haddock in Subarea IV and Division IIIa. Fitted growth curve parameter estimates, and projected mean weight-at-age (kg) for age 4 using both the growth model and a simple three-year mean, for the 1999 year class in total catches and three catch components.

Component

a b

Growth model 3-year mean

Total catch 2.565 0.616 0.474 0.497

Human consumption 1.060 0.212 0.447 0.524

Discards 2.278 0.430 0.364 0.326

Industrial by-catch 3.575 0.879 0.485 0.366

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Table 2

Haddock in Subarea IV and Division IIIa. Input data for catch forecast and linear sensitivity analysis for run 1 (F(scaled) basis, 0% derogation uptake, no effort multiplier, as in the WG report).

Label Value CV Label Value CV Number-at-age Weight in the stock N0 6233448 1.22 WS0 0.03 0.61 N1 573688 0.41 WS1 0.11 0.15 N2 45989 0.17 WS2 0.24 0.09 N3 316671 0.14 WS3 0.33 0.09 N4 898062 0.12 WS4 0.47 0.06 N5 5423 0.15 WS5 0.68 0.08 N6 2250 0.19 WS6 0.76 0.16 N7 2098 0.20 WS7 1.17 0.07 H.cons selectivity Weight in the HC catch sH0 0.00 0.00 WH0 0.00 0.00 sH1 0.00 0.64 WH1 0.34 0.12 sH2 0.05 0.83 WH2 0.38 0.11 sH3 0.22 0.65 WH3 0.42 0.05 sH4 0.47 0.28 WH4 0.45 0.05 sH5 0.38 0.08 WH5 0.69 0.08 sH6 0.35 0.83 WH6 0.77 0.15 sH7 0.34 0.83 WH7 1.21 0.11 Discard selectivity Weight in the discards sD0 0.00 1.08 WD0 0.04 0.20 sD1 0.01 0.64 WD1 0.14 0.19 sD2 0.05 0.83 WD2 0.22 0.09 sD3 0.05 0.65 WD3 0.29 0.07 sD4 0.02 0.28 WD4 0.36 0.07 sD5 0.00 0.08 WD5 0.37 0.03 sD6 0.00 0.83 WD6 0.10 1.73 sD7 0.00 0.83 WD7 0.26 0.87 Industrial selectivity Weight in Ind. by-catch sI0 0.01 1.08 WI0 0.03 0.85 sI1 0.03 0.64 WI1 0.07 0.15 sI2 0.02 0.83 WI2 0.14 0.24 sI3 0.04 0.65 WI3 0.19 0.46 sI4 0.01 0.28 WI4 0.48 0.03 sI5 0.00 0.08 WI5 0.36 0.37 sI6 0.00 0.00 WI6 0.00 0.00 sI7 0.00 0.00 WI7 0.00 0.00 Natural mortality Proportion mature M0 2.05 0.03 MT0 0.00 0.10 M1 1.65 0.05 MT1 0.01 0.10 M2 0.40 0.07 MT2 0.32 0.10 M3 0.25 0.19 MT3 0.71 0.10 M4 0.25 0.12 MT4 0.87 0.10 M5 0.20 0.17 MT5 0.95 0.10 M6 0.20 0.10 MT6 1.00 0.10 M7 0.20 0.10 MT7 1.00 0.00

Relative effort Year effect for natural mortality in HC fishery

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Table 3

Haddock in Subarea IV and Division IIIa. Exploitation patterns for alternative short-term forecasts.

Age Run 1 Run 2 Run 3 Run 4 Run 5 Run 6 Run 7 Run 8 Run 9

0 0.000 0.000 0.000 0.000 0.000 0.000 0.000 0.000 0.000

1 0.002 0.002 0.001 0.006 0.005 0.004 0.002 0.002 0.001

2 0.049 0.042 0.036 0.032 0.028 0.023 0.118 0.102 0.086

3 0.220 0.197 0.174 0.096 0.086 0.075 0.480 0.429 0.379

4 0.474 0.434 0.394 0.615 0.563 0.511 0.842 0.771 0.700

5 0.382 0.377 0.372 0.577 0.569 0.562 0.624 0.615 0.607

6 0.350 0.347 0.344 0.395 0.392 0.389 0.708 0.702 0.697

7 0.336 0.336 0.336 0.354 0.354 0.354 0.696 0.696 0.696

0 0.000 0.000 0.000 0.001 0.001 0.001 0.001 0.001 0.001

1 0.024 0.017 0.010 0.033 0.028 0.022 0.040 0.033 0.026

2 0.123 0.088 0.053 0.113 0.097 0.082 0.240 0.207 0.175

3 0.114 0.087 0.060 0.111 0.099 0.087 0.223 0.199 0.176

4 0.058 0.049 0.040 0.045 0.041 0.037 0.111 0.101 0.092

5 0.008 0.007 0.006 0.002 0.002 0.002 0.016 0.016 0.016

6 0.001 0.001 0.000 0.000 0.000 0.000 0.003 0.003 0.003

7 0.014 0.010 0.007 0.041 0.041 0.041 0.015 0.015 0.015

0 0.012 0.012 0.013 0.031 0.033 0.034 0.013 0.014 0.015

1 0.045 0.037 0.030 0.122 0.101 0.080 0.050 0.042 0.033

2 0.030 0.026 0.022 0.011 0.009 0.008 0.078 0.068 0.057

3 0.070 0.062 0.055 0.003 0.003 0.003 0.135 0.121 0.107

4 0.020 0.019 0.017 0.056 0.051 0.047 0.023 0.021 0.019

5 0.003 0.003 0.003 0.008 0.008 0.008 0.003 0.003 0.003

6 0.000 0.000 0.000 0.000 0.000 0.000 0.000 0.000 0.000

7 0.000 0.000 0.000 0.000 0.000 0.000 0.000 0.000 0.000

Age Run 10 Run 11 Run 12 Run 13 Run 14 Run 15 Run 16 Run 17 Run 18

0 0.000 0.000 0.000 0.000 0.000 0.000 0.000 0.000 0.000

1 0.001 0.001 0.000 0.002 0.001 0.001 0.001 0.001 0.000

2 0.016 0.014 0.011 0.010 0.009 0.007 0.038 0.033 0.027

3 0.070 0.063 0.056 0.031 0.027 0.024 0.153 0.137 0.121

4 0.152 0.139 0.126 0.197 0.180 0.164 0.270 0.247 0.224

5 0.122 0.121 0.119 0.185 0.182 0.180 0.200 0.197 0.194

6 0.112 0.111 0.110 0.126 0.125 0.124 0.226 0.225 0.223

7 0.108 0.108 0.108 0.113 0.113 0.113 0.223 0.223 0.223

0 0.000 0.000 0.000 0.000 0.000 0.000 0.000 0.000 0.000

1 0.004 0.003 0.002 0.011 0.009 0.007 0.013 0.011 0.008

2 0.015 0.011 0.007 0.036 0.031 0.026 0.077 0.066 0.056

3 0.015 0.011 0.008 0.035 0.032 0.028 0.071 0.064 0.056

4 0.007 0.006 0.005 0.014 0.013 0.012 0.035 0.032 0.029

5 0.001 0.001 0.001 0.001 0.001 0.001 0.005 0.005 0.005

6 0.000 0.000 0.000 0.000 0.000 0.000 0.001 0.001 0.001

7 0.001 0.001 0.001 0.013 0.013 0.013 0.005 0.005 0.005

0 0.003 0.004 0.004 0.010 0.010 0.011 0.004 0.005 0.005

1 0.009 0.007 0.006 0.039 0.032 0.026 0.016 0.013 0.011

2 0.006 0.005 0.004 0.003 0.003 0.002 0.025 0.022 0.018

3 0.011 0.010 0.009 0.001 0.001 0.001 0.043 0.039 0.034

4 0.004 0.004 0.003 0.018 0.016 0.015 0.007 0.007 0.006

5 0.001 0.001 0.001 0.003 0.003 0.002 0.001 0.001 0.001

6 0.000 0.000 0.000 0.000 0.000 0.000 0.000 0.000 0.000

7 0.000 0.000 0.000 0.000 0.000 0.000 0.000 0.000 0.000

Forecast exploitation pattern

Human consumption landingsDiscardsIndustrial bycatchDiscardsIndustrial bycatch

Forecast exploitation pattern

Human consumption landings

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Table 4

Haddock in Subarea IV and Division IIIa. Results from short-term forecasts run under 18 different configurations. All estimates are in thousand tonnes.

Run number Basis 2004 2005 2003 2004 2003 2004 2003 2004

1 F scaled 0% 1.00 368.0 271.0 159.0 116.0 9.0 3.0 7.0 3.0

2 F scaled 50% 1.00 383.0 286.0 148.0 118.0 7.0 3.0 7.0 3.0

3 F scaled 100% 1.00 399.0 302.0 136.0 119.0 6.0 2.0 6.0 3.0

4 F 2002 0% 1.00 322.0 201.0 172.0 133.0 20.0 6.0 21.0 10.0

5 F 2002 50% 1.00 338.0 215.0 161.0 136.0 18.0 6.0 19.0 9.0

6 F 2002 100% 1.00 355.0 230.0 150.0 139.0 16.0 5.0 18.0 9.0

7 F sq 0% 1.00 231.0 133.0 239.0 107.0 36.0 10.0 13.0 4.0

8 F sq 50% 1.00 250.0 147.0 225.0 113.0 34.0 10.0 12.0 4.0

9 F sq 100% 1.00 271.0 162.0 211.0 120.0 31.0 9.0 11.0 4.0

10 F scaled 0% 0.32 499.0 468.0 58.8 57.2 3.2 1.3 2.5 1.1

11 F scaled 50% 0.32 506.0 477.0 54.0 56.3 2.6 1.0 2.3 1.0

12 F scaled 100% 0.32 512.0 485.0 49.2 55.3 2.0 0.7 2.1 1.0

13 F 2002 0% 0.32 476.0 423.0 67.5 76.3 7.2 2.6 7.8 3.9

14 F 2002 50% 0.32 484.0 432.0 62.3 75.5 6.5 2.3 7.3 3.7

15 F 2002 100% 0.32 492.0 442.0 57.1 74.6 5.9 2.1 6.7 3.4

16 F sq 0% 0.32 430.0 369.0 101.0 79.0 15.0 5.0 5.0 2.0

17 F sq 50% 0.32 441.0 381.0 92.9 78.7 13.7 4.8 4.8 1.8

18 F sq 100% 0.32 452.0 394.0 85.1 78.3 12.4 4.4 4.4 1.7

Discards Industrial bycatch Derogation

uptake

Effort multiplier

SSB Human cons. landings

(12)

Table 5a

Haddock in Subarea IV and Division IIIa. Management option table from run 1.

+---+

| Year | | 2003 | 2004 | +---+---+---+---+---+---+---+---+---|

| Mean F Ages | | | | | | | | | | H.cons 2 to 4 | 0.29| 0.00| 0.11| 0.23| 0.29| 0.34| 0.46| 0.57|

| Ind BC 2 to 4 | 0.02| 0.02| 0.02| 0.02| 0.02| 0.02| 0.02| 0.02|

| | | | | | | | | | | Effort relative to 2002 | | | | | | | | | | H.cons | 1.00| 0.00| 0.40| 0.80| 1.00| 1.20| 1.60| 2.00|

| Ind BC | 1.00| 1.00| 1.00| 1.00| 1.00| 1.00| 1.00| 1.00|

+---+---+---+---+---+---+---+---+---|

| Biomass | | | | | | | | | | Total 1 January | 611| 496| 496| 496| 496| 496| 496| 496|

| SSB at spawning time | 457| 368| 368| 368| 368| 368| 368| 368|

| | | | | | | | | | | Catch weight (,000t) | | | | | | | | | | H.cons | 159| 0| 52| 96| 116| 134| 167| 195|

| Discards | 9| 0| 1| 3| 3| 4| 5| 6|

| Ind BC | 7| 3| 3| 3| 3| 3| 3| 3|

| Total Landings | 166| 3| 55| 99| 119| 137| 170| 198|

| Total Catch | 175| 3| 56| 102| 122| 141| 175| 204|

| | | | | | | | | | | Biomass in year.... 2005 | | | | | | | | | | Total 1 January | | 516| 458| 410| 388| 368| 333| 303|

| SSB at spawning time | | 396| 340| 293| 271| 252| 218| 189|

+---+---+---+---+---+---+---+---+---+

+---+

| Year | | 2003 | 2004 | +---+---+---+---+---+---+---+---+---|

| Effort relative to 2002 | | | | | | | | | | H.cons | 1.00| 0.00| 0.40| 0.80| 1.00| 1.20| 1.60| 2.00|

| Ind BC | 1.00| 1.00| 1.00| 1.00| 1.00| 1.00| 1.00| 1.00|

+---+---+---+---+---+---+---+---+---+

| | | | | | | | | | | Est. Coeff. of Variation | | | | | | | | | | | | | | | | | | | | Biomass | | | | | | | | | | Total 1 January | 0.11| 0.29| 0.29| 0.29| 0.29| 0.29| 0.29| 0.29|

| SSB at spawning time | 0.14| 0.21| 0.21| 0.21| 0.21| 0.21| 0.21| 0.21|

| | | | | | | | | | | Catch weight | | | | | | | | | | H.cons | 0.29| 0.00| 0.54| 0.29| 0.25| 0.23| 0.20| 0.19|

| Discards | 0.35| 0.00| 0.69| 0.53| 0.51| 0.50| 0.50| 0.51|

| Ind BC | 0.64| 0.81| 0.83| 0.84| 0.85| 0.86| 0.87| 0.89|

| | | | | | | | | | | Biomass in year.... 2005 | | | | | | | | | | Total 1 January | | 0.31| 0.34| 0.36| 0.38| 0.39| 0.42| 0.45|

| SSB at spawning time | | 0.23| 0.25| 0.26| 0.26| 0.26| 0.27| 0.28|

+---+---+---+---+---+---+---+---+---+

(13)

Table 5b

Haddock in Subarea IV and Division IIIa. Detailed forecast table from run 1.

Forecast for year 2003 F multiplier H.cons=1.00 F multiplier Indust=1.00

Populations Catch number

+----+---+ +---+---+---+---+

| Age| Stock No. | | H.Cons |Discards|By-catch| Total|

+----+---+ +---+---+---+---+

| 0| 6233448| | 0| 772| 27837| 28609|

| 1| 573688| | 563| 3716| 7450| 11729|

| 2| 45989| | 1761| 1692| 665| 4118|

| 3| 316671| | 53543| 11280| 8581| 73404|

| 4| 898062| | 298242| 13016| 8214| 319472|

| 5| 5423| | 1567| 13| 7| 1587|

| 6| 2250| | 605| 1| 0| 605|

| 7| 2098| | 545| 8| 0| 553|

+----+---+ +---+---+---+---+

| Wt| 611| | 159| 9| 7| 175|

+----+---+ +---+---+---+---+

Forecast for year 2004 F multiplier H.cons=1.00 F multiplier Indust=1.00

Populations Catch number

+----+---+ +---+---+---+---+

| Age| Stock No. | | H.Cons |Discards|By-catch| Total|

+----+---+ +---+---+---+---+

| 0| 6233448| | 0| 772| 27837| 28609|

| 1| 793812| | 779| 5142| 10309| 16230|

| 2| 105602| | 4044| 3884| 1527| 9456|

| 3| 27491| | 4648| 979| 745| 6372|

| 4| 182416| | 60579| 2644| 1668| 64892|

| 5| 421143| | 121653| 1029| 556| 123238|

| 6| 3016| | 811| 1| 0| 811|

| 7| 2520| | 655| 9| 0| 664|

+----+---+ +---+---+---+---+

| Wt| 496| | 116| 3| 3| 122|

+----+---+ +---+---+---+---+

(14)

Table 6a

Haddock in Subarea IV and Division IIIa. Management option table from run 2.

+---+

| Year | | 2003 | 2004 | +---+---+---+---+---+---+---+---+---|

| Ind BC 2 to 4 | 0.02| 0.02| 0.02| 0.02| 0.02| 0.02| 0.02| 0.02|

| Ind BC | 1.00| 1.00| 1.00| 1.00| 1.00| 1.00| 1.00| 1.00|

+---+---+---+---+---+---+---+---+---|

| Discards | 7| 0| 1| 2| 3| 3| 4| 5|

| Ind BC | 7| 3| 3| 3| 3| 3| 3| 3|

| Total Landings | 154| 3| 55| 100| 120| 139| 173| 202|

| Total Catch | 162| 3| 56| 102| 123| 142| 177| 206|

+---+---+---+---+---+---+---+---+---+

+---+

| Year | | 2003 | 2004 | +---+---+---+---+---+---+---+---+---|

| Ind BC | 1.00| 1.00| 1.00| 1.00| 1.00| 1.00| 1.00| 1.00|

+---+---+---+---+---+---+---+---+---+

| Discards | 0.35| 0.00| 0.67| 0.49| 0.47| 0.46| 0.46| 0.47|

| Ind BC | 0.64| 0.83| 0.84| 0.86| 0.87| 0.87| 0.89| 0.90|

+---+---+---+---+---+---+---+---+---+

(15)

Table 6b

Haddock in Subarea IV and Division IIIa. Detailed forecast table from run 2.

Forecast for year 2003 F multiplier H.cons=1.00 F multiplier Indust=1.00

Populations Catch number

+----+---+ +---+---+---+---+

| Age| Stock No. | | H.Cons |Discards|By-catch| Total|

+----+---+ +---+---+---+---+

| 0| 6233448| | 0| 600| 29533| 30133|

| 1| 573688| | 467| 2613| 6183| 9263|

| 2| 45989| | 1537| 1225| 580| 3343|

| 3| 316671| | 48745| 8786| 7813| 65344|

| 4| 898062| | 278479| 11245| 7670| 297393|

| 5| 5423| | 1550| 11| 7| 1568|

| 6| 2250| | 601| 0| 0| 601|

| 7| 2098| | 545| 6| 0| 551|

+----+---+ +---+---+---+---+

| Wt| 611| | 148| 7| 7| 162|

+----+---+ +---+---+---+---+

Forecast for year 2004 F multiplier H.cons=1.00 F multiplier Indust=1.00

Populations Catch number

+----+---+ +---+---+---+---+

| Age| Stock No. | | H.Cons |Discards|By-catch| Total|

+----+---+ +---+---+---+---+

| 0| 6233448| | 0| 600| 29533| 30133|

| 1| 793352| | 646| 3613| 8551| 12810|

| 2| 106560| | 3562| 2838| 1345| 7745|

| 3| 28117| | 4328| 780| 694| 5802|

| 4| 189422| | 58738| 2372| 1618| 62727|

| 5| 440140| | 125784| 915| 575| 127274|

| 6| 3032| | 810| 1| 0| 811|

| 7| 2525| | 656| 7| 0| 663|

+----+---+ +---+---+---+---+

| Wt| 513| | 118| 3| 3| 123|

+----+---+ +---+---+---+---+

(16)

Table 7a

Haddock in Subarea IV and Division IIIa. Management option table from run 3.

+---+

| Year | | 2003 | 2004 | +---+---+---+---+---+---+---+---+---|

| Ind BC 2 to 4 | 0.02| 0.02| 0.02| 0.02| 0.02| 0.02| 0.02| 0.02|

| Ind BC | 1.00| 1.00| 1.00| 1.00| 1.00| 1.00| 1.00| 1.00|

+---+---+---+---+---+---+---+---+---|

| Discards | 6| 0| 1| 2| 2| 2| 3| 3|

| Ind BC | 6| 3| 3| 3| 3| 3| 3| 2|

| Total Landings | 142| 3| 56| 101| 122| 141| 175| 205|

| Total Catch | 148| 3| 56| 103| 124| 143| 178| 208|

+---+---+---+---+---+---+---+---+---+

+---+

| Year | | 2003 | 2004 | +---+---+---+---+---+---+---+---+---|

| Ind BC | 1.00| 1.00| 1.00| 1.00| 1.00| 1.00| 1.00| 1.00|

+---+---+---+---+---+---+---+---+---+

| Discards | 0.35| 0.00| 0.63| 0.44| 0.42| 0.41| 0.40| 0.40|

| Ind BC | 0.66| 0.85| 0.87| 0.88| 0.89| 0.90| 0.91| 0.93|

+---+---+---+---+---+---+---+---+---+

(17)

Table 7b

Haddock in Subarea IV and Division IIIa. Detailed forecast table from run 3.

Forecast for year 2003 F multiplier H.cons=1.00 F multiplier Indust=1.00

Populations Catch number

+----+---+ +---+---+---+---+

| Age| Stock No. | | H.Cons |Discards|By-catch| Total|

+----+---+ +---+---+---+---+

| 0| 6233448| | 0| 428| 31229| 31657|

| 1| 573688| | 371| 1502| 4908| 6781|

| 2| 45989| | 1309| 748| 494| 2551|

| 3| 316671| | 43771| 6203| 7015| 56989|

| 4| 898062| | 257870| 9400| 7102| 274372|

| 5| 5423| | 1533| 9| 7| 1549|

| 6| 2250| | 597| 0| 0| 597|

| 7| 2098| | 545| 4| 0| 549|

+----+---+ +---+---+---+---+

| Wt| 611| | 136| 6| 6| 148|

+----+---+ +---+---+---+---+

Forecast for year 2004 F multiplier H.cons=1.00 F multiplier Indust=1.00

Populations Catch number

+----+---+ +---+---+---+---+

| Age| Stock No. | | H.Cons |Discards|By-catch| Total|

+----+---+ +---+---+---+---+

| 0| 6233448| | 0| 428| 31229| 31657|

| 1| 792892| | 513| 2076| 6783| 9372|

| 2| 107526| | 3060| 1749| 1155| 5964|

| 3| 28758| | 3975| 563| 637| 5175|

| 4| 196697| | 56480| 2059| 1556| 60094|

| 5| 459994| | 130032| 788| 595| 131415|

| 6| 3049| | 809| 0| 0| 810|

| 7| 2530| | 658| 4| 0| 662|

+----+---+ +---+---+---+---+

| Wt| 530| | 119| 2| 3| 124|

+----+---+ +---+---+---+---+

(18)

Table 8a

Haddock in Subarea IV and Division IIIa. Management option table from run 4.

+---+

| Year | | 2003 | 2004 | +---+---+---+---+---+---+---+---+---|

| Ind BC 2 to 4 | 0.02| 0.02| 0.02| 0.02| 0.02| 0.02| 0.02| 0.02|

| Ind BC | 1.00| 1.00| 1.00| 1.00| 1.00| 1.00| 1.00| 1.00|

+---+---+---+---+---+---+---+---+---|

| Discards | 20| 0| 3| 5| 6| 8| 10| 12|

| Ind BC | 21| 11| 11| 10| 10| 10| 9| 9|

| Total Landings | 193| 11| 73| 122| 143| 161| 193| 218|

| Total Catch | 212| 11| 76| 127| 149| 169| 202| 230|

+---+---+---+---+---+---+---+---+---+

+---+

| Year | | 2003 | 2004 | +---+---+---+---+---+---+---+---+---|

| Ind BC | 1.00| 1.00| 1.00| 1.00| 1.00| 1.00| 1.00| 1.00|

+---+---+---+---+---+---+---+---+---+

| Discards | 0.36| 0.00| 0.71| 0.56| 0.54| 0.54| 0.54| 0.55|

| Ind BC | 0.62| 0.79| 0.81| 0.84| 0.85| 0.86| 0.88| 0.90|

+---+---+---+---+---+---+---+---+---+

(19)

Table 8b

Haddock in Subarea IV and Division IIIa. Detailed forecast table from run 4.

Forecast for year 2003 F multiplier H.cons=1.00 F multiplier Indust=1.00

Populations Catch number

+----+---+ +---+---+---+---+

| Age| Stock No. | | H.Cons |Discards|By-catch| Total|

+----+---+ +---+---+---+---+

| 0| 6233448| | 0| 1547| 80500| 82047|

| 1| 573688| | 1488| 8858| 32317| 42663|

| 2| 45989| | 1132| 3970| 379| 5480|

| 3| 316671| | 24260| 28068| 816| 53144|

| 4| 898062| | 354090| 25887| 32322| 412298|

| 5| 5423| | 2165| 8| 30| 2203|

| 6| 2250| | 670| 0| 0| 670|

| 7| 2098| | 560| 64| 0| 624|

+----+---+ +---+---+---+---+

| Wt| 611| | 172| 20| 21| 212|

+----+---+ +---+---+---+---+

Forecast for year 2004 F multiplier H.cons=1.00 F multiplier Indust=1.00

Populations Catch number

+----+---+ +---+---+---+---+

| Age| Stock No. | | H.Cons |Discards|By-catch| Total|

+----+---+ +---+---+---+---+

| 0| 6233448| | 0| 1547| 80500| 82047|

| 1| 777734| | 2017| 12008| 43812| 57838|

| 2| 93793| | 2308| 8097| 772| 11177|

| 3| 26393| | 2022| 2339| 68| 4429|

| 4| 200049| | 78876| 5766| 7200| 91842|

| 5| 341805| | 136476| 508| 1889| 138873|

| 6| 2469| | 735| 0| 0| 735|

| 7| 2399| | 640| 74| 0| 714|

+----+---+ +---+---+---+---+

| Wt| 445| | 133| 6| 10| 149|

+----+---+ +---+---+---+---+

(20)

Table 9a

Haddock in Subarea IV and Division IIIa. Management option table from run 5.

+---+

| Year | | 2003 | 2004 | +---+---+---+---+---+---+---+---+---|

| Ind BC 2 to 4 | 0.02| 0.02| 0.02| 0.02| 0.02| 0.02| 0.02| 0.02|

| Ind BC | 1.00| 1.00| 1.00| 1.00| 1.00| 1.00| 1.00| 1.00|

+---+---+---+---+---+---+---+---+---|

| Discards | 18| 0| 3| 5| 6| 7| 9| 11|

| Ind BC | 19| 11| 10| 10| 9| 9| 9| 8|

| Total Landings | 181| 11| 74| 124| 146| 165| 198| 224|

| Total Catch | 199| 11| 76| 129| 151| 172| 206| 235|

+---+---+---+---+---+---+---+---+---+

+---+

| Year | | 2003 | 2004 | +---+---+---+---+---+---+---+---+---|

| Ind BC | 1.00| 1.00| 1.00| 1.00| 1.00| 1.00| 1.00| 1.00|

+---+---+---+---+---+---+---+---+---+

| Discards | 0.36| 0.00| 0.70| 0.54| 0.52| 0.51| 0.51| 0.52|

| Ind BC | 0.63| 0.79| 0.82| 0.84| 0.85| 0.86| 0.88| 0.90|

+---+---+---+---+---+---+---+---+---+

(21)

Table 9b