ICES NWWG REPORT

Transcription

1 ICES NWWG REPORT Icelandic cod 9.1 Summary The spawning stock (SSB2014) is estimated to be 427 kt and is higher than has been observed over the last five decades. The reference biomass (B4+\,2014) is estimated to be 1106 kt, the highest observed since the late 1970 s. Fishing mortality, being 0.3 in 2013, has declined significantly in recent years and is presently the lowest observed in last 6 decades. Year classes since the mid-1980s are estimated to be relatively stable but with the mean around the lower values observed in the period 1955 to According to the adopted management harvest rule the TAC will be 218 kt in the next fishing season. ICES has evaluated the plan and concludes that it is in accordance with the precautionary approach and the ICES MSY framework. Mean weight at age in the stock and the catches that were record low in have been increasing in recent years and are now around the long term mean. The input in the analytical assessments are catch at age and spring groundfish survey (SMB) indices at age from and fall survey groundfish survey (SMH) indices at age from The results from the AD-Model builder statistical Catch at Age Model (ADCAM) as was used as the final run, as done in the previous year. No changes were made in the model set-up compared with that applied last year. The reference stock (B4+) in 2013 is now estimated to be 1161 kt compared to 1173 kt last year. The SSB in 2013 is now estimated to be 437 kt compared to 479 kt estimated last year. Fishing mortality in 2012 is now estimated 0.28 compared to 0.28 estimated last year. Year classes were estimated to be 119, 183 and 151 million in last years assessment and are now estimated to be 123, 181 and 160 millions. 9.2 Stock description and management units The Icelandic cod stock is distributed all around Iceland and in the assessment cod within Icelandic EEZ waters it is assumed to be a single homogeneous unit in the assessment. Spawning takes place in late winter mainly off the south west coast but smaller, variable regional spawning components have also been observed all around Iceland. A slight but significant genetic difference has been observed between the cod spawning in the northern waters vs cod spawning in the southern waters (Pampoulie et al 2007). There are indications that different behavioural type (shallow vs. deep migration) may be found within cod spawning in the same areas (Pampoulie et al 2008). Both these information indicate that management measurements operating on a finer scale may be warranted, although appropriate non-ambiguous management measure in addition to maintaining low fishing mortality have not yet been identified. The pelagic eggs and larvae from the main spawning grounds off the south west coast drift clockwise around the island to the main nursery grounds off the north coast. A larval drift to Greenland waters has been recorded in some years and substantial immigrations of mature cod from Greenland which are considered to be of Icelandic origin have been observed in some periods. This pattern was quite prevalent prior to 1970, while condition in Greenlandic waters are thought to have been favourable for cod productivity. Periodic immigrations have been estimated in the assessment from anomalies in the catch at age matrix with timing and age of such events being based on expert judgement using external informations. The most recent of such migration was from the 1984 year class in 1990, the number estimated around 30 millions. Recent

2 282 ICES NWWG REPORT 2014 tagging experiments as well as abnormal decline in survey indices in West Greenlandic waters indicate that part of the 2003 and to some extent the 2002 year classes may have migrated from Greenland to Icelandic waters. In the current assessment the immigration at age 6 in 2009 is estimated around 9.7 millions corresponding an additional biomass of around 31 kt in The influence of this immigration on the current biomass estimate is minimal. Extensive tagging experiments spanning with some hiatuses over the last 100 year indicate that significant emigration from Iceland to other areas may be rare. In recent years it has been observed that cod tagged in Iceland has been recaptured inside Faroese waters close to the EEZ line separating Iceland and the Faroes islands. Anecdotal informations from the fishing industry indicate that may be some exchange of cod across the Denmark Strait. These migrations may be of different nature than the hypothesised net life history immigration of cod described above. 9.3 Data The data used for assessing Icelandic cod landings, catch-at-age composition and indices from standardized bottom trawl surveys. The sampling programs i.e log books, surveys, sampling from landings etc. have been described in previous reports Catch: Landings, discards and misreporting Landings in 2013 Landings of Icelandic cod in 2013 are estimated to have been kt (Table Error: Reference source not found and Figure Error: Reference source not found). Of the total landings kt were taken by Icelandic fleet and the remainder by other nations. The landings by month and gear metier are as follows (Gear code - 1: Longline, 2: Gillnet, 3: Hooks, 5: Danish seine, 6: Trawl): Total Historically the landings of bottom trawlers constituted a larger portion of the total catches than today, in some years prior to 1990 reaching 60% of the total landings. In the 1990 s the landings from bottom trawlers declined significantly within a period of 5 years, and have been just above 40% of the total landings in the last decade. (Figure Error: Reference source not found). The share of long line has tripled over the last 20 years and is now on par with bottom trawl. The share of gill net has over the same time period declined and is now only half of what it was in the 1980 s. The percentage split of the landings by gear in 2013 is:

3 ICES NWWG REPORT Gear Landings Percentage Longline Gill net Hooks Danish seine Trawl The trend in landings in last two decades is largely a reflection of the set TAC that is set for the fishing year (starting 1. September and ending 31 august) Landings in the 2012/2013 quota years According to the HCR the TAC for the fishing year 2012/13 was supposed to be capped to 196 kt. Landings of the Icelandic fleet was however Including additional landings from the foreign fleet this amounts to an overshoot of some 7.5% Predicted landings The best estimate of landings for the fishing year 2013/14 is 227 kt, this being based on data obtained from the Directorate of Fisheries. The catches in the first four months of the current fishing year (September December 2013) were 87 kt. The remainder of the estimated catch in the fishing year (227 kt) is 140 kt. Assuming that the same proportion of the allowable catch for the next fishing year is taken in the first four months (September December 2013) as last year landings (some 0.38), the catch in 2014 is estimated to be 224 kt Discards and misreportings Estimates of annual cod discards (Ólafur Pálsson et al 2010) since 2001 are in the range of % of numbers landed and % of weight landed. Mean annual discard of cod over the period was around 2 kt, or just over 1% of landings. In 2008 estimates of cod discards amounted to 1.1 kt, 0.8% of landings, the third lowest value in the period The method used for deriving these estimates assumes that discarding only occurs as high grading but larger fish is usually higher priced. In recent years misreporting has not been regarded as a major problem in the fishery of this stock. No scientific study is though available to support that general perspective. Production figures from processing plants do though seem to be in good agreement with landings figures according to the Fisheries Directorate (personal communication) Landings and weight by age Landings in numbers by age: Sampling protocol for estimating the age composition of the cod has been in effect since 1991 and has been described previous reports. The sampling intensity in 2013 is similar as it has been in previous years. The method for deriving the catch at age are described in the stock annex. The catch at age matrix is reasonably consistent (Table Error: Reference source not found), with CV estimated to be approximately 0.2 for age groups 4-10 based on a Shepherd-Nicholson model. Mean weight at age in the landings: The mean weight age in the landings (Table Error: Reference source not found and Figure Error: Reference source not found) declined from 2001 to 2007, reaching then a historical low in many age groups. The weight at age have been increasing in recent years and are in 2013 around the average weights

4 284 ICES NWWG REPORT 2014 observed over the period from 1985 and close to the long term mean ( ). The variation in the pattern of weight at age in the catches is in part a reflection of the variation in the weight in the stock as seen in the measurements from the spring survey (Table Error: Reference source not found and Figure Error: Reference source not found). The latest spring survey weight measurements (in 2014) are below average in younger ages but above average in older ages. The reference biomass (B4+) upon which the TAC in the fishing year is set (based on the HCR) is derived from population numbers and catch weights in the beginning of the assessment year. In recent years the estimates of mean weights in the landings of age groups 3-9 in the assessment years have been based on a prediction from the spring survey weight measurements in that year using the slope and the intercept from a linear relationship between survey and catch weights in preceding year. The same approach was used this year for predicting weight at age in the catches for I.e. the alpha and beta were estimated from : cwa\,2013alphabetaswa\,2013 and the catch weights for 2014 then from: cwa\,2014alphabetaswa\,2014 Based on this the mean weights at age in the catches in 2014 are predicted to be somewhat below the long term mean for age groups 4 to 7 but at the long term mean for age classes 8 and 9 (Figure Error: Reference source not found) Surveys Length based indices: The total biomass indices from the spring (SMB) and the fall (SMH) surveys (Figure Error: Reference source not found) indicate that the stock biomass has been increasing substantially in recent years as is in the last 3 years among highest since the start of the spring survey in The abundance of the fish smaller than 18 cm are a measure of incoming recruits (age 1) indicating that the 2008, 2009 and 2011 year classes are strong while the 2010, 2012 and 2013 year classes are weak to moderate. Age based indices: Abundance indices by age from the spring and the fall surveys (Tables Error: Reference source not found and Error: Reference source not found) show that the age 1 abundance indices of year classes 2008, 2009 and 2011 are among of the highest observed while the measurement of the 2010, 2012 and 2013 year classes indicate that they are below average. Indices of older fish are all relatively high in recent years despite the indices of these year classes when younger are low or moderate in size (Figure Error: Reference source not found). This is in part attributed to the recent estimated reduction in fishing mortalities. The variance of age groups 5-9 was abnormally high in the spring 2012 survey but the value for the last two years being normal (Table Error: Reference source not found). This high cv is in part attributed to one haul having extremely high cod catches. In last years NWWG report it was shown that the influence of the large haul did not have a significant effect on the SPALY assessment, this being attributed to survey residuals in a given year being modelled by a multivariate normal distribution (see stock annex). The variance of age group 2 in 2014 is anomalously high, but the estimates of this age group has no influence on the reference biomass B4+ and advise until 2016.

5 ICES NWWG REPORT Commercial cpue and effort Unstandardised CPUE and effort indices, based on log book records were not considered during this meeting. In previous reports it has been concluded that changes in these parameters, although to some extent a reflection of the dynamics in the stock they are confounded by other factors. 9.4 Assessment Last year, the results from a statistical catch at age model (sometimes refer to as AD- CAM) tuned with the spring and the fall survey was used as the final point estimator upon which advice was based (referred to as the SPALY model in the text that follows). In this framework the catch at age are modelled and the fishing mortality changes gradually over time, constrained by a random walk (further explanation of the model set-up are provided in the stock annex). In addition to the above model, the data have also been extensively explored in the TSA framework, using a Time Series Analysis developed and run by Guðmundur Guðmundsson (1994, 2004, details of model description are given in WD 29, NWWG 2013). Models where the catch/fishing mortality is not modelled (ADAPT) and where the fishing pattern is not considered to change each year (SEPARABLE) are also routinely run for comparative purpose. The SPALY framework from last year, i.e. tuning with both the spring and the fall survey using ADCAM show similar diagnostics as that observed last years (see Tables Error: Reference source not found, Error: Reference source not found and Error: Reference source not found and Figure Error: Reference source not found for the residuals). A negative residual block for spring survey indices age groups 2 to 5 in recent years may indicate that there may have been some change in catchability. The detailed result from the SPALY ADCAM run are provided in Tables Error: Reference source not found, Error: Reference source not found and the stock summary in Table Error: Reference source not found and Figure Error: Reference source not found. The reference biomass is estimated to be 1106 kt in 2014 and the fishing mortality 0.3 in Assessment based on ADCAM tuning with the spring and the fall survey separately have in recent years shown that the fall survey gives a higher estimate than the spring survey (Figure Error: Reference source not found). Tuning with spring survey only this year resulted in a reference biomass of 998 kt in 2014 and a fishing mortality of 0.34 in An assessment based on the fall survey only gave reference biomass of 1202 kt in 2014 and fishing mortality of 0.28 in There are hence conflict with respect to the extent of the increase in the biomass and reduction in fishing mortality in recent years between the two survey input sources. In addition there are conflict in the signals between the surveys on one hand and the catch at age matrix, the year classes declining at a faster rate in the fisheries than in the surveys. To demonstrate this a tuning run where the lamda weight in the likelihood component was set to 0.1 for both surveys gave a reference biomass of 940 and fishing mortality of 0.4. Further insight into these conflicts between different input sources were provided by Guðmundur Guðmundsson using his TSA analysis (NWWG 2014 WD 38). When M and the catchabilities were kept constant (as done in the ADCAM framework) the principal stock metrics (biomass, fishing mortality) obtained from the TSA runs were similar as in the ADCAM above (Figure Error: Reference source not found). A TSA analysis based on catch at age alone gave a biomass estimate of B4+ kt. Additional analysis were done where the catchability was not kept constant. The author concluded that "The residual correlations are satisfactory in the estimations without survey and when the trend [SMH] or random [SMB] walk are included. It is rather high in the estimation

6 286 ICES NWWG REPORT 2014 with the October [SMH] survey without trend (we don t know the exact distribution under the null hypthesis of no serial correlation) and certainly too high with the March [SMB] survey without random walk in catchability." The analysis were the catchability was not constant resulted in stock trajectory estimates that were similar to that estimated when using catch at age alone. From this analysis the author notes that "Significant estimates of linear trend or random walk in survey catchability are an important warning that results, based on the assumption that no permanent or long-term variations are present in the survey catchability are unreliable. But they are not a strong evidence for the assumption that linear trend or random walk are a good model of the actual process." For further details on the TSA results, including exploration for estimating M and discussion the reader is referred to the NWWG 2014 WD 38 from Guðmundur Guðmundsson. Although there are indication that there may be violation in the SPALY ADCAM setup it was considered premature to base the advice this year on one of the alternative models setup and assumptions. If the true reference biomass in 2014 is around 900 kt and the TAC is set at 218 kt it is equivalent to the decision being based on a 0.24 harvest rate. If this becomes the realized harvest in 2015 is is still among the lowest observed historical rates. The issues raised above and the alternative hypothesis that may explain the discrepancy between the survey and catch at age will be further scrutinized prior to the benchmark meeting in early Reference points In 2010 ACOM set the Blim as 125 kt based on recommendation of the NWWG. The basis for Blim is Bloss and/or the SSBbreak in a segmented regression based on recruitment from year classes on one hand and recruitment from year classes 1985 onwards on the other hand (Figure Error: Reference source not found). The splitting of the recruitment time series is based on the hypothesis that recruitment productivity as a function of spawning stock biomass, as it is presently measured, is lower in latter period compared with the former period. An harvest rate limit point derived deterministically from Blim according to the methodology outlined in SGMAS 2006 indicates that it is in the vicinity of Bpa and Fpa have never been set for this stock. Based on the ICES default methodology for the derivation of Bpa and Fpa from Blim and Flim these reference points would be somewhere in the vicinity of: Bpa = 1.4 Blim = 175 kt HRpa = HRlim/1.4 = 0.25 The Btrigger and the HRHCR in the HCR are thus respectively above and below the default candidate PA-reference points. Given the current ICES MSY framework, upon which the HCR for icod has been evaluated, definition of PA-reference points may be deemed as redundant. The NWWG does not suggest a formal establishment of PApoints for icod at this point. Fmsy point estimate, to be used in stock status classification in the advisory text has not been defined for this stock. The harvest rate in the management control rule upon which the TAC is based (landings being equal to 20% of the reference biomass (B4+) has been deemed by ICES to be in conformity with the ICES MSY approach. General comments on the use of reference points in the advisory framework were dealt with in NWWG 2011 report.

7 ICES NWWG REPORT State of the stock The spawning stock reached a historical low in 1993 (120 kt point estimates) but has since then increased and estimated to be 427 kt at present (Figure Error: Reference source not found, Table Error: Reference source not found). A spawning stock biomass above the current estimates has not been observed since the early the 1960 s. This increase in biomass of older fish occurs despite productivity in terms of recruitment of the year classes now contributing to the spawning stock having been relatively low. The driving factor is hence attributed to a significant decline in fishing mortality/exploitation rate in recent years, being at present within the same order as observed in the beginning of the time series. The 2008, 2009 and 2011 year classes are estimated to be at or above the long term average, but 2010, 2012 and 2013 year classes are below average. 9.7 Short term deterministic forecast Input: The stock in numbers in 2014 (Table Error: Reference source not found) for year classes 2013 and older are obtained from the current assessment (Table Error: Reference source not found). Given the current harvest control rule, where the TAC 2014/2015 is determined from the B4+\,2014, the only additional prediction needed is the estimates of weights in These were described in section Hence there is no need to carry through a short term prediction so what follows is just to keep up with the ICES convention. Additional assumptions used in the deterministic predictions are as usual: Weights and proportion mature in the spawning stock from 2014 onwards were kept constant. The fishing pattern used is the average of the years The estimated landings for the calendar year 2014 is 227 kt as discussed in section Details of the inputs values are provided in Table Error: Reference source not found. Output: The estimated reference biomass in 2014 is 1106 kt. The TAC in the current fishing year is 215 kt. According to the management harvest control rule, given that the current SSB estimates are above the SSBtrigger (220 kt), the TAC in the next fishing year is: TAC2014/2015kt Fishing mortality, which has been declining significantly in the last decade is not expected to change much in 2014 relative to the current estimate of 0.30 (Table Error: Reference source not found). The deterministic estimates of the reference biomass and the spawning stock are not expected to change much relative to the present. 9.8 Stochastic forecast Medium term forecasts up to year 2018 was run on the three ADCAM runs, both surveys in the tuning (SPALY), spring survey only and fall survey only. The platform used is the same as used in the assessment. Future harvest rate of 0.20 (for the SPALY assessment), 0.22 (for the SMB tuned assessment) and 0.18 (for the SMH tuned assessment) were used in the future, the latter two to accounting for potential under or overestimation of the stock. The analysis indicate there is high probability that the spawning stock size is and will remain above Btrigger (220 kt) and Blim (125 kt) (Figure Error: Reference source not found).

8 288 ICES NWWG REPORT Uncertainties in assessment and forecast Alternative model assumptions indicate that the reference biomass may be around ramge from kt in 2014, compared with the 1100 kt estimated from the SPALY model. The lower alternative state of nature implies that the reference biomass upon which the TAC is set may be 20% lower than used and that the realized harvest rate could materialize to be 24% given a TAC of 218 kt. According to the HCR evaluation (ICES 2009), this is close to the upper bounds of expected harvest rates Comparison with previous assessment, forecast and advise The reference stock (B4+) in 2013 is now estimated to be 1161 kt compared to 1173 kt last year. The SSB in 2013 is now estimated to be 437 kt compared to 479 kt estimated last year. Fishing mortality in 2012 is now estimated 0.28 compared to 0.28 estimated last year. Year classes were estimated to be 119, 183 and 151 million in last years assessment and are now estimated to be 123, 181 and 160 millions. A standard ICES retrospective plots (Figure Error: Reference source not found) show estimates of key metrics in recent years compared with current estimates. The basis for the assessment has not changed from last year. The basis for the advice this year is the same as last year: the management plan/msy/precautionary approach Management considerations Prior to allocating quota to the Icelandic fleet that is under the ITQ control, the managers should ensure subtracting all estimated catches from other sources, including any landings arising from new regulations. The amount is not known precisely in advance but is likely that small fish landings, VS landings and foreign landings will be of similar magnitude as in recent years, or around 12 kt. Cod and haddock are often caught in the same fishing operation. The TAC constraint on cod has resulted in significant reduction in fishing mortalities. This reduction is not in line with current fishing mortality trends in haddock. Anecdotal information from the fisheries indicates that the restrictions on the landings of cod in recent years changed the behaviour of the fishing fleet, fishermen trying to avoid catching cod but targeting haddock Regulations and their effects Exploitation rate and fishing mortality have been reduced significantly after the implementation of the catch rule in 1995 compared with the past. I.e. management measure by restricting landings based on the HCR are manifested in lower fishing mortality and higher stock biomass for the icod. A quick closure system has been in force since 1976, aimed at protecting juvenile fish. Fishing is prohibited, for at least two weeks, in areas where the number of small cod (< 55 cm) in the catches has been observed by inspectors to exceed 25%. A preliminary evaluation of the effectiveness of the system indicates that the relatively small areas closed for a short time do most likely not contribute much to the protection of juveniles. On the other hand, several consecutive quick closures often lead to closures of larger areas for a longer time and force the fleet to operate in other areas. The effect of these longer closures has not been evaluated analytically. Since 1995, spawning areas have been closed for 2-3 weeks during the spawning season for all fisheries. The intent of this measure was to protect spawning fish. In 2005, the

9 ICES NWWG REPORT maximum allowed mesh size in gill nets was decreased to 8 inches in order to protect the largest spawners. The mesh size in the cod-end in the trawling fishery was increased from 120 mm to 155 mm in Since 1998 the minimum cod-end mesh size allowed is 135 mm, provided that a so-called Polish cover is not used. Numerous areas are closed temporarily or permanently for all fisheries or specific gears for protecting juveniles and habitat, or for socio-political reasons. The effects of these measures have not been evaluated Changes in fishing technology and fishing patterns Changes in the importance of the various gears used to catch cod are described in section 9.3. The decline in the gill net fishery are likely to have resulted in overall shift in the fishing pattern away from the largest fish. The increase in the long line fishery in the north was partly the reason for the decline in the observed mean weight at age of oldest fish in the catches Environmental influence on the stock Environmental influence on the stock are partly integrated in the annual input data for the analytical assessment, both in terms of weight and stock indices. The causation is however poorly understood. An increased inflow of Atlantic water has been observed in Icelandic waters since 1997, resulting in higher temperature and higher salinity. A northward shift in distribution of immature capelin may be linked to these hydrographical changes, resulting in lower availability of capelin for cod. In the past low weights-at-age of cod have been related to a low biomass of capelin. The increase in mean weight-at-age in cod in recent years may, however, have more to do with reduction in fishing mortality than with changes in availability of capelin.

10 290 ICES NWWG REPORT 2014 Table 1: Icelandic cod in division Va. Nominal catches (tonnes) by countries as reported to ICES and WG best estimates of landings. Year Belgium Faeroe.Isla nds France Germany Greenland Iceland Norway Poland UK.Eng.Wal es.n.irl. UK.England.Wales UK.Scotlan d Total WG.estimat es

11 ICES NWWG REPORT Year Belgium Faeroe.Isla nds France Germany Greenland Iceland Norway Poland UK.Eng.Wal es.n.irl. UK.England.Wales UK.Scotlan d Total WG.estimat es Table 2: Icelandic cod in Division Va. Estimateded catch in numbers by year and age in millions of fish in year

12 292 ICES NWWG REPORT 2014 year

13 ICES NWWG REPORT Table 3: Icelandic cod in Division Va. Estimated mean weight at age in the landings (kg) in period the The weights for age groups 3 to 9 in 2014 are based on predictions from the 2014 spring survey measurements. The weights in the catches are used to calculate the reference biomass (B4+). year

14 294 ICES NWWG REPORT 2014 year

15 ICES NWWG REPORT Table 4: Icelandic cod in Division Va. Estimated weight at age in the spawning stock (kg) in period the These weights are used to calculate the spawning stock biomass (SSB). year

16 296 ICES NWWG REPORT 2014 year

17 ICES NWWG REPORT Table 5: Icelandic cod in Division Va. Estimated maturity at age in period the year

18 298 ICES NWWG REPORT 2014 year

19 ICES NWWG REPORT Table 6: Icelandic cod in Division Va. Estimated survey weight at age in the spring survey (SMB). year

20 300 ICES NWWG REPORT 2014 Table 7: Icelandic cod in Division Va. Survey indices of the spring bottom trawl survey (SMB). year

21 ICES NWWG REPORT Table 8: Icelandic cod in Division Va. Survey CV of the spring bottom trawl survey (SMB). year

22 302 ICES NWWG REPORT 2014 Table 9: Icelandic cod in Division Va. Survey indices of the fall bottom trawl survey (SMH). year Table : Icelandic cod in Division Va. Survey CV of the fall bottom trawl survey (SMH). year

23 ICES NWWG REPORT Table 11: Icelandic cod in Division Va. Catch at age residuals from the ADCAM model tuned with the spring (SMB) and the fall (SMH) surveys. year

24 304 ICES NWWG REPORT 2014 year

25 ICES NWWG REPORT Table 12: Icelandic cod in Division Va. Spring survey (SMB) at age residuals from the ADCAM model, assessment tuned with both the spring and the fall survey. year

26 306 ICES NWWG REPORT 2014 Table 13: Icelandic cod in Division Va. Fall survey (SMH) at age residuals from the ADCAM model, assessment tuned with both the spring and the fall survey. year

27 ICES NWWG REPORT Table 14: Icelandic cod in Division Va. Estimates of fishing mortality based on ACAM using catch at age and spring and fall bottom survey indices. year

28 308 ICES NWWG REPORT 2014 year

29 ICES NWWG REPORT Table 15: Icelandic cod in Division Va. Estimates of numbers at age in the stock based on ACAM using catch at age and spring and fall bottom survey indices. year

30 310 ICES NWWG REPORT 2014 year

31 ICES NWWG REPORT Table 16: Icelandic cod in Division Va. Landings (thousand tonnes, average fishing mortality of age groups 5 to 10, recruitment to the fisheries at age 3 (millions), reference fishing biomass (B4+, thousand tonnes), spawning stock biomass (thousand tonnes) at spawning time and harvest ratio. Year Yield F5-10 SSB Reference biomass Recruits Harvest rate

32 312 ICES NWWG REPORT 2014 Year Yield F5-10 SSB Reference biomass Recruits Harvest rate

33 ICES NWWG REPORT Table 17: Icelandic cod in Division Va. Inputs in the deterministic predictions. Age Parameter Catch weights Catch weights Catch weights Catch weights Catch weights Catch weights Catch weights Catch weights Catch weights Catch weights Catch weights Catch weights SSB weights SSB weights SSB weights SSB weights SSB weights SSB weights SSB weights SSB weights SSB weights SSB weights SSB weights SSB weights Maturity Maturity Maturity Maturity Maturity Maturity Maturity Maturity Maturity Maturity Maturity Maturity Selection Selection Selection Selection Selection Selection Selection

34 314 ICES NWWG REPORT 2014 Age Parameter Selection Selection Selection Selection Selection Stock numbers Stock numbers Stock numbers Stock numbers Stock numbers Stock numbers Stock numbers Stock numbers Stock numbers Stock numbers Stock numbers Stock numbers 0.653

35 ICES NWWG REPORT Table 18: Icelandic cod in Division Va. Output of the deterministic predictions. Year B4. Fmult Fbar SSB Landings 2016.B SSB SSB.change TAC.change % -100% % -77% % -74% % -70% % -67% % -63% % -60% % -56% % -53% % -49% % -46% % -42% % -39% % -36% % -32% % -29% % -26% % -23% % -20% % -16% % -13% % -10% % -7% % -4% % -1% % 2% % 5% % 8% % 11% % 13% % 16% % 19% % 22% % 25% % 28% % 30% % 33% % 36% % 38% % 41% % 44% % 46%

36 316 ICES NWWG REPORT 2014 Figure 1: Icelandic cod division Va. Total landings from 1905 to 2013 and landings by principal gear from 1955 to The proportion of landings by each gear is shown by the red line. Figure 2: Icelandic cod division Va. Estimated weight at age (numbers in panels indicate age classes) in the catches expressed as deviation from the mean. Weights at age in 2014 are predicted from 2014 spring survey weights. Note that values that are equal to the mean are not visible in this type of a plot.

37 ICES NWWG REPORT Figure 3: Icelandic cod division Va. Estimated weight at age (numbers in panel indicate age classes) in the spring survey (SMB) and fall survey (SMH) expressed as proportional deviations from the mean. No fall survey was conducted in Note that values that are equal to the mean are not visible in this type of a plot. Figure 4: Icelandic cod division Va. Abundance indices of cod in the groundfish survey in spring (SMB red, longer time series) and fall (SMH blue, shorter time series). Bottom left) Biomass index of 55 cm and larger, bottom right) Biomass index 80 cm and larger, top right) Abundance index of < 55 cm, top left) Abundance index of < 18 cm fish. The shaded area and the vertical bar show 1 standard error of the estimate.

38 318 ICES NWWG REPORT 2014 Figure 5: Icelandic cod division Va. Age based abundance indices of cod in the groundfish survey in spring (SMB) and fall (SMH). The indices are standardized within each age group and within each survey. Figure 6: Catch residuals (left), spring survey residuals (SMB, middle) and fall survey residuals (SMH, right) by year and age from the spaly ADCAM run. Note that values that are equal to the mean are not visible in this type of a plot and that no survey was carried out in the fall 2011.

39 ICES NWWG REPORT Figure 7: Icelandic cod in division Va. Assessment summary based ADCAM tuned with the spring and the fall survey. Medium term simulations are based recruitment patterns observed since year class 1985 and the application of management harvest control rule. The x-axis in the recruitment panel refers to year class, the vertical green line to the long term average recruitment. Vertical grey line demarks the assessment year (2014). Vertical green lines on the harvest rate and fishing mortality panel refer to expected medium value under the application of the harvest control rule. The different shades of grey refer to 90p, 80p and 50p pseudo-confidence intervals. Note that the x-axis does not cross the y-axis at zero. Two randomly drawn iteration is displayed. Figure 8: Icelandic cod in division Va. Comparison of different stock trajectories using alternative model frameworks, input and assumptions.

40 320 ICES NWWG REPORT 2014 Figure 9: Icelandic cod in division Va. Medium term simulation based on ADCAM. Figure 10: Icelandic cod in division Va. Spawning stock biomass and corresponding recruitment at age 3. The numerical values refer to year class with the horizontal lines referring to mean recruitment for year classes (red line) and (green line). Vertical lines refer to Blim (Bloss, red) and Btrigger (green). Figure 11: Icelandic cod in division Va. Empirical retrospective patterns from the 2004 to 2014 (this years assessment, marked in red) assessments as summarized in ICES annual advisory sheet.