Steps of the development and timetable for the 3M Cod benchmark to be carried out by April 2017Postprint0,000

González-Costas, F. (Fernando)

González-Troncoso, D. (Diana)

Mandado, M. (Mónica)

English

Steps of the development and timetable for the 3M Cod benchmark to be carried out by April 2017S

González-Costas, Fernando

González-Troncoso, Diana

Mandado, Mónica

Digital.CSIC

Full benchmark review of the 3M cod assessment

6 páginas, 4 tablasThe 3M Cod assessment model used since 2008 is an XSA Bayesian model developed by Fernandez  et al. (2008). The Bayesian model has been developed in a way that maximizes the incorporation of  catch information. For the years with catch-at-age data, it works starting from cohort survivors and reconstructing cohorts backwards in time using catch-at-age and the assumed mortality rate. For the rest of the years, if an estimate of total catch weight is available, this information can be incorporated in the model by means of an observation equation relating (stochastically) the estimated catch weight to the underlying population abundances (hence aiding in the estimation of fishing mortalities). An advantage of the model is that it allows to combine years for which catch-at-age is available with years where only estimates of total catch weight are available. Years with no information on commercial catch are also allowed.N

González-Costas, F.

www.nafo.int  NOT TO BE CITED WITHOUT PRIOR  REFERENCE TO THE AUTHOR(S)   Northwest Atlantic Fisheries Organization  Serial No. N6566 NAFO SCR Doc. 16/23  SCIENTIFIC COUNCIL MEETING – JUNE 2015   Full benchmark review of the 3M cod assessment by  Fernando González-Costas1, Diana González-Troncoso1 and Mónica Mandado2  1Instituto Español de Oceanografía, Vigo, Spain 2Instituto Investigaciones Marinas, Vigo, Spain    Introduction  The 3M Cod assessment model used since 2008 is an XSA Bayesian model developed by Fernandez et al. (2008). The Bayesian model has been developed in a way that maximizes the incorporation of catch information. For the years with catch-at-age data, it works starting from cohort survivors and reconstructing cohorts backwards in time using catch-at-age and the assumed mortality rate. For the rest of the years, if an estimate of total catch weight is available, this information can be incorporated in the model by means of an observation equation relating (stochastically) the estimated catch weight to the underlying population abundances (hence aiding in the estimation of fishing mortalities). An advantage of the model is that it allows to combine years for which catch-at-age is available with years where only estimates of total catch weight are available. Years with no information on commercial catch are also allowed.   In 2015, the NAFO Fisheries Commission (FC) agreed to carry out a 3M Cod full review benchmark (NAFO, 2015) to try to solve some of the uncertainties observed in the last 3M Cod SC approved assessment (Gonzalez-Troncoso, 2015). The FC proposed that “Scientific Council organizes a full benchmark review of the 3M cod assessment in two stages: For 2016 SC will agree on a standardized approach and prepare a plan for the benchmark process at NAFO including required resources. For 2017 SC will review the benchmark assessment metholology for 3M cod.” This request was included in the NAFO SC 2016 June meeting agenda. The NAFO Joint Fisheries Commission–Scientific Council Working Group on Risk-Based Management Strategies (FC-SC WG-RBMS) 2016 April meeting developed a detailed work plan for full benchmark assessment of this stock (NAFO, 2016). It was noted that the work plan was designed to interrelate the different processes affecting management of this stock: the MSE, the FC Request to SC to organize a full benchmark assessment and to revise the Flim value, and the PA Framework revision which is currently under discussion. The tentative timeline to the NAFO 3M Cod Benchmark and the NAFO 3M Cod MSE approved by the FC-SC WG-RBMS was the following:  NAFO 3M Cod Benchmark calendar 1. The Scientific Council (SC), in June 2016, will approve the main assessment issues to be revised during the 3M Benchmark. Among those issues, there the FC request to the SC (request number 8, SC SCS Doc16/01) that the SC should, in 2016, analyse whether the current Flim value for 3M cod is currently underestimated and to revise, if required, the relevant fishing mortality and biomass reference points appropriately. The RBMS WG recognizes that the best forum to carry out the Flim review is the benchmark process, so it would be recommended to undertake this task during that process. 2. Before the end of 2016 all data needed for the NAFO 3M Cod assessment will be reviewed and compiled. 3. Between June 2016 and March 2017 different teams of SC scientists will be working on the issues identified in the 2016 June SC meeting.  2 4. The benchmark will be carried out in April 2017. This may involve SC and external scientists. 5. The June 2017 SC meeting will carry out a new assessment taking into account the Benchmark conclusions. This assessment would inform the TAC decision for 2018 because the MSE may not be finalised before September 2017.  NAFO 3M Cod MSE calendar Little progress is expected here before June 2017: this is because the results of the 3M cod benchmark and the NAFO PAF review will be required prior to the resumption of the MSE process. This would be the expected steps: 1. In June 2017 a new 3M Cod assessment would be issued, according with the benchmark outputs as well as (ideally) the reference points arising from any revisions of the PAF, which at this stage would be tentative (not adopted by the FC). 2. After September 2017, if the FC adopts any relevant new elements of the PAF, the RBMS WG should revise the management objectives of the 3M cod MSE accordingly. 3. Between September 2017 and March 2018 different HCRs could be tested in order to see if they reach the established management objectives. 4. By June 2018 the RBMS WG and SC may revise the 3M Cod MSE to enable the proposal of a HCR. This HCR may be submitted for approval to FC in September, 2018. If and as approved by the FC, this HCR will be applied to determine the TAC in 2019 and onward.  The intent of this document is to present some information to help to address the FC request and the proposed FC-SC WG-RBMS work plan.     Main assessment issues  Table 1 presents some assessments characteristics of the North Atlantic cod management units. The main assessment issues that should be reviewed before and during the benchmark according to our opinion are presented below:  Assessment model:  The assessment model used in the 3M cod is coding in R. It should be necessary a depth review and debug of the R code used. This revision could be made by an independent expert in R and Bayesian assessment models with the assistance of the 3M Designated Expert (DE). This revision would be carried out during 2016.  The FC spotted an inconsistency in 3M cod risk advice table in 2015. The SC analysed this inconsistency in September 2015 and concluded that there are different ways to estimate the risk depending in the type of assessment results and it was demonstrated that the risk will differ to significant extent from one option to the other. This initiative is also in line with the setting of a technical subgroup in charge of revising the PAF (NAFO/FC Doc 15/19), where one of the ToR is dedicated to the standard risk computation. It will be necessary to review and debug the projections R code used till now in the 3M cod taking into account the conclusion of the technical subgroup in charge of revising the PAF.    The model estimates the natural mortality (M). M is constant for all ages and years. The last year estimation was M=0.16. Revision of North Atlantic cod assessment shows that this value of M is quite low compared with of other cod stocks (Table 1). It would be recommended to study other ways to estimate M (Lorenzen, 1996) or assume M. These scenarios could be presented during the benchmark.  Assessment Input Data:  It would be necessary to review the available assessment input data to try to improve the quality of them.  It should be explored the possibility of expanding the input data arrays in more ages. Table 2 and 3 show the otoliths collected in the EU-FC survey and in the Spanish commercial fleet. The current plus group used in the assessment is 8+ and it seems quite appropriated till 2010 based on the otoliths collected in the EU FC survey (Table 2) and in the age composition presented by Vazquez (1991) for the Spanish pair  3 trawlers fishery in the period 1988-1990. From the revision of other cod stocks (Table 1) it seems that this plus group could be appropriated, but it can be observed that in the last years the age composition has been expanded in the case of the 3M Cod. It will be good to make a study to see the possibility of increase the age of the plus group. To carry out this study it will be necessary to expand all the assessment inputs data as much as possible during 2016 to decide in the benchmark what should be the most appropriate plus group.  Aging and Age-Length Keys (ALKs):  The 3M cod is at present determined by the traditional method of annual ring interpretation. Some inconsistencies in age readings between readers and institutes have existed for age determination for this stock. In 2010, two commercial fisheries ALKs were available, one for the Portuguese data from the 3M FC survey data reader (IIM), and another one for the commercial Spanish data from a new reader (IEO). It was observed some differences between both ALKs. In order to maintain the consistency of the series, it was decided to use the survey reader ALK (IIM) for all the commercial catch because it comes from the same reader as the previous years for commercial and EU survey data (Vazquez, 2011 and Gonzalez-Troncoso and Vazquez, 2011). This problem has been exacerbated in recent years since there are three different ALKs (IIM survey, IEO commercial and IPMA commercial). The commercial ALKs (IEO and IPMA) are quite similar between them and have some differences compare with the survey ALK (IIM). In order to maintain the consistency of the series, it was decided to use the IIM ALK (IIM) for all the commercial and EU survey data because comes from the same institution as the previous years.  To solve this problem an otolith exchange should be recommended and it should take place well before the benchmark to try to solve the inconsistencies between the different institutions ALKs and to prepare the assessment data using the new commercial ALKs to be used during the benchmark.  Review of the Limit Reference Points:  Blim has been established by eye with a value of 14 000 tons. Probably this value could be reviewed with the new data points. It seems to be low compared with the current levels of SSB.   F30%SPR has been established as the best Flim proxy and has been estimated with all the series parameters values due to the observed big trend in these parameters and the estimated low M values. If these situations change it will be necessary to estimate new values. The FC requested the SC for 2016 to analyse whether the current Flim value for 3M cod is currently underestimated and to revise, if required, the relevant fishing mortality and biomass reference points appropriately. The best forum to carry out these reviews is the benchmark, so it would be recommended to take this task during the benchmark as was proposed by the FC-SC WG-RBMS.  Proposed timetable:  Table 4 shows the proposed timetable to carry out the benchmark and the main tasks described above. It is proposed to perform the benchmark in April 2017 to allow having time to prepare the assessment to be held in the Scientific Council of June 2017 with the conclusions of the benchmark. It would be appropriate that the SC nominate responsible for each task of the benchmark and that at least two external experts with experience in the cod stocks assessment and benchmark processes participate in NAFO 3M cod Benchmark.     4 References  Fernández, C., S. Cerviño and A. Vázquez, 2008. Assessment of the Cod Stock in NAFO Division 3M. NAFO SCR Doc. 08/26. Serial Number N5391.  González-Troncoso, D. and A. Vázquez, 2011. Assessment of the Cod Stock in NAFO Division 3M. Serial No. N5923. NAFO SCR Doc. 11/38.   González-Troncoso, D. 2015. Assessment of the Cod Stock in NAFO Division 3M. Serial No. N6458. NAFO SCR Doc. 15/033.  Lorenzen, K. The relationship between body weight and natural mortality in juvenile and adult fish: a comparison of natural ecosystems and aquaculture. Journal of Fish Biology (1996) 49 (4) 627-642. [DOI: 10.1111/j.1095-8649.1996.tb00060.x]  NAFO. 2015. Report of the Fisheries Commission and its Subsidiary Body (STACTIC). 37th Annual Meeting of NAFO, 21-25 September 2015. Serial No. N6526 NAFO/FC Doc. 15/23.  NAFO. 2016. Report of the NAFO Joint Fisheries Commission–Scientific Council Working Group on Risk-Based Management Strategies. 4-6 April 2016 Tórshavn, Faroe Islands. Serial No. N6532 NAFO FC/SC Doc. 16/01.  Vázquez, A.– 1991. Cod catch sampling of pair-trawlers fishing on the Flemish Cap, 1988-1990. NAFO SCR Doc., 91/78, 8pp.  Vazquez, A. 2011. Validation of Flemish Cap cod ageing. Serial No. N5913 NAFO. SCR Doc. 11/028.         5 Table 1.  Information about the models assessment, plus group and Fmsy of the different North Atlantic cod management units. The year column shows the last assessment consulted.     Table 2.  Number of collected otoliths in the Flemish Cap survey by year and age.     Area Management Unit Model Plus Group M Fmsy YearNAFO Northern Labrador Cod (NAFO Div 2GH) Not informationNAFO Labrador / Grand Bank (NAFO 2J+3KL) SURBA 2-12 Z=0.5 2013NAFO Flemish Cap (NAFO 3M) Bayesian XSA 1-8+ 0.16 F30%=0.131 2015NAFO Southern Grand Bank (NAFO 3NO) ADAPT 2-12 0.2 0.3 2015NAFO Southern Newfoundland (NAFO 3Ps) SURBA 1-10 Z=0.5 2014NAFO northern Gulf of St. Lawrence (3Pn, 4RS) ADAPT 1-13 Time V 0.3-0.5 2014NAFO S. Gulf of St Lawrence (NAFO 4TVn) VPA (ADAPT) Age Var 2009NAFO Sydney Bight  (NAFO Subdivision 4Vn) Surveys 2015NAFO Eastern Scotian Shelf (4VsW) VPA (ADAPT) 1-15 Age Var 1-4, 5+ 2011NAFO Southern Scotian Shelf and Bay of Fundy (NAFO 4X5Yb) VPA 1.5? 2011NAFO Gulf of Maine (NAFO Division 5Y) ASAP (Age Structured Assessment Program) 1-9+ 0.2 F40%=0.185 2014-2015NAFO Georges Bank (NAFO 5Z) ASAP (Age Structured Assessment Program) 1-10+ 0.2 F40%=0.169 2012-2015AFWG Northeast Arctic (ICES Subareas I and II) XSA 3-13+ 0.2 2015AFWG Norwegian coastal waters (ICES Subareas I and II) XSA 2-10+ 0.2 2015NWWG Offshore West Greenland (NAFO Subdivisions 1A-1E) Surveys 1-10+ 2015NWWG in inshore (NAFO Subarea 1) Surveys 3-10+ 2015NWWG ICES Subarea XIV and NAFO subarea 1 (offshore waters) Surveys 3-10+ 2015NWWG Iceland (ICES Va) statistical catch-at-age (ADCAM) 3-14+ 0.2 2015NWWG Faeroe Bank (ICES Vb2) ASPIC/Surveys 2015NWWG Faeroe Plateau (ICES Vb1) XSA 2-10+ 0.2 2015WGCSE West of Scotland (ICES VIa) Analytical age-based assessment (TSA) 1-7+ Lorenzen (1996) 2015WGCSE Rockall (ICES VIb) data-limited stocks (Only landings) 2012WGCSE Eastern Channel and Southern Celtic Seas (ICES VIIe–k) XSA 1-7+ 0.2 2015WGCSE Irish Sea Cod in (ICES VIIa) SAM (State-space assessment model) 1-6+ 0.2 2015WGNSSK North Sea, Skagerrak (Subarea IV and Divisions VIId and IIIa West) Age-based analytical assessment (SAM) 1-11+ Var age 1-3,older Cons=0.2 2015WGBFAS Eastern Baltic Sea (ICES Subdivisions 25–32 and Subdivision 24) Surveys 2015WGBFAS Western Baltic Sea (ICES Subdivisions 22–24) Age-based analytical assessment (SAM) 1-7+ 0.8,0.24,0.2 2015WGBFAS Kattegat (ICES IIIa East) stochastic state-space model (SAM) 1-6+ 0.2 2015Year 1 2 3 4 5 6 7 8 9 10 11 12 13 14 Total 8+ %1993 306 1234 1574 112 246 34 122 26 3654 26 0.71%1994 293 159 785 384 15 10 1 16 1 1664 17 1.02%1995 380 1068 278 996 264 10 8 6 2 3012 8 0.27%1996 10 852 1276 204 672 58 2 2 3076 2 0.07%1997 18 54 1383 1962 162 405 9 3 3996 3 0.08%1998 4 12 13 172 219 11 22 1 454 1 0.22%1999 1 38 23 22 121 70 3 2 280 2 0.71%2000 39 2 47 29 15 73 32 3 3 1 1 245 8 3.27%2001 107 274 2 18 13 3 23 18 1 1 1 461 21 4.56%2002 173 85 4 9 5 4 15 5 1 301 21 6.98%2003 138 9 110 32 6 7 1 1 7 6 317 14 4.42%2004 2 420 9 187 51 2 4 2 1 3 1 682 7 1.03%2005 368 2 145 10 89 17 2 1 1 635 4 0.63%2006 390 347 7 197 11 79 16 1 1 2 1 1052 5 0.48%2007 340 290 464 3 160 8 62 11 2 3 1343 16 1.19%2008 243 454 448 328 6 113 7 30 10 2 1641 42 2.56%2009 197 300 267 341 92 1 38 22 2 1260 24 1.90%2010 222 237 86 66 132 137 1 45 6 27 3 962 81 8.42%2011 315 599 257 104 155 155 92 17 8 1702 25 1.47%2012 280 314 84 159 98 168 123 74 3 11 2 11 2 1329 103 7.75%2013 153 262 338 101 191 178 186 135 42 6 5 4 1 1602 193 12.05%2014 214 70 251 328 162 190 199 156 139 58 9 6 1 1783 369 20.70%2015 89 207 150 190 135 317 196 120 88 47 27 3 3 3 1575 291 18.48%Total 4109 7377 8082 5949 3024 2051 1151 659 354 167 61 30 6 6 33026 1283 3.88%Ages 6 Table 3.  Number of collected otoliths in the Spanish commercial fishery in the period 2006-2015 by year and age.        Table 4.  Proposed schedule to carry out the NAFO 3M cod Benchmark and related tasks.     Year 2 3 4 5 6 7 8 9 10 11 12 13 17 Total 8+ %2006 3 1 1 1 6 2 33.33%2007 1 5 26 3 16 2 53 18 33.96%2010 33 97 168 130 191 70 65 32 35 12 833 144 17.29%2011 8 53 168 102 107 18 37 5 13 1 512 74 14.45%2012 1 72 59 65 137 135 107 19 16 11 17 3 1 643 174 27.06%2013 11 123 341 96 55 29 10 5 1 1 672 17 2.53%2014 62 113 303 178 136 166 91 27 2 1 1079 287 26.60%2015 26 28 195 171 358 105 60 32 16 991 108 10.90%Total 71 390 930 941 1047 586 443 219 100 38 20 3 1 4789AgesTask 1st Q 2nd Q 3rd Q 4th Q 1st Q 2nd Q 3rd Q 4th QReview Assessment R codeReview projectionst R codeAssessment input data reviewM valuesPlus Group dataCommercial ALKsReview Reference PointsBenchmark AprilSC meeting June2016 2017

Steps of the development and timetable for the 3M Cod benchmark to be carried out by April 20170,000

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Full benchmark review of the 3M cod assessment

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