FN Archimer Export Format
PT J
TI Working group on the biology and assessment of deep-sea fisheries resources (WGDEEP)
BT 
AF ICES
SI NANTES
   LORIENT
TC 0
AC ICES
UR https://archimer.ifremer.fr/doc/00810/92228/98231.pdf
LA English
DT Article
CR EVHOE EVALUATION HALIEUTIQUE OUEST DE L'EUROPE
   INTERNATIONAL BOTTOM TRAWL SURVEY (IBTS)
AB The ICES working group on biology and assessment of deep-sea fisheries resources (WGDEEP) provides scientific advice on 29 assessment units including stocks of deep-water species and those on shelf areas and in deep waters. Advice is provided every other year for each stock, except for stocks from ICES Division 5.a (Iceland) with annual advice. First draft of advice was prepared for 13 stocks. Due to the Covid 19 disruption, the meeting was conducted entirely by web-based correspondence. Available time-series for international landings and discards, fishing effort, survey indices and biological information were updated for all stocks and are presented in Sections 4–15 of the report. Due to covid19 complications in 2020 there was no survey in Azores ICES division 10a which affected the assessment of blackspot seabream. Also, there was not a full spatial coverage in the Norwegian slope survey and this to some extend affected the assessment of greater silver smelt in ICES areas 1, 2, 3a and 4. Atlantic Wolffish was introduced as a potential species to be included in WGDEEP. A benchmark is being requested for 2022. The main fishing grounds for Atlantic wolffish are in the west and northwest part of the Icelandic shelf. The catches are mainly taken in waters 0-180 m. Since 2001 the Gadget model has been used for analytical assessment of Atlantic wolffish in Icelandic waters. Main conclusions regarding each stock with advice 2021 were: Greater silver smelt in 1, 2, 3a and 4 was benchmarked in 2020. New precautionary approach was applied for the trend-based advise. While direct fisheries in 2 have decreased in later years the bycatch in are 4 has increased substantially. Greater silver smelt in 5a and 14 was benchmarked in 2020. The assessment framework has been upgraded from category 3 to category 1. The spawning stock biomass has slightly decreased from last year´s historical high level. Recruitment shows an increasing trend since 2006. Greater silver smelt in 5b and 6a was benchmarked in 2020. The assessment framework has been upgraded from category 3 to category 1 age based assessment (SAM) with reference points. The fishing mortality is below FMSY and the spawning biomass is above MSY Btrigger. The recruitment is very constant. When the MSY approach is applied the advice of catch increases substantially from previous precautionary trend-based advice. Greater silver smelt in 6b, 7, 8, 9, 10 and 12 has not been benchmarked. The fisheries from this area is very minor and there are no directed fisheries. For previous years, the discards have been very high compared to the landings, while for this year the landings accounted for around 40 percent of the total catches. Although the present catches are minor, it is important to monitor and follow if new fisheries emerge, as catches have been considerable in the past. The recruitment of blue ling in 5a and 14 has been low since 2010. Biomass indices have decreased in recent years, resulting in lower advice for the next fishing years. An exploratory Gadget model was presented. The biomass index for ling in subareas 1 and 2 based on Norwegian longliners increased steadily from 2000 to 2017, and then decreased until 2020. Because of this decrease and because the precautionary buffer was applied the advice for 2022 and 2023 was lowered. Ling in subareas in subareas 6–9, 12, and 14, and in divisions 3.a and 4.a. The main fisheries are in Subarea 6 and Division 4.a, where the biomass index increased from 2000 to 2011 but then levelled off. In subareas 7 and 8, survey data show a declining abundance, which suggest that the assessment unit may encompass more than one biological stock. Recent biomass levels of ling in 5a show a downward revision, causing an upward revision in harvest rate and lower advice for the next fishing year. Ling in Division 5b was benchmarked in 2021. The assessment framework has been upgraded from category 3 to category 1 age-based assessment (SAM) with reference points. The spawning biomass is well above MSY Btrigger. The fishing mortality is above FMSY but below Fpa and Flim. F6- 10 has generally been around 0.4; but F decreased to FMSY in 2017 and 2018, and has since increased again to 0.3 in 2020. The increase in SSB and decrease in F is explained by good recruitments. Blackspot seabream in subarea 10. There was no new information regarding samples from the fishery and survey (2020) in area 10. Survey abundance indices are high for 20172019. The standardized commercial CPUE has been variable but shows no overall trend, it has not been updated for the recent years (20172020). Current landings are low and below advice, and there are severe management regulations in place. The biomass index for tusk in subareas 1 and 2 based on Norwegian longliners increased steadily from 2004 to 2017 then decreased until 2020. Because of this decrease and because the precautionary buffer was applied the advice for 2022 and 2023 was lowered. The landings of tusk in subareas 4 and 7–9, and in divisions 3.a, 5.b, 6.a, and 12.b has decreased since 2000. The biomass index (20002020) based on Norwegian longliners increased from 2003 to 2012, since then it has been relatively stable. For the 20222023 advice the precautionary buffer was applied, and the advice is slightly lower than the previous advice. Tusk in 5a and 14. There has been a downward correction of the whole times series of biomass levels for tusk in 5a as well as a large downward revision of biomass trends estimated over the last decade. Total biomass is shown to be decreasing, and spawning-stock biomass has been stable only slightly above Bpa since 2005. Errors in the survey index used for the model tuning and possibly insufficient criteria for model optimization are the likely reasons for these downward revisions not detected until last year. 
PY 2021
SO ICES Scientific Reports/Rapports scientifiques du CIEM
SN 2618-1371
PU ICES
VL 3
IS 47
DI 10.17895/ices.pub.8108
ID 92228
ER

EF