5..37 Advice June 3 Version, 5--3 ECOREGION STOCK Celtic Sea and West of Scotland Sole in Divisions VIIf,g (Celtic Sea) Advice for ICES advises on the basis of the MSY approach that catches in should be no more than 9 t. Discards are considered to be low; therefore all catches are assumed to be landed. Stock status MSY (F MSY ) Precautionary approach (F pa,f lim ) F (Fishing Mortality) Above target Increased risk SSB (Spawning-Stock Biomass) 3 SSB in t 9 7 5 3 MSY (B trigger ) Precautionary approach (B pa,b lim ) Above trigger Full reproductive capacity..... Fishing Mortality (ages -) Landings Recruitment (age ) Landings in t.5.5 97 97 9 9 99 99 Recruitment in millions 5 5 97 97 9 9 99 99 F(ages -) Fishing Mortality.7 Flim. Fpa.5 FMSY..3... 97 97 9 9 99 99 SSB in t Spawning Stock Biomass Bpa MSYBtrigger 97 97 9 9 99 99 Figure 5..37. Sole in Divisions VIIf,g. Summary of stock assessment. Predicted recruitment values are shaded. Top right: SSB/F for the time-series used in the assessment. Catches and landings are assumed to be the same. The spawning-stock biomass has been above MSY B trigger since. Fishing mortality has decreased from F lim in 3 to F MSY in 5 and remained there until. In it increased to above F pa. Recruitment has been fluctuating around average. The 9 year class is the lowest of the time-series. Management plans No specific management objectives are known to ICES. ICES Advice 3, Book 5
Biology The main spawning areas for sole in the Celtic Sea are in waters 75 m deep, off Trevose Head. Spawning usually takes place between February and April. Juvenile sole are found in relatively high abundance in depths up to m, while adult sole (fish aged 3 plus) are generally found in deeper water. Spawning and nursery grounds are well defined. The results of recent tagging experiments suggest that there is only limited movement of sole between the Bristol Channel (Division VIIf) and adjacent areas (Division VIIg). The fisheries Sole are taken mainly in a beam trawl fishery that started in the early 9s and, to a lesser extent, in the longer established otter trawl fisheries. In the 97s, the fishery was mainly carried out by Belgian beam trawlers and Belgian and UK otter trawlers. The use of beam trawls increased during the mid-97s, and the Belgian otter trawlers have now been almost entirely replaced by beam trawlers. In the Celtic Sea, the beam and otter trawl fleets also take other demersal species such as plaice, cod, rays, brill, turbot, and anglerfish. Catch distribution Total landings () = 9 t (% beam trawlers, 3% otter trawlers, and % Other gear). Beam trawl discards were 5% in weight. Effects of the fisheries on the ecosystem Although discard rates of sole are low in beam trawl fisheries (about 5% in weight), discard rates of other (commercial and non-commercial) species can be considerable. Beam trawling, especially when using chain-mat gear, is known to have a significant impact on the benthic communities, although less so on soft substrates and in areas which have been historically exploited by this fishing method. Benthic drop-out panels have been shown to release around 75% of benthic invertebrates from the catches. Quality considerations Incoming recruitment of strong year classes may be overestimated. The research beam trawl survey and commercial indices show divergent signals on recruitment. Discards are currently not included in the assessment, but given the low discard rates of sole it is unlikely that the inclusion of discards would change the perception of the stock. There is a tendency to overestimate SSB and underestimate fishing mortality. SSB (' tonnes) Fishing mortality: - Recruitment. Age: 5.7 Millions..5 3..3.. 99 3 3. 99 3 3 99 3 3 Figure 5..37. Sole in Divisions VIIf,g (Celtic Sea). Historical assessment results (final-year recruitment estimates are included). Scientific basis Assessment type Stock data category Input data Age-based analytical assessment (XSA). Category. Commercial catches: international landings, ages and length frequencies from catch sampling by métier; one survey index (UK(E&W)-BTS-Q3); two commercial indices (BE-CBT and UK(E&W)-CBT); maturity data from a combined-sex maturity (ICES, 99); natural mortality is assumed to be constant. Discards are assumed low and not included in the assessment. None. Discards and bycatch Indicators Other information *This stock is scheduled to be benchmarked in. Working group report WGCSE (ICES, 3). *Ver. Sentence inserted ICES Advice 3, Book 5
5..37 Supporting information June 3 ECOREGION STOCK Celtic Sea and West of Scotland Sole in Divisions VIIf,g (Celtic Sea) Reference points Type Value Technical basis MSY MSY B trigger t. B pa. Approach F MSY.3 Provisional proxy based on stochastic simulations. Precautionary Approach (unchanged since: ) Outlook for B lim Not defined. B pa t. There is no evidence of reduced recruitment at the lowest biomass observed and B pa can therefore be set equal to the lowest observed SSB. F lim.5 F lim : F loss. F pa.37 This F is considered to have a high probability of avoiding F lim and maintaining SSB above B pa for ten years, taking into account the uncertainty of assessments. F pa : F lim.7 implies a less than 5% probability that (SSB MT < B pa ). Basis: F (3) = F sq = mean (F ) =.3; R (3) = GM (97 ) = (thousands); Catches (3) = 9 (no discards); SSB () = 35. Rationale Catches () Basis F () SSB (5) %SSB change ) % TAC change ) MSY approach 9 F MSY.3 35 +5% % Precautionary approach 7 F pa.37 33 +% 3% Zero catch F =. 377 +33% % Other options 935 TAC 5%.3 35 +5% 5% (F 3.9) F 3.3 33 +3% 9% Stable TAC.3 37 % % Weights in tonnes. ) SSB 5 relative to SSB. ) Catches relative to TAC 3. MSY approach (F 3.) 5 TAC + 5% (F 3.9).5 3 5% +5% Following the ICES MSY approach implies a fishing mortality at.3, resulting in catches of 9 t in. This is expected to lead to an SSB of 35 t in 5. Discards are considered to be low; therefore all catches are assumed to be landed. No transition to the ICES MSY approach is needed since in the fishing mortality was already below F MSY. Precautionary approach The fishing mortality in should be no more than F pa, corresponding to catches of less than 7 t in. This is expected to keep SSB above B pa in 5. Discards are considered to be low; therefore all catches are assumed to be landed. Additional considerations Sole are mainly taken in a beam trawl fishery as part of a mixed demersal fishery with plaice and, to a lesser extent, cod. ICES Advice 3, Book 5 3
The Celtic Sea is an area without days-at-sea limitations for demersal fisheries. In the past this has resulted in increased effort in the Celtic Sea as a direct result of restrictive effort in other areas. This was particularly the case in 5 when effort in the sole fishery increased because of restrictive days-at-sea in the eastern Channel (Division VIId). The removal of the restrictive days-at-sea EU regulation in Division VIId that was in place prior to, resulted in an area shift of the Belgian beam trawl fleet back to Division VIId and a strong decrease in effort deployment in the Celtic Sea by that fleet. Since the effort of this fleet has gradually increased to the levels observed before the days-at-sea limitations were introduced in Division VIId. Regulations and their effects Since 5, ICES rectangles 3E, 3E, and 3E3 have been closed during the first quarter (in EU Council Regulations for TACs) with the intention of reducing the fishing mortality of cod. The effects of the closure on sole are not known although there have been spatial and temporal changes in the distribution of effort. Changes in fishing technology and fishing patterns Beam trawlers account for the majority of the vessels targeting sole. High fuel costs may have contributed to a reduction in effort in Divisions VIIf,g since. In addition, several vessels of this fleet segment are developing methods to reduce fuel costs. Effort deployment of the Belgian beam trawl fleet increased substantially in. Uncertainty in the assessment and the forecast The higher estimate of fishing mortality in is considered to be uncertain. Comparison with previous assessment and advice Historical trends in SSB and fishing mortality are consistent with last year s assessment. The most recent F values () have been revised upwards by %, and SSB in has been revised downwards by %. The basis for advice this year is the same as last year. Sources ICES.. Report of the Working Group on the Celtic Seas Ecoregion (WGCSE), 9 May, Copenhagen, Denmark. ICES CM /ACOM:. ICES. 3. Report of the Working Group for the Celtic Seas Ecoregion (WGCSE), 7 May 3, Copenhagen, Denmark. ICES CM 3/ACOM:. ICES. 99. Working Group on Southern Shelf Demersal Stocks (WGSSDS). ICES CM 99/Assess:. WD presented to the WGSSDS by Pawson, M. G., and Harley, B. F. M: Revision of maturity ogives for plaice and sole in the Celtic Sea (ICES Div. VIIf+g). Trebilcock, P., and de Rozarieux, N. 9. National Federation Fishermen s Organisation Annual Fisheries Reports. Cornish Fish Producers Organisation / Seafood Cornwall Training Ltd, March 9. Recruitment (age ) in millions Stock - Recruitment Bpa MSYBtrigger 3 5 7 9 Yield/R (dashed line).5..5..5 Yield and Spawning Stock Biomass per Recruit.5 3.5 3.5.5.5...3..5..7. SSB/R (line) SSB in t Fishing Mortality (ages -) Figure 5..37.3 Sole in Divisions VIIf,g (Celtic Sea). Stock recruitment (left panel) and yield-per-recruit analysis (right panel) plots. ICES Advice 3, Book 5
Table 5..37. Sole in Divisions VIIf,g (Celtic Sea). Advice, management, and landings. Year ICES Advice Predicted catch corresp. to advice Agreed TAC Official landings ICES landings 97 Status quo F; TAC...3. 9 F = F(pre-); TAC.9...5 99 F at F( 5); TAC...99.99 99 No increase in F....9 99 No increase in F...5. 99 No long-term gains in increasing F....9 993 No long-term gains in increasing F -..3.93 99 No long-term gains in increasing F -... 995 No increase in F...7. 99 % reduction in F.... 997 % reduction in F..9..93 99 % reduction in F.7.5.. 999 Reduce F below F pa..9.95. Reduce F below F pa <....9 Reduce F below F pa <....7 Reduce F below F pa <..7..35 3 Reduce F below F pa <....39 Reduce F below F pa <..5.3.5 5 Reduce F below F pa <.... Reduce F below F pa <..95.9.95 7 Reduce F below F pa <..9.9.95 Keep F below F pa <..9.75. 9 No long-term gain in increasing F <.9.993.73.79 No long-term gain in increasing F <.9.993.7. See scenarios -...3 MSY approach <.... 3 MSY approach <.. MSY approach <.9 Weights in thousand tonnes. ICES Advice 3, Book 5 5
Table 5..37. Sole in Divisions VIIf,g (Celtic Sea). Official nominal landings (t), 9, and data used by ICES (all catches are assumed to be landed). Year Belgium Denmark France Ireland UK(E.&W,NI.) UK(Scotland) Netherlands Total- Official Unallocated 9 39 * - 3 99-39 97 7 * - 7 9 37 - - - 9 75 * - 7 37 - - -5 99 * - 7 3 - - 99 99 99 7 * - 3 353-39 -5 9 99 9 * - 3-9 -39 7 99 53 * - 5 35 - -79 9 993 575 * - 5 5-3 - 9 99 9 * - 9 37 - -9 9 995 73 * - 9 - - 5-57 99 95 * - 9 5 - - 995 997 * - 99 5-3 - 97 9 99 75 * - 9 9 - - 3-3 75 5 999-5 3-97 5 9 9-7 9 3 - - 5 9 7-77 35 - - 73-5 3 3 + - 7 35 7 3 75-3 + - 7 5 39 735-79 33 3 - - 3 9 9 5 5 5-3 7 - - 997 7 57-75 3 3 - - 9 5 9 95 7 5-5 3 - - 93 95 9 - - - 7 9 9 53-7 9 - - 7-5 993-5 7 79 - - 7 5 7 993 7-5 3 - - 3 9 7-33 7 - - 7 9 Preliminary. * Including Divisions VIIg k. Used by ICES TAC ICES Advice 3, Book 5
Table 5..37.3 Sole in Divisions VIIf,g (Celtic Sea). Summary of stock assessment (all catches are assumed to be landed). Year Recruitment SSB Landings Mean F Age Ages thousands tonnes tonnes 97 9.39 97 73 35 7.5 973 335 59 39.3 97 3 5 5.3 975 97 5 99.93 97 59 353 35.33 977 3 7 9.9 97 59 3757 7.55 979 3533 3 95. 9 53 7 3.95 9 59 3.39 9 7 355.33 93 793 35 373.37 9 73 39.39 95 555 33 3. 9 357 33.5 97 573 57.559 9 9 77.5353 99 37 99.5 99 3 9. 99 97 33 7.5 99 55 5 9.375 993 75 9.33 99 3 55 9.57 995 33 5 57.33 99 5 77 995.533 997 57 7 97. 99 9 75.575 999 5.55 7 93 9.355 5 3. 773 9 35.379 3 59 37 39.5339 535 35 9.3 5 977 35.3 337 37 9.3 7 39 35 95.35 97 95.7 9 73 33 5.9 37 3575 7.3 3 377 9. 733 3 9.7 3 * 339 Average 5 33 3.395 * Geometric mean (97 ). ICES Advice 3, Book 5 7