Carrera-López, P. (Pablo)

Cunha, E. (Emília)

Dias, C.A. (Carlos Afonso)

Farinha, A. (Anabela)

Figueiredo, I. (Ivone)

Marques, V. (Vítor)

Pestana, G. (Graça)

Porteiro-Lago, C. (Carmen)

Soares, E. (Eduardo)

English

Carrera, P. (Pablo)

Marques, V. (Vitor)

Repositorio Institucional Digital del IEO

Pelagic Fish Cornrnittee ICES CM 1997/H:lREPORT OF THEPLANNING GROUP FOR A SARDINE ACOUSTIC SURVEYIN ICES SUB-AREAS VIII AND IXLisbon, Portugal27-28 January 1997This report is not to be quoted without prior consultation with theGeneral Secretary. The document is a report of an expert groupunder the auspices of the International Council for the Exploration ofthe Sea and does not necessarily represent the views of the Council.International Council for the Exploration of the SeaConseil International pour I'Exploration de la MerPaleegade 2-4 DK-1261 Copenhagen K DenmarkTable of ContentsSection Page1 INTRODUCTION 12 PARTICIPANTS 13 REVIEW OF THE DESIGN OF ACOUSTIC SURVEYS FOR SARDINE PLANNED FOR 1997.CO-ORDINATION OF SURVEY RESULTS PRESENTATION 14 CO-ORDINATION OF ACOUSTIC AND DEPM SURVEYS 35 CONCLUSIONS AND RECOMMENDATIONS 36 REFERENCES 3APPENDIX 1 - Analysis of the Previous Portuguese Acoustic Sardine Data 71 INTRODUCTIONThe abundance estimates of sardine from the acoustic surveys carried out by both Spainand Portugal are used to tune the VPA in the assessment of this species. The best tuningresults have been obtained when the surveys were carried out simultaneously. However,due to the important changes in the stock distribution area which have occurred in the lastfew years, the survey design needs to be revised in order to obtain more precise estimates.Following the terms of reference set by the ICES Annual Science Conference (84thStatutory Meeting) (c. Res. 1996/2:42), the Planning Group for a Sardine AcousticSurvey in ICES Sub-Areas VIII and IX (PGSAS) met at the Instituto de Investigacáo dasPescas e do Mar (IPIMAR), Lisbon, from 27-28 January 1997 to:a) co-ordinate the timing and methodologies for acoustic surveys for sardine;b) review the survey design (including hydrographic sampling) in the light ofprevious surveys, and propose survey improvements.In addition, at the same time as these surveys, Spain and Portugal will perform twoichthyoplankton surveys in order to apply the Daily Egg Production Method (DEPM) tothe Spawning Stock Biomass of sardine.2 PARTICIPANTSPablo CarreraEmília Cunha *Carlos Afonso Dias*Anabela Farinha*Ivone Figueiredo*Vítor MarquesGraca PestanaCarmela PorteiroEduardo Soares*Partial attendance.Spain (Chairman)PortugalPortugalPortugalPortugalPortugalPortugalPortugalSpain3 REVIEW OF THE DESIGN OF ACOUSTIC SURVEYS FOR SARDINE PLANNED FOR 1997.CO-ORDINATION OF SURVEY RESULTS PRESENTATIONBoth countries agreed to co-ordinate and carry out a joint acoustic survey for sardine in1997. Spain will survey the Cantabrian and Galician coasts with the new RIV "Thalassa"from 3-29 March and Portugal will survey the Portuguese coast and the Gulf of Cadiz(Spain) from 3-27 March with RIV "Noruega". It was agreed that both surveys will followthe same methodology (Dias et al.,1983; Anon, 1986).Acoustic data of the last acoustic surveys undertaken by both countries were analysed inorder to get an adequate coverage of the sardine distribution area and to improve the1acoustic sampling. Minimum suitable distances between acoustic transects were estimatedfor both Spanish and Portuguese surveys. A distance of 6 nautical miles between transectswas found as more adequate for the Spanish survey (Porteiro et al, 1996), while for thePortuguese it was estimated to be 8 nautical miles distance between transects (seeappendix 1).Thus, it is planned that R/V "Thalassa" will follow an acoustic track with paralleltransects equally spaced of 6 nautical miles and extending from the coast up to 200mdepth. Besides, the extension of the transects beyond the outer limits of the sardinedistribution area (around 200m isobath) is due to the fact that this survey is also plannedto estimate the abundance of blue whiting which occurs in deeper waters. In order to getsome information about sardine the southem part of the French continental shelf will bealso covered. An inter-calibration of R/V "Thalassa" and R/V "Comide de Saavedra"along the Galician coast will precede the beginning of this survey. The Portuguese surveywill follow parallel transects equally spaced of 8 nautical miles and extending up to the200m depth. Figure 1 shows the acoustic track around the whole area.An acoustic and electronic calibration of the acoustic equipment will be undertaken at thebeginning of these surveys.Despite the adverse conditions frequently found, the Planning Group stressed that someeffort should be especially focused on the implementation of the sampling trawl stationsas they are fundamental for the acoustic method. Sampling trawl stations will beundertaken in both surveys in order to identify the acoustic targets, to collect biologicalinformation on the species and to determine the age and length structure of sardine.Besides it was agreed that some extra sampling will be performed in arder to provide theadult parameters which are necessary for the application of the DEPM method (see point4). In both surveys it was planned to use two pelagic gears and one semipelagic trawl.In what concems the estimated sardine abundance by age groups, Spain will apply anagellength key for the whole Spanish surveyed area and Portugal will use a different keyfor each zone of the Portuguese surveyed area.The relation between hydrography and sardine distribution has been pointed out duringthis meeting (Dias et al., 1996; Anon., 1997). Thus the Planning Group agreed thatOceanographic parameters should be collected during these surveys. The allocation ofthese stations was discussed. It was decided that CTD casts will be performed alongtransects over the 50, 100, 200 and 500m bathymetrics and at an outermost stationapproximately 10 nautical miles beyond this depth. Distance between transects will be 24nautical miles.It was agreed to co-ordinate the presentation of the survey results and to get the reportready for the next meeting of the ICES Working Group on the Assessment of Mackerel,Horse-Mackerel, Sardine and Anchovy in September.24 CO-ORDINATION OF ACOUSTIC AND DEPM SURVEYSThese acoustic surveys will be carried out simultaneously with two surveys for Daily EggProduction Method, DEPM (Parker, 1980). The DEPM surveys will be undertaken in thesame area by the Spanish RIV "Cornide de Saavedra" and Portuguese RIV "Capricórnio"(Figures 2a, b).Adult parameters (spawning fraction and batch fecundity) for the Egg Production Method(EPM) will be collected during the acoustic surveys.The need for sampling females with hydrated oocytes in order to determine the batchfecundity was stressed by the Planning Group during the co-ordination with the DEPMsurveys. It was agreed that, for this purpose, samples should be collected during daytime,from 6 to 22 hrs GMT.The histological processing and analysis of gonads on microscope slides will be done onland in the laboratories of both institutes (lEO and IPIMAR).5 CONCLUSIONS AND RECOMMENDATIONSA co-ordinated joint acoustic survey for sardine will be carried out in 1997along the Atlantic Iberian coast;- Both surveys will follow the same methodology;The Spanish acoustic survey will follow an acoustic track with parallel transectsequally spaced of 6 nautical miles and some of those extending up to the 1000metres isobath in order to assess the Spanish fraction of blue whiting;The Portuguese acoustic survey will follow parallel transects equally spaced of8 nautical miles and extending up to the 200m depth;- Oceanographic parameters will be collected by CTD along transects;- Adult parameters for Daily Egg Production Method (DEPM) will be collectedduring the acoustic surveys;- The presentation of results will be co-ordinated and the report will be ready inSeptember for the next meeting of the ICES Working Group on the Assessmentof Mackerel, Horse Mackerel, Sardine and Anchovy.6 REFERENCESAnon, 1986. Report of the Planning Group for Acoustic Surveys in ICES Sub-Areas VIIIand IX, Lisbon 1-4 April 1986. ICES CM 1986/H:27, 7pp.Anon, 1997. Report of Working Group on the Assessment of Mackerel, Horse Mackerel,Sardine and Anchovy, 13-22 August 1996. ICES CM1997/Assess:3.3Dias, c.A., Pastor, X., Pestana, G., Porteiro, c., Soares, E. and Alvarez, F., 1983. Resultsof the Spanish-Portuguese joint acoustic survey for pilchard (ICES Divisions VIDeand IXa), August-September1982. ICES CM 1983/H:42.Dias, C.A., Pestana, G., Soares, E. & Marques, V., 1996. Presente State of Sardine Stockin ICES Divisions VIDe and IXa. Working Document presented to the ICES"Working Group on Assessment of Mackerel , Horse Mackerel, Sardine andAnchovy" (1996 W.G. Meeting).Parker, K., 1980. A direct method for estimating northern anchovy, Engraulis mordax,spawning biomass. Fish. Bul!., 78:541-544.Porteiro, c., Carrera, P. and Miquel, J. 1996. Analysis of Spanish acoustic surveys forsardine, 1991-1993: abundance estimates and inter-annual variability. ICESJournal of Marine Science, 53:429-433.445°Latitude (N)200 m <,44°43°42°41 °40°39°38°'/'-'-_/(/37° 1),/,0\J/------.:.-..---,---36° ¿~r: ---/I---10° 9° 7° 2° 0°6° S° 4° 3°8°Longitude (W)Figure 1: Acoustic track for the spring 1997 acoustic surveys.51°44'1 . .; ~ J:--' :: :../::. ~j../:./1A.:: ;/'......... '. ( :y .:•.•... ¡,..-:.. '43 '1 \.l·,• •.• J. •.\· .....\ .;' ,.) I· \ !/42'1 ..... j' ...\45'lO' 9'~~~:~~~~~..........•..., ."-..... }... .I......... 1. .\....... \ .\: : : ·:t: ... ::::(:: : : :~: .~llL~~Y~8 • 6' 4'7' S' 3' 2'Figure 2a: Survey design to be followed during the Spanish Ichthyoplankton surveyI42º I 200m : ' I ,. ','o' • '\,N41º40º39º3Bº37º36º,','•....'.. . . . . " ..............r• ••• 'l' ••••• •••• l •••••," ',o,, . '· ',' ...· . ~I-':"":'". . -~:.-'....... . .· .,.,.,'....'-;· ..- ...,• •••• "l'','0\''".... ',',•• 1.r, - ':':..~~-:-~-~-:o~',''o',, '... \.l'Figure 2b: Survey design to be followed during the Portuguese Ichthyoplankton survey, >C_............,,,,,35º LI~------~~--------L---------~---------L--~~~~-----------11" { I10° 9° BO 7" 6° w 5°6O'APPENDIX 1Analysis of the Previous Portuguese Acoustic Sardine Databy Pablo CarreralEO, A Coruña, POB 130 E-15300 A Coruña SpainAs it was already referred, the Planning Group discussed the acoustic survey track designin order to get a suitable coverage of the surveyed area and to improve the acousticsampling of sardine.The Portuguese acoustic sardine data of the surveys undertaken in the last year (in springand summer 1996) were analysed using geostatistics methods (Petitgas, 1993; Petitgas andPrampart, 1993). In order to know the mean size of the sardine aggregations., the sardinedistributions were analysed and the experimental variograms performed on both raw andlogarithmic data has been fitted , when possible, to theoretical models. It was alsoassumed that the range of these variograms are good estimators of the mean size of thesardine patches. Thus, a good distance between transect could that which coincides to thismean size.Survey design consisted in a zigzag grid with 10 nmi between peaks. As in the Spanisharea, total backscattering values (SA values, m2 nmi") were collected and stored everynautical mile with its geographical position. These values has been allocated into differentspecies, according to fishing stations performed at the same time. SA values by nmiallocated to sardine are shown in figure 1a,b. In contrast to the distribution found in theSpanish area, sardine was distributed all around the Portuguese coast. There were no gapsamong transects and sardine showed a widespread distribution, as far as 200 m depth.Trends against longitude and latitude were almost negligible. Only in the spring survey,high values are mainly located at the south part of the distribution area, which gave ascarce correlation between latitude and sardine SA values. Trends against depth has nochecked. Thus, in absence of clear trends, data can be treated as a whole. Neverthelesssardine size composition showed a distribution pattem along the coast. According to that,data could be split into three main areas: Central-North, from the Spanish-Portugueseborder to 39° N, Central South, which is the westem coast until 37° N and South.This analysis has been firstly performed using the whole set data, with the 200 m isobathas the outer border of the distribution area. Then, the area was split into the three mainzones in order to check differences in aggregation pattem according to the different sizecomposition along the coast. In this particular case, distribution area has been matched tothe positive area of sardine presence.Table 1 shows the main features of data as well as the fitted variograms models for eachanalysed area. Due to the survey design, to perform experimental variograms, a lag of 1.5nmi with a tolerance of 35° in two main directions, (north-south and west-east) were used.Both experimental variograms and their theoretical models can be also seen in Figures2a,b.7As most of the acoustic data, sardine SA values presented a skewed distribution. Fewvalues gave important contribution on both mean and its variance. As it was pointed out inthis case, log transformations improve the knowledge of the spatial structure and gavemore stable variograms than raw data (Femandes, 1996). Thus, this analysis was firstlyperformed on log transformation data.The spatial structure seemed to be isotropic, with no differences between North-Southdirection and West-East direction. Nugget effect was an important feature of thesevariograms. Ranges varied between 10 to 6 nmi, being higher in the northem area. Thiscould be related to the size of the continental shelf as well as the different sizecomposition around the coast. In fact, in the southem part younger (age groups I and TI)are mainly distributed.From this prelirninary analysis, ranges of the spatial structures are higher than those foundin the Spanish area. This and the continuity of the sardine distribution around the coast arethe main differences between the Spanish and the Portuguese sardine distribution.In order to avoid problems with the independence of transects when zigzag design areused, systematic parallel survey design with a random start seems to be more appropriate.In the Portuguese coast, distance between transects could be 8 nmi.ReferencesFemandes, P. G. The application of a logbacktransformation in geostatistical analysis todetermine dataset selection in North Sea herring acoustic surveys. 1996. ICES CM1996/D: 13Petitgas. P. 1993. Geostatistics for fish stock assessments: a review and an acousticapplication. ICES Joumal of Marine Science, 50: 285-298.Petitgas, P. and Prampart, A. 1993 EVA (Estimation VAriance). A geostatistical softwareon IBM-PC for structure characterisation and variance computation. ICES CM1993/D:651.Porteiro, c., Carrera, P., and Miquel, J. 1996. Analysis of Spanish surveys for sardine,1991-1993: abundance estimates and inter-annual variability. ICES Joumal ofMarine Science, 53: 429-433.8Neo Survcy Total No Arca Mean varíance No of valucs and tbeir contribulion 10 mean and varience ('i-) McdcíNo zcrocs (sqnmi) (Sa) szooo ,1000 ,500 ,200 (pcrformcd ovcr raw data and lag transf. inlnside insidc No 'J.m 'i-v No ~m 'íl-v No s-m %v No IJ.m ~v wholc area and only on 101::by sebareas)Wholcarca Spnng 990 516 8452.1 352.52 685122.9 44 44.2 79.6 107 66.6 87.5 198 84.1 89.2 366 96.8 89.5 lOOOCO+Sph(565000;IO); O.42+5ph(8: 10)Summer 959 557 8452.\ 391.35 1073460 62 59.4 86.7 108 74.6 90.2 189 87.9 90.8 320 97.8 91 474001}+Sph(600000;9): I+Sph(8.7; 9)Cenual-N Spnng 276 52 2104.69 297.46 477339 5 25.9 83.4 16 42.8 91.5 36 57.5 93.3 138 89.4 95.7 1.5 + Exponcntial(3.5: 8)Surnmcr 256 39 2137.87 732.81 1712482 31 57.6 85.1 57 74.3 76.8 100 88 87.1 160 97 90 3.5 + Spherical(2.4: 6)Central S Spring 65 8 433.92 975.38 1442191 11 55.2 78.2 25 79 78.7 39 93.7 80.5 52 99.2 87.6 Nugget eñecrSummer 3. 5 328.71 1533.33 5634910 10 82.9 79.3 13 89.1 79.6 18 93.7 81.9 31 99.S 91.6 2 + Spherical(6; 7)South Spring 243 11 2060.34 877.78 1233549 28 45.1 77.7 69 69.5 80.9 131 89.8 82.2 198 98.4 90.3 0.5 + Sphcrical{2.3: 6)Summer 188 17 1738.01 787.77 1313268 24 52.4 81 44 69.3 83.4 56 86 84.1 145 98.2 90.7 1.2 + EX.E,0ncmial(3.2; 6)Table 1: Number total of data inside each area, number of nil values, surface (nmi"), meanSA value and its variance, number of values higher than 2000 SA, 1000 SA, 500 SA and 200SA and their contribution in percentage to mean and its variance and fitted variogram foreach area and survey.942°1 136°I(IIJ35°1 , , , ,11° 10° 9° 8° 7° 6° 5°41°40°39°38°37°Figure la: Sardine backscattering values in spring 1996. Zeroes values are denoted byblack dots . Positive values are represented in classed increasing circles (1-200; 200-500;500-1000 and >1000 SAvalues).1042° I ) I I41 °40°39°38°37°36°I(IIJ35°1 , , , ,II° 10° 9° 8° 7° 6° S°,/IFigure lb: Sardine backscattering values in surnmer 1996. Zeroes values are denoted byblack dots . Positive values are represented in classed increasing circles (1-200; 200-500;500-1000 and >1000 SAvalues).119 ~ An-4: Cl!rllrtJl Not1h ~o + I I I IO 3 6 9 12 15 18 21 24 27 30,.•.J:*• -> •••• '+.. '" .' J:5".,. ..•... ..:~ "1.:' ••.•••+...... \. J: •••••,'r";" ",",> •3 ••.. '.+.':0:- ••• +.' ':t i ".""'.;';2 ' '" '.¡..+, r ..•...O'--+--90"o t------ t .-t--+-- ¡--+--f----+--+--i---+---I I +---I---tO 3 6 9 12 15 18 21 24 27 30,.•.~ Arra:"Ci!rtIral SoIllIr+SoUlIrJOAua:Cl!rII,."ISlIullr:: f." ~ __•. ··0°_.+. -90~o+- I f.- t---+-------+--+- I IO 3 6 9 12 15 18 21 24 27"'''Ñ'i!a:Soulllt.;. 10 •• -ir .•.': f' :.+.... *• ~ ~. '!'- : '.+.' '. .:i:,t '+; X. +. : .. .., '.4 ., ••••• +. -+-., ,.....• "'" T ±2 f *-_ .. :" +' . ... 1" • "X" '+O I I I l·... I I I I I I IO J 6 9 12 15 18 21 24 27 30,.•.'6 WJwU:Ana. Log valUI!S;l'"~~ 3l+. ~•.•.•••.•.. ;':. ././ \../ '" '+¡.. '..J(,,", ,+.... JIf.J(..'L 'X- -S ,'::¡' - +' .....', .: 'X'S ••'" ic .%,:: .J1. ""J(' I ::::::,. I"J:',. .:0:'''''4 --"--0"--+"90" J:OO--~+-+--i~~MI --o--<27 30Figure 2a: Experimental variograms and fitted models (0° and 90° directions) for eacharea and the whole area ofthe spring acoustic survey.12.'1l.+.... +"i'"42I I I I I I3 9 12 15 18 21 24 27 30''''"100 ••12 18 2112 WIf(lIt' Ana. Raw dataJ(io I ..•... o' I S·-Xf --+"90" X,o,j : :J:" ',..J(' J:' .:\\ •• "1.1 4 -~.+-~.+ +.i -0+, .;* ' •. -+-,+_.+2 •12AtU: Celtlral N.rflf'*8- +,+' 'i;:tAna-: Celtlmt S.uth+;" .. +..•.: !t'7 - "25'+.+, •.. ,b...••.. ~6~~ ••I :.', o'S - • .(. ')1.4 t ",.' +'.3 - _ •-l.--X '" :'.,.20 ._"--0"__+__9QuJ:'l(_ 'S .•15~~ +-10~":.:Jl.'·"""~S .0"': \]( ~':. '+. -+-- ", ,- -. +.+O t--t--t--+-+--Z-t - lit- +-+----+------1O 3 6 9 12 15 18 21 24 27 30l•••-+-"'o+. ...2 .; •••. • :x..1+ I ...•.. 0" rOll·",· •• ·J:·.lI. .:···'"•• +.-90"O~--- ._- f---+- I I I I 1- -+--+---+- I ----+----t-- -+-+--~O 3 6 9 12 15 18 21 24 27 30l•••10 Arftl:Sou/1f~:1:. '.. "+ 1'" .'6 ~ • ~. ~ ,Z ." • +S ."1.+. .: :'J: . . -1' • ',4 .+. ::J' .+. .••.••. .'x' lO( ": I ...•.. o" .¡._+"90"Whole Area. Lor ~alueJ14{J2108~- ." :f-'lI ..•••",i6 .:..,.41· I, .o I I Ix .. ]1, .r·J:·.,.z· *" ·:I:--*. x. ,....+--+ •..•••.~-+~...,.--~+'.,'_ ••.•• 00--+ -'90Q!--f !--f !--fo I I I I I I I I I I Io 12 15 18.... 27 30" 2418 24 27 30 30o J 6 J2 15l•••nWJwk Area. Ralt' da/.ai.6'":o:.":·T·lK. ,,'1.4 ~ • .x....•~- L2 • .*.• "':o:. ,¡...+l !t':""~' "'\ .,:.:'.••..+--+ .:e .." . .:~ .••. +-.+.! +.....•...¡ 06 'f1 0:4:i.+. ,''¡'•• •. ··0••"+"90"0.212 is 18'.•. " 24 27Figure 2b: Experimental variograms and fitted models (0° and 90° directions) for eacharea and the whole area of the summer acoustic survey.13

Report of the Planning Group for a Sardine Acoustic Survey in ICES Sub-Areas VIII and IX

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Report of the Planning Group for a Sardine Acoustic Survey in ICES Sub-Areas VIII and IX

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