Resource Survey of the Great Australian Bight Trawl Fishery 2009

Transcription

1 R28/848 l 4/5/29 Rourc Survy of t Grt Autrlin Bigt Trwl Firy 29 In In Knucky, Mtt Koopmn nd Rull Hudon 29

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3 Rourc Survy of t Grt Autrlin Bigt Trwl Firy 29 In Knucky, Mtt Koopmn nd Rull Hudon AFMA Projct 28/ Fiwll Conulting i AFMA Projct 28/848

4 Rourc Survy of t Grt Autrlin Bigt Trwl Firy 29 In Knucky, Mtt Koopmn nd Rull Hudon AFMA Projct 28/ Publid: Fiwll Conulting Pty Ltd 22 Bridg St Quncliff VIC 3225 ISBN: Gnrl diclimr Ti publiction my b of itnc to you but t Fiwll Conulting nd it mploy do not gurnt tt t publiction i witout flw of ny kind or i wolly pproprit for your prticulr purpo nd trfor diclim ll libility for ny rror, lo or otr conqunc wic my ri from you rlying on ny informtion in ti publiction. Ti publiction i copyrigt. No prt my b rproducd by ny proc xcpt in ccordnc wit t proviion of t Copyrigt Act Prfrrd wy to cit: Knucky, I., Koopmn, M., nd Hudon, R. (29). Rourc Survy of t Grt Autrlin Bigt Trwl Firy 29. AFMA Projct 28/848. Fiwll Conulting 2pp. Fiwll Conulting ii AFMA Projct 28/848

5 Excutiv Summry T Grt Autrlin Bigt Trwl Firy (GABTF) trgt two min pci, dpwtr fltd (Nopltycplu contu) nd Bigt rdfi (Cntrobryx grrrdi). Indutrybd firy-indpndnt rourc urvy of t Grt Autrlin Bigt (GAB) v bn conductd inc 25 wit t primry gol of obtining robut nnul indic of rltiv biom of t two min pci. T indic r incorportd into forml tock mnt, wic wr prviouly mprd by input dt wit littl contrt. T Grt Autrlin Bigt Indutry Aocition (GABIA) upportd implmnttion of t indutry-bd firy-indpndnt rourc urvy of t GABTF, drivn lrgly by indutry dir for bttr undrtnding of t xtnt of lf rourc of tir min trgt pci. Survy r conductd during Fbrury April c yr uing tndrd rrc nt. Rltiv biom timt r clcultd uing wpt r clcultion, voiding t nd to mk umption rgrding t ctcbility nd fficincy of t gr. Indutry obrvtion, upportd by prliminry nlyi of dt from t 25 urvy, owd lrg diurnl ffct on ctc rt of Bigt rdfi, but not dpwtr fltd. Conquntly, only dt from nigt ot (wn ctc rt r igr) r ud in clcultion of rltiv biom timt of Bigt rdfi, but dt from bot dy nd nigt ot r ud in clcultion for dpwtr fltd. Ti rport dtil t rult of t 29 GABTF rourc urvy t fift concutiv nnul urvy. T two trip of t GABTF rourc urvy r gnrlly conductd during t wk lding up to t full moon in Fbrury nd Mrc. During 29, t occurrnc of t full moon w rly witin t clndr mont o it w dcidd to conduct t two urvy trip during t wk lding up to t full moon in Mrc nd April 29. Svnty-fiv vlid urvy ot wr compltd ovr t two urvy; dpwtr fltd nd Bigt rdfi occurrd in 1% nd 97% of t ot rpctivly. Rltiv biom indic wit CV<.2 wr obtind for dpwtr fltd, Bigt rdfi nd otr min pci witin t urvy r uing wpt r timt from trwl ot in trtifid rndom urvy dign. T rltiv biom timt of Bigt rdfi for 29 w 23,41 t (CV =.13), wic i 6% igr tn t 28 timt nd 12% igr tn t 25 timt. Etimt of rltiv biom of Bigt rdfi in 25, 26, 27 nd 28 wr 2,887 t (CV =.13), 25,38 t (CV =.16), 25,713 t (CV =.16) nd 14,591 t (CV =.11) rpctivly. T rltiv biom timt of dpwtr fltd during 29 w 1,181 t (CV=.4). Ti i 32% igr tn t 28 timt nd 16% lowr tn t 25 timt. Etimt of rltiv biom of dpwtr fltd in 25, 26, 27 nd 28 wr 12,152 t (CV =.5), 8,415 t (CV =.6), 8,54 t (CV =.5) nd 7,725 t (CV =.6) rpctivly. In prviou yr, Bigt rdfi (2% 26%) bn t mot commonly cugt pci during t urvy. Ti yr, dpit t incr in rltiv biom of Bigt rdfi, tr wr vry lrg ctc of ocn jckt nd ty comprid t grtt portion (25%) of t urvy ctc. Bigt rdfi comprid 19% of t totl ctc nd ltct, wid tingr nd dpwtr fltd wr t nxt mot commonly cugt pci. Lngt-frquncy murmnt wr md on 1,382 dpwtr fltd nd 1,287 Bigt rdfi. T modl lngt of Bigt rdfi in mpl from 29 w ~31 cm nd own conitnt dclining trnd from round 35cm rcordd from t 25 inugurl urvy. Tr i lo om vidnc of rducd proportion of lrgr (>45cm) fi in t urvy Fiwll Conulting iii AFMA Projct 28/848

6 mpl ovr ti priod. Ti my b n indictor of rcnt fiing prur on t tock but i not rflctd by rduction in t bundnc indx. T iu ould b furtr xplord during t nxt mnt. Modl lngt of dpwtr fltd from 29 mpl (~43 cm) w imilr to t prviou tr yr but mllr tn tt from 25. T proportion of lrgr niml pcilly in t 45-6cm iz rng lo pprd to rduc ovr t priod of t urvy. Otolit mpl of 23 dpwtr fltd nd 216 Bigt rdfi wr lo collctd during t urvy. Dt from t ging of t otolit will b ud during t nxt mnt to b conductd for Bigt rdfi during 29 nd dpwtr fltd during 21. T rult of ti urvy provid t fift concutiv yr of firy-indpndnt indx of bundnc for bot dpwtr fltd nd Bigt rdfi nd r now providing n xtrmly uful indictor of tock ttu wic cn b quntittivly incorportd into t tock mnt. In ddition to t two importnt trgt pci, w now v fiv-yr timri of rltiv bundnc indic for mny of t importnt byctc nd byproduct pci in t GABTF including ocn jckt, common wrk gummy rk, jck morwong, knifjw, ltct, ornt nglrk nd piky dogfi. Fiwll Conulting iv AFMA Projct 28/848

7 Tbl of Contnt EXECUTIVE SUMMARY...III TABLE OF CONTENTS...V LIST OF TABLES... VI LIST OF FIGURES... VI INTRODUCTION... 1 OBJECTIVES... 1 MATERIAL AND METHODS... 2 SURVEY DESIGN... 2 CALCULATION OF RELATIVE BIOMASS AND COEFFICIENT OF VARIATION... 3 Dtrmining t dnity... 3 RESULTS... 4 SURVEY COVERAGE... 4 GEAR PERFORMANCE... 4 CATCH COMPOSITION AND LENGTH FREQUENCIES... 4 RELATIVE BIOMASS ESTIMATES... 5 DISCUSSION... 5 SURVEY COVERAGE... 5 GEAR PERFORMANCE... 6 CATCH COMPOSITION AND LENGTH FREQUENCIES... 6 RELATIVE BIOMASS ESTIMATES... 7 Bigt rdfi... 7 Dpwtr fltd... 7 Otr pci... 7 CONCLUSIONS... 7 ACKNOWLEDGMENTS... 8 REFERENCES... 8 Fiwll Conulting v AFMA Projct 28/848

8 Lit of Tbl Tbl 1. Dcription of trt mpld during t 29 urvy Tbl 2. Mn nd tndrd dvition (SD) lngt (m), wpt r (km 2 ), pd (knot) nd dpt (m) of ot in c trtum Tbl 3. Totl ctc (kg) of ll pci in c trtum nd cro ll trt during t 29 urvy Tbl 4. Ctc (kg) Bigt rdfi nd dpwtr fltd for c trtum point mpld during t 29 urvy Tbl 5. Spci nd numbr of fi for wic lngt, x, nd otolit mpl wr collctd during 29 urvy... 2 Tbl 6. Etimtd totl rltiv biom (t) wit cofficint of vrition (c.v.) of mjor commrcil pci in cro ll trt from 25, 26, 27, 28 nd 29 urvy uming nt widt of 16.3 m... 2 Lit of Figur Figur 1. Survy trt nd ot loction of trwl urvy Figur 2. Proportion (of wigt) of mjor pci cpturd during t 29 urvy Figur 3. Frquncy of ctc (kg) of Bigt rdfi during t 29 urvy... 1 Figur 4. Frquncy of ctc (kg) of dpwtr fltd during t 29 urvy Figur 5. Mn nd tndrd rror of Bigt rdfi ctc by tim of dy during t 29 urvy Figur 6. Mn nd tndrd rror of dpwtr fltd ctc by tim of dy during t 29 urvy Figur 7. Lngt-frqunci of Bigt rdfi during t urvy Figur 8. Lngt-frqunci of dpwtr fltd during t urvy Figur 9. Rltiv biom timt (t +SE) of Bigt rdfi, dpwtr fltd, ocn jckt, common wrk nd gummy rk from nnul urvy Figur 1. Rltiv biom timt (t +SE) of jck morwong, knifjw, ltct, ornt nglrk nd piky dogfi from nnul urvy Fiwll Conulting vi AFMA Projct 28/848

9 Introduction T Grt Autrlin Bigt Indutry Aocition (GABIA) upportd t implmnttion of n indutry-bd firy-indpndnt rourc urvy of t Grt Autrlin Bigt Trwl Firy (GABTF) inc it implmnttion in 25. Ti bn lrgly drivn by indutry dir for bttr undrtnding of t xtnt of lf rourc of tir min trgt pci, dpwtr fltd (Nopltycplu contu) nd Bigt rdfi (Cntrobryx grrrdi), nd t lvl of impct tt fiing migt b ving on t rourc. Until 26, t GABTF w mngd by input control limiting t numbr of oprtor in t firy to tn. Only mll numbr (typiclly 4 5) of t tn SFR oldr d bn ctiv in t firy during ny on yr ovr t dcd to 22. Ctc nd ffort dt from t vl logbook owd no ovrll trnd in ctc rt for itr dpwtr fltd or Bigt rdfi nd tr rmind littl contrt in t dt. Tim ri of lngt- nd gfrquncy dt do not indict ny ignificnt impct on t rourc from ti lvl of fiing itr. Stock mnt modl up to 26 for Bigt rdfi nd dpwtr fltd wr dvncd, but uffrd from t lck of contrt in ny of t min firy indictor. A rult, tr w conidrbl uncrtinty urrounding modl output including timt of tock biom. Tr w incrd prticiption in t firy nd incr in fiing ffort nd fiing fficincy of ctiv vl during Givn t uncrtin ttu of t tock t ti tim, ti rid concrn bout futur utinbility of t lf rourc. Undr ti cnrio, indutry grd tt quot mngmnt of t min trgt pci would b introducd from 26. Ty lo grd on qul lloction of quot btwn t tn SFR oldr. Wit t pnding introduction of quot during 26, tr w concrn tt low TAC would b introducd bd on t ig uncrtinty of biom timt rulting from tock mnt modl nd ti my inibit t utinbl dvlopmnt of t firy. Morovr, onc quot wr introducd it w blivd t u of commrcil CPUE dt t min indx of bundnc in t modl would b compromid nd unlikly to provid t contrt tt i ndd to improv modl output. Indutry invtigtd t fibility of conducting firy-indpndnt urvy to provid tim-ri of rltiv bundnc indic for dpwtr fltd nd Bigt rdfi tt cn b ud n input to tock mnt modl (FRDC Projct 22/72). Prliminry urvy of t min lf r of t firy wr uccfully conductd during 25 (Knucky t l, 26), nd continud during 26 (Knucky nd Hudon, 27), 27 (Knucky nd Hudon, 27b) nd 28 (Knucky t l, 28). Continuing t rndom trtifid urvy during 29 xtnd t tim ri of rltiv biom timt of Bigt rdfi nd dpwtr fltd nd provid furtr vidnc of wtr pproprit TAC v bn t. Objctiv 1. Dtrmin rltiv bundnc indx for Bigt rdfi nd dpwtr fltd in t currnt rgion of t min GABTF lf firy during Collct biologicl nd popultion dt on t pci. 3. Dtrmin rltiv bundnc indx of otr min pci in t currnt lf firy. Fiwll Conulting 1 AFMA Projct 28/848

10 Mtril nd Mtod Survy Dign Dtild dcription of urvy dign nd vl nd gr pcifiction r rportd in Knucky t l, (26). A brifly dcription i givn blow. Altoug fiing for lf pci occur outid of t r, t urvy w rtrictd to dpt of 12 2 m nd btwn longitud 126º nd 132º3. T longitudinl rng w dividd into four primry trt; 126º 127º45 (Wt1), 127º45 129º (Wt2), 129º 13º15 (Cntrl1), 13º º3 (Cntrl2) (Tbl 1). Ti rprnt t min fiing r of t lf componnt of t firy. Ctc rt of Bigt rdfi fluctut trougout t yr, bing igt during Fbrury April. Ctc rt of dpwtr fltd lo fluctut onlly, owvr, not muc Bigt rdfi. Conquntly t urvy i conductd during Fbrury April. Initil nly of t ctc nd ffort dt indictd ctc rt for Bigt rdfi wr not ffctd by tim of dy of t ot, wil ctc of dpwtr fltd wr igr during t dy from Fbrury to April. Howvr, rult from t prliminry urvy during 25 indictd ctc of Bigt rdfi wr igr during nigt ot, nd futur nly of Bigt rdfi ould only includ nigt ot (Knucky t l, 26). For dpwtr fltd tr w no ignificnt diffrnc btwn dy nd nigt ot, nd furtr nly of ti pci would pool ll ot. T indiction v provn corrct in ubqunt yr, o urvy dign nd mtod v bn rptd nnully bd on t nly. Anlyi of t ctc nd ffort dt uggtd t vrition of ctc rt for Bigt rdfi w igr for trwl durtion <2.5 our (including tting nd rtriving nt). A imilr rult w obrvd for dpwtr fltd but w not pronouncd. To mintin conitnt mpling tim it w grd for c urvy ot t nt ould b trwld for 2.5 our nd tim tting nd rtriving t nt not includd. Furtr nlyi of logbook dt indictd minimum of 76 ot would b ndd to civ CV of <2% for Bigt rdfi. Ti nlyi w bd on combining bot dy nd nigt ot. Aftr t prliminry urvy w conductd in 25, it w obrvd t numbr of ctc ( contributing fctor to ig CV) of Bigt rdfi w not ig xpctd, nd nc n nlyi of only nigt ot (pproximtly lf of t 76 ot) providd n ccptbl CV (Knucky t l, 26). Numbr of ot lloctd to c of t primry trt w proportionl to t ctcwigtd tndrd dvition of CPUE. Sot loction wr lctd rndomly. A ot i dmd to b ccptbl if t ot p witin 5 m of t lctd poition. If t ot to b bndond du to gr problm, it cn till b conidrd ccptbl if towd for minimum of 1 our nd pd troug t poition. T trt nd fini poition of c ot w rcordd long wit minimum nd mximum dpt, vrg trwl pd, nvironmntl condition nd dirction of tow. T ot wr compltd in pcifid ordr to rduc tmporl bi in t dt collction, toug t ordr of vrl ot w rrrngd for logiticl ron. Sot wr conductd t pd rnging knot, wit t kippr dciding on t trting poition nd dirction of t tow. Wn t ot w compltd, t nt w uld bord nd t ctc mptid on to t dck. Commrcil pci wr gtrd in fi bin nd pproximt wigt of c pci timtd. Dicrdd byctc wr idntifid to pci wr poibl nd n pproximt wigt of c pci timtd. Wn t ctc w unlodd in port t corrct wigt of Bigt rdfi nd dpwtr fltd wr obtind nd comprd to t Fiwll Conulting 2 AFMA Projct 28/848

11 urvy timt. If tr w diffrnc of ± >2% tn t urvy timt wr djutd. Lngt murmnt wr collctd rndomly during t urvy for dpwtr fltd nd Bigt rdfi, t totl lngt murd for fltd nd fork lngt for Bigt rdfi. Otolit mpl of t two pci wr lo collctd rndomly during t urvy rcording t lngt nd x of c mpl. Clcultion of Rltiv Biom nd Cofficint of Vrition T timtion of t rltiv biom i bd on t mtod doptd by Scnut nd Hig (23), wr in implitic trm, typicl urvy conit of numrou tow, c ot giving biom dnity timt biom cpturd Dnity = r wpt by nt And totl biom (bundnc) timtd by clculting t mn dnity (wit n ocitd cofficint of vrition) from ll ot nd pplying tt to bitt or trtum r Biom = dnity r (Scnut nd Hig, 23) Dtrmining t dnity For ot wr Bigt rdfi nd dpwtr fltd r prnt in t ctc (non-zro murmnt), t mn dnity for c trtum i µ = 1 n n i= 1 µ i T qurd invr of t CV i v = µ 2 2 T mn dnity of murmnt for c trtum i ( ) δ = 1 p µ T vrinc of dnity of murmnt c trtum i σ = µ ( 1 p )( + ) 1 pν ν T timtd biom of c trtum i b = A δ T CV of biom timt of c trtum i cv = σ b n 2 Wr p i t proportion of ul wit zro ctc for t pci in trtum, µ i t mn kg pr r wpt (m 2 ) of pci wr ctc >zro, i t td kg pr r wpt (m 2 ) of pci wr ctc >zro, A i t totl r of trtum, n i t numbr of ot nd b i t timtd rltiv biom. Totl rltiv biom nd CV for c pci wr clcultd follow B = b Fiwll Conulting 3 AFMA Projct 28/848

12 cv = cv T numbr of ot, n, in c trtum tt producd t dird cofficint of vrition, cv, w rndomly lloctd witin c trtum. Rltiv biom w timtd uing t wpt r mtod. T dnity mur w timt follow µ i C = i v i d i E i Wr c ot i in pctrum known ctc of C i, ffort (ot durtion our) E i, vl pd (m/our) v i nd door prd d i. T wpt r of t trwl nt cn b xprd itr t r wpt by t nt or t r wpt by t door. Nt widt w timtd 5% of t dlin lngt wil door widt involvd muring t ditnc btwn t wrp t t pully (block) tn 1 mtr long t wrp towrd t trwl nt. T diffrnc in widt would tn b multiplid by t lngt of t wrp lt out ( w w ) WL ( ) d = w2 wr w 1 i t ditnc btwn t wrp on mtr down from t block, w 2 i t ditnc btwn t wrp t t bck of t block nd WL i t wrp lngt. Rult Survy Covrg Survy wr uccfully compltd for c of t trt witin t tim frm nd budgt lloctd. T rndom trtifid urvy mpld 75 it during Mrc nd April 29 (Figur 1). On ot (ot 72) w bndond du to nd xciv ctc of ocn jckt. It w timtd from t iz of t bg tt t lt 7 t of ocn jckt wr cugt during ti tow, but t kippr nd onbord cintit dcidd to bndon it du to prcticl ron. Dt from ti ot w not includd in nly. T mn ot lngt in t four trt during t Mrc nd April crui wr 14.9 km nd 14.9 km (Cntrl 1), 15.3 km 14.8 km (Cntrl 2), 15.3 km nd 15.1 km (Wt 1) nd 15.2 km nd 15.1 km (Wt 2) (Tbl 2). Gr Prformnc Door prd w timtd on 8 occion to monitor gr prformnc. Door prd murmnt rngd m rflcting t uncrtinty nd difficulty in muring t ditnc btwn wrp to t nrt cntimtr mtr from t block. Mn door prd w 17.5 m (+ 8.2 m SD). Ti i witin t rng obrvd during prviou urvy of 84. m 19.6 m (Knucky t. l. 26; Knucky nd Hudon, 27; Knucky nd Hudon, 27b; Knucky t. l. 28). Ctc Compoition nd Lngt Frqunci T totl ctc during t Mrc nd April urvy combind (133.5 t) comprid 91 idntifid pci or pci group wit t lrgt ctc occurring in t Cntrl1 trtum (Tbl 3). Ocn jckt 28.2 t (25%), Bigt rdfi 21.1 t (19%), nd ltct 14.9 t (13%) md up t mjority of t ctc, followd by wid tingr 13. t (11%), nd dpwtr fltd 13. t (11%) (Figur 2). Dpwtr fltd nd Bigt rdfi occurrd in 1% nd 97% of ot rpctivly during 29. Fiwll Conulting 4 AFMA Projct 28/848

13 Ctc of Bigt rdfi vrid mor tn ctc of dpwtr fltd (Figur 3, Figur 4, Tbl 4). Tirtn ul contind mor tn 5 kg of Bigt rdfi wil tird of ul contind ctc rnging 5 kg. T lrgt ul of dpwtr fltd w 43 kg nd, 65 of t 75 ul conductd cugt btwn 5 25 kg of dpwtr fltd. Ctc of Bigt rdfi vrid conidrbly wit tim of dy. Mn ctc of Bigt rdfi in ot tt commncd during 18: our nd 6: our wr tr fiv tim grtr tn ctc from ot tt bgn btwn 12: our nd 18: our (Figur 5). T mn ctc in ot tt bgn btwn 6: our nd 12: our w two tr tim mllr tn nigt tim ctc. T two ot tt contind kg of Bigt rdfi wr bot conductd btwn 12: our nd 18: our. In contrt tr w no diffrnc in ctc of dpwtr fltd btwn nigt nd dy ot (Figur 6). T lngt of 1,287 Bigt rdfi wr murd during t 29 urvy (Tbl 5). Lngt rngd cm, owvr, mot fi murd wr btwn cm (Figur 7). T modl lngt w 31 cm. T lngt of 1,382 dpwtr fltd wr murd during t 29 urvy (Tbl 5). Lngt rngd cm, owvr, mot fi murd wr btwn 4 46 cm (Figur 8). T modl lngt w 43 cm. A totl of 23 otolit wr collctd from dpwtr fltd, wil 216 wr collctd from Bigt rdfi (Tbl 5). Rltiv Biom Etimt Uing only nigt ot (18 6 our) nd nt-widt in wpt-r clcultion, t rltiv biom timt of Bigt rdfi for t 29 urvy i 23,41 t wit CV of.13 (Tbl 6). T rltiv biom timt for 29 i 6% igr tn t 28 timt of 14,591 t, 9% lowr, 8% lowr nd 12% igr tn timt md in 27, 26 nd 25 rpctivly (Figur 9). Uing bot dy nd nigt tim ot nd nt-widt in wpt-r clcultion, t rltiv biom timt of dpwtr fltd for t 29 urvy i 1,181 t wit CV of.4 (Tbl 6). T rltiv biom timt for 29 i 32% igr tn t 28 timt of 7,725 t, nd 19% igr, 21% igr nd 16% lowr tn timt md in 27, 26 nd 25 rpctivly (Figur 9). Rltiv biom timt for numbr of otr importnt GABTF pci wr lo clcultd (Tbl 6). CV of t pci wr ll blow.2. Otr pci wit t grtt rltiv biom timt during 29 wr ocn jckt (22,33 t) nd ltct (12,484 t). Trnd in rltiv biom timt vrid from pci to pci (Figur 9 nd Figur 1). Spci tt owd dcr in during wr jck morwong ornt nglrk, nd piky dogfi, wil rltiv biom timt of ocn jckt, common wrk, knifjw nd ltct incrd. Rltiv biom timt of gummy rk wr imilr btwn 25 nd 29 urvy. Dicuion Survy Covrg T primry objctiv of t rndom trtifid urvy w to dtrmin rltiv bundnc indx for Bigt rdfi nd dpwtr fltd in t currnt rgion of t min GABTF lf firy. No ttmpt v bn md to timt bolut biom from t urvy rult. T urvy w lo dignd to collct biologicl nd popultion dt on t pci, nd Fiwll Conulting 5 AFMA Projct 28/848

14 to dtrmin rltiv bundnc indx of otr min pci in t currnt lf firy. All of t objctiv wr mt, wit 75 it uccfully urvyd during Mrc nd April 29, dding to t xiting four-yr tim ri. Gr Prformnc It bn continully trd tt tr r mny uncrtinti nd umption rgrding rding, cpmnt nd ctcbility ocitd wit trwl nt nd u of t GABTF trwl urvy rult n bolut indx of bundnc (g. Knucky nd Gon 26; Knucky t. l. 26). Additionl uncrtinti rlt to pci popultion dynmic nd tt t urvy trt do not ncomp t ntir popultion of itr Bigt rdfi or dpwtr fltd itr ptilly or tmporlly. On xmpl i t fct tt dpwtr fltd, Bigt rdfi nd otr lf pci r rgulrly cugt in dpt to t lt 25 m, but urvy covrg i only btwn 12 2 m dpt in c trtum. Importntly, bcu of diurnl migrtion of Bigt rdfi troug t wtr column, rltiv biom timt for tt pci r clcultd from nigt ot only. For t bov ron, t dt collctd during t urvy r only intndd to b ud rltiv indx of biom to b input into t tock mnt modl. Wit rpct to prformnc of t gr, it i only ncry to nur tt it prform conitntly from yr to yr. Door prd i t min mur of gr prformnc during t urvy. Altoug it would b prfrbl to v t Nt-ond quipmnt to continully monitor t urvy nt crctritic, ti quipmnt rgulrly fild to work. Murmnt of wrp ngl, owvr, v llowd timt of door prd nd t 29 rult ppr to b conitnt wit prviou yr. Ctc Compoition nd Lngt Frqunci Until t 29 urvy, Bigt rdfi d comprid t lrgt portion of t ctc in ll urvy (prt from t Dcmbr 25 urvy); 22% in 25 (Knucky t. l. 26), 26% in 26 (Knucky nd Hudon, 27), 25% in 27 (Knucky nd Hudon, 27b) nd 2% in 28 (Knucky t. l. 28). Du to lrg incr in ctc of ocn jckt (25% of t ctc) in 29, Bigt rdfi comprid t cond lrgt portion of t ctc t 19%. T proportion of t totl ctc compriing dpwtr fltd dcrd from 19% in 25 to 15% in 28 nd 11% in 29. Ltct wr cugt in lrg numbr during 29 nd comprid 13% of t totl ctc. Modl lngt of Bigt rdfi murd during 25, 26, 27, 28 nd 29 urvy wr 35 cm, 35 cm, 34 cm, 31 cm nd 31 cm rpctivly (Figur 7). Ti dclin ovr fiv yr i of not. A in 28, rltivly lrg proportion of fi murd during 29 wr l tn 3 cm nd tr i om vidnc of rducd proportion of lrgr (>45cm) fi in t urvy mpl ovr t fiv yr priod during wic t urvy v bn conductd. Ti my b n indictor of rcnt fiing prur on t tock but i not rflctd by rduction in t bundnc indx. T iu ould b furtr xplord during t nxt mnt. Modl lngt of dpwtr fltd murd during 25, 26, nd 29 urvy wr 46 cm, 43 cm, 43 cm, 45 cm nd 44 cm rpctivly (Figur 8) but r mor difficult to intrprt tn rdfi tr r multipl pk. Modl lngt of dpwtr fltd from 29 mpl ppr imilr to t prviou tr yr but mllr tn tt from 25. T lngt-frquncy ditribution in 29 contin grtr numbr of fi ovr rducd nd mllr iz rng comprd wit prviou yr nd in prticulr, mllr proportion of lrg fi tn w obrvd during t 25 nd 26 urvy. Importntly, t Fiwll Conulting 6 AFMA Projct 28/848

15 proportion of lrgr niml pcilly in t 45-6cm iz rng pprd to rduc ovr t priod of t urvy. Agin, ti ould b invtigtd during t nxt mnt. Rltiv Biom Etimt Bigt rdfi T 29 rltiv biom timt of Bigt rdfi of 23,41 t w lmot 12% igr tn t 25 timt (2,887 t) nd 6% igr tn t 28 timt of (14,591 t). T timt wr bd on nigt ot only. T CV for nigt ot during 29 (.13) w wit in t rng obrvd in prviou yr (.13.16). T 29 CV w lrgr tn t 28 CV bcu tr w lrgr rng in ctc during t currnt yr, including 13 ul tt contind mor tn 5 kg of Bigt rdfi. Dpwtr fltd T rltiv biom timt for dpwtr fltd (dy nd nigt ot combind) during 29 (1,181 t) i bout 16% lowr tn t 25 Fbrury nd Mrc timt (12,152 t), bout 2% igr tn t 26 nd 27 timt (8,415 t nd 8,54 t), nd 32% igr tn t 28 timt (7,725 t). It i unclr wtr t dclin in rltiv biom timt to 28 rprntd dclin in t popultion or imply onl vribility in t timt, owvr t ubqunt incr during 29 in ncourging. T CV obtind for rltiv biom timt during 29 for dy nd nigt ot combind (.4) w t lowt obtind inc t urvy bgn in 25. In otr yr, CV wr.5.6. Otr pci Tr w conidrbl nnul vrition in rltiv biom timt of otr min pci. Spci tt owd dcr in during wr jck morwong ornt nglrk, nd piky dogfi, wil rltiv biom timt of ocn jckt, common wrk, knifjw nd ltct incrd. Rltiv biom timt of ocn jckt nd ltct owd prticulrly lrg incr of pproximtly 19% nd 24% rpctivly from 28. Rltiv biom timt of gummy rk wr imilr btwn 25 nd 29 urvy. Concluion T 29 Grt Autrlin Bigt rourc urvy civd ll of it objctiv. T trgt CV for rltiv biom timt wr civd for bot Bigt rdfi nd dpwtr fltd nd t rltiv biom timt wr comprbl to rult from prviou yr. In ddition, rltiv biom timt of otr importnt pci wr timtd wit low to mdium CV. Sufficint lngt-frquncy nd otolit mpl wr collctd for bot trgt pci for u in t tock mnt. T rult of ti urvy provid t fift concutiv yr of firy-indpndnt indx of bundnc for bot dpwtr fltd nd Bigt rdfi nd r now providing n xtrmly uful indictor of tock ttu wic cn b quntittivly incorportd into t tock mnt. In ddition to t two importnt trgt pci, w now v fiv-yr timri of rltiv bundnc indic for mny of t importnt byctc nd byproduct pci in t GABTF including ocn jckt, common wrk gummy rk, jck morwong, knifjw, ltct, ornt nglrk nd piky dogfi. Fiwll Conulting 7 AFMA Projct 28/848

16 Acknowldgmnt W wi to tnk t ownr, Mr Smi Skoljrv, nd t kippr nd t crw of t Explorr S for tir profionl pproc to conducting t 29 urvy. Mik Grnr (AFMA) itd wit t onbord obrving during Trip 1. W lo cknowldg Ann Gon for r prompt nlyi of t rltiv biom timt. Rfrnc Hudon, R.J. nd Knucky, I. A. (25). Hrding modl nd tir ppliction to Bigt rdfi nd dpwtr fltd. GABRAG ppr Sptmbr 25, 17 pp. Knucky, I, nd Hudon, R. (27). Rourc Survy of t Grt Autrlin Bigt Trwl Firy Fiwll Conulting, 2pp. Knucky, I, nd Hudon, R. (27b). Rourc Survy of t Grt Autrlin Bigt Trwl Firy AFMA Projct R26/833. Fiwll Conulting 2pp. Knucky, I., Hudon, R., nd M. Koopmn (28). Rourc Survy of t Grt Autrlin Bigt Trwl Firy 28. AFMA Projct R26/833. Fiwll Conulting 19pp. Knucky, I., Koopmn, M., Gon, A. nd Hudon, R. (26). Rourc urvy of t Grt Autrlin Bigt Trwl Firy. Fiwll Conulting / Primry Indutri Rrc Victori, Quncliff, 4pp. Knucky, I.A. nd Gon, A.S.H. (26). Aing t fibility of n indutry-bd firy indpndnt urvy of t Sout Et Firy. Firi Rrc nd Dvlopmnt Projct 22/72 Finl Rport. Fiwll Conulting, 55pp. Scnut, J.T. nd Hig, R. (23). A imultion modl for digning groundfi trwl urvy. Cn. J. Fi. Aqut. Sci. 6: Fiwll Conulting 8 AFMA Projct 28/848

17 Figur 1. Survy trt nd ot loction of trwl urvy. Fiwll Conulting 9 AFMA Projct 28/848

18 All otr pci 12% Ocn jckt 25% Knifjw 1% Spong 1% Brrcout 2% Swllowtil 2% Ornt nglrk 3% Bigt rdfi 19% Dpwtr fltd 11% Wid tingr 11% Ltct 13% Figur 2. Proportion (of wigt) of mjor pci cpturd during t 29 urvy c y n u q F r Ctc (kg) Figur 3. Frquncy of ctc (kg) of Bigt rdfi during t 29 urvy. Fiwll Conulting 1 AFMA Projct 28/848

19 2 c y n u q F r Ctc (kg) Figur 4. Frquncy of ctc (kg) of dpwtr fltd during t 29 urvy. 6 5 g ) (k 4 c tc 3 g r v 2 A 1 :-5:59 6:-11:59 12:-17:59 18:-23:59 Sot trt tim Figur 5. Mn nd tndrd rror of Bigt rdfi ctc by tim of dy during t 29 urvy. Fiwll Conulting 11 AFMA Projct 28/848

20 25 2 g ) (k 15 c tc g r 1 v A 5 :-5:59 6:-11:59 12:-17:59 18:-23:59 Sot trt tim Figur 6. Mn nd tndrd rror of dpwtr fltd ctc by tim of dy during t 29 urvy. Fiwll Conulting 12 AFMA Projct 28/848

21 y c n 6 u q 5 r F 4 % n = Fork Lngt (cm) y c n 6 u q 5 r F 4 % n = Fork Lngt (cm) y c n 6 u q 5 r F 4 % n = Fork Lngt (cm) y c 6 n 5 u q r 4 F % n = Fork Lngt (cm) n = y c 8 n u q 6 r F % Fork Lngt (cm) Figur 7. Lngt-frqunci of Bigt rdfi during t urvy. Fiwll Conulting 13 AFMA Projct 28/848

22 9 8 7 y c 6 n u 5 q r 4 F % n = Totl Lngt (cm) y c n5 u q4 r F3 % n = Totl Lngt (cm) 12 1 y c 8 n u q 6 r F % n = Totl Lngt (cm) c y 6 n 5 u q r 4 F % n = Totl Lngt (cm) 12 1 y c 8 n u q 6 r F % n = Totl Lngt (cm) Figur 8. Lngt-frqunci of dpwtr fltd during t urvy. Fiwll Conulting 14 AFMA Projct 28/848

23 3 m (t) io 2 b t tiv tim 1 l R Bigt rdfi 16 m (t) 12 io b t 8 tiv tim 4 l R Dpwtr fltd 24 m (t) 18 io b t 12 tiv tim 6 l R Ocn jckt m io b tiv l R (t) t tim Common wrk m io b tiv l R (t) t tim Gummy rk Figur 9. Rltiv biom timt (t +SE) of Bigt rdfi, dpwtr fltd, ocn jckt, common wrk nd gummy rk from nnul urvy. Fiwll Conulting 15 AFMA Projct 28/848

24 m io b tiv l R (t) t tim Jck morwong m io b tiv l R (t) t tim Knifjw m io b tiv l R (t) t tim Ltct m io b tiv l R (t) t tim Ornt nglrk m io b tiv l R (t) t tim Spiky dogfi Figur 1. Rltiv biom timt (t +SE) of jck morwong, knifjw, ltct, ornt nglrk nd piky dogfi from nnul urvy. Fiwll Conulting 16 AFMA Projct 28/848

25 Tbl 1. Dcription of trt mpld during t 29 urvy. Strtum Dpt (m) Longitud Ar (km 2 ) Numbr of ot Cntrl Cntrl Wt Wt Tbl 2. Mn nd tndrd dvition (SD) lngt (m), wpt r (km 2 ), pd (knot) nd dpt (m) of ot in c trtum. Strtum Mont Sot lngt Ar wpt Sot pd Sot dpt Mn Mn Mn Mn SD (km) (km 2 SD SD ) (knot) (m) SD Cntrl 1 Mr Cntrl 2 Mr Wt 1 Mr Wt 2 Mr Cntrl 1 Apr Cntrl 2 Apr Wt 1 Apr Wt 2 Apr Not: Ar wpt clcultd uing widt of nt (16.3 m) Tbl 3. Totl ctc (kg) of ll pci in c trtum nd cro ll trt during t 29 urvy. Spci Ctc (kg) Cntrl 2 Cntrl 1 Wt 2 Wt 1 Totl Autrlin burrfi Brrcout Brrd grubfi Bc-d-mr 1 1 Bigt rdfi Bigcl rubyfi Blckpot borfi Blckpottd gurnrd prc Blu mckrl Blu morwong Blu wrou Brodno rk Bronz wlr Bug.5.5 Bulld gurnrd Common bllowfi Common wrk Common vilfin Congr l Cuttlfi Dpwtr bug Dpwtr fltd Dpwtr trgzr Fl bilr ll Footbllr wp Fourpin ltrjckt Gmfi Gould quid Grny dogfi Gummy rk Hpuku 4 4 Hrmit crb Jck mckrl Fiwll Conulting 17 AFMA Projct 28/848

26 Spci Ctc (kg) Cntrl 2 Cntrl 1 Wt 2 Wt 1 Totl Jck morwong Jon dory Knifjw Ltct Littl pinpplfi.2.2 Mlbourn kt Moic ltrjckt Notbl wiptil 4 4 Ocn jckt Offor ocn prc Ornt nglrk Pcock kt Pink ling 2 2 Port Jckon rk Rd cod Rd gurnrd Rdbit Ringd todfi Roug gurnrd prc Ruty crptrk Smonfi Sndppr fi Sndybck tingr Swtil ctrk Scool rk 6 6 Str Srgnt bkr Srpno vngill rk Silvr dory Silvr trvlly Smoot tingry Snppr Snip l.2.2 Soft corl Soutrn clmri Soutrn cimr Soutrn fiddlr ry Soutrn rock lobtr Soutrn round kt 1 1 Soutrn wrk Soutrn nip l.2.2 Spiky dogfi Spiny boxfi Splndid prc Spong Spottd wobbgong Swllowtil Tmnin numbfi 5 5 Tti fi Trpin crdinlfi Tuk Vlvt ltrjckt Wtrn ovlno ry 3 3 Wtrn moot boxfi Witbrrd boxfi Wid tingr Yllowy rdfi Yllowpottd borfi Totl Fiwll Conulting 18 AFMA Projct 28/848

27 Tbl 4. Ctc (kg) Bigt rdfi nd dpwtr fltd for c trtum point mpld during t 29 urvy. Sot cod Sot Strtum point Sot dt Tim of ot Strt Point Fini Point Ctc (kg) Lt Long Lt Long Lt Long Bigt rdfi Dpwtr fltd C ' ' 5/3/29 18: ' ' ' ' C ' 132 1' 5/3/29 21: ' ' ' ' C ' 132 4' 6/3/29 1: ' ' ' ' C ' ' 6/3/29 5: ' ' ' ' C ' ' 6/3/29 8: ' ' ' ' 9 68 C ' 13 13' 6/3/29 16: ' ' ' 13.' C ' 13 13' 6/3/29 19: ' ' ' ' C ' 13 7' 6/3/29 23: ' ' ' ' C ' ' 7/3/29 2: ' ' ' ' C ' ' 7/3/29 5: ' ' ' 129.' C ' ' 7/3/29 9: ' ' ' ' C ' ' 7/3/29 12: ' ' ' ' C ' ' 7/3/29 15: ' ' ' ' C ' 129 1' 7/3/29 18: ' ' ' ' C ' 129 4' 7/3/29 21: ' ' ' ' W ' ' 8/3/29 2: ' ' ' ' 9 18 W ' 128 4' 8/3/29 6: ' ' ' ' W ' ' 8/3/29 17: ' ' ' ' W ' ' 8/3/29 22: ' ' ' ' W ' ' 9/3/29 1: ' ' ' ' W ' ' 9/3/29 4: ' ' ' ' W ' ' 9/3/29 8: ' ' ' ' W ' ' 9/3/29 12: ' ' ' ' W ' ' 9/3/29 22: ' ' ' ' W ' ' 1/3/29 1: ' ' ' ' C ' 129 7' 1/3/29 5: ' ' ' ' C ' ' 1/3/29 9: ' ' ' ' C ' ' 1/3/29 12: ' ' ' ' C ' ' 1/3/29 15: ' ' ' ' C ' ' 1/3/29 18: ' ' ' ' C ' ' 1/3/29 21: ' ' ' ' C ' 13 4' 11/3/29 : ' ' ' ' C ' 13 1' 11/3/29 3: ' 13.72' ' ' C ' 13 13' 11/3/29 6: ' ' ' ' C ' ' 11/3/29 14: ' ' ' ' C ' ' 11/3/29 18: ' ' ' ' C ' ' 11/3/29 21: ' ' ' ' C ' 132 4' 12/3/29 1: ' ' ' ' C ' ' 12/3/29 4: ' ' ' ' C ' ' 6/4/29 17: ' ' ' ' C ' ' 6/4/29 2: ' ' ' ' C ' ' 7/4/29 : ' ' ' ' C ' ' 7/4/29 4: ' ' ' ' C ' 131 1' 7/4/29 7: ' ' ' ' C ' 131 ' 7/4/29 1: ' ' ' ' 6 92 C ' ' 7/4/29 19: ' ' ' ' C ' ' 7/4/29 22: ' ' ' ' C ' ' 8/4/29 1: ' ' ' ' C ' ' 8/4/29 4: ' ' ' ' C ' ' 8/4/29 7: ' ' ' ' C ' 129 5' 8/4/29 1: ' ' ' ' W ' ' 8/4/29 13: ' ' ' ' W ' ' 8/4/29 16: ' ' ' ' W ' ' 8/4/29 19: ' ' ' ' W ' ' 9/4/29 3: ' ' ' ' W ' ' 9/4/29 11: ' ' ' ' W ' ' 9/4/29 15: ' ' ' ' 244 W ' ' 9/4/29 21: ' ' ' ' W ' ' 9/4/29 18: ' ' ' ' W ' ' 1/4/29 : ' ' ' ' W ' ' 1/4/29 6: ' ' ' ' W ' ' 1/4/29 13: ' ' ' ' 214 W ' ' 1/4/29 18: ' ' ' ' W ' ' 1/4/29 22: ' ' ' ' C ' 129 1' 11/4/29 1: ' ' ' ' C ' ' 11/4/29 4: ' ' ' ' Fiwll Conulting 19 AFMA Projct 28/848

28 Sot cod Sot Strtum point Sot dt Tim of ot Strt Point Fini Point Ctc (kg) Lt Long Lt Long Lt Long Bigt rdfi Dpwtr fltd C ' ' 11/4/29 7: ' ' ' ' C ' ' 11/4/29 1: ' ' ' ' C ' ' 11/4/29 13: ' ' ' ' C ' ' 11/4/29 16: ' ' ' ' C ' 129 5' 11/4/29 19: ' ' ' ' C ' 131 1' C ' ' 12/4/29 6: ' ' ' ' C ' 131 4' 12/4/29 11: ' ' ' ' 3 61 C ' 131 5' 12/4/29 15: ' ' ' ' C ' 132 1' 12/4/29 17: ' ' ' ' Tbl 5. Spci nd numbr of fi for wic lngt, x, nd otolit mpl wr collctd during 29 urvy. Spci Lngt frquncy (unxd) Otolit collctd Dpwtr fltd Bigt rdfi Tbl 6. Etimtd totl rltiv biom (t) wit cofficint of vrition (c.v.) of mjor commrcil pci in cro ll trt from 25, 26, 27, 28 nd 29 urvy uming nt widt of 16.3 m. Etimtd Rltiv biom Spci t c.v. t c.v. t c.v. t c.v. t c.v. Bigt rdfi A Dpwtr fltd Ocn jckt Common wrk Yllowpottd borfi Gummy rk Jck morwong Knifjw Ltct Ornt nglrk Spiky dogfi Otr pci A nigt ul only Fiwll Conulting 2 AFMA Projct 28/848