A Comparison of Catch Between Research and Commercial Vessels During a Trawl Survey of Hecate Strait, May 30 June 13, 1996

A Comprison of Ctch Between Reserch nd Commercil Vessels During Trwl Survey of Hecte Strit, My 3 June 13, 1996 J. Frgo nd G. D. Workmn Fisheries nd Ocens Cnd Science Brnch, Pcific Region Pcific Biologicl Sttion Nnimo, British Columbi V9R 5K6 1997 Cndin Mnuscript Report of Fisheries nd Aqutic Sciences 2425 Fisheries Peches 1+1 nd Ocens et Ocens

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Cndin Mnuscript Report of Fisheries nd Aqutic Sciences 2425 1997 A COMPARISON OF CATCH BETWEEN RESEARCH AND COMMERCIAL VESSELS DURING A TRAWL SURVEY OF HECATE STRAIT, MAY 3 - JUNE 13,1996 by J. Frgo nd G.D. Workmn Fisheries nd Ocens Cnd Pcific Region, Science Brnch Pcific Biologicl Sttion Nnimo, British Columbi V9R5K6

- ii Minister of Supply nd Services Cnd 1997 Ct. No. Fs 97-412425E ISSN 76-6473 Corred citti'1 for this publiction: Frgo, J., nd G. D. Workmn. 1997. A comprision of ctch between reserch nd commercil vessels during trwl survey of Hecte Strit, My 3 - June 13, 1996. Cn. Mnuscr. Rep. Fish. Aqut. Sci. 2425: 41 p.

-iii- ABSTRACT Frgo, J., nd G.,.D. Wor1<mn. 1997. A comprision of ctch between reserch nd commercil vessels during trwl survey of Hecte Strit, My 3 - June 13, 1996. Cn. Mnus-. Rep. Fish. Aqut. Sci. 2425: 41 p. We nlysed replicte hul dt from bottom trwl survey conducted in Hecte Strit. The huls mde by the reserch vessel were replicted by trwler using commercil trwl net with 6 inch mesh. The purpose of this work ws to exmine the vlidity of the reserch vessel CPUE dt for stock ssessment work nd to evlute the effect of the mesh regultion imposed by the DFO in this re in 1995. We found no significnt difference in the replicte CPUE dt between the two vessels for Pcific cod (Gdus mcrocephlus), Dover sole (Microstomus pcificus), English sole (Pleuronectes vetulus) nd Rock sole (Plueronectes bilinet). However, length composition dt did differ between the two vessels due to the different mesh sizes in the nets used. Men lengths for the four commercil species were significntly greter for the commercil vessel using 6 inch mesh thn the reserch vessel using 3.5 inch mesh. Ctch rtes for juvenile fltfish for the commercil vessel were s 1% of those for the reserch vessel. Ctch-rtes for lrger fish were 1.5-2 times greter for the commercil vessel thn the reserch, possibly due to the greter herding effect for the commercil ger. The length-specific selectivity rtio for the Commercil vessel pproched 1 t length corresponding to the recommended minimum size limit for ll of the fltfish species. The chnge in size selectivity for commercil fltfish species due to the lrger mesh size must be ccommodted in ctch-ge nlysis used for stock ssessment of these species. The differentil ctch rtes for lrger fish between the two vessels should be evluted on the next survey.

- iv- RESUME Frgo, J., nd G. D. Workmn. 1997. A comprision of ctch between reserch nd commercil vessels during trwl survey of Hecte Strit, My 3 - June 13, 1996. Cn. Mnuscr. Rep. Fish. Aqut. Sci. 2425: 41 p. Nous vons nlyse les donnees obtenues pr trits repetes pendnt un releve u chlut dns Ie detroit d'hecte. Les trits effectues pr Ie nvire de recherche ont ete repetes pr un chlutier nne pour Ie chlutge commercil vec un filet millge de 6 pouces. L mission vit pour objet de verifier l vlidite des donnees CPUE obtenues pr Ie btiment de recherche pour Ie trvil d'evlution des stocks, et de determiner I'effet de l reglementtion sur Ie millge imposee en 1995 pr Ie MPO dns cette region. Nous n'vons ps observe de difference significtive dns les donnees CPUE obtenues en prllele pr les deux bteux pour l morue pcifique (Gdus mcrocephlus), l limnde-sole (Microstomus pcificus), Ie crlottin nglis (Pleuronectes vetulus) et l sole pcifique (Pleuronectes bilinet). Les donnees sur l composition pr longueur differient toutefois entre les deux bteux cuse des millges employes. Les longueurs moyennes pour les qutre especes commerciles etient nettement plus grndes vec Ie chlutier commercil utilisnt un millge de 6 pouces qu'vec Ie bteu de recherche qui employit un filet it millge de 3,5 pouces. Les tux de cpture des poissons plts juveniles etient # 1 % de ceux du btiment de recherche. Les tux de cpture des poissons plus gros etient 1,5 2 fois superieurs vec Ie chlutier, ce qui peut etre do I'effet de regroupement plus efficce vec Ie greement commercil. Le rpport de selectivite specifique l longueur dns Ie filet commercil pprochit de 1 it une longueur correspondnt it l limite minimle de tille recommndee pour tous les poissons plts. Le chngement de l selectivite pr tille des especes commerciles de poissons plts doit etre pris en compte dns I'nlyse de I'ge l cpture qui sert I'evlution des stocks de ces especes. L difference entre les deux bteux dns Ie tux de cpture des poissons de grnde tille doit etre evluee lors du prochin releve.

INTRODUC1"ION Between My 3 nd June 13, 1996 we conducted bottom trwl survey in Hecte Strit using the reserch vessel W.E. RICKER. This ws the eighth survey in binnul series (Workmn et t 1997). Informtion from the surveys is used in stock ssessment work t the Pcific Biologicl Sttion. On the 1996 survey commercil fishing vessel ws chrtered to replicte huls mde by the reserch vessel. This ws done to compre the ctch-rte nd biologicl dt for typicl commercil vessel with tht for the reserch vessel to ssess: 1) how pproprite the reserch vessel CPUE indices re for stock ssessment work, nd 2) the length-specific selectivity of commercil groundfish species under the current minimum mesh regultion in the Strit. This report presents the results of nlyses compring ctch-rte nd biologicl dt between the reserch vessel, W.E. RICKER, nd chrtered commercil trwler, the STEADFAST. METHODS VESSELS AND GEAR Specifictions for the two vessels nd their fishing ger hve been reported by Workmn et l. (1997). Briefly, the RN W.E. RICKER (WER) is 25 hp, 57.3 m steel stem trwler which used Ynkee 36 trwl of hevy construction with 8.75 cm (3.5 in) mesh throughout nd 2.5 em codend liner. The FN STEADFAST (STD) is 38 hp, 2 m steel stem trwler tht ws chrtered to replicte sites occupied by WER during the first hlf of the survey. The net used by STD ws Sfri 5 with 15.2 em (6 in) mesh throughout. This net is typicl of the commercil fishery in Hecte Strit. The systemtic strtified design for the survey hs been described in Westrheim et l. (1984) nd Frgo et t (1984). The hul loctions re pproximtely the sme on every survey conducted. The survey covers the entire Strit nd replicte huls were done throughout the Strit on the 1996 survey. Fishing occurred during dylight hours only. Towing time ws 3 minutes, mesured from the time the wrp drums were locked to the time net retrievl begn. For replicte huls STD wited until WER hd locked its wrps nd then set off the port or strbord stem qurters, usully within 5 m of WER. CATCH DATA To fcilitte comprison between vessels we stndrdized the dt for differences in towing time, net configurtion nd net mesh size. First we corrected for differences in the size of the re swept by the two nets, using mesurements of vrious fishing components ssuming tht the effective re swept by trwl net ws

- 2 best represented by the door spred (Ngtegl 1986). We estimted the door spred for ech net using the method of Crrothers (198). Wingspred, sweep length nd bridle length were used for these clcultions. Wingspred for the Ynkee 36 (WER), mesured directly during the survey, rnged from 1 m to 12 m. For the Sfri net rigged with Thyboron 96 doors we used vlue of 1.75 m for the wingspred determined from flume tnk studies conducted on the Atlntic cost (Jon Johnnesson, Cntrwl Pcific Ltd., prs. comm.). We lso used two lternte methods of estimting the wingspred: 1) dividing the length of the hedline in hlf; nd 2) dividing the length of the hedline plus the footrope by 4 (Tble 1) (Hnd et l. 1995, Ymnk et I.1996). The re swept by the doors ws djusted for the curvture of the ground wrp using ctenry prmeters determined in previous work (Ymnk et l. 1996). We ssumed tht the herding effect of the sweeplines ws similr for both vessels. The finl estimte of door spred for STD ws 14% greter thn tht for WER nd we multiplied the ctches for STD by.86 to correct for this difference. We corrected for minor differences in towing time by clculting the ctch weight for one hour of towing (corrected CPUE) for ech vessel. To correct for differences in net mesh size we used the length frequency dt nd corresponding length-weight reltionship to estimte the ctch of fish greter thn 34 em (the size fltfish re grded for t se by the fishermen for the processing plnts nd pproximtely equivlent to the size fully selected for the STO net). For the few instnces where length dt were not collected we used the men weight of fish greter thn 34 em for the 48 replicte huls for given species nd vessel. We tested for differences in CPUE between the two vessels using the Fisher test nd the non-prmetric Mnn-Whitney signed rnk test. We used the Fisher rndomiztion test (Mnly 1991) to test for differences in men corrected CPUE between vessels. Both tests re pproprite for dt tht re not normlly distributed s is typicl of CPUE dt. The Fisher test re-smples the differences from the replicte CPUE dt to produce distribution of differences from which the probbility level for the men of the differences is determined. The Mnn-Whitney test gives rnk sum sttistic for the two sets of CPUE dt tht ws used to test for differences between the two sets of dt. We removed replictes where CPUE ws zero for both vessels prior to sttisticl testing. We estimted the length-specific retention rtios for S-rO compred to WER for Pcific cod (Gdus mcrocephlus), Dover sole (Microstomus pcificus), English sole (Pleuronectes vetulus) nd Rock sole (Pleuronectes bilinet) using the following proce,dure. For the fltfish species, we clculted the numbers cught per hour for 3 em length intervls nd divided these vlues for STD by those for WER. The resulting rtio then reflects the length-specific retention rtes for the fltfish species for STO compred to WER. We used the sme procedure for Pcific cod but grouped the dt by 5 em length intervls.

- 3 BIOLOGICAL DATA We,compred the numbers cught nd the size composition dt between the two vessels for four importnt commercil species in the region: Pcific cod, rock sole, Dover sole nd English sole. Rndom sub-smples were collected from lrge ctches of individul species. All fish were smpled from smller ctches «5 kg) We extrpolted from sub-smples to totl numbers cught using the rtio of totl weight cught, the numbers sub-smpled nd the weight of the sub-smple. RESULTS CATCH DATA The two vessels completed 48 replicte huls on the survey (Figure 1). Both totl ctch nd species composition for replicte huls were similr between the two vessels (Tble 2). Ctches of fltfish nd roundfish were higher for WER while ctches of rockfish nd selchii were higher for STD (Figure 2). Rockfish nd selchii re not primry trgets of the survey. The uncorrected ctch for the four species exmined is presented by vessel in Figure 3. The uncorrected ctch for Pcific cod nd rock sole ws nerly the sme between the two vessels while tht for Dover nd English soles ws higher for WER (Tble 3, Figure 3). The corrected ctch for Pcific cod, rock sole nd Dover sole ws higher for STD while the corrected ctch for English sole ws slightly higher for WER (Tble 3, Figure 3). CPUE dt by replicte hul, species nd vessel re presented in Tble 4. Sttistics for corrected nd uncorrected CPUE by species for ech vessel re presented in Tbles 5-6. The uncorrected men CPUE for English sole nd Dover sole ws higher for WER while the uncorrected men for Pcific cod ws higher for STD (Figure 4) nd the uncorrected men for rock sole ws nerly the sme between the two vessels. Correcting for door spred reduced the species men CPUEs of STD becuse the net used by STD hd lrger swept re thn tht of WER. However, correcting for mesh size hd the most significnt effect on the finl estimtes of the ctches nd men CPUEs. This resulted in decrese in ctch nd men CPUEs clculted for WER. The men corrected CPUE for Pcific cod, rock sole nd Dover sole ws higher for STD while tht for English sole ws nerly the sme for both vessels (Figure 4). The 9% confidence intervls of the mens for ll four species overlpped between the two vessels. We used non-prmetric sttistics to test the CPUE dt for differences between the two vessels. Plots of the corrected CPUE dt (Figure 5) suggest tht there ws little difference in CPUE in replictes between the two vessels, lthough the highest CPUEs for both vessels did not necessrily occur on the sme hul. There

- 4 ws no significnt difference in the corrected CPUE dt mong replictes for the two vessels for ny of the species exmined (Fisher test, Mnn-Whitney test). BIOLOGICAL DATA Summry sttistics for the length dt for ech vessel re presented in Tbles 7 nd 8. The men length offish smpled for ll four species ws significntly greter for STD for ll four species (t test, p<.1). There were significnt differences in the species length distributions between the two vessels s well (Mnn Whitney test, P<.1) (Figures 6-9). Rock sole cught by WER showed modes t 21 em nd 33 em. The 21 em mode is bsent in length frequency distributions for STD. For Pcific cod, mode t 28 em is prominent in the distribution for WER but is not in the distribution for STD. Dover sole cught by WER showed strong mode t 3 cm while fish cught by STD showed modes t 33 em nd 43 em. English sole cught by WER showed mode t 26 em compred to mode t 33 em for fish cught by STD. Cumultive frequency plots of numbers-t-iength for the four species re presented by vessel in Figure 1. Approximtely fifty percent of the Pcific cod cught by both vessels were less thn 5 em. However, 29% of the Pcific cod cught by WER were less thn 4 em while only 13% cught by STD were less thn 4 cm. For rock sole 53% of the fish cught by WER were less thn 25 em while only 4% of those cught by STD were under 25 em. For English sole 47% of the fish cught by WER were less thn 25 em while only 11 % of those cught by STD were under 25 cm. For Dover sole 65% of the fish cught by WER were less thn 3 cm while only 7% of the fish cught by STD were under 3 em. The length-specific retention rtios for STD I WER re presented by species in Figure 11. The lines in the plots indicte the lowess smoothed trend to these dt. Overll STD cught fewer smller nd more lrger fish thn WER for ll four species. However, the smll smple sizes t the high end of the length rnge contributed to high vribility of the rtio in ll cses. The STD retention rtio for Pcific cod rnged from.2 for fish of 26 em to between 1-2.3 for fish lrger thn 5 em. The retention rtio for Pcific cod pproched 1 t size of 35 em. The retention rtio for rock sole rnged from. for fish smller thn 2 em to 1.2-2. for fish lrger thn 35 em. The retention rtio for rock sole pproched 1 t size of 33 cm. The retention rtio for Dover sole rnged from. for fish smller thn 3 cm to between 2.-8.4 for 'fish lrger thn 4 em. The retention rtio for Dover sole pproched 1 t size of bout 38 em. The retention rtio for English sole rnged from. for fish smller thn 2 em to 1-1.3 for fish lrger thn 36 em. The retention rtio pproched 1 t size of bout 36 em.

- 5 DISCUSSION Overll the species ctch composition between the two vessels did not differ pprecibly. In fct, the ctch of fltfish ws nerly identicl. The differences in the ctch of roundfish between the two vessels were due minly to smll noncommercil species tht were cught by WER nd not by STD. STD cught more rockfish thn WER, however this is to be expected. The Sfri 5 (STD) is high lift box trwl, which is better for ctching off-bottom species like rockfish while the Ynkee 36 (WER) is flt trwl with groundline composed of 152 mm (6 inch) rubber discs designed to ctch ll sizes of fltfish. There ws no mesurble difference in CPUE between the two vessels fter correcting for differences in the fishing ger used. This is despite the fct tht depth nd loction differed slightly between the two vessels for the replicte huls. However, the highest CPUEs for ll species did not occur on the sme hul. This is probbly due to the fct tht the hbitt in the Strit is very diverse nd the distributions for individul species re not homogeneous (Frgo nd Tyler 1991 ). There were significnt differences in species size composition between the two vessels due to the different mesh size in the two nets. WER cught more smll non-commercil species nd juveniles of commercil species thn STD did. STD cught greter numbers of lrge fish thn WER. To be ble to relte this to the fishing ger used we require more detiled knowledge of the ger voidnce behviour of these species. It is well known, however, tht longer sweep lines hve greter herding effect on fltfish species (Hrden Jones et l. 1977). Underwter cmer work in the Gulf of Alsk nd in Hecte Strit indictes tht fltfish swim continuously in front of pproching trwl ger until they re exhusted nd re either cptured or the groundline nd net psses over them. The lrgest individuls re the strongest swimmers. The longer sweep lines of STD my hve contributed to greter herding effect forcing the lrger individuls to swim hed of the net for longer period, mking them more susceptible to exhustion nd cpture. More work on fish voidnce behviour nd fishing ger performnce is necessry to confirm this. If we ssume tht WER cught 1% of the juvenile 1~tfish vilble then the net used by STD ws 1% selective for rock sole t 33 em, English sole t 38 em nd Dover sole t 36 em. Length t 5% mturity hs been used s guidnce for setting minimum size regultions for fltfish nd other groundfish species. This corresponds to size/ge where yield per recruit is mximized for moderte-fst growing species. Length of 5% mturity is 34.1 em for rock sole, 35.5 em for English sole nd 38.1 em for Dover sole. Thus, there is evidence from this work tht 6 inch mesh size significntly lowers the discrd rte for juvenile sole (ges 1-3) nd Pcific cod (ges 1,2). In ddition, the byctch of smll, non-commercil species such s Pcific snddb (Cithrichthys sordidus), C-O sole (P/euronichthys coenosus), curlfin sole (P/euronichthys decurrens), sblefish (Anp/opom fimbri) nd others ws lso reduced.

- 6 The selectivity rtios determined in this study cn be used to djust the size nd ge dt for the fltfish species to ccount chnges in fishery selectivity fter the mesh size regultion imposed in 1995. This will result in more ccurte popultion estimtes from ctch-ge nlysis used for stock ssessment of these species. ACKNOWLEDGMENTS The uthors wish to thnk the Cptin Sirj Gulti nd Fishing Mster Brin West bord the W.E. RICKER nd Cptin Kelvin Mrk nd crew bord the STEADFAST. Their enthusism nd coopertion contributed gretly to the success of this study. Funding for the chrter ws provided by the Cndin Groundfish Reserch nd Conservtion Society. Smpling personnel for the FN STEADFAST were provided by Archipelgo Mrine Reserch Ltd. Ron Tnsichuk review drft of the mnuscript nd provided mny helpful suggestions. REFERENCES Crrothers, P.J.G. 198. Estimtion of trwl door spred from wingspred. J. Northw. Atl. fish. Sci. Vol 1: 81-89. Frgo, J., AV. Tyler, J. Cooper, S.C. Sheilds, nd S. Stebbins. 1984. ARCTIC OCEAN ssemblge survey of Hecte Strit, My 28-June 17, 1984. Cn. Dt Rep. Fish. Aqut. Sci. 491: 18 p. Frgo, J.,AV. Tyler, nd RP. Foucher. 199. Distribution of demersl fishes in Hecte Strit, British Columbi, Bsed on systemtic trwl surveys conducted from 1984-1987. Cn. Tech. Rep. Fish. Aqut. Sci. 1745: 115 p. Frgo, J., nd AV. Tyler. 1991. Distribution of demersl fishes in Hecte Strit, British Columbi, bsed on systemtic trwl surveys conducted from 1984-1987. Cn. Tech. Rep. Fish. Aqut. Sci. 1745: 115 p. Hrden Jones" RF., AR Mrgetts, M. Greenwlker, nd G.P. Arnold. 1977. The efficiency of the Grnton otter trwl determined by sector-spnning sonr nd coustic trnsponding tgs. Rpp. P-V. Reum. Cons. Int. Explor. Mer. 17: 45 51. Mnly, B.F.J. 1991. Rndomiztion nd Monte Crlo Methods in Biology. Chpmn nd Hll. London U.K p.43-49.

- 7 Ngtegl. D. A., B.M. Lemn nd R.D. Stnley. 1986. Ctches nd trwl loction of the RN G.B.REED nd the MN EASlWARD HO during the Pcific Ocen Perch ssessment cruise to Queen Chrlotte sound, August - September, 1984. Cn. Dt Rep., Fish. Aqut. Sci. 611: 19 p. Westrheim, S.J., A.V. Tyler, R.P. Foucher, M.W. Sunders, nd S.C. Shields. 1984. G.B. REED groundfish cruise no. 84-3, My 24-June 14,1984. Cn. Dt Rep. Fish. Aqut. Sci. 488: 131 p Workmn, G.D., J. Frgo, B. Bell, nd E. Hildebrnd. 1997. RN W.E. RICKER nd FN STEADFAST trwl survey of Hecte Strit, My 3-June 13,1996. Cn. Dt Rep. Fish. Aqut. Sci. (In press). Ymnk, KL., L.J. Rutherford, nd G.D. Workmn. 1996. Bottom trwl survey for rockfish in Queen Chrlotte Sound, September 11-22, 1995. Cn. Mnuscr. Rep. Fish. Aqut. Sci. 2362: 116 p.

- 8 Tble 1. Net Dimensions nd clculted door spred (Crrothers 198). Mesured wingspred vlues were used, but two lternte methods of estimting wingspred were evluted to provide some dt for comprison. Vlues selected to stndrdize the dt re in bold. Net Hedline Sweep Bridle Wingspred Method for Doorspred length (ft) Length (ft) length (ft) (ft) estimting (ft) wingspred Ynkee 36 6 6 6 3 HLJ2' 97 Ynkee 36 6 6 6 35 HLFR/4 2 121 Ynkee 36 6 6 6 39 M-FS33 3 126 Sfri 5 72 9 12 36 HLJ2 1 151 Sfri 5 72 9 12 41 HLFR/4 2 185 Sfri 5 72 9 12 35 M-Fr 145 1 HLJ2 Hedline length divided by 2 2 HLFR/4 = Hedline length plus Footrope length divided by 4 3 M-FS33 = Men net opening mesure with FS33 hedline net sounder 4 M-FT = Mesured in flume tnk, Jon Johnnesson t Cn-Trwl Pcific Pers. Comm.

- 9 Tble 2. Ctch by species for 48 replicte huls mde by the RN W.E. RICKER (WER) nd the FN STEADFAST (STD) on the Hecte Strit groundfish survey, My 29 - June 14,1996. Ctch (kg) % of Totl ctch Species WER STD WER STD Fltfish Arrowtooth flounder 4878 5138 15.9 2.7 Petrle sle 29 89.1.4 Rex sle 2186 198 7.1 4.4 Flthed sle 229 148.7.6 Pcific hlibut 1911 1616 6.2 6.5 Butter sle 166 8.5.3 Rock sle 1618 1668 5.3 6.7 Slender sle 22 6.1. Dover sle 955 461 3.1 1.9 English sle 4134 2861 13.4 11.5 Strry flounder 16 4.1. Curlfin sle 12 17.1 Snd sle 91 144.3.6 Pcific snddb 845 221 2.7.9 Totl 1792 13551 Roundfish Pcific herring 1775 5.8 Chinook slmon 3. Eulchon 48.2 Pcific cod 174 176 5.7 6.9 Pcific hke 1. Pcific tomcod 98.3 Wlleye pollock 2739 29 8.9.8 Eelpouts 2. Wolfeel 1 2. Sndlnce 51.2 Sblefish 1185 416 3.9 1.7 Greenlings 4.

- 1 Tble 2 - Con't. Ctch by species for 48 replicte huls mde by the RN W.E. RICKER (WER) nd the FN STEADFAST (STD) on the Hecte Strit groundfish survey, My 29 - June 14, 1996. Ctch (kg) % of Totl ctch Species WER STD WER STD Roundfish (Cont'd) Lingcod 27 268.7 1.1 Sculpins 6 7 Pochers 3 Totl 869 2611 Rockfish Redbnded rockfish 2 19.1.4 Silvergry rockfish 2 16.1 Yellowtil rockfish 91 211.3.9 QlJillbck rockfish 4 3.1.1 Bocccio 25 23.1.1 Cnry rockfish 2 6.. Redstripe rockfish 1.. Yelloweye rockfish 1 5.. Pygmy rockfish 5.. Totl 196 4 Selchii Spiny dogfish 1112 9 3.6 3.6 Sktes 675 146 2.2 5.7 Spotted rffish 3797 599 12.4 23.8 Totl 5584 8215 Grnd Totl 3941 24777 1. 1.

- 11 Tble 3. Actul (uncorrected) ctch (kg) nd ctch corrected for differences in fishing ger used by the FN Stedfst nd the RN WE Ricker. Stedfst Percent WE Ricker Percent uncorrected corrected Chnge uncorrected corrected Chnge Pcific cod 176 154-12 174 1344-23 Rock sole 1668 12-39 1618 816-5 Dover sole 461 328-29 955 197-79 English sole 2861 17-63 4134 185-74

- 12 Tble 4. Uncorrected nd corrected CPUE for four commercil species cught on the 1996 Hecte Strit survey by vessel, species nd replicte. Uncorrected CPUE (kglh) Correctted CPUE (kh/h) Replicte Species STD WER STD WER 1 Pcific Cod 4. 6. 3.7 5.8 2 Pcific Cod 442. 198. 379.6 198. 3 Pcific Cod 13.6 52. 1.1 13.8 4 Pcific Cod. 1. 5.4 1. 5 Pcific Cod.... 6 Pcific Cod.... 7 Pcific Cod 75.. 59.5. 8 Pcific Cod 8. 1. 6.4 1. 9 Pcific Cod. 1.. 1. 1 Pcific Cod 3. 4... 11 Pcific Cod.... 12 Pcific Cod 22.5. 19.6. 13 Pcific Cod 3.4. 3.. 14 Pcific Cod. 12.. 9.9 15 Pcific Cod 45. 6. 38. 5.1 16 Pcific Cod.... 17 Pcific Cod 23.3 26. 22.5 26.9 18 Pcific Cod 1. 1. 9.7 9.6 19 Pcific Cod 8.3. 9.4. 2 Pcific Cod 92.7 46. 85. 42.4 21 Pcific Cod 54.9 238. 53.1 236. 22 Pcific Cod. 36. 49.2 33.5 23 Pcific Cod.... 24 Pcific Cod.... 25 Pcific Cod 2. 2... 26 Pcific Cod 176. 88. 15.5 85.2 27 Pcific Cod 11.3 28. 115.1 26.9 28 Pcific Cod 117.6 64. 116.8 57.6 29 Pcific Cod 28. 3. 25.5 32.1 3 Pcific Cod 68. 6. 62.2. 31 Pcific Cod 1.7... 32 Pcific Cod.... 33 Pcific Cod.... 34 Pcific Cod.... 35 Pcific Cod 1.7... 36 Pcific Cod. 1.. 1.

- 13 Tble 4 - Con't. Uncorrected nd corrected CPUE for four commercil species cught on the 1996 Hecte Strit survey by vessel, species nd replicte. Uncorrected CPUE (kglh) Corrected CPUE (kh/h) Replicte Species STD WER STD WER 37 Pcific Cod 352. 1278. 36.2 1226.9 38 Pcific Cod 252. 48. 219.2 47.7 39 Pcific Cod 82.8 9. 69.7 88.5 4 Pcific Cod 24.8 88. 21.4 87. 41 Pcific Cod 732. 22. 63.5 22. 42 Pcific Cod 14.1 2. 11.1 1.9 43 Pcific Cod 1. 82. 1.4 82. 44 Pcific Cod 237.8 38. 216.7 38. 45 Pcific Cod 62. 3. 56.3 28.8 46 Pcific Cod 226.3 94. 21.8 9.2 47 Pcific Cod 48.9. 41.. - 48 Pcific Cod. 8.. 7.7 1 Rock sole.... 2 Rock sole.... 3 Rock sole. 24.. 8.6 4 Rock sole 856. 1. 655.1.5 5 Rock sole 33.8. 2.9. 6 Rock sole 1.7. 1.3. 7 Rock sole 7.5 1. 3.9.5 8 Rock sole 11. 34. 69.9 14.3 9 Rock sole 66.9 74. 56.8 29.6 1 Rock sole 123. 12. 96.8 84.6 11 Rock sole 8. 4. 4.8 3.7 12 Rock sole 4.5. 3.. 13 Rock sole.... 14 Rock sole.... 15 Rock sole 5. 6. 2.5 3.2 16 Rock sole 1.... 17 Rock sole.... 18 Rock sole.... 19 Rock sole.... 2 Rock sole.... 21 Rock sole. 1...5 22 Rock sole.... 23 Rock sole 284.6 446. 152. 131.8 24 Rock sole 116. 16. 61.8 56.2

- 14 Tble 4 - Con't. Uncorrected nd corrected CPUE for four commercil species cught on the 1996 Hecte Strit survey by vessel, species nd replicte. Uncorrected CPUE (kglh) Corrected CPUE (kh/h) Replicte Species STD WER STD WER 25 Rock sole 76. 56. 5.4 16.1 26 Rock sole. 1...5 27 Rock sole 4.9 16. 3.. 28 Rock sole 57.6 6. 36.5 17.4 29 Rock sole 24. 1184. 14.9 844.7 3 Rock sole 168. 148. 121.9 81.6 31 Rock sole 24. 112. 11.9 71.1 32 Rock sole 472. 172. 334.5 13.5 33 Rock sole 66. 68. 31.2 15.2 34 Rock sole 78.2 84. 5. 21.3 35 Rock sole 318.9 194. 119.3 55.8 36 Rock sole 138. 62. 65. 15.1 37 Rock sole 34. 76. 19.4 4.3 38 Rock sole 28.8. 9.8. 39 Rock sole 6.2 4. 4.3 2.1 4 Rock sole 51.7 2. 32.9 1.1 41 Rock sole.... 42 Rock sole.9 1. 1.5.5 43 Rock sole. 6.. 3.2 44 Rock sole.... 45 Rock sole.... 46 Rock sole.... 47 Rock sole 11.1 18. 7.1 9.5 48 Rock sole.... 1 Dover sole 6.. 7.7. 2 Dover sole 1. 14..7 1.1 3 Dover sole. 1...2 4 Dover sole.... 5 Dover sole 3.8. 5.. 6 Dover sole 6.9 34. 3.5 2.4 7 Dover sole. 154.. 5.3 8 Dover sole. 2...4 9 Dover sole.... 1 Dover sole.... 11 Dover sole 1. 2...4 12 Dover sole 258. 12. 27. 6.7 -

- 15 Tble 4 - Con't. Uncorrected nd corrected CPUE for four commercil species cught on the 1996 Hecte Strit survey by vessel, species nd replicte. Uncorrected CPUE (kglh) Corrected CPUE (khlh) Replicte Species STD WER STD WER 13 Dover sole 17.1 24. 13.4 7.6 14 Dover sole 9.4 62. 5.7 11.8 15 Dover sole. 2...4 16 Dover sole 1. 8... 17 Dover sole. 3...8 18 Dover sole 6.7 86. 3.4 18.1 19 Dover sole 6.7 56. 6.8 11.2 2 Dover sole 8. 192. 63.3 47.2 21 Dover sole.... 22 Dover sole 16. 156. 83.3 33.5 23 Dover sole 6.9 1. 5.1.2-24 Dover sole.... 25 Dover sole.... 26 Dover sole 4. 452. 18.3 89.5 27 Dover sole 6.5 26. 4.9 4.9 28 Dover sole 2.4 4. 1.2. 29 Dover sole 6. 3. 7.3 6.3 3 Dover sole. 1...2 31 Dover sole.... 32 Dover sole.... 33 Dover sole.... 34 Dover sole.... 35 Dover sole.... 36 Dover sole.... 37 Dover sole. 28.. 5.9 38 Dover sole. 92... 39 Dover sole. 46. 1.6 4.3 4 Dover sole 153.1 86. 126.6 47.7 4 1 Dover sole 28. 54. 14.4 17. 42 Dover sole. 1...2 43 Dover sole 8. 19. 21. 64.4 44 Dover sole 31.1 18. 27.1 3. 45 Dover sole 1. 6. 7.5 1.3 46 Dover sole.... 47 Dover sole.... 48 Dover sole 29. 6. 21.7 1.3

- 16 Tble 4 - Con't. Uncorrected nd corrected CPUE for four commercil species cught on the 1996 Hecte Strit survey by vessel, species nd replicte. Uncorrected CPUE (kg/h) Corrected CPUE (khlh) Replicte Species STD WER STD WER 1 English sole 2.... 2 English sole 2. 18. 1.7 8.7 3 English sole 5.8 8. 3.5 5.7 4 English sole.. 2.5. 5 English sole 65.6. 29.4. 6 English sole 13.7 1. 3.4 1.8 7 English sole 16.9 28. 12.6 22.1 8 English sole. 138.. 27.1 9 English sole 3.4 8. 1.4.8 1 English sole. 12... 11 English sole 44. 144. 3.1 4.1 12 English sole 88.5 2. 17.9. 13 English sole 32.6 24. 6.2 4.3 14 English sole 86.3 138. 12.7 16.7 15 English sole 12. 256. 31.4 26. 16 English sole 44.5 194. 8.5 11.1 17 English sole 28.3 72. 11.7 6.5 18 English sole 46.7 66. 18.7 18.5 19 English sole 51.7 14. 2.3 32.9 2 English sole 5.9 172. 24. 55.2 21 English sole 75.4 32. 2.2 61.5 22 English sole 62. 114. 2.4 34.7 23 English sole 8.6 4. 3.6 1.1 24 English sole 2. 2..7.6 25 English sole 8. 14. 5.3 2.4 26 English sole 38. 4. 14.3 6.7 27 English sole 98.9 94. 27.3 13.2 28 English sole 86.4 126. 24.6 9.3 29 English sole 28. 132. 6.3 28. 3 English sole 62. 7. 21.8 6.5 31 English sole 3.4 2. 1.9. 32 English sole. 1...3 33 English sole 2. 4. 1.1. 34 English sole. 1...3 35 English sole 5.1 4. 1.6 1.1 36 English sole 4. 1. 4.3.3 -

- 17 Tble 4 - Con't. Uncorrected nd corrected CPUE for four commercil species cught on the 1996 Hecte Strit survey by vessel, species nd replicte. Uncorrected CPUE (kg/h) Corrected CPUE (khlh) Replicte Species STD WER STD WER 37 English sole 1186. 155. 196. 434. 38 English sole 592.8 34. 226. 63.7 39 English sole 333.1 678. 129.7 261.7 4 English sole 229.7 76. 17.1 52.2 41 English sole 766. 624. 431.3 41.2 42 English sole 254.1 146. 13.1 35.6 43 English sole 18. 648. 51.6 237.6 44 English sole 153.3 182. 39.3 17.6 45 English sole 242. 664. 14.9 123. 46 English sole 181.7 186. 124.2 52.1 47 English sole 364.4 18. 187.7 5. 48 English sole 38.7 6. 14.8 52.9

- 18 Tble 5. Summry sttistics for uncorrected CPUE (kglh) by species nd vessel. 1 n Men Medin Stndrd 9% confidence intervl devition Species WER STD WER STD WER STD WER. STD Pcific Cod 13 58.7 69.9 6. 1. 188. 137.5 14.1-13.3 37.2-12.6 Rock Sle 15 64.2 66.2 1.5 5.6 182.5 149.3 2.9-17.5 3.8-11.6 English Sle 2 161.8 117.1 74. 44.3 273. 219. 97.-226.6 65.1-169.1 Dover Sle 16 39.1 17.2 5..5 79. 45.8 2.4-57.8 6.3-28.1 Number of huls where the ctch of both vessels ws zero. Tble 6. Summry sttistics for corrected CPUE (kglh) by species nd vessel. 1 n Men Medin Stndrd 9% confidence devition intervl Species WER STD WER STD WER STD WER. STD Pcific Cod 13 56. 62.7 3.5 1.1 181.1 119.3 13.-99. 34.4-91. Rock Sle 15 34. 42.5.5 3.4 123.4 17.4 4.7-63.3 17.-68. English Sle 2 45.2 44.6 1.2 13.5 95.2 81.1 22.6-67.8 25.3-63.9 Dover Sle 16 8.2 13.7.4. 18.3 36.8 3.9-12.5 5.-22.4 1 Number of huls where the ctch of both vessels ws zero

- 19 Tble 7. Summry sttistics for length dt (em) collected during the RN W.E. RICKER ssemblge survey, Hecte Strit, My 29 - June 14,1996. Species Men Stndrd Medin Mode n Devition Pcific Cod 5.3 16.2 52 28,47,61 461 Rock Sole 26.9 8.2 26 2,33 2541 Dover sole 28.5 5.1 29 3 2386 English sole 27.1 5.8 27 26 8455 Tble 8. Summry sttistics for length dt (em) collected on the FN STEADFAST, for the 1996 Hecte Strit survey, June 1-6, 1996. Species Men Stndrd Medin Mode n Devition Pcific Cod 54.7 13.4 53 32,48 635 Rock Sole 35.3 4.7 35 34 179 Dover sole 38.9 6.5 39 33,43 567 English sole 31.4 4.7 31 33 3781

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- 21 o o. o Fig. 1. Loction of replicte huls mde by the w. E. RICKER AND STEADFAST during the 1996 Hecte Strit survey.

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18 I I 16 14 12 ~ W.E. RICKER o STEADFAST - ~ ~ 1 ~ (J.$ 8 N W {:. 6 4 2 o -+-1----' Fltfish Roundfish Rockfish Selchii Species group Fig. 2. Ctch composition (weight) by species group by vessel.

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- 25 45 4 35 3 mw.e. RICKER [] STEADFAST ~ ụ. ~ 25 III 2 15 1 5 Pcific cod Rock sole Dover sole Species English sole 16 14 12 rw.e. RICKER []STEADFAST 1 Di ~ ~ 8 u 'Iii 6 4 2 Pcific cod Rock sole Dover sole English sole Species Fig. 3. Uncorrected (top pnel) nd corrected (bottom pnel) ctch for four commercil species by vessel.

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- 27 o C\l - ~... ~ w ::> 11. u I (f) «LL o «w I (f) o 1... - o... - o -... /~"."H ole / /~Jsole Englis~ sole I I I I I I o 5 1 15 2 25 o....' o - ex>.' ~... Pcifi cod / ~ w ::> 11. U o <D I Englis h.$dle (f).' «LL o «w I (f) o C\l ~~:.// ROC~.S6r~,.. ".'....'.'... o.'.' o 2 4 6 8 1 W.E. RICKER CPUE(kg/h) Fig. 4. Uncorrected (top pnel) nd corrected (bottom pnel) men CPUE by species nd vessel. The crosses represent the 9% confidence intervls nd the dotted line is the line of 1:1 correspondence.

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- 29 co co 1 :2 :2 C) C) -- -- ~ ~ ur ur v =>.... => v (,) (,) I en C') I- en «u. «u. Cl Cl ««w w C\I I I- C\I en en Rock sle 2 4 6 8 12 2 4 6 BOO W.E. RICKER CPUE(kg/h) W.E. RICKER CPUE(kg/h) C\I v Dover sle English sle -- ~ 1 :2 C) C) ~ ~ C') ur =>.... => (,) (,) I I- ««C\I u. u. Cl Cl en... en «w «w I I en en 1 ur... 2 4 6 8 1 2 3 4 W.E. RICKER CPUE(kg/h) W.E. RICKER CPUE(kg/h) Fig. 5. Corrected CPUE by species nd vessel. The digonl line in the plots indictes 1:1 correspondence.

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- 31 Pcific cod LO C! v ci W.E. RICKER c::: C') ci :e c.. ~ C\l 11. ci... C! ci.1 1111.11 111.1... 2 4 6 8 Length (cm) LO ~ STEADFAST C') c::: C! o :e o c.. ~ 11. ~ ci... o ci o ci 2 4 6 8 Fig. 6. Length (cm) Length frequency histogrms for Pcific cod by vessel.

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- 33 Rock sole C\J c co t (...... -.;to C! W.E. RICKER C\J _JIIII 11111 1111111.. 1 2 3 4 5 Length (em) C\J STEADFAST c co t (. C!..... -.;to C! ~ C\J 11.1111 11111 Fig. 7. 1 2 3 4 5 Length (em) Length frequency histogrms for Rock sole by vessel.

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- 35 Dover sole co C! o W.E. RICKER ( C! c: t C! """..... N _..-111 111.11... -- 1 2 3 4 5 6 7 Length (em) co C! o ( STEADFAST c: t """ C!..... N C! o 1 2 3 4 5 6 7 Fig. 8. Length (em) Length frequency histogrms for Dover sole by vessel.

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- 37 English sole co C! o CD W.E. RICKER c :e "<t. C! ' (L ('J C! ci JI.I.I 1111111.. -- 1 2 3 Length (em) 4 5 co C! o STEADFAST CD C! c :e "<t C!. e (L ('J o o 1 2 3 4 5 Fig. 9. Length (em) Length frequency histogrms for English sole by vessel.

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q ~ q... C 1: CXl Ul e c- GI ~.!'!l '<t :::l E :::l () Pcific cod...//.. C\l W.E.RICKER... STEADFAST --,... I 2 4 6 8 \ l"1 I q q......... CXl CXl Dover sle I.. I C c 'E 1: c- Ul c- Ul e e o c c- C 'E c- e c- GI,~ CXl Ul!i '<t :::l E :::l () C\l GI GI ~,~ I'll '<t iu '<t "'5 "3 E E :::l :::l () () C\l d W.E. RICKER I STEADFAST ---_... _-... - d -,, I I I 1 2 3 4 5 6 7,I C\l Rock sle ~....,.' W.E.RICKER STEADFAST 1 2 3 4 5 English sle -------..,'././... W.E RICKER STEADFAST 1 2 3 4 5 Fig. 1. Length (cm) species cumultive length frequency by vessel. Length (cm)

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- 41 Pcific cod.q iii... C') s= iii :: w C\l :E I- en.q ~ s= U1 iii :: w :E I- en U1 C\l Rock sle C? C\l C? It) 2 4 6 8 Length (em) ~ 1 2 3 4 5 Length (em) C'! co Dover sle C? English sle. ~.-...---..._._-- -.-.... - ).Q... (l) iii s= ~ :: W ~ :E I- en.q ~ co s= iii (l) :: w :E ~ I- en C\l C\l 1 2 3 4 5 6 2 3 4 5 Length (em) Length (em) Fig. 11. Selectivity rtios by species length ctegory for the STEADFAST in comprison with the W. E. RICKER. The line in ech plot represents the lowess smoothed fit.