Size Selectivity of 75 and 90 mm Square Mesh Windows (SMW) Codend for Four Species in Persian Gulf (Hormuzgan Province, Iran) Dhow Prawn Fisheries

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1 Turkish Journl of Fisheries nd Aqutic Sciences 16: (216) ISSN DOI: / v16_1_11 RESEARCH PAPER Size Selectivity of nd 9 mm Squre Mesh Windows (SMW) Codend for Four Species in Persin Gulf (Hormuzgn Province, Irn) Dhow Prwn Fisheries Seyed Hesm, Kzemi 1,*, Seyed Yousef Pighmbri 1, Tuğçe Şensurt 4, Rez Abspour Nderi 3 Cellettin Aydin 2,* 1 Gorgn University of Agriculturl Sciences nd Nturl Resources, Fisheries Deprtment, Gorgn, Irn. 2 Ege University, Fculty of Fisheries, 351, Bornov, Izmir, Turkey. 3 Irnin Fisheries Orgniztion, Tehrn, Irn. 4 A ü k U y y E z. * Corresponding Authors: Tel.: ; Fx: ; E-mil: hesm_pep@yhoo.com; cydin@gmil.com Abstrct Received 3 September 215 Accepted 4 Mrch 216 Squre mesh windows (SMWs) with (SMW; 37.5 mm br length) nd 9 mm (9SMW; 45 mm br length) nominl mesh size were tested for determining size selectivity in dhow prwn fisheries of the Persin Gulf (Hormuzgn province). Fishing trils were conducted on the commercil fishing grounds of Hormuzgn province of the northern Persin Gulf by commercil dhow trwler. Covered codend methods were utilized for collecting dt during October nd November 212. Totlly 21 nd 16 vlid huls were performed with SMW nd 9SMW, respectively. The men L 5 vlues of SMW 9 SMW. ±..7 ±. Peneus merguiensis).9 ±..9 ±. Jing shrimp (Metpeneus ffinis) 8. ± ±. ork length for Indin ilish (Ilish melstom), nd 8. ±. 8. ±. k ulphur gotfish (Upeneus sulphurous), respectively. This study clerly shows tht there is not ny notble different in size selectivity of squre mesh windows with different mesh sizes for investigted species. Future studies on different by-ctch reduction methods such s full squre mesh codends or grids should improve size selectivity of the species nd efforts to reduce by-ctch in this fishing system. Keywords: Dhow trwl, codend selectivity, squre mesh windows, Persin Gulf. Introduction The Persin Gulf, with N 9 - E Sdrinsb, 26). There is wide vriety of mrine biot in the Persin Gulf nd lots of these fishes re endemic nd hevily dependent on the Gulf environment (UNEP, 1999). Peneids hve high commercil vlue nd cught throughout the Persin Gulf using minly trwls, gillnets, set nets from vrious fishing vessels such s, bots, dhows nd trwlers. Trwl is the most importnt fisheries techniques for ctching prwns, minly hs been ccomplished by dhows. Dhows re smll-scle prwn trwlers nd limited to 3 m nd mde of wood or fibreglss. They re concentrted t depth of 8-3 m nd fishing time is between 1-3 hours depends on fishing re nd ctch bulk. Hormuzgn Province is the most importnt Peneid fishing re in the Persin Gulf nd the min trget species is bnn prwn (Peneus merguensis). Other commercilly importnt species re Scomberomorus commerson, Pmpus rgenteus, Psettodes erumei, Eleutheronem tetrdctylum, nd Published by Centrl Fisheries Reserch Institute (CFRI) Trbzon, Turkey in coopertion with Jpn Interntionl Coopertion Agency (JICA), Jpn Sillgo sihm. As smller individuls of mny commercil fish species such s Scomberomorus commerson, Prstromteus niger, Sillgo sihm, Otolithes ruber, Trichiurus lepturus, Pennhi mcrophthlmus, nd Pompus rgenteus, re being cught. So, dhow prwn fishery is destructing their stocks nd increse overfishing in the re (Kzemi et l., 214). From the scientific studies conducted on by-ctch nd discrds rte of prwn trwl fishery in the Persin Gulf, bout 68 % incidentl nd discrd ctches were cught by dhow Peneid fisheries (Azr, 1981; Ibrhim et l., 1989; Yimin et l., 2; Pighmbri et l., 23; Vlinssb et l., 26; Kzemi et l., 214). Improving selectivity hs been strong priority in terms of chieving the sustinble mngement of mrine resources (Ohus, 199; Schoning et l., 1992; Alverson et l., 1994; Alverson nd Huges, 1996; Alverson, 1997; Crwder nd Murwski, 1998; Kelleher, ; Ctchpole nd Gry, 21). Furthermore from the biodiversity perspective, byctch, discrding nd cptured of smll individuls ffect the ecology of mrine system, the economy of fisheries nd mngement structure, nd the sociology of community (Alverson et l., 1994). Trwl

2 14 S.H.Kzemi et l / Turk. J. Fish. Aqut. Sci. 16: (216) fisheries for prwn nd demersl finfish ccount for over 5 percent of totl estimted discrds nd tropicl prwn trwl fisheries hve the highest discrd rte nd ccount for over 27 percent of totl estimted discrds (Kelleher, ). A gret del of progress hs recently been mde in reducing by-ctch nd discrds (Suuronen, ). There re mny scientific ppers conducted on reduced discrd rte nd byctch (improving size nd species selectivity) round the world. There is one study bout using BRD in the Persin Gulf which relted trwlers (Pighmbri, 23), but there is no studies conducted on the Persin Gulf dhow prwn trwl. There re some codend modifictions to improve trwl selectivity, such s increse mesh size, using squre mesh codend, lstridge rope nd nrrowed codend, etc. (Stewrt, 22), mong which squre mesh window fitted in the top pnel of the trwl codend is the simplest method to decrese by-ctch nd improve trwl selectivity (Arkley, 199; Ulmestrnd nd Lrsson, 1991; Thorsteinsson, 1992; Briggs nd Robertson, 1993; Robertson nd Shnks, 1994; Metin et l., ). The im of this study is to determine the size selectivity squre mesh windows (SMWs) with (SMW; 37.5 mm br length) nd 9 mm (9SMW; 45 mm br length) for bnn prwn (Peneus merguiensis), jing shrimp (Metpeneus ffinis), Indin ilish (Ilish melstom) nd sulphur gotfish (Upeneus sulphurous). Size selection performnce of squre mesh windows were ssessed for the first time from dhow prwn fisheries in the Persin Gulf (Hormuzgn province). Mteril nd Methods The study ws crried out in Hormuzgn province of the Persin Gulf (Figure 1) during October nd November 212. Averge towing durtion nd trwling depth were 1.5 h ( h) nd 14.5 m (5-22 m), respectively. A totl of 37 vlid huls were conducted using two different codends; 21 huls for SMW nd 16 for 9SMW. All huls were done in dylight t n verge speed of 2.5 knots ( knots). Smplings were conducted bord 19.8 m long conventionl dhow prwn trwler with 4 HP min engine. The dhow ws rigged with bottom trwl net mde of polyethylene mteril (PE 3mm dimeter double brided), the overll length, footrope nd hedline were 26.5m,.1m nd 22.3m, respectively (Pighmbri, 23). The rtio between the number of meshes in extension nd codend circumferences ws 1:1. Squre mesh windows (SMWs) with (SMW; 37.5 mm br length) nd 9 mm (9SMW; 45 mm br length) were tested during the experiment. Both windows re sme length size: SMW hs 57 brs in length, 34 brs in height; 9SMW hs 48 brs in length nd 28 brs in height. Both SMWs were inserted in the upper pnel of the codend. The codend ws polyethylene mteril with nominl mm mesh size nd 4.3 m in length (Figure 2). The hooped covered codend method ws used to collect the selectivity dt for four species (Wilemn et l., 1996). The cover ws 7 m in length nd ws mde of 1 mm mesh size PE netting. To prevent msking, supported by two 1.8 m dimeter hoops mde of 5 cm dimeter polyvinylchloride (PVC) mteril ws rigged. The hoop ws mounted t distnce of 2.5 m nd 4. m from the ends of the funnel (Figure 2). After huling up the ger, ctches from the codend nd cover were emptied on the deck seprtely, sorted by species, nd weighed. The totl ctch ws clssified s prwn, incidentl (some specific species) nd discrded ctch, nd ech prt ws weighed seprtely. Sub-smples were tken from prwn nd discrd ctch. The length clss frequencies were then estimted by rising the subsmpled frequencies obtined by the rtio of the totl weight to the sub-smple weight. Crpce length (from the orbitl sinus to the internl posterior mrgin of the crpce) of Peneus merguiensis nd Metpeneus ffinis were mesured by digitl cliper, fork lengths of Ilish melstom nd Upeneus sulphureus were mesured by mesuring bord s nerest cm. Selectivity curves of the individul huls were obtined by fitting the logit function: r(l)=exp(v 1 +v 2 l)/[1+exp(v 1 +v 2 l)] by mens of mximum likelihood method (Wilemn et l., 1996) where the prmeters v 1 nd v 2 re the intercept nd slope of the liner logistic function, respectively. Selectivity prmeters for individul huls nd pooled dt were estimted by using the CC2 softwre (ConStt, 1995). The men selectivity of individul huls ws found by tking into ccount between-hul vrition (Fryer, 1991) using the ECModeller softwre (ConStt, 1995). Individul selectivity prmeters were nlyses ccording to existence of investigted species both in codend nd cover. Men selectivity results ccording to Fryer (1991) were nlyses from vlid huls. On the other hnd, ll specimens were dded in pooled dt for clculting the selectivity prmeters. Results Totlly 37 vlid huls, 21 with SMW nd 16 with 9SMW, were performed. We found more thn 5 species of teleost fishes, elsmobrnches, cephlopods, crustcens nd invertebrtes. A totl weight of nd kg prwns nd nd kg by-ctch were cught in the SMW nd 9SMW codends nd covers combined, respectively. Sufficient mount of specimens were presented in order to estimte the selectivity, only for two crustcens nd two fish species Tble 1 shows numbers nd weight nd % totl ctch of both codend nd cover in SMW nd

3 S.H.Kzemi et l / Turk. J. Fish. Aqut. Sci. 16: (216) 15 Figure 1. Study re (Hormuzgn province of the Persin Gulf). Test Codends 9SMW SMW 9 mm br length mm br length 48 br in length 56 br in length 28 br in height 34 br in height Cover PE Ø 3 1 mm mesh size 9 m in length 45 meshes in circumferences Codends PE Ø 3 mm mesh size Hoop PVC Ø 5 mm 1.8 m in dimeter 2.5 m 4. m 4. 3 m Figure 2. Schemtic digrm of codend nd cover used in experiments. 7. m 9SMW. The totl ctch (codend +cover) of SMW contined.8 % Peneus merguiensis, 9.2 % Ilish melstom, 8.8% Leiognthus sp., 7.2 % Upeneus sulphureus, nd 3.6% Trichiurus lepturus, nd 1.8 % Metpeneus ffinis in terms of weight. 9SMW totl ctch consist of 27.1 % Peneus merguiensis, 9.8 % Ilish melstom, 7.8% Trichiurus lepturus, 7.1% Leiognthus sp, 6.6% Upeneus sulphureus nd 1.6% Metpeneus ffinis. All other remining species (fish, crustcen nd invertebrte) ccounted for 43.6 nd 4.1 % of the ctch in SMW nd 9SMW, respectively. Some of the other commercil species were yellowtil scd (Atule mte), jelly fish (Aureli urit), Ponyfish (Leiognthus.) B zz shd (Nemtlos nsus), Cuttlefish (Sepi phronis), Fourfinger thredfin (Eleutheronem tetrdctylum), Silver pomfret (Pmpus rgenteus) nd Indin hlibut (Psettodes erumei). A totl of 14 nd 11 huls estimted for Peneus merguiensis selectivity in SMW nd 9SMW, respectively. Figure 3 give selectivity curves for individuls nd men curves of bnn prwn. Figure 3 lso give (right Y -xis) tht normlized length frequency distributions in the codend nd cover for ech length clss. The men L 5 vlues for SMW 9 SMW. ±..7 ±. respectively. SR vlues for SMW nd 9SMW. ±.. ±. y (Tble 2). There ws no significnt differences both L 5 nd SR vlues between two nets (P>.5). Selectivity curves for 12 nd 8 individul huls were estimted for Metpeneus ffinis in the SMW nd 9SMW, respectively nd men curves re shown in Figure 4. Figure 4 lso present (right Y - xis) tht normlized length frequency distributions in the codend nd cover for ech length clss. The men L 5.9 ±..9 ±. SMW nd 9SMW, respectively. SR vlues for 7 SMW 9 SMW. ±. 9 ±. 8 cm, respectively (Tble 2). The men L 5 vlues of both nets were higher thn L 5 (2.71 cm). The differences were not significnt between two nets both L 5 nd SR vlues (P>.5). A totl of 13 nd 7 vlid huls were obtined

4 Percent retined (%) Number of specimens 16 S.H.Kzemi et l / Turk. J. Fish. Aqut. Sci. 16: (216) Tble1. Totl ctch of investigted species from codend nd covers of two modified nets; 21huls with SMW nd 16 huls with 9SMW; N: SMW 9SMW Codend Cover Codend Cover Species N W N W % in totl N W N W % in totl Peneus merguiensis , ,8, , ,4 27,1 Ilish melstom , ,9 9, , ,6 9,8 Leiognthus Sp , ,1 8, , ,1 7,1 Upeneus sulphureus , ,5 7, , ,8 6,6 Trichiurus lepturus , ,9 3, , ,8 7,8 Metpeneus ffinis , ,8 1, , ,1 1,6 Others 19,3 243,4 43,6 939,33 177,4 4,1 Totl 4294,2 678,5 2321,8 464,9 Number of individuls, W: Totl weight (kg) Number of individuls, W: Totl weight (kg) b Crpce length (cm) Figure 3. The selection curves nd length distribution of the bnn prwn (Peneus merguiensis),y-xis left: percentge retined for the selection curves of: ; SMW nd b; 9SMW (thick drwn lines; men selection curve, thin drwn lines; individul selection curves). Y-xis right: normlized length-frequency distribution, drwn lines; codend specimens, broken lines; cover specimens. from selectivity nlyses of Ilish melstom in the SMW nd 9SMW, respectively. Figure 5 shows individuls nd men selectivity curves for Indin ilish. Figure 5 lso shows (right Y -xis) tht normlized length frequency distributions in the codend nd cover for ech length clss. The men L 5 7 SMW 9 SMW 8. ± ±. y. SR 7 SMW 9 SMW.7 ±.. ±.44 cm, respectively (Tble 2). SMW gve significntly higher L 5 vlue (P<.5), while smller SR vlue did not significntly different from 9SMW (P>.5). Selectivity curves for 12 nd 14 individul huls were estimted for Upeneus sulphurous in the SMW nd 9SMW, respectively. Figure 6 shows individuls nd men curves (bsed on Fryer, 1991) of sulphur gotfish. Figure 6 lso shows (right Y - xis) tht normlized length frequency distributions in the codend nd cover for ech length clss The men L 5 7 SMW 9 SMW 8. ±. 8. ±. y. SR SMW nd 9SMW we. ±.. ±.7 cm, respectively (Tble 2). The men L 5 vlues of both nets were smller thn Lm (9.9 cm of FL).T y L 5 nd SR vlues between two nets (P>.5). Although, νi 2 vlue ws significntly differed between the nets (P<.5). Discussion This reserch ws tken under commercil condition nd it is the first report of using squre mesh window in the Persin Gulf dhow prwn trwl fishery. A mm mesh size codend (conventionlly used) destructive effect on species cught by dhow trwl (Kzemi et l., 214). Therefore, it ws not

5 Upeneus sulphureus (Fork length) Ilish melstom (Fork length) Metpeneus ffinis (Crpce length) Peneus merguensis (Crpce length) S.H.Kzemi et l / Turk. J. Fish. Aqut. Sci. 16: (216) 17 Tble 2. Men (ccording to Fryer, 1991) nd pooled selection prmeters nd estimted number in codend, cover nd totl of investigted species for SMW nd 9SMW. All mesures re in centimetre. (L 5, 5% retention lengths; SR, selection rnge; se, stndrd error; v i1 nd v i2 regression prmeters; F.: men prmeters ccording to Fryer; P.: pooled prmeters) SMW 9SMW Ctch (number) Ctch (number) L 5 se S.R. se v i1 vi2 Codend Cover Totl L 5 se S.R. se v i1 v i2 Codend Cover Totl 1 2,9,47 2,1 1, -2,976 1, ,6,12,6,21-12,572 3, ,6,16 1,,3-8,149 2, ,5,21 1,6,74-4,786 1, ,6,53 3,5 3,2-2,1, ,5,87 3,6 3,72-2,14, ,7,19 1,3,6-6,137 1, ,4,43 2,7 2,31-2,841, ,7,55 5,2 2,62-1,596, ,6,18 1,4,62-5,777 1, ,2,14,9,34-9,673 2, ,9,48 3,7 4,3-2,29, ,3,28 1,8 1,1-3,978 1, ,,52 3,4 1,88-2,574, ,5,49 3,1 2,32-2,457, ,,49 3,9 4,62-2,268, ,6,45 3,1 2,72-2,527, ,5,74 5,5 8,94-1,391, ,9,87 1,6 1,65-5,332 1, ,9,62 3,6 3,89-2,386, ,7,54 1,1,97-7,397 2, ,4,33 1,9 1,5-3,96 1, ,3,16,8,26-8,824 2, ,5,18 1,2,36-6,329 1, ,3,16 1,,3-7,579 2, P 3,5,21 3,2 1,27-2,362,684 3,6,24 3,9 2,1-2,3,569 F 3,6,3 1,,3-4,131 1, ,7,2 1,2,1-3,41, ,8 2,74 1,1,61-5,66 2, ,6,63 3,7 3,61-2,93, ,,37 2,6 2,23-2,5, ,,5 3,3 2,78-1,952, ,9,44 2,3 1,96-2,777, ,2,19 1,4,57-5,7 1, ,,78 4,6 7, -1,428, ,,52 3,5 3,49-1,851, ,1,2 1,4,55-4,771 1, ,5 1,91 5,7 1,46 -,961, ,,24 1,7 1,8-3,886 1, ,5,41 2, 1,12-2,747 1, ,2,69 3,2 4,39-2,199, ,6,22 1,,42-5,918 2, ,9 1,49 2,8 3,41-1,469, ,2,18,8,34-8,712 2, ,5,7 3,4 3,39-1,66, ,9,29 1,6 1,14-3,849 1, ,8,53 3,1 2,91-2,, ,,33 2, 1,3-3,211 1, P 2,7,18 3,9 1,14-1,49,561 2,8,17 3,3,82-1,849,667 F 2,9,3 1,3,9-2,731, ,9,5 1,,8-2,498, ,8,85 3,2 2,29-5,362, ,6 1,78 11,3 8,29-1,873, ,2 2,67 9,5 15,15-1,93, ,6 1,98 5,3 6,51-3,15, ,9 2,3 1,1 9,11-1,719, ,3 6,68,,16-362,27 49, ,6,4 3, 1,28-5,479, ,9 1, 1,6 8,84-1,853, ,3 2,54 1,4 11, -1,532, ,4 1,6 5,3 4,13-4,31, ,9 1,65 7,3 6,12-2,394, ,8, 4,7 2,4-4,528, ,5 4,41 8,3 13,6-1,714, ,5,36 1,4,53-14,523 1, ,2,6 2,1,94-8,783 1, ,9 4,4 16,8 44,71 -,897, ,3 1, 7, 7,58-2,914, ,1 4,21 16,6 15,59-1,211, ,1 1,55 1,3 7,86-1,947, ,7,99 3,8 3,2-4,45, P 7,8,74 9,1 3,69-1,883, ,5,83 9,2 3,82-2,285, F 8,,8 2,7,2-2,351, ,5,11 2,2,44-2,639, ,1,28 1,2,61-15,387 1, ,3 1,2 2,3 2,98-7,853, ,6,53 2,5 1,41-6,747, ,1,55 2,7 1,87-6,69, ,6,77 3,6 2,67-4,6, ,3,58 3,4 1,43-6,67, ,4 1,27 5,2 5,87-3,16, ,4 1,12 5,7 3,98-3,626, ,6,36 1,2,56-13,93 1, ,2,38 1,8,58-11,5 1, ,4,34 1,7,71-1,778 1, ,2,68 3,7 2,17-4,89, ,5,44 2, 1,31-8,67 1, ,8,46 2,9 1,87-5,924, ,,24,9,43-18,967 2, ,,77 4, 2,37-4,96, ,4,28 1,,43-18,724 2, ,5,52 2,8 1,43-6,668, ,,27,9,4 21,612 2, ,2, 1,,48-17,454 2, ,8,26,8,34-24,37 2, ,6,24,6,27-28,992 3, ,9,35 1,3,58-13,249 1, ,,64 3,2 1,59-6,172, ,4,28 1,,48-17,947 2, ,3,63 3, 1,74-6,88, P 8,,2 2,7,56-6,663, ,7,16 3,3,46-5,72, F 8,1,4 1,1,5-6,658 1, ,4,3 1,4,7-5,546, tested in the study. In order to improve size selectivity squre mesh windows with nd 9 mm mesh size (37.5 mm nd 45 mm br length, respectively) were investigted for four species. There ws no significnt difference between the nd 9mm SMWs effectiveness bsed on size selectivity of the species,

6 Percent retined (%) Number of fish Percent retined (%) Number of specimens 18 S.H.Kzemi et l / Turk. J. Fish. Aqut. Sci. 16: (216) b Crpce length (cm) Figure 4. The selection curves nd length distribution of the jing shrimp (Metpeneus ffinis).y-xis left: percentge retined for the selection curves of: ; SMW nd b; 9SMW (thick drwn lines; men selection curve, thin drwn lines; individul selection curves). Y-xis right: normlized length-frequency distribution, drwn lines; codend specimens, broken lines; cover specimens b Fork length (cm) Figure 5. The selection curves nd length distribution of the Indin ilish (Ilish melstom). Y-xis left: percentge retined for the selection curves of: ; SMW nd b; 9SMW (thick drwn lines; men selection curve, thin drwn lines; individul selection curves). Y-xis right: normlized length-frequency distribution, drwn lines; codend specimens, broken lines; cover specimens. except L 5 of Indin ilish (which ws significntly higher in SMW, Tble 2). We fitted SMWs close to codend exctly before it, s suggested by Robertson, (1993). This probbly mde chnges in SMW open meshes when lrge mount of jelly fishes (Aureli urit) hve cught in trwl net. This prt of by-ctch especilly when lrge mount of it cught in hul (we hve cught nerly 6 kg jellyfish in hul by SMW) cn ltered codend geometry nd degree of mesh opening in SMW nd codend both, incresing ctch bulk nd drg, lso this mde fishers distrught, becuse they spent long time seprting nd returning jellyfish to the se. From mngement stndpoint, it is n importnt fctor to convince fishers to fit by-ctch excluder devices (BRD) in their nets. It seems tht using grid for removing big hydro-bios (mostly Aureli urit, Portunus pelgicus nd Sepi phronis) nd fltfish, which dded to squre mesh window or codend, could be useful for removing byctch in such multispecies system tht most of the byctch species hve length close to trget species nd

7 Percent retined (%) Number of fish S.H.Kzemi et l / Turk. J. Fish. Aqut. Sci. 16: (216) b Fork length (cm) Figure 6. The selection curves nd length distribution of the sulphur gotfish (Upeneus sulphurous). Y-xis left: percentge retined for the selection curves of: ; SMW nd b; 9SMW (thick drwn lines; men selection curve, thin drwn lines; individul selection curves). Y-xis right: normlized length-frequency distribution, drwn lines; codend specimens, broken lines; cover specimens. removing rther by-ctch is the min im (Stewrt, 22; Brodhurst et l., 24; Aydin et l., 211). Rogers et l. (1997) demonstrted tht ger efficiencies depended on locl species composition nd size distributions. Furthermore, size selection is not only depend on species lengths; mesh size, twine dimeter (Sl et l. 7) T k ç et l., 24; Devl et l., 26), ctch bulk (Cmpos et l., 23; Brodhurst et l., ; Aydin et l., 214), towing speed (Brodhurst et l., ), number of meshes in the codend circumference nd hnging rtio (Brodhurst nd Millr 29; Grhm et l., 29) ll cn effect on species escpe, So, we cnnot compre the result of the present work with ny other study. There were 4.38 nd less thn 1 % of Peneus merguiensis individuls below LFM (3.21 cm; Sfei, ) in SMW nd 9SMW codends, respectively. Wheres, nd 12.4 % of Metpeneus ffinis subsmples were found below LFM (2.716 cm; Kmrni et l., ) in the SMW nd 9SMW codends, respectively. These were due to the different behviours in different Peneid species (Whitker et l., 1992; Rogers et l., 1997). However, very lrge mount of fish species re cught below their sexul legl length in this fishing system t Hormuzgn province nd removing further fish species should be the im of mngement strtegies. In conclusion, this study clerly shows tht there is not ny notble different in size selectivity of squre mesh windows with different mesh sizes for investigted species. On the other hnd, reduction in weight of juvenile species could be chieved by dding squre mesh windows in the dhow prwn trwl nets of the Persin Gulf. Also, nevertheless, future studies on different by-ctch reduction methods such s full squre mesh codends or grids should improve size selectivity of the species nd efforts to reduce by-ctch in this fishing system. References Alverson, D.L., Freeberg, M.H., Pope, J.G. nd Murwisk, S.A., A globl ssessment of fisheries by-ctch nd discrds. FAO Fisheries Technicl Pper. 339, Alverson, D. L. nd Hughes, S.E By-ctch: from emotion to effective nturl resource mngement. Review in Fish Biology nd Fisheries, 6, Doi: 1.17/BF1643. Alverson, D. L Globl ssessment of fisheries byctch nd discrds: summry overview, Globl Trends. Fisheries Mngement Americn Fisheries Society Symposium 2, Arkley, K Fishing trils to evlute the use of squre mesh selector pnels fitted to Nephrops trwls - MFV `Hether Sprig' (BCK 181). Sefish Report No Ay ı C. T k ç A. U ş A. M k y B. Ş T Selectivity of 4 mm squre nd 5 mm dimond mesh codends for five species in the estern Mediterrnen demersl trwl fishery. Africn Journl of Biotechnology, 1, Doi: /AJB Ay ı C. Ş T. Öz Y. T ğ Z The effect of number of meshes round protective bg circumference on size selectivity of demersl trwl codend. Journl of Applied Ichthyology, 3: Doi: /ji Azr, R Report of distribution nd bundnce of Byctch species in shrimp trwls of the Persin Gulf. Publiction of Irnin Fisheries Orgniztion. 56P. (In Persin). Briggs, R.P. nd Robertson, J.H.B Squre mesh pnel studies in the Irish Se. ICES CM1993/B:2. Brodhurst, M.K., Millr, R.B., Kennelly, S. J., Mcbeth, W. G., Young, D.J. nd Gry, C. A. 24. Selectivity

8 11 S.H.Kzemi et l / Turk. J. Fish. Aqut. Sci. 16: (216) of conventionl dimond- nd novel squre-mesh codends in n Austrlin esturine peneid-trwl fishery. Fisheries Reserch, 67, Doi: 1.116/j.fishres Brodhurst, M.K., Mcbeth, W.G. nd Wooden, M.E.L.. Reducing the discrding of smll prwns in NSW's commercil nd recretionl prwn fisheries. Finl Report to the Fisheries Reserch & Development Corportion. Project No. 21/31. NSW Deprtment of Primry Industries - Fisheries Finl Report Series No pp. Brodhurst, M.K. nd Millr, R.B. 29. Squre-mesh codend circumference nd selectivity. ICES Journl of Mrine Science, 66, Doi: 1.193/icesjms/fsp1. Cmpos, A., Fonsec, P. nd Henriques, V., 23. Size selectivity for four fish species of the deep ground fish ssemblge off the Portuguese southwest cost: evidence of mesh size, mesh configurtion nd codend ctch effects. Fisheries Reserch, 63, Doi: 1.116/S (3)6-2. Ctchpole, T.L. nd Gry, T.S. 21. Reducing discrds of fish t se: review of Europen pilot projects. Journl of Environment Mngement, 91, Doi: 1.116/j.jenvmn ConStt, CC selectivity Grnspettevej 1, DK-98 Hjjlrring, Denmrk. Crowder, L.B. nd Murwski, S.A Fisheries byctch: Implictions for mngement. Fisheries, 23, Doi: / (1998)23<8:FBIFM>2..CO;2. D M.C. Bök T. A ş C. Öz H.. Selectivity of PE nd PA mteril cod ends for rose shrimp Prpeneus longirostris in Turkish twin rigged bem trwl fishery. Fisheries Reserch, 81, Doi: 1.116/j.fishres Froese, R. nd Puly, D FishBse. Avilble t Retrieved 7 September 215. Fryer, R.J A model of between-hul vrition in selectivity. ICES Journl of Mrine Science, 48: Doi: 1.193/icesjms/ Grhm, K.J., Brodhurst, M. nd Millr, R.B. 29. Effects of codend circumference nd twine dimeter on selection in south-estern Austrlin fish trwls. Fisheries Reserch, 95, Doi: 1.116/j.fishres Ibrhim, M.A., El-Bry, K.A. nd Al-Khyt, J.A By-ctch of commercil bottom trwl fishery from Qtr wters. Qtr University Science Bulletin, 9, Kmpf, J. nd Sdrinsb, M. 26. The circultion of the Persin Gulf: numericl study. Ocen Science, 2, Doi: /os Kmrni, E., Mojzi A.B. nd Sfee, M.. Reproductive biology of Jing Shrimp (Metpeneus ffinis) in costl wters of Hormozgn province, Southern Irn. Irnin scientific fisheries journl. 13 (4), Kzemi, S.H., Pighmbri, S.Y. nd Abspour Nderi, R By-ctch nd Discrd composition of dhow Peneid Trwl Fisheries in Hormuzgn Province, the Northern Persin Gulf. J. Persin Gulf (Mrine Science). 5, Kel.. D. An updte. FAO Fisheries Technicl Pper No. 47. Rome: FAO, 131 pp. M C. Öz H. T ğ Z. Gökç G. Ay ı C. M G. U ş A. yk ç H. Lök A. Düz ı F.O. T k ç A.. E squre mesh escpe window on codend selectivity for three fish species in the Aegen Se. Turkish Journl of Veterinry nd Animl Science, 29, , Ohus, T By-ctch. Pcific Fishing. 199, Pighmbri, S.Y. 23. Study on efficiency of some By ctch Reduction Devices in Shrimp Trwling in the Persin Gulf. Ph.D Thesis. Trbit Modres University. Mrine Science Fculty.112p. Pighmbri, S.Y., Tghvi, S.A., Ghdirnejd, S.H., Seyfbdi, J. nd Fghihzde, S. 23. Compring the effect of severl BRD on reducing commercil species fishing smller thn LM5 in shrimp trwls fishery in the Persin Gulf. Irn Journl of Fisheries Science, 12, (In Persin). Pope, J.G The ICES multi-species ssessment working group: Evolution, insights, nd future problems. ICES Journl of Mrine Science, 193, Robertson, J., nd Shnks, A., Anlysis of fishing trils, using the twin trwl system, of nets with windows of squre mesh, SOAFD, MAFF, Scottish Fisheries Working Pper, 2/94. Robertson, J.H.B Design nd fitting of squre meshwindows in whitefish nd prwn trwls nd seine nets. Scottish Fisheries Informtion Pmphlet No. 2. Rogers, D.R., Rogers, B.D., de Silv, J. nd Wright, V.L Effectiveness of four industry-developed by- L. Fisheries Bulletin, 95, Sfei, M.. Popultion dynmics bnn shrimp (Peneus merguiensis) in costl wters of Hormozgn province. Pjouhesh nd Szndegi. 67, (In Persin). Sl, A., Lucchetti, A. nd Buglioni, G. 27. The influence of twine thickness on the size selectivity of polymide codends in Mediterrnen bottom trwl. Fisheries Reserch, 83, Doi: 1.116/j.fishres Schoning, R.W., Jcobsen, R.W., Alverson, D.L., Gentle, T.H. nd Auyong, J Proceedings of the Ntionl Industry By-ctch Workshop, Februry 4 6, 1992, Newport, Oregon (vilble from Nturl Resources Consultnts, st W., Settle, WA 98199). Suuronen, P.. Mortlity of fish escping trwl gers. FAO Fisheries Technicl Pper, pp. S P. A. M. : A fi selectivity in the Mediterrnen. FAO COPEMED Report No. 9, Rome, Itly, 57 pp. Thorsteinsson, G Experiments with squre mesh windows in the Nephrops trwling off South Icelnd. ICES CM, B, p. 3. T k ç A. Öz. H. T ğ Z.. E PA nd PE mteril on codend selectivity in Turkish bottom trwl. Fisheries Reserch, 67: Doi: 1.116/j.fishres Ulmestrnd, M. nd Lrsson, P.O Fishing trils with 7 mm squre mesh in the top of Norwegin lobster trwl. ICES Fish. Technology nd Fishing Behviour Working Group. Ancon, April. UNEP., Overview on Lnd Bsed Sources nd Activities Effecting the Mrine Environment in the ROPME Se Are. UNEP/GPA coordintion office nd ROPME 127 pp. Vlinssb, T., Zrshens, G.A., Ftemi, M.R. nd

9 S.H.Kzemi et l / Turk. J. Fish. Aqut. Sci. 16: (216) 111 Otobide, S.M. 26. By-ctch composition of smllscle prwn trwlers in the Persin Gulf (Hormuzgn province), Irn. Irn Journl of Fisheries Science, 15, (In Persin). Whitker, J.D., De Lncey, L.B. nd Jenkins, J.E A pilot study to exmine the efficiency of finfish excluder devices in shrimp trwl. Finl Report, Project Number F-47. South Crolin Wildlife nd Mrine Resources. Dep., Chrleston, p. 23. Wilemn, D.A. Ferro, R.S.T. Fonteyne, R. nd Millr, R.B. (eds.) Mnul of Methods of Mesuring the Selectivity of Towed Fishing Gers. Copenhgen, ICES Coopertive Reserch Report No pp Yimin, Y., Alsffr, A.H. nd Mohmmed, H.M.A. 2. By-ctch nd discrds of the Kuwit shrimp fishery. Fisheries Reserch, 45, Doi: 1.116/S (99)15-8