Synthetic fibres for fishing gear
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Authors Radhalekshmy, K.; Gopalan Nayar, S.
Download date 26/09/2021 00:02:55
Link to Item http://hdl.handle.net/1834/33629 ETIC fl FIS I GEA
Smt. K. RADHALEKSHMY & S. GOPALAN NAYAR Central Institute of Fisheries Technology, Cochin-5
INTRODUCTION which they are marketed, the classifica tion is sohwn in table I. In India polya A variety of synthetic fibres are at mide group of fibres is marketed under present in use as fishing gear material, the trade names Garnyl and Jaykaylon, the earliest one being the polyvinyl chlo while polyethylene is marketed under the ride group introduced for traps in 1936 trade name Garfil and Marfil and polye (von. Brandt 1957). Since then synthetic thylene. Mostly the trade names are related fibres became increasingly popular among to the manufacturer's name. the advanced fishing nations of the world. The latest synthetic fibre which has been RAW MATERIALS AND PRODUCTION successfully used in fishing is polypropy lene developed in Italy in 1954. The basic materials for production of yarns for synthetics are prepared from The exact period when synthetic :fibres petroleum, natural gas, hydrocarbon, mo became popular as a fishing gear material lasses, grain, cobs, oat hulls, lime and in India is not clearly 1 known; however coal (Himmelfarb 1957). it has been stated that the first lot of nylon came to India in 1954-55 under Polymnide Fibres (PA) The discovery Of the TCM aid. Terylene (polyester group pJlY<:tmide 66 (Nylon 66) is credited to of :fibres) gill nets were subsequently in Dr. Wallace Hume Carrothers (Arzane troduced (Anon. 1958). In the initial years 1959). Nylon 66 polymer is prepared by the country was depending on imports for heating hexamethyiene diamene and adipic these materials. In 1962 nylon multifila acid. A polym:r made from Caproluctum ment yarn (polyamide group of fibres) sui is the Jap::J.nese equivalent to nylon. The table for making fishnet twines was ma American Caprolactum p)lyamide is desi nufactured in Jndia. Subsequently poly gnated as nylon 6. Structurally both nylon thylene group of fibres in the form of 66 and nylon 6 consist of the same amide mono5Jaments and tapes were also manu group differently arranged to constitute the factured in India. Production of nylon long chain molecule (Him:nelfarb 1957). in the form of mo:10.S.laments has also G~nerally it can be said that type 66 can been started recently. be made stronger than type 6 but the latter is cheaper. CLAS3IFICATION Polyester Fibres (PES) The fibre is a Hans Stutz (1959) has made an ela British invention made by J. R. Whinfield borate classification of textile fibres based and J. T. Dickson. Later the world patent on the source of the fibre, the raw mate rights with the exception of the United rial and the process of manufacture to States of America were acquired by the gether with the various trade names under Imperial Chemical Industries Ltd. U. K.
142 FISHERY TECHNOLOGY t"'B
:>< TABLE I
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tv TEXTILE FIBRES iO 0 ·0.. \.0 NATURAL FIBRES CHEMICAL FIBRES INORGANIC FIBRES ;:I> --....) >:> w -~ {/) ;::s'l> ;:! ....
NATURAL POLYMERS SYNTHETIC POLYMERS R<> Gl 0 POLYCONDENSATION COMPOUNDS POLYMERIC COMPOUNDS POLY ADDITIVE "\.:1" 2.. 0 COMPOUNDS ;:! z ::. Polyester Poliamide Mixed Polyvinyl Polyvinyl Polyacry !o:1i!rile Polyethylene Polyurethai1e ... Polymerics Alcohol Chloride C/1 Terylene Nylon '-"! ;:: Dacron Vinylon PCV Orion Polythene Per1on - U ..... Perl on Dynel ;::s'l> Terital Saran Kuralon Pe Ce Acrilan Courlene Fibre - 32 "' Grilon ;:;·- Tergal Kapron Vinyon Cremona Rhovyl PAN Reevon .... -,.,N Terlenka Enkalon Harlon Mewlon Thermovyl Dralon Wynene ... "'{/) Tr~vira A milan Verel Synthofil Vinyon- HH Red on Teflon ...,_, 0 Diolen Livlon Woolon Pe Ce- U Courtelle ...... -{/) Lanon Caprolan Cry Ion ;::s'l> ;· Delfion Dolan ~==~======~d=~~==~====~-~ ,~ ~ -~~ ·______- -~ -w~ 'R.adf1alefisfnny & 9opalan Nayar: 8yntfietic fi6res for fisfiini) gear and the name Terylene became a registered lythylene group, the filaments are stretched trade mark, the property of the Imperial to 8-10 times the original length in boi Chemical Industries Ltd. It is a conden ling water and then wound up under sation product of terephthallic acid and constant tension (Kloppenburg & Reuter ethylene glycol but is actually manufac 1964). The process has got some influ tured by the ester interchange of glycol ence on the physical property of the fi and dimethyl terephathallate. nished product. Polyethylene Fibre ( P E) The fibre is pre TYPES OF YARN pared by polymerising ethylene at high pressure (1500 psi) Usually synthetic fibre yarns that go to make up the net material is available Polypropylene Fibres (P P) This bas been as staple or spun and continuous filament known for many years as an oil although yarns. A yarn is called staple when it for various reasons it had no comm~rcial is cut up into fibres of staple length of importance. In 1954 Prof. Natta whose about 3" (Carrothers 1957) and spun work has been concerned with stereospe into a yarn just like cotton. It is a con cific polymerisation of olefines using or tiiiuous filament yarn when filaments run 1::>o-anomettallic catalysts of Zeigler type through out the whole length. A conti discovered how to make isotactic materials nuous filament yarn is also describ:ed as with regular ordere1 molecular structure. 'drawn' since during the manufacture the The Imperial Chemical Industries recognised material is drawn to specified lengths. A the great potential for the new material and continuous filament yarn can be either a negotiated a patent license from the Ita monofilament or a multifilament yarn. lian Chemical firm of Montecatini in Another development in synthetic yarn August 1960. production is the manufacture of tapes. It is initially prepared as a sheet of uno PREPARATION OF YARN riented film , which is chilled and fed Essentially it consists of two stages, through the cutter, followed by passag:e melt spinning and cold drawing. It is through an orientation zone. Tapes are effected by an extrusion technique followe:i also produced in continuous lengths with by an orientation stage. The p::>lymer from a width of 2-4 mm and denier sizes of molted reactants is extruded as a ribb:m, 750-1000. The conversion of tapes into ground into pe!L:ts and remeted. The split fibres that can be spun into sisal molten mass is fed by melting pumps like cordage product was evolved by mid through spi :1nerts which on emerging is 1960, while Rummkr (1954) reports th~ solidified by cooling in a current of air. availability of Perlon in G~rmany as con It is then condens:!d and wound into bJ tinuous, staple, tape and monofilaments bins as undrawn yarn. In a subsequent as early as 1954. Production of synthe operation the filaments are coU drawn and tic tap.:s for fish net twines has been wound to pirns. The extent to which yarn started recentl; in India. is drawn depends 0:1 the ty,J; of polymer and sometimes th; same pJlymer is stre YARN NUMBEI.UNG SYSTEMS tched to different deg,~es. Carrothers (1957) mentions that nylon ma;1Ufacturers Basically there are two different sys stretches the yarn 3-4 times the original tems of yarn numbering, the Indirect Sys length whereas L::>hani (1961) states that tem and the Direct System. In the for the stretching is 4-5 times. For the po..: mer weight is kept constant and length 144 FISHERY TECHNOLOGY 'R.adftale~slhny & 9opalan Nayar: Synttietic fiiJro;s for fisfiing gear various hence higher the number thinner the textile industry as described by Gee the yarn. In the latter the length is kept (1954) and for netting yarns as described constar,t and the weight varies, hence hi by Klust (1 764 a) confirm to the above gher the number the thicker the yarn. basic principles The yarn numbering systems followed in L Indirect. System: i) When 840 yds of yarn weigh l lb it is 1 Ne (British Count) 840 xn " 1 lb 2 n Ne ii) 1000 m " 1 kg " 1 Nm (Metric Count) 1000 xn " 1 kg " n Nm 2. Direct Syst~m , i) 9000 m " 1 gm 1 D (Denier) 9000 m " n gm " n D ii) 1000 m " 1 gm " Tex 1000 m " n gm " n Tex The British Standards Institution has tional Standards Organisation. The sugge drawn out standards for textile yarns and stions of Indian Standards Institution is also suggests the adoption of 'Tex' system re on the same lines as that of the International commended in tlu International Standards Standards Organisation. Eventhough the Organisation conf~rence held in Southport Tex system has been recommended for in 1956. The two fishing congress also universal adoption this has not been fully stress the importance of yarn numbering implemented and for easy conversion of system with a recommendation for the the different numbering systems to the Tex adoption of 'Tex' given by the Interna- system the following formula is applied. Tex = 0.111 x Total Denier* = 590.5 1000 1,00.0000 496055 Ne = ·Nm = MsjKg - Yds/lb SIZE OF YARN nier sizes and types of synthetics described by Honda and Osada (1964) are poly The yarns are produced in standard propylene ] 80 Denier, polyamide (Amilan) sizes, mostly the size is specific to specific 210 Denier, polyester (Tetron) 210 Denier, group of synthetic fibres. Nylon conti polyvinylchloride (Saran) 360 Denier nuous filament yarn is available in 210 and Teviron 300 Denier. In India Denier, Terelene in 250 Denier, Ulstron polyamide fibre (NylJn) is mostl; produ in 190 Denier. Carrothers (1957) men c~d in 210 Denier size. 420 and 840 tions about Terylene yarns made to seve Denifr sizes are produced to a les~er ral sizes of 50, 75, 100, 125, and 250 extent. Deniers while Shimozaki (1959) describes the properties of Amihn (polyamide group A nylon multifilament yarn generally of fibres) yarn of 60, 110, 210, and 250 comprises of 24 filaments. Carmody (1968) Deniers and Teviron (polyvinylchloride mentions the production of yarns with 24, group of fibre) of 300 Denier. Perlon 18, ] 5, 12, 7, and 6 filaments and is of (polyamide group fibre) is available in opinion that yarns with 15, 7 and 6 fi 21 J, 630, 750, and 840 Deniers (Perlonwa laments are more suited for netcing. renseichenverband 1959). The different de- Nylon yarns of 140 Denier with 68 fi- VoL X No. 2 1973 145 'I Diameter. For determining the diameter the lowest and vinylidenechloride the high of a twine usually the following formula· est value of specific gravity. The specific is applied. gravity of a fibre is usuaUy determined from the following formula. d = K '-'n/Nm (Andreev 1962) 0.998 Specific gravity = where d is the diameter of the twine, 1- We in water n the number of yarns, Nm the count Air dry weight number in the metric system and K a constant. The values of K have been The specific gravity of some of the worked out as 1.3, 1.5-1.6, and 1.4 for commonly used fishing gear materials is cotton, kapron and hemp respectively. The furnished below. diameter of twine is an important factor Material Specific gravity to be reckoned with especially in the case of gill nets as it affects the fishing abi- Polyamide Ll4 1ity as reported by von Brandt & Liepolt Polyester 1.38 (1955), Mohr (1961) Gulbadamov (1962), Polyvinyl alcohol 1.30 Steinberg (1964), znamensky (1963), Nayar Polyvinylidene chloride 1.72 et.al (1967) and Sulochanan & Rao (1964). Polyvinyl chloride 1.40 It is assumed that thicker twines are ea Polyethylene 0.95 sily recognisable by the lateral line of Polypropylene 0.91 fish than soft and thin material The in Specific gravity and specific volume fluence of diameter also appears to depend being reciprocally proportional, the diame Dn the schooling behaviour of fish: sma ter increases with decreasing density. Ar Uer schools being more sensitive to this zano (1959) illustrates this with examples· factor than larger ones (Steinberg 1964). In the case of 125 Denier monofilaments The most desirable combination between the diameter expressed in 1I 1000 ths of diameter of twin~ and mesh size for gill nets is when the ratio of diameter 'd' of an inch are, Courelene 5.4, Nylon 4.9, twine mesh bar 'a' is 0.0 1-0.02. In tra Acetate 4.5, Viscose 4.5. wls a finer and stronger twine reduces the Twist. The quality of a twine is depen resistance to drag which indirectly retards dent firstly on the type of fibre and se the fuel consumption or helps in using a bigger net. condly on the number of twists imparted to the strand and twine. Two aspects are Specific gravity. Most of the synthetic fi to be considered under twist (i) the direc bres posses specific gravity lesser rhan natu tion of twist, and (ii) the amount of twist. ral fibres. Fibres with lesser specific gra The direction of twist is denoted as 'S' vity allows a greater length of netting for and 'Z'. In 'S' twist the slope of the com a given weight of yarn and may permit ponents of th~ twisted product follows the lighter fitting and savings in power and direction of the central portion of the handling (Lonsdale 1959). On the other letter 'S' while in 'Z' the spiral follows hand a low specific gravity may not be the central portion of 'Z'. Divergent views desirable where quick sinking of the net have been expressed in designating the 'S' is required as in the case of purse sei and 'Z' twist as right and left twist. nes and cast nets. Specific gravity also Garner (1949) and Takayama (1959) reco influences the form of the net while fish gnise 'S' twist as right and· 'Z' twist left mg. Among synthetics polypropalene has while Himmelfarb (1957) and Linton (1957) VoL X No. 2 1973 147 'Radfwlelisfimy & 9opalan Nayar: 8yntfietic fi6res for fis#iing gear describes 'S' as left and 'Z' as right. force in terms of fibre or yarn denier, British standards (2052:1963) mentions 'Z' whereas tensile strength is the force in te as right and 'S' as left. Indian Standards rms of unit area of cross section (Marsh (832:1964; 5815 (part iii) 1970) indicate the 1957). The first is expressed as gmsjde direction of twist as 'S' and 'Z' without nier and the second gmsfsq. mm. The incorporating the usage right or left. The breaking force denoted by breaking length, suitability of twine for a particular use is according to textile terms and definitions influenced by the amount of twists inser is the length of the specimen whose wei-: ted to the strand and twine. The degree ght is equal to the breaking load. The of twist is indicated by the number of ratio of twine strength to aggregate yarn turns per unit length and demarcated as strength is known as doubling efficiency soft, medium, hard and extra hard arbi (Lonsdale 1959) and is 95% in the case trarily. The stability of a twine depends of nylon. on the corre.::t amount of twists imparted to the strands and twine. Twines with Strength of nylon compared with other balanced twists show no tendency to snarl natural fibre twines indicates that it is Tauti (1929) points out that the balance bet twice as strong as Manila (Anon 1955 a) ween primary twist for making strands from and thrice as cott m (Anon 1956). A ny yarns and secondary twists to make twine lvn rope can withstand shock three times from strands is very important because as great as that required to snap Italian while an increased twist augments strength h~mp and five times as Manila rop~. Klu to a certain point an excessive twist pro st (1958 a) arranges the various !materials duces an opposite effect. Konda (1938) in the decreasing order of breaking stren and Koijumi (1954; 1955) p')inted out to gth as follows; polyamide continuous, po the same with regard to both cotton and lyesters, p)lyethylene, polyvinyl alcohol, synthetic fibres. Additional twists have p )lyvinyl chloride, and polyvinylidene. The the following effects, i) breaking strength dry tensile strength of nylon as repxted is reduced, ii) extension at break is in by Lonsdale (1959) lies in the range of creased, iii) length per unit weight is re 4.5 to 9.0 gmsjdenier with an extension duced, iv) resistance to abrasion and gene at break of 25 to 12%. The correspon ral wear is improved (Gayhurst & Robinson ding value L)[ polyester continuous fila 1959). ,central Institute of Fisheries Tech ment yarn is 6 to 7 gms/ denier and sta nology has worked out the twist specifi ple yarns 3.5 to 4.0 gmsjdenier with exten cations for nylon fish net twines for gill sion values of 12.5 to 7.5% and 40 to nets and trawls and these have been accep 25% respectively. The tenacity of a po ted as the Indian Standards (IS 4401: 1967). lymer is maximum as multifilament yarns with monofilament and staple following in. Strength & Extension. Strength of a mate order as illustrated for polypropylene by rial denotes the loading capacity which Honda (1964). together with extension gives an indica tion about its ability to withstand the Strength/denier of Polypropylene yarn strain. It is basically depended on the type of polymer, type of yarn, degree of Multifilament Monofilament Staple stretching, the construction and the amount 7.5- 8.0 6.5- 7.0 5.5 - 6.5 of twist. Strength of materials of diffe rent specifications are compared on the The tenacity values for some of the the basis of tenacity, tensile strength, or groups of synthetic fibres used in twines breaking length. Tenacity is the breaking and ropes as monofilament are given by 148 FISHERY TECHNOLOGY 'Radfialefbftmy & 9opalan Nayar: Syntfteiic filhes for fisliing gear Ede & Henstead (1964) and are reproduced ngth of man made fibres is ascribed to below. the weakening of the lateral cohesion between the long chain molecule. Him Synthetic fibre group Tenacity gfd melfarb (1959) gives data for the :differ Polyvinyl chloride 2.0 ence in strength of cordage and twines Polyamide 5.0- 7.0 by wetting. Polyester 5.0- 7.5 Polypropylene 5.0- 8.0. Type Effect of wetting Measured on strength strength ratio In India there are only two groups of synthetic fish 'net twines; 1) polyamide wet- dry as multifilament twines, 2) polythylene as Nylon Loss 0.7- 0.95 twisted monofilaments and tapes. Indian Dacron Slight gain 0.9- 1.10 Standards Institution has fixed yarn tena Polyethylene Gain 1.0- 1.15 city values for nylon as 5.5 gjd and polye thylene monofilament as 33.75 gjtex and Shimozaki (1959) reports that with Te tape as 40g/tex. viron, Envilon, Saran and Krehalon the twines are slightly stronger (3.5%) in the The strength of fibres change in the wet condition, while the polyamide shows wet condition. In the case of natural a reduction in strength by wetting. Klust fibres there is an increase in strength in (1964 b) reports that polyester, polyethy wet condition, but opposite is the effect lene, and polypropylene have the same noted in some of the synthetic fibres. breaking strength in wet and dry condi While discussing this aspect Himmelfarb tions. (1957) states that the increase in strength of natural fibres is due to the water mo Arzano (l959) lists the comparative kcule in the amorphous region acting as strength and extension properties of some a lubricant releasing internal stresses in of the synthetic fish net twines. Carter the long chain molecule anchored to the & West (l964) make a comparative state crystalline region and thereby increasing ment likewise with the inclusion of some the fibre strength by a more uniform dis of the later additions of synthetic group tribution of stress. The decrease in stre- of textile fibres which is as follows. Group of synthetic fibre Property Polypropylene Polyethylene Polyester Polyamide Polyvinyl alcohol Tenacity (g/d) Dry 8.0 8.5 4.5- 6.0 6.0- 7.0 7.0-9.0 3.0-7.0 Wet 6.0-7.9 2.6-5.9 " " " VoL X No. 2 1973 149 'R.adfiale#f,sfimy & 9opalan Nayar: 8yntfietic fi6res for fisliing gear Group of synthetic fibre Property Polypropylene Polyethylene Polyester Polyamide Polyvinyl alcohol Extension at break% Dry 18-22 25-35 6-14 12-18 15-28 Wet 19-28 20-30_ " " " When a knot is tied to a twine it (von Brandt & Klust 1970). constitutues the place of weakness thereby reducing the effective strength of the twine. Molin (1951) has made a comparison The reduction in strength by knotting is of the loss in strength by knotting and dependent on the type of polymer, type wetting of polyamide imported from differ of yarn, type of knot; constr_uction of ent countries. His data indicate that stre twine as well as on the degree of stret ngth loss is more for filament yarn than ching. Synthetic twines with high draw for staple. The same finding has been !no ratio though they are stronger than their ted for polypropylene (Tani 1964). The lesser stretched counterparts, loose much change in breaking strength of twines due of their strength by knotting (Klust 1957). t-J wetting and knotting has been exten The wet knot strength of polyamide twine sively studied by V olkov & Mikahilova is two and a half times more compared (1955). The authors find that the initial to cotton of equivalent size (Starr 1957). high breaking strength of nylon go to However Volkoe & Mikahilova (1957) main make up for the loss due to wetting and tain that the knot breaking strength of greater reduction is strength by knotting. polyamide twines is on an average 1.5 times higher than that of cotton twines Knot efficiency can be stated as the of similar specifications. Polyvinyl alcohol ratio between the dry knot strength to twines posses only 2/3 the strength of co strength of dry unknotted straight twine tton when wet and made into knot (Ca (or alternatively wet knotted strength to rrothers 1955), eventhough as twines the strength of wet unknotted straight twines) former is twice stronger. A comparison (Lonsdale 1959). Knot efficiency changes of knot breaking strength of trawl twines with diameter and type of netting twine made of different synthetic fibres with the (Perlonwaren zeichenvervand 1959, Klust same runnage shows a decreasing sequence ] 964 b). Studies conducted with perlon from polyamide to polypropylene to po monofi1aments ( opcit) of different diame lyester, polyethylene, and polyvinyl alcohol ters reveal the following:- Knot efficiency 70-80 % for smaH dia ( 0.1 - 0.3 mm) 60--70 % , Medium , (0.35 - 0.70 mm) 50-60 % , large , ( over 0.70 mm) The influence of diameter on the knot (twisted and braided) in the case of po efficiency together with variations due to lypropylene has bexen studied by Klust type of knot and type of netting twines (1964 b). His data reveal the following:- 150 FISHERY TECHNOLOGY 'Radfiale~sftmy & 9 0 palan Nair: Syntfietic fi!Jres for fisfiing geay % Loss of strength by knoting. English knot Overhand knot Finest netting twine (twisted) 24 30 Twisted netting twine of medium strength (approximately from R 130-500 Tex) 39 45 Thicker netting twines (twisted) 50 53 Braided trawl twines 49 49 Klust (1968) has also observed that monofilaments by we1thering and states twines with single overhand knot tied oppo that polyethylene can be safely used out site to the direction of twist of the twine doors in temperate climates for many give comparab1e values of strength to that years. Radhalekshmy & Kuriyan (op. cit) of the weavers knot. have studied the action due to weathering of various types of synthetics at two test Weather resistance. Both synthetics and sites a tempe:ate and tropical site. The natural fibres are weakened by exposure authors endorse the views of Ede & Hen to sunlight. Unlike vegetable fibres diffe stead ( op. cit) that polyethylene monofi rent typs of synthetics sh')W CO;}siderable laments could be used in temperate regions variations in their degree of resistance to without much deterioration. The same light and weathering. The degradation is authors have found polypropylene as pot due primarily to the effect of light in the much resistant to weathering at both test visible voilet and blue ranges of waveleng sites. Deterioration due to weathering is ths (Inderfurth 1953). Klust (1959 a) has more rapid at ce:·tain locations than others compared the weather resistance of diffe because of difference in duration of that rent groups of synthetic fibres. He con particular wavebngth of light which dama cludes that for traps and other basket ges the fibre (Inderfurth 1953). Filament types of nets which stand partly on the sizes and thickness also affect the weather water or close below the surface of water resistance. Fibres with high denier per polyvinyl chloride, polyacrylonitrile, and filament are more resistant than fibres polyamide monofilament will be suitable. with low denier per filament. Normally Himmelfarb (1957) makes a comparison the resistance is better with thicker ropes, of weather deterioration of nylon as mo as the layers below are protected by the nofilament, multifilament, and staple yarn degraded outer layers and since ultra and concludes that nylon in monofilament voilet rays cannot penetrate more than 1 mm. form is more resistant than multifilament Findings of Ede & Henst~ad (1964) o:1 and staple yarn. The ab we findings have monofilaments also give evidence that thi been corraborated by Koura (1963) and cker the monofilament better the resista Radhalekshmy & Kuriyan (1969). The su nce. To increase the weathere resistance periority of monofilament:s in their weather certain dyeing techniques have been re resistance has been explained by Klust commended. von. Brandt (1954) stresses (1955 a). He attributes this to the favou rable proportion between surface and vo that though the damaging effect can be lume of the material. Ede & Henstead reduced by dyeing care should be taken (1964) makes a comparison of the loss in to select the proper dye as some dyes strength of different types of synthetic can even increase the effect of light. VoL X No. 2 1973 151 'Radfwlefisftmy & 9opalan Nair: 8yntftetic fi6res for fisfting gear Klust (1955 b) advocates the use of cutch materials, identical runnage, diameter or (4-6%) to secure protection against wea breaking strength is taken as the basis. thering. Tests conducted by the Central (Klust 1959 a). Klust ( op. cit) has a made Institute of Fisheries Technology on Indian an elaborate study ,of the abrasion resis nylon showed that acid dyes of green and tance of different materials, based on the yellow impart a certain amount of wea above criteria. As per his studies the ther resistance to the materiaL abrasion resistance of trawl twine having runnage of above 350 mjkg with the va A nylon twine exposed continuously lue of cotton taken as 100 are as follows:- to sunlight of normal intensity for 2 months can lose as much as 40% of its Manila 130., strength and a twine of Perlon staple Hemp 280., without protection when hung in sunlight 'Polyester continuous filament 230 may lose strength up to 7 5% in the first Polyamide continuous filament 460. three months (Rummier 1954). However other excellent properties of polyamide For finer twines the same author has more than compensate for its lower resis given ther following figures taking the value tance weathering. Besides, the intial high of cotton of equivalent size as 100 breaking strength of nylon makes it po 50-55 ssible for polyamide to remain superior Polyvinyl chloride Rhovyl staple in strength after exposure for a certain PCU Staple 75 period. Polyvinyl alcohol Staple 50-60 Filament 110 Polyacrylonitrile Continuous fila Abrasion resistance: Abrasion or wear to ment 70 fishing nets is caused by two ways, one Polyamide Staple 170-250 by friction with hard substances such as Continuous fila- sea bottom huH of boat, and net line ment 400-500 haulers and the other by friction between net twines at the seam and knots. The Ede & Honqstead (1964) have consi life of a net is influenced to a certain dered the abrasion resistance of monofi extent by abrasion resistance and it is de laments of different polymers having equal pendent on the type of materia], the kind diameters and observes that the abrasion of fibre, the construction of the netting resistance is in the following order; polya and the thickness of the material. Among mide, polypropylene, polyester, and poly synthetics, polyamide pJsses the maximum vinyl chloride. Inderfurth (1953) attributes abrasion resistance (von. Brandt, 1957). the high degree of abrasional resistance Polyamide filaments twines used in the of polyamide (nylon) to the inh~rent tou German trawl fishery show that it is ten ghness and natural pliability and its abi times more durable than manila nets. This liiy to undergo a high degree of flexing is not only due to rot proofness but also without breakdown. Coupled with this the due to greater a~rasion 'resistance. Twines smooth filament surfaces do not readily of polyester have only half the abrasion create friction when rubbed against them resistance of polya:nide but the resistance selves or other surfaces. Among the va is better than cotton and manila. Abra rious types of twines, monofilament is sion resistance is usually represented in better than multifilament and between arbitrary units on comparison with a stapl~ and multifilament, the latter .is su material taken as a standard. In study perior (Klust 1955 b, 1959 a). The rela ing the abrasion resistance of different tion of twist on frictional resistance 152 FISHERY TECHNOLOGY 'Radftale~sfimy & 9opalan Nair: cSyntftetic filires for fisfting gear has been explained by Shimozaki (1959), mounting ropes, or for the production of Klust (1959 a), and Ede & Honstead (1964). combination ropes with natural fibres. They observe that strand twist affects the Firth (1950 a) states that one of the first abrasion resistance more as they seem to commercial application of nylon is for the play the greatest role in increasing the construction of gill nets. The use of Per rigidity of the tvvines. Preliminary studies Ion monofilame:1t for hand lines and giH conducted by the Central Institute of Fi nets and Perlon continuous filaments for sheries Technology on the abrasional resis tuna long lines and whale tow warps has tance of two groups of indigenously pro be~n cited by Klust (1952). Rankovie duced synthetic twines viz polyamide mul (1957) mentions nylon as servisable for tifilament (nylon) and polyethyle:1e mono eel long lines in Lake Scutary. Examples filament ir:dicate that the former posses of whale runners and purse lines of cir= a high degree of abrasion re}istance cling nets with man made fibres are cited compared to latter. by Klust (1958 a). Klust (1959 b) states that polyamide staple fibre twines are used The second type of abrasion is inter for lines, scoop nets, fyke nets, caste nets, friction between twines. When synthetics lift nets, drift nets, river stow nets and are rubbed against each other, abrasion drag nets. Polyamide continuous filament between hard quality twines result in quick twines are used for stronger or fine gill snapping. When a hard twine is rubbed nets. Plaitd twines of continuous multi against a scft one the latter breaks ~first; filament perlon are specially strong and if both are soft the abrasion resistance of suited for large stow nets in the river both seems to be improved. Between fishery. When lowest possible extension . twines of the same kind the number of is wanted (e. g. some pound nets, lift nets, frictions to break them is mostly as many gill nets and trammel nets) net twines of as, but sometimes a litH~ more than the p0lyefter are preferred. Klust (1960) is of number required to break cotton (Shimo opinion that polyamide and polyester are zaki 1959). t'1e two groups of chemical fibres that are most suitable for gill nets. SELECTION OF DIFFERENT GROUPS OF SYN Eventhouh synthetics are widely used THETIC MATERIALS FOR FISHING GEAR for gill nets their use for the fabrication As is evident from the foregoing, of trawls is of a restricted nature. In synthetic fibres are available in a wide sea fisheries trawls made of perlon are variety of groups and forms with changes particularly used in herring f1shery (von. in physical prop~rties and it is desirable Brandt 1956 a). While reviewing fle pro to choose from among these a particular perties of a particular type of synthetic material which is most suited for a spe twine, its application and suitability or cific fishing g~ar. While there is no ideal otherwise to diff,;rent classes of nets like material which can be used for all types purse seines, trawls, giH nets, ring nets, of fishing gear, the various types of syn midwater trawls, drag nets etc have been thetics each having different properties stressed by various authors (Anon 1957, provide a range of choice from which a Teiko Rayon Co. 1959, Amano 1959, Car selection can be made for what is best ter & West 1964). Ruggerio (1960) men for each type of gear. tions that trawls made wholly of 4.76 mm braided nylon cord were used in trawling Synthetics are used either for the en over bottom which is ·considered too rough tire fabric of the net or part of it or as for natural fibres in Gulf of Mexico. VoL X No. 2 1973 153 'Radftalefzsftmy & 9opalan Nair: 8yntfietic filhes for fisliing gear In spite of being buoyant the possibility Polyamide : Gin nets (Salmon & Trout) of using Ulstron for purse seines with Purse Seines (Sardines & proper rigging and weighting is cited by Tuna) Carter & West (1964). While studying the Polyvinyl alco- characteristics of synthetic materials of hol : Purse seines (Mackeral, bottom and mid water trawls, von Brandt Horse mackeral & Tuna) & Klust (1970) enumerates the sp~cific requ Polyethelene : Trawls irements with regard to b:Jttom and mid Vinylidene : Set nets (Yell ow tail) water trawls. These authors h~ ld the view Lift nets (Mackeral & Pike) that for bottom trawls the netting yarns Polyester : Purse seines (Horse macke- should combine high wet knot breaking rals & Mackerals) strength at smallest possible diameter, high : Set nets. abrasion resistance, relatively high exten Polypropylene : Entangling nets (Crabs) sibility under fishing conditions, good elas Polyvinyl chlo- ticity for withstanding shock loads and no ride : Set nets & Lift nets. knot slippage or inversion of knots. von Brandt ( op. cit) also emphasised that for CATCH EFFICIENCY OF NETS pelagic trawls apart from good wet knot breaking strength the netting yarn should AU over the world synthetic fibres combine high extension and elasticity. have increasingly become popular mainly Klust (l959 a) suggests the selection of because of the spectacular increase in fish synthetic twines for a particular gear based catches of synthetics over traditional ma on the strain on the net material and has terials- Among synthetics the most wide spread use of nylon is in gill nets. The classified aU the fishing gear of Germany extensive use of nylon in gill nets is due under three main groups viz, 1. low strain to the ability of nylon to catch much 2. medium strain 3. high strain. Fine gill more than a gill net of n~tural fibre. nets belong to group 1, fishing lines, Reports of the fishing experiments of You baskets, traps and box nets, scoops, gape ng (1950) on white fish in Great Lakes nets, dragged gear, also bottom trawls of indicate that nylon has a superior catch smaller vessels, floating trawls of cutters efficiency of 3.2 : l over linen. With spring seiners and drift nets belong to group two, Salmon his experiment show that the fishes and bottom trawls of large vessels and gape caught in nylon gill nets were 7.3 lbs ave nets set in fast moving rivers belong to rage weight compared to 6.6 lbs in linen group three. Based on the above criteria nets. Molin (1950) reports that nylon gill he suggests the following guidelines for the nets are 2-3 times superior over cotton selection of synthetic fibre twines for the nets, while Lawler (1950) finds its supe different categories of fishing gear. riority as three times over comparable cot ton and linen nets. Another instance of Mamoi Fishing Net Manufacturing Co greater catches by synthetic nets is repor Ltd (1959) and Japan Chemical Fibre Asso ted by Giesel (1953) equal t·) 7.5 times ciation (l964, 1970) have :also made certain more than cotton nets i.n Lake Laach. observations regarding the utility of diffe It has been stated (Anon 1954) that for rent types of synthetic fibre twines for cod and coal fish also nylon has proved different classes of nets based on the pro to be successfuL The catch of 27 fish perties of the different materials. The ing days for cod indicates an average of choice indicated by Japan Chemical Fibre 2·8 fishfnetj day for cotton net and 8.24 Association (1970) is as follows:- fishjnetjday for nylon and 6.4 for Perlon. 154 FISHERY TECHNOLOGY 'Radtialefzsfimi & Gopalan Nair: 8yntlietic fi15res for fisfiing gear TABLE II Fibre Trade names Characteristics Suitable for use in Polyvinyl F. Rhovyl Medium breaking strength chloride G. PCU, Rhovyl Medium abrasion resistance Group 2 J. Envilon Very good resistance to J. Teviron weathering Polvyinyl J. Vinylon Low price, medium strength alcohol J. Manryo medium abrasion resistance, J. Kuralon good resistance to weathering. J. Trawlon Group 2 J. Cremona J. Mewlon G.PVA Polyester GB Terylene Very high breaking strengh USA. Dacron low extensibility Group 1 G. Diolen medium abrasion resistance and 2 G. Trevira relatively good resistance Group 3? F. Teegal to weathering I. Terital J. Tetron Polyethylene GB. Courlene X3 High breaking strength GB. Drylene very high abarasion Group 2 N. Nymplex resistance, wiry Grouy 3? G. Polyathylen swimming in water Hoechst Polypropy I. Merkaklon Low price, rne:iium to USA high breaking strength, low Group la. 3? resistance to weathering, swimming in water Polyamide Nylon-monofil Transparency (little vissible Group 1., mono Perlon-monofil ness in water) very good Group 2., filament Platil resistance to weathering Fyke nets wiry Polyamide Nylon-staple High breaking strength staple Perl on-staple high abrasion reoistance good knot stability Group 2. very high extensibility, low resistance to weathering Polyamide Nylon-filament Very high breaking strength All 3 groups Continuous Perlon-filament very high abarsion resistance, of high elastcity, low resistance gear to weathering F=France, GB =Great Britain, G=Germany, l=Italy, J =Japan, N =Netherlands VoL X No 2 1973 155 'Radftaletisftmy & 9opalan Nayar: Syntftetic fit'nes for fisfting gear The corresponding values for coal fish frequency and length weight of fish lan were 7.5 for hemp and 9·2 for nylon. ded by these nets over linen counterparts. According to Atton (1955) greater catch George & Mathai (1972) have conducted efficiency of nylon nets decreases with in comparative fisning trials with nylon and crease in mesh size and these nets cau cotton gill nets in the inland waters of ght fishes of somewhat larger average India. Their findings also establish the weiahtb than cotton nets of same size. superiority of synthetic fibre nets, the ratio This the author attributes to the elas- of catch being 9 times by weight and 7.6 ticity of the twines. He further stresses times by number between nylon and cot that the selectivity of nylon nets compa ton. However a counter argument for red to cotton varies with sp;;cies and with nylon is put forward by Runnstrom (1964). availability of size groups in the popula His results are based on the experimeEts tion, and the main selective action of in Sweedish lakes in '62-63. The author nylon nets is in the capture of greater indicates that the flexibility of nylon net proportion of larger fishes of the same is not significantly higher than that of group which are also caught in cotton cotton. He attributes the ability of fish giU nets. The elasticity of nylon allows to dodge the net by experience, as the the fish to force the twines apart and reason for the difference in results from become caught which account for the cap other workers. ture of larger size fish (Young 1950, and du Pont Nemours & Co 1959) or wider Studies on the catch efficiency of gill range of fish sizes (Saetersdal 1959) with nets with synthetics of different yarn types a given mesh size. Results of compara such as spun, monofilament and multi tive fishing trials with coastal giH nets filament have been made by various au made partly of Perlon and partly of cot thors (Anon 1952, Molin 1955, 1956, von ton carried out by Fisheries School, Mer Brandt & Liepolt 1955). Catch efficiency wot yam Israel, are reported by Shabtay for spun and fihment nylon nets is dis (1956). His results indicate that Perlon cussed on comparison with cotton in the half of the net lands about 80% of the experiments conducted by the Sweedish total catch. Anon (1957 is of the view Institute of fresh water research, Drotting that the greater catching ability of nylon holm (Anon 1952). It is in the ratio of gill nets is due to its translucency ia water, 1:2:7 for cotton, spun nylon and filament use of finer twines for a given strength, nylon. Molin (op. cit.) distinguishes sepa surface smoothness and the possibility of rately the output of spun nylon and dyeing to match the surroundings. The monofilament nylon over cotton. Mono fishing power of nylon gill nets compa filament nylon superseded spun nylon and red to cotton studied by Saetersdal (I 959) cotton by 3 & 7 times respectively in the indicates the values to be 2.5-4 4, 1.4-2.3 case of shallow nets. Superiority of mo & 1.2-1.3 for 3 types of fishes cod, coal nofilament nylon diminishes with the depth fish and mackerel. Effectivness of syn of the net and these nets will have the thetic gill nets is reviewed in a C·Jmpre same efficiency as spun nyl m nets at depths hensive manner by Muncy (1960). Field of about 6.1 m. Molin (1956) takes into trials were conducted during the spring of account the catch efficiency with regard 1959 by the author to compare the di to two types of fishery, white fish and fference in catch of soft rayed fish by pyke perch. For white fish the tolal catch synthetic fibre (ny!o:a) and natural fibre on monofilament nets was 50% higher gill nets. Statistical analysis revealed the than spun nylon nets. However the higher superiority of nylon nets in numbers, length fishing power could not be compared with 156 FISHERY TECHNOLOGY 'Radfwlefblimy & 9opalan Nayar: Syntfietic fif'mzs for fisfting gear that shown by the more shallow nets tested Teviron and nylon drift nets for salmon earlier but it was iHustrated that mono and trout in North sea reveal teviron nets filament nylon is advantageous for deep to be as efficient as nylon. Number of water nets as welL The size of mono fishes caught in each operation was 2.27 filament used for earlier experim~mts (Mo for Teviron and 2.22 for nylon. Zaucha lin 1955) was 0.2-0.22 mm while it is 0.16 (op. cit.) cited the example of Polyvinyl mm for the later studies, which accoun alcohol a!ld polyamid and opines that in ted for the disparity in results. With pyke spite of many good qualities of polyvinyl perch nets the results were negative as alcohol has better overan utility for her monofilament nylon gave even smaller than ring drift nets. Between polypropylene and spun nylon. Rahm (1955) states that mo polyamide the latter possesses better catch nofilaments recommend themselves by the efficiency_ (Honda & Osada 1964). The la= greater efficiency, better utilization and te3t development in the material for gin longer life. His results based on 7 mon nets . is single yarn nylon. It was intro ths operation indicate a catch efficiency of duced in 1963 by Japanese fishermen in 1:1.9 for cotton and~ nylon gill nets. von Lake Bawa, Honolulu Island. The single Brandt & Liepolt (1955), in their investi yarn. net is made of continuous nylon twisted gations in the Coregone fishery gill nets, into a yarn of 102/1 of 34 filaments for have found that identical nets of cotton, smaller fishes up to 16 ems length; HOD/1 Perlon and Platil recorded catch in the of 30 filaments for 10-20 ems fish; and ratio of 1:1.2:1.9. The authors add to 210D,1 of 24 filaments for larger fish say that thickness of monofdaments is a (Anon 1967). Experience has shown that factor to be reckoned with since with the catching ability is twice as that of increasing thickness, effectiveness reduces. nets made of multi stranded twines. This is illustrated with regard to the catch in trout fishery. With regard to trawl nets also, ad vent of synthetics has effected some im Material Catch efficiency provements. Firth (1950 b) mentions that Cotton 1.0 nylon trawls were about 4-5 times more Perlon monofilament 0.15mm 4.9 effective than ordinary cotton trawls in 0.25mm 4.3 Norwegian fishing experiments. The po 0.30mm 3 3 ssible explanation is that nylon is light, 0.40mm 2.8 does not absorb much water and is smooth offering less resistance during towing, and Carrothers (I 959) distinguishes the cat it is likely that nylon trawl gives a larger ch efficiency between monofilament and opening. Miyazaki (1962) comparing the multifilament nylon gill nets. He reports efficiency between Amilan and cotton beam that the catch/day is better with mono trawls reported that in term of catch per filament n~ts but no appreciable difference drag the Amila.n net had, in catching was noted between the nets during night bottom swimmers efficiency twice as high operations. as the cotton net, while there was no significant difference for the bottom bur Comparative catch efficiency between rowers. The trawl net operated by the various types of synthetic twines has also United States Bureau of Commercial Fi received attention at the hands of various sheries in their experimental vessel in 1961 research worke:s (Teikoku Rayon Co. 1959, where the ·top wings, top belly and square Zaucha 1964, Honda & Osada 1964). In were made out of polypropylene twine ,of vestigations by Teikoku Rayon Co. with size equivalent to the diameter of 42 VoL X No. 2 1973 157 'Radlialeftsfnny & 9opa!an Nayar: Syntlietic fi6res for fisliing gear thread cotton, fetched 57% of the catch polyethylene (in the upper part) and cotton while the comparative data for a trawl (in the bwer parts). The studies indicate made ovt of Manila was 43%. Based on higher catch rate for polyethylene and these experiments it has been suggested combination net over cotton. that the upper portions of trawl can be replaced by buoyant synthetic materials. Synthetic twines have been used suc Black polypropylene trawl used by the cessfully for the construction of other Bureau of commercial fisheries at Glou types of gear as welL von Brandt's cester, Massachussetes accounted for 67 (1956 b) experiments in a Lake in West & 58% compared to 33 and 42% for tra G.:::rmany have shown that the catch ratio wls made out of Manila of the same of cotton and polyamide monofilament s1ze under similar conditions (Anon 1965). fyke nc:t is 1:1.8 Kajewski (1957) points The explanation put forward for the higher out that a Perle)n trap produced 4350 kg rate of catch is that the buoyancy of of eel off Baltic coast whib traps of c.Jt polypropylene in the top sections allowed ton caught on aa average 3355 kg. the head rope to rise higher reducing Perlon traps catching lesser amount of wat~r resistance and aHowed the trawl to smaller eels. Rankovie (1957) made some be dragged more easily. Kuriyan (1965) attempts to as certain how long lines made while reviewing the trends in the deve of cotton, flax, hemp and nylon could lopment of prawn fishing technique in influence the yield. The results indicate India mentions about the comparative tra wling experiments in Indian waters with that thinner nylon not only yielded [he cotton and nylon. In the words of the largest output but also no hook was lost author' in fact the cotton net caught more. and when the season was over nylon lines Being a heavier material the cotton net had not lost strength as compared to might have dragged more on the mud'. natural fibres. The present authors feel that since in these experiments nylon twines indigenously pro GUIDE LINES FOR REPLACEMENT OF NA duced for gill nets have been used, which TURAL FIBRE TWINES WITH SYNTHETICS being of a soft and flexible nature might not have retained the desirable mesh shape Klust (1954 a), 1958 b) and Sunna while trawling. This may be the reason (1956) give tabular statements as refereiJ.Ce for the apparent inferiority of nylon tra to replace cotton with nylon continuous wl net. Miyazaki & Tawara (1970) have filament twines base1 on equal wet knot investigated the feasibility of nylon and str~ngth. Sunnana ( op. cit.) adds to say p)lyethylene monofilament trawls for semi that the approximate correct number of pelagic and demersal fishes. The experi nylon is got by increasing the runnage by ment establishes the superiority of polya 50% ii1 the case of cotton. For equal mide monofilaments for semi pelagic nets weights, the net surface of nyloa will be while for demersal fishery. both the nets 2! times more than that of cotton (Klust had equal efficiency. The lower visibility 1957). The Central Institute of Fisheries of the former materials is ciced as the Technology has fou:1d that for equal wet cause for better efficiency. mesh strength the runnage vaLles of cot ton and nylon conform to the ratio of Central Institute of Fisheries Techno 1:2.34 and between polyamide multifila logy has conducted comparative fishing ment and poly-.thylene monofilament twines trials with cotton polyethylene monofila with equal runnage in both will have ments and a combination trawl net of almost equal wet mesh strength. !58 FISHERY TECHNOLOGY 'Radt1.ale~st1my & 9opalan Nayar: 8yntl1etic {i5res for fisfiing. g.ear ECONOMICS hemp with running length of 176 ms costs $1.50 while the price of nylon rope of The main facbr that deserve consi equivalent thickness is $6.3/kg with 600 m deration in the case of fish net materials of length showing that the latter is 3t are efficiency, durability, price, maintenance, times longer for equal weight. Ulstron operational costs and saving of material Granton Trawl in braided monofilaments by way of runnage. These factors in turn C.)Sts £160-210 compared to £130 forMa influence the economics of using a parti nila based on equivalent diameter. But cular net material. In the case of synthe on a price life basis Ulstron trawl have tics the price relJtion with natural fibres an advantage of 50% over Manila (Carter is so unfavourab~e that the use of it & West 1964), also a bottom trawl of would apparently endanger the profitabi Ulstron weighs 250 lbs compared to 450 lity of fishing enterprices. A nylon net lbs in the case of Manila. With the in is cited as lighter by 28% (Klust 1954 b) troduction of different type~ of synthetic or l/3 the bulk (Anon 1955 b) of fibres it has been found useful to corn corresponding cotton nets and 16-38% pare the price/length aspect with regard lighter than Manila. The weight of cot to different kinds of synthetic materials. ton and Perl on trap is given as 3280 and Ulstron is in the same strength bracket 2000 kg respectively in Briestenstein and as polyamide and polyester ropes and con Jager·s (!953) investigations. Fontan (!958) siderably stronger than polyethylene and makes a comparison of th~ priceflength possesses greater runnage for a given wei relation of hemp and nylon. l kg of ght. (Carter & West 1964) Material Ropes of l" circumferances 1bs/120fms .Breaking load in lbs Cost/100ft- Ulstron 16.0 2100 37s 6d Nylon 21.5 2240 48s 9d Terylene 24.75 2100 58s 8d In India the price of nylon is Rs. 45/ 50% in its resistance to pull and weight kg compared to Rs. 20-25 for cotton. it can supp01 t (Fontan 1958). Reduction However the price of polyethylene mono in the total weight of equipment, no ex filaments is much less coming to about penditure on net preservation, less labour Rs. 18/kg. Takirg the example of a 1 mrn to handle the gear, water saturated nets twine, in the three cases, the rnnning can- be safely stowed with a useful life lengths will be 1600, 1465 and 1320 m;kg of at least double to cotton nets are some respectively for nylon, polyethylene and of the advantage claimed for Perlon sta cotton. This indicates, that nylon is len ple purse seine (Perlon ware~12eichenver- . gthier by 15% and polyethylene by 10% · band 1959). than cotton of equivalent size for a given weight. iii) Durability: Various reports are on record pertai ii) Operational cost and maintenance: ning to the greater service life of synthe Low weight, flexibility, and fineness make tic nets over those of natural fibres. The it easy to handle synthetic fibre nets and data are based on :comparative fishing tri finer twines considerably reduce the tow als with two type of nets. Klust (1954 b) drag. Nylon exceeds hemp by more than gives the comparative life of cotton and VoL X No 2 1973 159 'Radfialetisfrmy & 9opalan Nayar: Syntfietic fi5res for fisil.ing gear Perlon purse seine in Portugese fishery as 3 cotton nets would have to be purcha 450-500 and 900 fishing days respectively. sed costing DM 3270.00. Mugaas (1959) A cotton bag net is sreviceable only for referes to the tests conducted by Directo 2 years with 7-10 preservative treatments rate of Fisheries, Norway. Tests indicate while synthetics last for 3 years with no that Kurlon traps had been in use con damage and by this service life the ini tinuously for 4-5 months with no sign of tial cost could be recovered. A Perlon reduction in strength in the twines. Traps trawl was found to be serviceable even made from hemp and cotton had to be after 14 voyages with an output of 45,000 renewed every 7th week. Carter & West baskets of herring (Klust 1955 c). Bries (1964) repon that in coaro:e fishing grounds tenstein and Jagers's (1953) investigations the average life of braided Ulstr ,m trawl with braided continuous Perlon and cotton iS about 5 weeks. Making allowance for traps show that after the first fishing sea accidental losses by snagging or submer son cotton nets have become useless but ged obj::cts and similat' mishaps the ave Perlon traps are useful for a span of 5 rage life is reduced to 2 or 3 weeks. years with a price relation cf 1:4. A The corresponding average life of M.wila Perlon trawl after 5 years 1056 fishing trawl is 1-lt weeks. days) has been found to be serviceable even with a loss of 54.5% (Klust 1956) ACKNOWLEDGEMENTS of its strength. Perlon is 15 times more useful than Manila, while the price is only The authors wish to express their 3-4 times more, thus establishing its supe"' thanks to Dr. S. Z. Qazim, Director, Cen rior profitableness (Klust 1956). A Perlon tral Institute of Fisheries Technology for rope 3-iJ' dia. with a breaking strength of the permission granted to publish this H,800 kg retain 4460 kg after 916 fishing · paper. We are also greateful to Shri days (Klust 1956) Perlon warenseichen G. K. Kuriyan, Senior Fisheries Scientist verband (1959) reports the service life of cum Head of Divisicn, Craft & Gear, Ce:1- Perlon continuous filament purse line of tral Institute of Fisheries Tenhnology fur 30 mm dia as 19 times to that of sisal critically going through the manuscript and rope where as the price of the former is and for the suggestions offered. only 5 times the latter. The author also mentions about a bottom trawl of Perlon REFERENCES which hnded 12800 cwt. of herring and having a useful life of 8-10 times more Amano, M. 1959 The features and use of than that of manila trawl. He has also 'Amilan' fishing nets. Modern Fishing refered to the merits of Perlon in the Gear of the World Fishing News case of purse seines and stow nets. Cot (Books.,) London: 150-151 ton purse seines have a useful life of 400-500 fishing days while Perlon staple Andreev, N. N. 1962 Hand book of fishing net was op~rated for BOO days without gear and rigging Pischepromizdat Mos becoming unserviceable. Cotton stow net3 kva. Translated from Russian T T have a useful life of 2 years only if trea"' 66-51046. United states Department of ted 7-10 times with coal tar to preserve Intersor & Natural Science Foundation, and stiffen while stow nets of Perlon can Washington D. C. be used for 6 years, with only two treat ments during the period. Cost of the Anon 1952 Sweedish experiments with ny latter which is serviceable amounts only to lon fish nets. Fishery Product Report DM 1625.00 during which period at least No. 203: 2-3 160 FISHERY TECHNOLOGY 'Radiia!e/Zsftmy & 9opalan Nayar: 8yntftetic fifhes for fisliing gear Anon 1954 Fishing tests with nylon and Carmody, E. 1968 Netting in state of con perlon cod gin nets compared with stant change The Fishermen's News, common materials and with coal fish 14 (19 ), 7. gill nets Fiskets gang 40 (23): 290-295 Carrothers, P. J. G. 1955 Results of Ku Anon 1955 a What is late>t on synthetic ralon staple twine. Progress Report ropes Marine Engineering ( 3) 203 of Pacific Coast Station., No. 103., 55-57 Anon 1955 b Why haul by hand: Reel and nylon save work. Pacific Fisher Carrothers, P. J. G. 1957 The selection and man 53 (I) 21 care of nylon gill nets for salmon. Industrial Memorandom: 19., Fisheries Anon 1956 Nylon for machine made nets Research Board of canada. -preventing fracture at knots. Fishing News 2244, 7-8 Carrothers, P. J. G. 1959 Monofilament nylon web for salmon giU nets. Fi Anon 1957 Are synthetic nets the answer: sheries Research Board of Canada Parts I & I World Fishing, 6 (10 & II), Biological Station Circular No. 51. , 53-59 & 34-40- 54-58. Anon 1958 A new fibre for the fish net Carter, C. L. B., & West, K. 1964 Use of industry : Terylene. West.:rn Fisheries 'Ulstron' polypropylene in fishing. 55 ( 5)' 12-18 Modern fishing Gear of the World., 2., 57-63., Fishing News (Books), Anon 1965 Trawl twine testing programme London. points way to advances. Fishing ga zette 81 ( 3) 12-13 du Pont de Nemours & Co. 1959 Synthe tic fibre in fishing industry. Modern Anon ] 967 Single yarn gill nets increas:: Fishing gear of the World., 147-149., catch rate Fishing News International. Fishing News (Books)., London. 6 (10), 65 Ede, D. F. C., & Henstead, W. 1964 Mono Arzano, R. 1959 Man made fibres. Mo filament in fishing. Modern Fishing dern Fishing Gear of the world. Fi Gear of the World., 2., Fishing News shing News (Books) Ltd.. London. (Books) Ltd., London. Atton, F. M. 19 55 Relative efficiency of Firth, F. E. 1950 a Nylon gill netting pro nylon and cotton gill nets. The ves successful Atlantic Fishermen., 31 ., Canadian Fish Culturist (17), 18-27. (10)' 16-20 British Standard 1963 Specification for ro Firth, F. E. 1950 b Experiments with nylon pes made from coir, hemp, manila nets. Fishing News 1967., 14-15 and sisal. BS:2052:1963 British Stan dards Institution London Fontan, G. 1958 Synthetic fibres in fish ing industry. Industries pesqueras 32 Briestenstein, W & Jager, K 1953 Report (745/746) 62-64. on a three year experiment with Per Ion fishing gear at Fisheries College. Garner, W. 1959 Textile Laboratory Ma- Hubertushahe Zeitschrift., l (5/6), 463 nuaL The National Trade Press, - 79 London VoL X No. 2 1973 161 'Radfiale~sfimy. & 9opalan Nair: Syntfietic fiBres for fisfiing gear Gayhurst, G. A. & Robinson, A. 1959 Con Indian Standard 1967 Specifications for struction and numbering of Synthetic nylon fish net twines IS:4401:1967. net twines. Modern Fishing Gear of Ibid. the World., 4-5., Fishing News (Books) Ltd. London. Indian Standard 1968 Method for desig nating netting yarns in the Tex system. Gee-, N. C. 1954 Textile Calculations. The IS:4640:1968. Ibid. Bristish Continental Trade Press Ltd., London Indian Standard 1970 Method for fish George, N. A. & Joseph Mathai, T. 1972 ing gear materials - determination of A note on the comparative catch effi twist. IS:5815:Part iii 1970. Ibid. ciency of nylon over cotton gill nets in reservoir fishing. Fish. Techno!., Japan Chemical Fibre Association 1964 9., (1).,: 81-82. Synthetic fibre fishing nets and ropes made in Japan. Madern fishing Gear Giesel, P. 1953 Three years experience of the World., 2., 64-66. Fishing New~ with platil nets in Lake Laach. Der (Books)., London. Fischwirt., 3., (9 )., : 310-13 Gulbadamov. P. P. 1952 FAO (1962) Sup Japan Chemical Fibre Association 1964 pliment to Report to the Government Synthetic fibres used in Japan for of India on the improvement of fish purse seines and trawls. F Il:FF;l0/11., ing techniques in Inland Reservoirs of 6pp. Paper presented at the technicn] India. FAOjETAP Rep. 1499 conf renee on fish finding purse sein ing and aimed irawling by FA 0 at Hans Stutz 1959 Terminology and count Reykjavik 24th to 30th May. of synthetic fibre twines for fishing net purposes. Modern Fishing Gear of John Carrothers, P. 1960 The use of syn the World., 1-3 Fishing News (Books) thetic fibres in commercial fi>ihing gear. Ltd., London. Fisheries Research Board of Canada., Himmelfarb, D. 1957 The technology of University of British Colombia., Ex of cordage fibres and ropes. Leonard tension De.partment., Fisheries short Hill (Books) Ltd., London. Course. Himmelfarb, D. 1959 man made textile encyclopedia. Textile Book Publishing Kajewski, G. 1957 Contributions to the Co., New York. Perlon question. Deutsche Fischerei Zeitung., 4 (6)., 161-67. Honda, K & Osada, S. 1964 polypropylene twines in Japan. Modern Fishing Gear Kloppenburg, C. C., & Reuter, J. 1964 of the World., 2., Fishing News (Books) Ropes of polyethylene monofilaments Ltd., London. Modern Fishing gear of the World., 2., 81-87., Fishing News (Books)., Inderfurth, K. H. 1953 Nylon technology. Ltd., London. McGraw Hill Book Co. Inc., New ·York. Klust, G. 1952 Review of the present pos Indian Standard I 964 Method for deter sibilities for the use of Perlon in fi mination of twist in yarn. IS:832:1964. sheries. Protokolle Zur Fischereitech Indian Standards Institution,, New Delhi nik., 2., ( 12)., 1-8. 162 FISHERY TECHNOLOGY 'Radftalelhf1my & 9opalan Nair: Syntfi~tic fifhes for fisl1ing gear Klust, G. 1954 a Guide for the selection Klust, G. 1964 a Standardisation of ter of Perlon for fishing nets. Der Fis minology and numbering system for chwirt., 4, (7)., 191-95. netting twines. Modern Fishing Gear of the World., 2., 3-7 Klust, G. 1954 b Experiences with Perlon Fishing News (Books)., London, in the Portugese fishery. Die Fisch wirtashaft 6., (6)., 148-50. Klust, G. 1964 b Netting twines of Poly propylene and Polyamide compared. Klust, G. 1955 a Influence of light and Modern Fishing Gear of the World., water on the life time of Perlon. 2. , 50 - 54 Fishing News ( Books ). , Protokolle Zur Fischereitechnik., 3., London. (13)., 217-19. Klust, G. 1968 Experiments on the knot Klust, G. 1955 b Keeping quality of Perlon breaking load and mesh breaking load net. Der Fischwirt S., (5)., 106-11. of materials of fishing nets. Prato kolle Zur Fischerei Technik., 61., (liL Klust, G. 1955 c Perlon trawling gear of 150-250. trawlers. Die Fischwirtschaft., 6., ( 4) ., 91-107. Koijuma, K. 1954 The tensile strength of Saran netting cord of various twists. Klust, G. 1956 Perlon nets and perlon Bull. of the Jap. Soc. of Sci. Fish., ropes in the purse seine fishery. Ibid., 20., (7)., 560-70. 8., (8) 231-33 Koijuma, K. 1955 The tensile strength of Klust, G. 1957 Investig1tions on fish net Amilan netting cords of various twists. twines made of continuous polyamide. Ibid., 21., (3) 139-40 Archiv fur Fischereiwissenchaft 8., 1{) 151-75. Kondo, J. 1938 Influence of the difference in size of cotton yarns composing the Klust, G. 1958 a On lines and ropes made netting cord on the breaking strength of synthetic fibres. ]bid., 9., (2). and the flexibility of the cord. Ibid., Klust, G. 1958 b New net twine of con 4., (5) tinuos Perlon. Wissenchaft lnforma Koura, R. 1963 Preservation of cotton tionen fur die Fischereipraxis., S., (6)., twines against rotting and the effect 202. of the Egyptian Mediterranian waters on the prepared cotton and man made Klust, G. 1950 a The efficiency of synthe fibre twines. Protokolle Zur Fische tic fibres in fishing especially in reitechnik., 38., (8) 261-9L Germany. Modern Fishing Gear of the World., 139 - 46 Fishing News Kuriyan, G. K. 1965 Trends in develop (Books)., London. ment in the prawn fishing techniques Klust, G. 1959 b Choice and use of syn in India- a review. Fish. Techno!., thetic fibres for freshwater fishery. 2., (1)., 64-68. Fischwirt, 9., (8)., 221-34. Lawler, G. H. 1950 The use of nylon Klust, G. 1960 Synthetic net materials for netting in the gill net fishery of the fine giU nets. Fischeret Zeitung., 68., Lake Erie white fish. Canadian Fish (2)., 38-40 Culturist., 7., 22-25. VoL X No. 2 1973 163 'Radftalelisftrny & 9opalan Nair: 8ynttletic fiores for fisliing gear Linton, G. E. 1957 The Modern Textile sheries. Modern Fishing Gear of the Dictionary. Duell Sloan and Pearce, World. 159-62., Fishing News (Books), New York. London. Lonsdale, J. E. 1959 Nylon in fishing nets. Muncy, R. J. 1960 A study of. the com Modern Fishing Gear of the World, parative efficiency between nylon and 30-33 Fishing News (Books)., London. linen giU nets. Chesupeake svenei , L, (2)., 96-102. Mamoi Fishing Net Manufacturing Co. 1959 Development of synthetic netting Nayar S. Gopalan, Shahul Hameed, M & and its effect on the fishing industry Verghese, M. D. 1967 Exp~rimental Ibid., 152-53. fishing in Gandhisagar Reservoir, Ma dhya Pradesh. Paper presented at the Marsh, J. T. 1958 Textile Science Chap seminar on Ecology and Fisherie$ of man & Hall London. Freshwater Reservoirs conducted by the !CAR at the CIF RI Barrackpore. Miyazaki, C., & Tawara, Y. 1970 Compa rative efficiency of nylon monofilament Pedonwarenzeichenverband, E. V. 1959 and polyethylene monofilament net The technological characterstice of ting for small otter trawls. F. 11. Perlon for fishing equipment. Mo FFj70j62., 5 pp., Paper presented at dern Fishing Gear of the World., 34-42. the technical conference on fish finding Fishing Ne~vs (Books)., London. purse seining and aimed trawling by FAO at Reykjavik 24th Jl;[ay to 30th Rahm, J. 1955 Gill nets made of Perlon May. monofilaments. Deutsche Fischerei Zei tung., l , (3)., 76-80. Mohr, H. 1961 Note on the behaviour of herring in a round tank. Comp Fish. R,adhalekshmi, K. & Kuriyan G. K. 1969 Comm. No. 87. Int. Counc. Explor. Experiments on the preservation and Sea. weathering of net twines. Fish Tech no!., 6., (2), 108-116. Molin, G. 1950 The applicability of nylon thread for the manufacture of fishing Rankovie, N. J. 1957 Yugoslav experiments gear. Svensk Fisherei., 59., (3)., 42-46. with eel lines DerFischwirt., 7., (1)., 15-17 Molin, G. 1951 Nylon versus cotton. Se vensk Fiskerei Tidstkrift., 60., (3)., Ruggerio, M. 1960 Braided synthetic twines 44-59. and their use in New England trawl fishery. Comm Fish. Revw., 22., (3)., Molin, G. 1955 Results from continued 6~1 L nylon fishing nets. Ibid., 64., (3 )., 40-43. Rummier, H. J. 1954 Perlon fibre as a material for fishing gear. Zeitschaft Molin, G. 1956 Results of nylon fishing fur fischerei., 3., (1/3)., 27-110. tests in Lake Malaren. Ibid., 65., (3)., 40-46. Rummier, H. J, 1957 The importance of tenacity for judging and selecting net Mugaas, N. 1959 Experiments with syn fibres net twines, and monofilaments. thetic materials in the Norwegian Fi- Ibid., 6., (1-7)., 489-502 164 FISHERY TECHNOLOGY 'R.adftale~sftmy & 9opalan Nair: Syntlietic fi~res for fisfting gear Runnstrom, H. 1964 Fishability of nylon Teikoku Rayon Co. 1959 Tevirou for fi nets., Svnsk Fiskerei Tidskrift 13., shi>.g nets. Ibid. 55-56. (5 /6)., 71-74. Volkov, A. V., & Mikahilova, E. N. 1955 Saetersdal, G. 1959 On the fishing power Tensile strength of Kapron twines of nylon gill nets Modern Fishing used in fishing nets. Trudy., VNIRO., Gear of the World. 161-62 Fishing 30 ' 196-206. News (Books), London. Shabtay, A. 1956 Experiments with a Per von. Brandt, A. 1954 Experience with Per Ion gill net at the Fisheries School. Ion in the Pcrtugese fishery. Die Fis Fishermen's Bulletin, 7., 1 pp chwirtrchaft., 6., (6) 148-50. Shimozal VoL X No. 2 1973 165