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J. Exp. Zool. India Vol. 21, No. 1, pp. 43-48, 2018

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ISSN 0972-0030

TECHNICAL SPECIFICATIONS AND DESIGN CHARACTERISTICS OF POMFRET GILL NETS OF SINDHUDURG, MAHARASHTRA Kishan Waghmare*, Rahul Sadawarte, Ashish Mohite, Vijay Mulye and Jayyapa Koli1 Department of Fisheries Engineering, College of Fisheries (Dr. B. S. Konkan Krishi Vidyapeeth, Dapoli), Ratnagiri - 415 629, India. Department of Fisheries Technology, College of Fisheries (Dr. B. S. Konkan Krishi Vidyapeeth, Dapoli), Ratnagiri-415 629, India. *e-mail : [email protected]

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(Accepted 5 November 2017) ABSTRACT : Pomfret gill nets of Sindhudurg, were fabricated exclusively of PA monofilaments of 0.23 to 0.32 mm diameter, as the material for the main webbing of the net. The mesh size ranged between 115 to 125 mm with the hanging coefficient of 0.41 to 0.56. Colorless or light green color gill nets were most commonly used with the hung length and hung depth of 50 to 55 m and 8.15 to 9.20 m, respectively. Pomfret gill nets in Sindhudurg had total fleet length of 750 to 825 m and depth of operation varied between 9 to 12 m. Head rope and foot rope of PP of 3 to 4 mm diameter was used without mounting rope. For surface operations, in Sindhudurg, 14 to 16 number of floats as well as sinkers were used. It was recorded that, 10 to 15 numbers of units were joined end to end to form a netting fleet. Key words : Design, pomfret, gill net.

INTRODUCTION Sindhudurg district is located in the southern part of Maharashtra and has three coastal Talukas namely Devgad, Vengurla and Malvan. The small-scale fisheries sector comprising of the traditional craft and gear plays a significant role in Sindhudurg fisheries along the coast. Sindhudurg district has 121 km coast line with 1503 mechanized vessels and 698 non non-mechanized vessels engaged in fishery. In the year 2015-16, fish production by gill nets with mechanized vessels was 6439 tonnes and by non-mechanized vessels recorded was 581 tonnes (Fish Production Report, 2015-16). In 1991, pomfret gill nets were operated as bottom set gill nets mostly from motorized fishing vessels (Vijayan et al, 1993). Pravin et al (1998) recorded that pomfret gill nets were used as surface drift; column drift and bottom drift in Gujarat either from the non-motorized as well as inboard or outboard motor craft. Kazi et al (2010) observed in Ratnagiri, pomfret gill nets were of drifting type operated from mechanized, motorized or traditional non mechanized fishing vessels according to the movement of the target species either in the surface or column water. Many changes have taken place in the gill nets with respect to the material used, net dimensions, mesh size, mode of operation (Vijayan et al, 1993) etc. The present day gill nets are mostly resource specific. The present study is undertaken with the objective of documenting the technical specifications and design characteristics of

the pomfret gill nets operated from Sindhudurg. METHODOLOGY Interview schedule was prepared in proper way to collect required information to satisfy the objectives of the present study. Structured data collection schedule formulated for the present study comprised of two major sections. The first section dealt with the particulars of gill net owner and the fishing vessel used for gill net operation. The second section deals with the technical specifications design aspects, rigging and the mode of operation of the pomfret gill nets used by the fisherman of Sindhudurg district. The information included in the first section was recorded according to Kazi et al (2010) whereas; the information in the second section was physically collected and recorded according to Pravin et al (2009). The net designs of the pomfret gill nets was presented according to Nedelec (1975). In Sindhudurg District (16 0 34' 92'' N latitude and 730 55' 94'' E longitudes) three important fish landing centres namely Devgad, Malvan & Vengurla were selected for the present study. RESULTS AND DISCUSSION Technical specifications of the typical pomfret gill nets operated from Sindhudurg district is mentioned in the Table 1 and its design characteristics are presented in the Fig. 1. Pomfret gill nets were operated as drift nets in the surface or column waters according to the movement of the target species with the help of motorized and mechanized fishing vessels; from the three coastal

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Kishan Waghmare et al

in Andaman Island with 210d×2×3 was carried out by Thomas et al (2005). PA monofilament of 0.20 and 0.23 mm diameter was exclusively used as the material for the pomfret gill nets in Kerala (Thomas and Hridayanathan, 2006). Polyamide (PA) monofilament of diameter 0.23 to 0.32 mm was used as a material for pomfret gill nets operating from Ratnagiri as described by Kazi et al (2010). PA monofilament twine having the diameter of 0.23 to 0.28 mm were used for pomfret gill nets operated from Satpati (Khatavkar et al, 2017). In the present study, it was observed that PA multifilament was not used as a gear material for pomfret gill net, however only PA monofilament was in use.

Talukas of Sindhudurg district namely, Devgad, Malvan and Vengurla.

The mesh size for pomfret gill nets ranged between 115 to 125 mm in Sindhudurg. Banerjee and Chakrabarty (1972) observed that the 101 mm mesh size was most effective for P. argenteus in drift gill netting in Lower Sundarbans, West Bengal. Panickar et al (1978) worked out 126 mm as the optimum mesh size for the capture of P. argenteus. The mesh size of 100 to 120 mm was used for catching pomfrets in Kerala as recorded by Vijayan et al (1993). In Gujarat, Pravin et al (1998) reported that the pomfret gill net of mesh size 80 to 120 mm and big black pomfret gill nets of mesh size 140 to 200 mm. Ramarao et al (2002) observed that pomfret gill nets of mesh size 120 to 150 mm were used in Andhra Pradesh. The pomfret drift gill nets with mesh size of 120 to 180 mm in Gujarat, 110 to 115 mm in Karnataka, 100 to 118 mm in Kerala 60 to 130 mm in Andhra Pradesh and 76 mm in Andaman Islands were observed by Thomas et al (2005). Mesh size 100 to 118 mm ranged for pomfret gill nets from the Kerala coast were recorded by Thomas and Hridayanathan (2006). CIFT has suggested optimum mesh size for silver pomfret gill nets of 126 mm with common mesh size of 110 to 130 mm (Meenakumari et al, 2009).

In Sindhudurg, pomfret gill nets operated were made from PA monofilament of 0.23 to 0.32 mm. Vijayan et al (1993) studied PA monofilament of 0.23 mm diameter was in use as a material for pomfrets gill nets in 1991 along Kerala coast. In Gujarat for catching pomfret, gill nets made of PA monofilament of 0.16 to 0.32 mm twine diameter and for catching big black pomfrets, gill nets made up of PA monofilament of 0.23 to 0.32 mm twine and PA multifilament twine of 210d×1×3 to 210d×3×3 were used (Pravin et al, 1998). The pomfret gill nets of Andhra Pradesh were made of PA monofilament of 0.23 to 0.32 mm diameter twine and PA multifilament gill nets of 210d×10×3 to 210d×12×3 twine were reported by Ramarao et al (2002). The use of pomfret gill nets in Karnataka with material specification of 210d×9×3 and

For catching pomfret, gill nets of mesh size ranging in between 100 to 130 mm were commonly operated from Ratnagiri as investigated by Kazi et al (2010). In Sindhudurg, mesh sizes recorded for the pomfret gill nets were of similar magnitude as compared to the mesh size reported by other studies along the Indian coast (Banerjee and Chakrabarty, 1972; Panickar et al, 1978; Vijayan et al, 1993; Thomas and Hridayanathan, 2006; Meenakumari et al, 2009 and Kazi et al, 2010) except for the upper range exceeding to 150 mm in Andhra Pradesh (Ramarao et al, 2002),140 to 200 mm in Gujarat (Pravin et al, 1998) and lower range of 60 mm in Andhra Pradesh and 76 mm in Andaman Islands (Thomas et al, 2005). The mesh size of pomfret gill nets ranged from 130 to 140 mm in Satpati (Khatavkar et al, 2017). Mesh size observations

Fig. 1 : Design characteristics of Pomfret gill nets operated from Sindhudurg.

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Technical specifications and design characteristics of pomfret gill nets

Selvedge meshes

Mesh stapling

Rigging of float

Rigging of sinker

Joining of two unit at head rope

Seaming of two unit

Photo 1 : Rigging pomfret gill nets operated from Sindhudurg.

for pomfret gill nets as recorded in the present study are within the optimum range as suggested by CIFT and observed by other workers along the Indian coast. Pomfret gill nets with the hanging coefficient of 0.41 to 0.56 were recorded from Ratnagiri. Panickar et al (1978) recommended hanging coefficient of 0.60 for commercial exploitation of P. argenteus, which was higher than the observed hanging coefficient during the

present study. In Andhra Pradesh, hanging coefficient of 0.50 to 0.65 for pomfret gill nets as reported by Ramarao et al (2002). Thomas and Hridayanathan (2006) observed the hanging coefficient ranged from 0.45 to 0.62 for pomfret gill nets in Kerala. Kazi et al (2010) recorded pomfret gill nets with the hanging coefficient of 0.41 to 0.56 from Ratnagiri while hanging coefficient between 0.30 to 0.36 was recorded by Khatavkar et al (2017) from Satpati. In the present study, hanging coefficient of

Kishan Waghmare et al Table 1 : Technical Specification of Pomfret gill nets operated from Sindhudurg. Station

Sindhudurg

Local name

Pasa, Garpel and Papletcha Jal

Main webbing mesh size (mm)

115

Mean main webbing mesh size (mm)

121.13 ± 0.52

Twine type

PA Mono

PA Mono

Twine specification / diameter (mm)

0.23

0.28-0.32

No. of meshes in depth

80

Horizontal hanging coefficient (E)

0.41-0.56

Mean horizontal hanging coefficient (E)

0.49 ± 0.004

Vertical hanging coefficient (1-E2)

0.69-0.84

125

0.41-56 0.69-0.84

Mean vertical hanging coefficient (1-E2) 0.75 ± 0.004 No. of meshes per unit

846-1036

Mean no. of meshes per unit

931.40 ± 6.63

Hung length (m)

50-55

Mean hung length (m)

121.09 ± 0.41

Hung depth (m)

8-9

Color of webbing

Light Green / Colourless

Selvedge twine type

PA Mono

Selvedge specification / diameter (mm)

0.32

Selvedge mesh size (mm)

115-125

No. of selvedge meshes in depth

1

Selvedge hung depth (m)

0.07-0.10

Total hung depth (m)

8.15-9.20

Mean total hung depth (m)

8.83 ± 0.05

Head rope material

PP

Head rope diameter (mm)

3-4

Float material

PVC

Float dimension (mm)

115×10

No.of floats per unit

14-16

Mean no.of floats per unit

15.22 ± 0.10

Foot rope material

PP

Foot rope diameter (mm)

3.5-4

Sinker material

Cemented

Sinker dimension (mm)

60×40

Sinker weight (g)

100

No. of sinkers per unit

14-16

Mean no. of sinkers per unit

15.22 ± 0.10

Total fleet length (m)

750-825

Mean total fleet length (m)

796.02 ± 3.91

Depth of operation (m)

9-12

Fishing craft

Wooden and FRP Motorised, Wooden Mechanised

Horse power of the engine (HP)

9.9-55

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pomfret gill nets was within the range of observation as recorded by Ramarao et al (2002); Thomas and Hridayanathan (2006), Kazi et al (2010) and Khatavkar et al (2017). Pomfret gill nets used in Sindhudurg were colorless or light green in colour. Along the Andhra coast, the effect of white, green, blue and yellow colored drift gill nets on the catch efficiency with respect to seer, pomfret, tuna and sharks was studied by Sitarama Rao et al (1980) and was observed that colored gill nets caught more P. niger. Experimental fishing conducted using white, yellow, orange, blue, brown and green gill nets to study the effect of colour of webbing on the efficiency of gill nets for hilsa and pomfret off Veraval; indicated that yellow and white were recommended for hilsa and pomfret fishing by Kunjipalu et al (1984). Mohan Rajan and Mathai (1988) studied with respect to the operation of coloured gill nets off Saurashtra coast and inferred that, yellow and white coloured gill nets were observed to be more effective for both hilsa and pomfret. Kazi et al (2010) observed in Ratnagiri, that for pomfret gill nets colorless or light green colour were commonly used. In Satpati, white, green, blue translucent coloured twines were used for main webbing for pomfret gill nets (Khatavkar et al, 2017). In the present study, colourless or light green coloured gill nets for pomfret were used which contradicted the inference drawn by Kunjipalu et al. (1984) and Mohan Rajan and Mathai (1988); however they match the observations by Sitarama Rao et al (1980) along Andhra coast, Kazi et al (2010) in Ratnagiri and Khatavkar et al (2017) in Satpati. Pomfret gill nets of Sindhudurg had hung length varying from 50 to 55 m for each unit. On the contrary, Ramarao et al (2002) observed pomfret gill net units with the hung length of 27 to 1260 m in Andhra Pradesh. In Kerala, Thomas and Hridayanathan (2006) reported the pomfret gill net units with average hung length of 160 m. Kazi et al (2010) recorded that in Ratnagiri, the pomfret gill net were used with the hung length varying from 41.25 to 108.57 m for each unit. During the present study the hung length observed for pomfret gill net was within the range reported by Ramarao et al (2002); Thomas and Hridayanathan (2006) and Kazi et al (2010). Total hung depth for pomfret gill nets operated from Sindhudurg varied from 8.15 to 9.20 m.

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Technical specifications and design characteristics of pomfret gill nets

Vijayan et al (1993) recorded that the pomfret gill nets with hung depth of 6.5 to 9.5 m were in operation during 1991 along Kerala coast. Hung depth for pomfret gill nets ranged between 5.5 to 10 m in Andhra Pradesh as recorded by Ramarao et al (2002). Pomfret gill nets from Kerala with the total average hung depth of 8.83 m were reported by Thomas and Hridayanathan (2006). Hung depth for pomfret gill nets varied from 4.41 to 11.92 m operated from Ratnagiri were studied by Kazi et al (2010). The hung depth observations recorded for pomfret gill net by the authors (Vijayan et al, 1993; Ramarao et al, 2002; Thomas and Hridayanathan, 2006 and Kazi et al, 2010) along the Indian coast were within the range of the hung depth for pomfret gill net as observed during the present study in Sindhudurg. The total fleet length varied for pomferet gill nets varied from 750 to 825 m and depth of operation varied in between 9 to 12 m in Sindhudurg. During 1991, pomfret gill nets with total fleet length of 600 to 750 m were operated with depth of operation ranging in between 15 to 25 m as reported by Vijayan et al (1993). Average total fleet length for pomfret gill net along the coast of Kerala was 640 m as observed by Thomas and Hridayanathan (2006). In Ratnagiri, the total fleet length of pomfret gill net varied from 182 to 915 m and depth of operation varied in between 10 to 55 m as recorded by Kazi et al (2010). In Satpati, the fleet length of Pomfret gill net ranged from 9600 to 13200 m and were operated at a depth of 30 to 50 m, as surface and column set gill nets (Khatavkar et al, 2017). In the present study, it was found that the pomfret gill nets operated from Sindhudurg were within similar range (Vijayan et al, 1993; Thomas and Hridayanathan, 2006 and Kazi et al, 2010) for total fleet length but variations were observed in depth of operation for pomfret gill nets. The pomfret gill nets of Satpati were quite huge in comparison to the nets studied by workers along the Indian coast. Ramarao et al (2002) recorded that 2 to 35 units were operated from each fishing craft in Andhra Pradesh. In Kerala, Thomas and Hridayanathan (2006) studied the pomfret gill nets and reported that, mostly 4 mm diameter polypropylene (PP) head rope were used along with the polyvinylchloride (PVC) floats of average 33.33 number and 3 mm diameter PP foot rope were used along with concrete sinkers of 250 g. Kazi et al (2010) observed that head rope and foot rope of PP of 3 to 4 mm diameter was used for this type of net. Mounting rope was mostly not used. For surface net operation, in Ratnagiri 5 to 8 number of floats as well as sinkers were used and for column net operation two methods of float and sinker arrangement were used. In the first method 5 to 8 number

of floats and 10 to 15 number of sinkers were used. In the second method, 10 to 15 number of floats and 5 to 8 number of sinkers were used. During the pomfret gill net operation in Ratnagiri 5 to 20 number of units were joined end to end to form a netting fleet. PP rope of 3 to 4 and 3.5 to 4 mm diameter were used for head rope and foot rope for pomfret gill nets. For surface net operation 14 to 16 numbers of floats as well as sinkers were used. During the present study in Sindhudurg, it was recorded that, 10 to 15 number of units were joined end to end by making knots at head rope and foot rope and seaming at regular interval throughout the depth of net to form a netting fleet. It was estimated that the twine size-mesh size relationships in pomfret gill nets was 0.002, the distance between floats as percentage of hung depth of net ranged from 81.94 – 98.43 with an average of 87.72. In Sindhudurg, fishing vessels ranging from 15 ft (4.45 m) to 35 ft (10.40 m) in overall length (LOA) were used for pomfret gill net fishing operations. These included wooden plank built canoe with or without outrigger, wooden vessel, fibber reinforced plastic (FRP) coated wooden vessels and FRP vessels. FRP coated or pure FRP vessels in the motorized sector were fitted with outboard engines of 9.9 hp and the mechanized sector comprised of wooden plank built or FRP boats fitted with inboard diesel engines of 16 to 99 hp. Single day gill net fishing operations with 2 to 3 persons onboard motorized vessels and 4 to 5 crew members on mechanized vessels was commonly practised in Sindhudurg. The documented information on the technical specifications and design of pomfret gill nets of Sindhudurg district of Maharashtra, would serve as a base line information for the technological modifications the gear may undergo to increase its efficiency in the coming years. ACKNOWLEDGEMENT Authors wish to thank the authorities of College of Fisheries, Shirgaon, Ratnagiri (Dr. Balasaheb Sawant Kokan Krishi Vidyapeeth, Dapoli) for providing the necessary facilities, and their kind encouragement and guidance during the course of the investigation. REFERENCES Banerjee S and Chakrabarthy R D (1972) Drift gill netting in Sundarbans, West Bengal. Indian Journal of Fisheries 16, 7581. Fish Production Report (2015-16) Department of Fisheries, Govt. of Maharashtra, Mumbai, Maharashtra State: 1-161. Kazi T G, Mohite A S and Jadhav R R (2010) Design characteristics of mackerel encircling gill nets of Ratnagiri, Maharashtra. Engineering and Technology in India I(2), 68-73. Khatavkar S, Desai A, Mohite (2017) Design and Technical Aspects

Kishan Waghmare et al of Pomfret gill nets of Satpati, Maharashtra. J. Exp. Zool. India 20 (Supplement 2), 1193-1197. Kunjipalu K K, Boopendranth M R, Kuttuppan A C, Subramanian Pillai N, Gopalkrishnan K and Kesavan Nair A K (1984) Studies on the effect of colour of webbing on the efficiency of gill nets for hilsa and pomfret off Veraval, Fishery Technology 21, 51-56. Meenakumari B, Boopendranath M R, Pravin P, Thomas S N and Edwin L (2009) Gill nets and their operation, In: Handbook of Fishing Technology, India: 195-212. Mohan Rajan K V and George Mathai P (1988) Operation of coloured gill nets off Saurashtra coast. Fishing Chimes 8(2), 30-37. Naidu R M (1985) Catch efficiency of trammel net in relation to twine size and hanging coefficient. In: Harvest and Post Harvest Technology of fishery. Ravindran K, Unnikrishnan Nair N, Perigreen P A, Madhavan P, Gopalkrishanan Pillai A G, Panicker P A and Mary Thomas (eds.) Society of Fisheries Technologists (India), Cochin: 221-222. Nedelec C (1975) FAO Catalogue of Small Scale Fishing Gear. Fishing News Books (Ltd.), Farnham, Surrey, England: 191. Panicker P A, Sivan T M, Mhalathkar H N and Mathai P (1978) Selectivity of gill nets for Hilsa toli and Pampus argentenus. Fishery Technology 15, 61-68. Pravin P, Ramesan M P and Mathai P G (1998) Gill net fishing in Gujarat, In: Advances and Priorities in Fisheries Technology,

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Balachandran K K, Iyer T S G, Madhavan P, Joseph J, Perigreen P A, Raghunath M R and Varghese M D (eds.). Society of Fisheries Technologists (India), Cochin: 170-176. Pravin P, Thomas S N, Meenakumari B, Baiju M, Baruah D, Barman J, Kakti B, Daimari P and Mumtaz V R (2009) Design and General characteristics of Gill nets of Assam. Fishery Technology 46(2), 107-122. Ramarao S V S, Rajeshwari G and Raghu Prakash R M (2002) Studies on the gill nets of Andhra Pradesh. Fishery Technology 39(1), 15-19. Sitarama Rao J, Precy Dawsaon and Sreekrishna Y (1980) Effect on colour on the catch of gill nets. Fishery Technology 17, 75-77. Thomas S N, Meenakumari B, Pravin P and Mathai G P (2005) Gill nets in marine fisheries of India. Monograph, Agricultural Technology Information Center, Central Institute of Fishery Technology (ICAR), Matsyapuri, Cochin. Thomas S N and Hridayanathan C (2006) Design and general characteristics of marine gill nets of Kerala. Fishery Technology 43(1), 17-36. Vijayan V, Varghese M D, Leela Edwin, Thomas S N and George V C (1993) Coastal gill nets of Kerala – changes in three decades, In: Low Energy Fishing, Fishery Technology. (Special Issue) Society of Fisheries Technologists, India: 172-176.