J. Bangladesh Agril. Univ. 5(2): 353-364, 2007 ISSN 1810-3030 Structural and operational variations of marine set-bag-net (MSBN) used in the Bay of Bengal of Bangladesh

M.J. Rahman, M.A. Mazidl, M. Zaher2 and A.K.Y. Haroon Bangladesh Research Institute, Marine Fisheries & Technology Station, Cox's Bazar-4700, Bangladesh, 'Bangladesh Fisheries Research Institute, Mymensingh-2201, Bangladesh and 2Bangladesh Fisheries Research Institute, Freshwater Station, Mymensingh-2201, Bangladesh Abstract

Structural and operational variations of marine set-bag-net (MSBN) in the Bay of Bengal of Bangladesh were studied comprehensively during July 2003-June 2004. Total number of crafts, gears and owners of MSBN in different areas of the country were also estimated. The estimated total number of MSBN was 6,055 and total number of boats used to operate these nets was 909. The total number of people dependent for their livelihood on the MSBN fishery was about 2,52,000 individuals. Detail structures (dimensions, mesh size and twine) and functions of different parts and sub-parts of the gear were analyzed. Details about the operation of MSBN such as, area of operation, setting duration, number of set per day, how many days operate in a month, off season, peak season, etc. were also recorded from each of the operating areas. Observations on the structural design of the gear revealed the potential of improving the efficiency and selectivity of the gear by changing the mesh sizes and incorporating a simple device to prevent escaping of larger individuals, while escaping of small individuals. Keywords: Marine set-bag-net, Structure, Operation, The Bay of Bengal, Bangladesh Introduction

Set-bag-net is one of the most important commercial gears in the artisanal marine fisheries of Bangladesh. There are two types of set-bag-nets, estuarine set-bag-net (ESBN) and marine set-bag-net (MSBN). The net is developed traditionally and looks like a cone shaped bag (similar to the trawl net), and local fishers call it ibhendi or tehundi that means tied-up something with rope. The fishing activities mainly take place in the offshore marine environment and in the estuary. The main problem concerning the gear is its non-selectivity regarding size and species and hence indiscriminately catches juveniles, youngs and adults (BOBP, 1993; MFTS, 2004; Mazid and Rahman, 2005). Studies conducted on ESBN fishery indicated that those are operated in the nursery grounds of the most finfish and shellfish, so, the gear is extremely harmful to the resources (BOBP, 1993 and 1994; DOF, 1999 and 2001). In fact, all set-bag-nets having mesh size <30 mm in the cod end are banned by the Fish Act (The Marine Fisheries Ordinance 1983) because of their destructive impact on the small . However, the Act is not in practice and an enormous amount of larvae as well as sub-adults of numerous and shrimps are regularly taken out from shallow nursery areas of the estuarine waters by such gears (BOBP, 1993; BFRI, 1994).

The MSBN (locally called, sagor behundi) fishery is relatively resource friendly compared to the ESBN as the fishing activities mainly take place in the offshore marine environment and the mesh size in the cod end Is larger, but still it catches numerous juveniles and needs further attention to minimize its harmful effect (Mazid and Rahman, 2005). According to the BOBP (1993), MSBN contributes about 27% of the total set- bag-net catch. However, no detailed study on MSBN, particularly on its operational and structural details, except some 354 Structure & operation of MSBN

preliminary works on catch rate and catch composition is available so far (BOBP, 1993 and 1994; Quayum et aL, 1991; Islam et aL, 1991; Mazid and Rahman, 2005; Rahman et al., 2007). These types of studies are very important pre-requisites for any attempt to improve those traditionally innovated harmful gear to make more economically efficient but resource friendly, which is extremely necessary for sustainable development and management of the marine fisheries resources.

To overcome the shortfalls of the information about the MSBN and its impacts on the marine resources of Bangladesh, this qualitative and quantitative study was undertaken. The structure and operation of MSBN from different operational sites of Bangladesh were studied intensively in view of the assessment of the qualities of the traditionally developed gear and hence to suggest any possible modification necessary for the gear.

Materials and Methods

All MSBN operating areas in Bangladesh were included in the study. The territorial areas where most MSBN operators inhabit were Cox's Bazar Sadar, Moheshkhali, Kutubdia, Chakoria and Teknaf of Cox's Bazar, Bashkhali of Chittagong, Khepupara of Patuakhali and Dubla Island (Dublarchar) of Khulna districts (Fig. 1).

Five data collectors were deployed to conduct a comprehensive survey on the crafts and gears used for MSBN fishery covering all the study areas. The survey was conducted during July 2003-June 2004. Total number of owners of MSBN, total number of MSBN for each of the owners, total number of crafts for each of the owners, number of boats used to operate those gears, number of MSBN per boats were recorded carefully for each of the study areas.

Detailed structure of MSBN from different sites was studied intensively in view of the assessment of the qualities of the gear and hence to suggest any possible modification necessary for the gear. For this, 100 randomly selected crafts and gears from each of the major operating areas viz Cox's Bazar Sadar, Moheshkhali, Kutubdia, Khepupara and Dublarchar were studied. The dimensions (length and width) of the crafts and gears were measured in meter and the horsepower of the engine of the crafts were recorded. Detail structures (dimensions in meter, mesh size in cm and twine number) and functions of different parts and sub-parts of the gear were recorded (Fig. 2). Finally, the structural variations of the gears in different important areas were noted.

To locate different MSBN operating spols and observe the operational details of the gear, three voyages were conducted using hired boat. Approximate locations of the MSBN fishing spots together with the distances of the spots from Cox's Bazar were measured (Fig.1) using Arc View computer software, by which distance between two points of a map can be measured in km using the map as input. The water depths of the spots were measured in Bam/Biew (the word 'Biew/Bam' is a local measurement of depth in the sea which approximately equals to 2.0 m) directly using rope and weight method. Rahman et aL 355

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Details about the operation of MSBN such as, area of operation, setting duration, number of set per day, how many days operated in a month, off season, peak season, etc. were recorded from each of the operating areas.

Results and Discussion

Area-wise estimated numbers of crafts and gears of the MSBN fishery in Bangladesh are presented in Table 1. Total number of owners, boats and nets of MSBN fishery in Bangladesh were 703, 909 and 6,055, respectively during July 2003-June 2004. The figures for only Cox's Bazar area (Cox's Bazar Sadar, Moheshkhali, Kutubdia, Chakoria and Teknaf) were 373, 548 and 4,409, respectively during July 2003-June 2004 (Table 1).

The results obtained in this study could not be sufficiently compared to other works due to the lack of previous work on MSBN. Quayum et al. (1991) estimated a total of 3,852 units of MSBN operated in 1990-91, but during the present study period, the total units was 6,055, which is about double of the previous estimate (Table 1). Therefore, due to the increase of fishing units remarkably, catch per unit effort was supposed to be declined. In fact, the catch per unit effort has remarkably declined (Mazid and Rahman, 2005), which indirectly supports the present findings. 356 Structure & operation of MSBN

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Fig. 2. Schematic diagram showing different parts and sub-parts of a typical marine set-bag- net(MSBN) in Bangladesh Rahman et aL 357

Table 1. Estimated owners, boats and gears used in MSBN fishery in different areas of Bangladesh (the figures with hyphenation indicate range and figures in the parentheses indicate mode)

Total Total Total MSBN per Boats per MSBN per owners MSBN boats boat owner owner 4 1-4 (1) 3-64 (8) Cox's Bazar 105 1,308 166 3-16 (8) , Moheshkhali 207 2,156 273 1-24 (8) 1-6 (1) 1-59 (8) Kutubdia 32 652 65 4-13 (8) 1-8 (1) _ 4-97 (8) Chakoria 17 258 32 6-12 (6) 1-3 (2) 6-29 (18) Teknaf 12 35 12 2-5 (2) 1-1 (1) 2-7 (2) Sub-total for 373 4,409 548 1-24 (8) 1-8 (1) 1-97(8) Cox's Bazar area Bashkhali, Chittagong 47 431 75 4-12 (5) 1-5 (1) 4-60 (5) Khepupara, Patuakhali 134 504 134 3-16 (8) 1-1 (1) 2-8 (4) (Kuakata & Mohipur) Dublarchar (Khulna) , 149 711 152 2-8 (4) 1-2 (1) 2-9 (3) Total for Bangladesh 703 6,055 909 1-24(8) 1-8(1) 1-97(8)

Akerman (1986) obtained the highest average catch of 60 kg/haul/MSBN in 1986, while Mazid and Rahman (2005) reported a remarkable lower catch of about.35 kg/haul/MSBN in 2003. The most probable cause of this lower catch might be due to the increase of the number of MSBN operating at the moment as indicated by the present findings. Another possibility could be the depletion of the resources, which led to lower catch rate. However, the last argument could be nullified by the reported increase of the total annual catch, being 26,111 t in 1991 (Quayum et aL, 1991) and increased to 48,830 t in 2003 (Mazid and Rahman, 2005). In the depleted stocks, the total catch cannot be increased remarkably.

The structure of MSBN from different sites was studied intensively in view of the assessment of the qualities of the gear. The detailed structure of a typical MSBN is shown in Fig. 2, and briefly described in Tables 2 and 3. The average length and width of MSBN were 38.0 & 13.0; 36.3 & 12.3; 41.5 & 15.5; 24.0 & 10.5; and 41.3 & 13.7 m, respectively for Cox's Bazar, Moheshkhali, Kutubdia, Khepupara and Dublarchar (Table 2). The average length and width of MSBN operating boats were 14.0 & 3.5, 14.0 & 3.6, 14.8 & 3.7, 9.8 & 1.9 and 14.0 & 3.1 m, respectively for Cox's Bazar, Moheshkhali, Kutubdia, Khepupara and Dublarchar (Table 2). Details structure of the crafts and gears of minor stations (Chokoria, Teknaf and Bashkhali) were not studied.

The net looks like a cone shaped bag with tapered end, and this bag is set in a fixed place by two poles, so, the name 'set-bag-net' derived (Fig. 2). Local fishers call it thencli that means tied-up something with rope and the cod-end called as 'thole' means bag. The divide the net into three main parts: mukh (mouth), jal (net) and thole .(cod-end)., There are different small parts within the main parts. A brief description of the parts (local name of each of the parts is shown in parenthesis) is as follows and summarized in Table 3. 358 Structure & operation of MSBN

Table 2. Summary of the dimensions of the MSBN, its crafts and engine power used in different areas of Bangladesh

Area Measurement Minimum Maximum Average Mode Standard deviation Length of MSBN (m) 36.0 40.0 38.0 38.0 1.2 Width of MSBN (m) 12.0 14.0 13.0 13.0 0.6 Cox's Bazar Length of boat(m) , 11.0 16.0 14.0 14.0 0.5 , Width of boat(m) 3.0 4.5 3.5 3.5 0.2 Engine power(HP) 10.0 65.0 36.0 36.0 9.4 Length of MSBN (m) 27.0 45.0 36.3 36.0 1.6 Width of MSBN (m) 11.0 , 13.0 12.3 V 12.0 0.4 Moheshkhali Length of boat(m) 8.6 20.6 14.0 13.0 1.5 Width of boat(m) 2.4 4.5 3.6 3.8 0.3 Engine power (HP) Manual 74.0 39.0 22.0 16.2 Length of MSBN (m) 36.0 45.0 41.5 41.0 1.7 Length of boat(m) _ 13.0 16.0 14.8 15.0 0.6 Kutubdia Width of boat(m) 3.0 4.0 3.7 3.8 0.1 Engine power (HP) 18.0 74.0 45.0 65.0 13.8 Length of MSBN (m) 20.0 30.0 24.0 27.0 1.9 Width of MSBN (m) 10.0 14.0 10.5 10.0 0.6 Khepupara Length of boat(m) 8.0 11.0 9.8 10.0 0.5 . Width of boat(m) 1.6 2.2 1.9 2.0 0.2 Engine power (HP) Manual 22.0 16.0 16.0 8.1 Length of MSBN (m) 39.0 55.0 41.3 41.0 1.6 Width of MSBN (m) 13.0 14.0 13.7 13.7 0.2 Dublarchar Length of boat(m) 12.0 16.0 14.0 15.0 1.3 Width of boat(m) 2.3 4.3 3.1 3.2 0.3 Engine power(HP) 18.0 45.0 33.0 33.0 3.2

The mouth is the opening side of the net, which consists of two arms (hata, chon), two eyes (chokh), two eyebrows (jhanker), ground rope (nicher kachhi), head rope (uporer kachhi) and mouth net (mukh jal) (Fig. 2). The arm (one in each side) consists of two ropes (extension of head and ground rope) and a piece of net, which is about 1.0 m wide and 12.0 m long. The end of the net piece is the end of the arm, but the extension of the ropes still extend further 10.0-12.0 m, which is used to tie-up the nets to the pole. The arms also help to guide the fish to enter into the mouth. The eye located just at the beginning of the arm and it is a round hole necessary to hold a bamboo pole. The bamboo pole is necessary to fix and to open the mouth vertically about 6.0-7.0 m wide. The eyebrow situated just around the eye to protect the eye and surrounding nets from the friction with the bamboo pole. The area of the eyebrow is about 30.0 x 60.0 cm2 and made of thicker and stronger twine. The ground and head ropes are very strong, made of no.16 rope (kachhi) and extend through the arm to the main pillar to fix the net. The mouth net is the strongest net of the MSBN and it holds the ground and head ropes. The first three meshes are bigger (13.0 cm) and stronger (12/3 no. twine) and the mesh size of the remaining portion is about 12.0 cm. The mouth net is about 20.0 m wide. The mouth is the main part through which fish enters into the net following the tidal current. Rahman et al. 359

The main net is very simple and consists of five pieces of nets with different mesh size and/or twine. Due to the conical shape of the net, each portion is also conical and hence the lower side of each portion is matched with the upper side of the next portion (Fig. 2). Each of the five pieces have different local names viz. i) mukh jal- upper side about 20.0 m wide and the lower portion about 16.0 m wide, mesh size about 10.5 cm and the length is about 7.0 m, the twine size is no. 9/3; ii) head jal, which is about 8.0 m long and 16.0-14.0 m wide, mesh size is about 8.0-7.0 cm; iii) baraba rash, which is about 9.5 m long, wide about 14.0-10.0 m and mesh size is about 6.0-5.0 cm; iv) chotobarash, is about 6.5 m in length, 10.0-6.0 m wide, mesh size is about 4.0-3.0 cm; v) harani or olang, the final portion of the main net, which is attached to the cod-end portion. The haranVolang is about 2.5 m long and 4.5-2.5 m wide, mesh size is about 3.0-2.5 cm and made of 6/3 no twine (Fig. 2 and Table 3).

This is the last part of the MSBN, and in fact this is the actual 'bag or locally called 'thole' or melang', where the fish gathers. The bag is about 3.6 m long and about 2.5 m wide in the upper side and 1.2 m in the lower side. The mesh size is about 3.5-1.5 cm (note: according to the fish act, the mesh size can not be smaller than 3 cm) and made of two types of twine, plastic cod or nylon twine no.6/3. Normally two pieces of nets, each about 1.8 m long are joined together to make the 3.6 m long bag. The end of the net is normally open (not closed), but after setting net, one strong rope is tied-up at about 30.0 cm before the actual end to close it. The rope knot is opened after hauling the cod-end to release the entrapped fish.

The structural variations of MSBN operated in different areas are presented in Tables 4-8. The structure of the MSBN in the Moheshkhali area (Table 4) is very similar to those in the Cox's Bazar (Table 6). The main difference is the mesh size of the cod-end part. Mesh size is larger in Cox's Bazar area than that of in Moheshkhali. Moderate sized MSBN is also available in both the areas.

Table 3. Structure and function of the parts of a typical MSBN in Bangladesh (the range indicates upper and lower end of that part)

Name of the Parts Structure Function . Length Width Mesh Twine (m) (m) (cm) No 1. The Mouth 0.5 20.0 12.0 12-18/3 Guide fish to get in to get in 1.1 Arms 12.0 1.0 _ 13.0 18/3 Guide fish 1.2 Eye - - 18.0 18/3 To fix and open mouth 1.3 Eyebrow 0.06 0.03 13.0 18/3 To protect the eye and surrounding net - 1.4 Head and ground rope 42.0 - - 16 rope Handling, fixing and opening 1.5 Mouth net , 0.5 20.0 13.0-12.0 12/3 Drive the fish in the main net fish in the cod- end 2. The Main Net 33.5 20.0-3.0 10.5-2.5 _ 9-6/3 Drive the 2.1 Mukh jal 7.0 20.0-16.0 10.5 9/3 Drive the fist)- in the Head jal 2.2 Head jal 8.0 16.0-14.0 8.0-7.0 6/3 Drive the fish in the Barobarash 2.3 Barobarash 9.5 14.0-10.0 6.0-5.0 6/3 Drive the fish in the Chotobarash - 2.4 Chotobarash 6.5 10.0-6.0 4.0-3.0 6/3 Drive the fish in the Harani 2.5 Harani 2.5 4.5-2.5 3.0-2.5 6/3 Drive the fish:in the Thole (cod- end) 3. The Cod-end 3.6 2.5-1.2 3.5-1.5 6/3 Gather and hold the fish entered 3.1 Upper part 1.6 2.5-2.0 3.5-1.5 6/3 Drive the fish in the lower part of the cod end and gather the fish when lower . or , plastic part is full. 3.2 Lower part 2.0 2.0-1.2 3.5-1.5 6/3 Gather the fish and release the fish' or after hauling _ plastic _ 360 Structure & operation of MSBN

Table 4. Different parts of MSBN in the Moheshkhali area (the range indicates upper and lower end of that part) , Name of the Parts Structure Comments Length Width Mesh Twine (m) _ (m) (cm) No 1. The Mouth 0.4 22.0 13.0 12/3 _ The structure of the MSBN in the 1.1 Arms 12.0 1.0 13.0 12/3 Moheshkhali area is very similar to 1.2 Eye - - 18.0 18/3 .those in the Cox's Bazar (Table 6). The 1.3 Eyebrow , 0.06 0.03 13.0 18/3 main difference is the mesh size of the 1.4 Head cod-end part. Mesh size is larger and ground rope 40.0 - - 16 mm rope in the _ nets used in Cox's Bazar area than 1.5 Mouth net , 0.4 22.0 13.0-12.0 12/3 that of in Moheshkhali. 2. The Main Net - 32.0 20.0-3.0 10.5-2.5 9-6/3 , 2.1 Mukh jal 7.0 20.0-16.0 10.5 9/3 2.2 Head jal 8.0 16.0-14.0 8.0-7.0 6/3 2.3 Barobarash 9.0 14.0-10.0 6.0-5.0 6/3 2.4 Chotobarash 5.5 10.0-6.0 4.0-3.0 6/3 2.5 Harani 2.5 4.5-2.4 3.0-2.5 _ 6/3 3. The Cod-end 3.2 2.4-1.4 2.5-1.5 9/3 1.4 2.4-1.4 2.5-2.0 9-12/3 or 3.1 Upper part plastic 1.8 2.4-1.4 2.0-1.5 9-12/3 or 3.2 Lower part plastic

The structure of the MSBN in the Kutubdia area (Table 5) is very similar to those in the Dublarchar area (Table 8). The main difference is the cod-end part. In Kutubdia the cod-end is mostly made of plastic rope, but in Dublarchar twine is more frequent than plastic. Moreover, mesh size is larger in Kutubdia than that of in Dublarchar. Large sized MSBN is also available in both the areas.

Table 5. Different parts of MSBN in the Kutubdia area (the range indicates upper and lower end of that part)

Name of the Parts Structure Comments Length Width Mesh Twine (m) (m) (cm) No . 1. The Mouth 0.5 22.0 13.0 12/3 The structure of the MSBN in the 1.1 Arms 14.0 1.0 13.0 12/3 Kutubdia area is very similar to 1.2 Eye _ - 18.0 18/3 those in the Dublar char area 1.3 Eyebrow (Table 8). Th Kduifftuebredniacethies 0.06 0.03 13.0 18/3 1.4 Head and ground the cod-end pearTalinn rope 44.0 - - 16 mm rope cod-end is mostly made of plastic 1.5 Mouth net 0.5 20.0 13.0-12.0 12/3 rope, but in Dublar-char twine is more frequent than plastic. 2. The Main Net 35.5 20.0-2.5 10.5-2.5 9-6/3 Moreover, mesh size is larger in 2.1 Mukh jal 8.0 20.0-16.0 10.5 9/3 _ the nets used in Kutubdia than 2.2 Head jal 8.5 16.0-14.0 8.0-7.0 6/3 that of in Dublarchar. Large sized 2.3 Barobarash 10.0 14.0-10.0 6.0-5.0 6/3 MSBN is available in both the 2.4 Chotobarash - areas. 6.5 10.0-6.0 2.5 Harani 4.0-3.0 6/3 2.5 4.5-2.5 3.0-2.5 6/3 3. The Cod-end 3.6 2.5-1.5 3.2-1.5 9/3 . 3.1 Upper part 1.6 2.5-2.0 3.2-1.5 9-12/3 or plastic 3.2 Lower part 2.0 2.0-1.5 3.2-1.5 9-12/3 or plastic Rahman et aL 361

The structure of the MSBN in the Khepupara (Kuakata and Mohipur) area (Table 7) is little bit different from the MSBN of other areas. The main difference is the size and mesh size of the gear. The size as well as the mesh size of the gear is smaller than that of other areas (Table 4, 5,6 and 8).

Different steps of MSBN setting and hauling were observed in different operating spots. The first step of setting the net is piling and fixing two long poles made of bamboo joint with a pointed wood with metal casing. After fixing the poles the two arms of the net tied up with the poles. The mouth kept open against the tidal current with the help of bamboo pole along the eye-like hole of the net (Fig. 2) and the cod-end tied up with a piece of rope. After six hours, when the tidal flow almost stops (juncture period between the tides) the net is pulled to the boat and the end of the cod-end untied and the catch released.

Details about the operation of MSBN such as, area of operation, setting duration, number of set per day, how many days operated in a month, off season, peak season, etc. and some important characteristics of water of that area were collected from different sampling stations. The summary of the findings was shown in Table 9. There were some variations in the operating areas, number of fishing days and fishing seasons, but the number of set per day and duration of each set were the same for all stations (Table 9). Although, there were some variations in the operational details in different regions as shown in Table 9 obviously there were many operational similarities in different locations as well.

Table 6. Different parts of MSBN in the Cox's Bazar upazila (the range indicates upper and lower end of that part)

Name of the Parts Structure Comments Length Width Mesh Twine (m) (m) (cm) No 1. The Mouth 0.5 22.0 13.0 12/3 The structure of the MSBN in 1.1 Arms 14.0 1.0 13.0 12/3 the Cox's Bazar area is very 1.2 Eye similar to those in the - - 18.0 18/3 Moheshkhali (Table 4). The 1.3 Eyebrow 0.06 0.03 13.0 18/3 main difference is the mesh 1.4 Head and ground rope size of the cod-end part. Mesh 39.0 - - 16 mm rope 1.5 Mouth net size is larger in the nets used 0.5 20.0 13.0-12.0 9/3 in Cox's Bazar area than that 2. The Main Net 34.0 20.0-2.5 10.5-2.5 9-6/3 of in Moheshkhali. Moderate sized MSBN is available in 2.1 Mukh jal 7.5 20.0-16.0 10.5 9/3 both the areas. 2.2 Head jal 8.5 16.0-14.0 8.0-7.0 6/3 2.3 Barobarash 9.0 14.0-10.0 6.0-5.0 6/3 2.4 Chotobarash 6.5 10.0-6.0 4.0-3.0 6/3 2.5 Harani 2.5 4.5-2.5 3.0-2.5 6/3 3. The Cod-end 3.5 2.5-1.5 3.0-1.5 9/3 1.5 2.5-2.0 3.0-1.5 12/3 or 3.1 Upper part plastic 3.2 Lower part 2.0 2.0-1.5 3.0-1.5 12/3 or plastic 362 Structure & operation of MSBN

Table 7. Structural details of different parts of MSBN in the Khepupara (Kuakata and Mohipur) area (the range indicates upper and lower end of that part)

Name of the Parts Structure Comments , Length Width Mesh Twine (m) (m) (cm) No 1. The Mouth 0.3 14.0 7.0 9-12/3 .The structure of the MSBN in 1.1 Arms 10.0 0.5 7.0 12/3 the Khepupara/Mohipui area is - little 1.2 Eye bit different from the MSBN - - 7.0 16/3 of other areas. The main 1.3 Eyebrow 0.06 _ 0.03 7.0 16/3 difference is the size and mesh 1.4 Head and ground rope 33.0 - - _ 16 mm rope size of the gear. The size as 1.5 Mouth net - well as the mesh size of the 0.3 14.0 7.0-5.0 9/3 ,gear is smaller than that of in 2. The Main Net 23.5 10.0-2.5 5.0-2.0 9-6/3 other areas. 2.1 Mukh jal 5.0 10.0-9.0 5.0-4.5 9/3 . 2.2 Head jal 6.0 , 10.0-9.0 5.0-4.5 6/3 . 2.3 Barobarash 7.0 9.0-8.0 4.5-3.5 6/3 2.4 Chotobarash 4.0 , 8.0-6.0 4.0-3.0 6/3 2.5 Harani . • 1.5 4.5-2.5 3.0-2.0 6/3 3. The Cod-end 2.5 2.5-1.5 2.0-1.5 9/3 , 3.1.Upper part 1.0 2.5-2.0 2.0-1.5 9/3 , 3.2 Lower part 1.5 2.0-1.5 _ 2.0-1.5 9/3

Table 8. Different parts of MSBN in the Dublarchar area (the range indicates upper and lower end of that part)

Name of the Parts Structure Comments Length Width Mesh Twine (m) (m) (cm) No 1. The Mouth 0.5 22.0 13.0 12/3 The structure of the MSBN in - the Dublarchar area is very 1.1 Arms 13.0 1.0 13.0 12/3 similar to those in the Kutubdia 1.2 Eye - - 18.0 18/3 area (Table 5). The main 1.3 Eyebrow . difference is the cod-end part. 1.4 Head and ground rope 0.06 0.03 13.0 18/3 In Kutubdia, the cod-end is mostly made of plastic rope, 1.5 Mouth net 39.0 - - 16 mm rope but in Dublar char, twine is more frequent than 0.5 20.0 13.0-12.0 3 plastic. 12/ Moreover, mesh size is larger 2. The Main Net 35.0 20.0-2.5 10.5-2.5 9-6/3 in Kutubdia than that of in Dublar char. 2.1 Mukh jal Large sized 8.0 20.0-16.0 10.5 9/3 MSBN is available in both the 2.2 Head jal areas. 8.5 16.0-14.0 8.0-7.0 6/3 2.3 Barobarash - 9.5 2.4 Chotobarash 14.0-10.0 6.0-5.0 6/3 2.5 Harani 6.5 10.0-6.0 4.0-3.0 6/3 2.5 4.5-2.5 3.0-2.5 6/3 3. The Cod-end 3.6 2.5-1.5 3.0-1.2 9/3 3.1 Upper part 1.6 2.5-2.0 3.0-1.2 9/3 3.2 Lower part . 2.0 2.0-1.5 3.0-1.2 9/3 Rahman et al. 363

Table 9. Operational details of MSBN at different sampling stations of Bangladesh , Off season Sampling area Major operating areas* No. of days No. of Duration of Peak season operate in a set per each set month . day (Hour) From May to Moheshkhali Nayader, Baroder, Gulirder, 20-24 4 6 From mid September to July Jalchirerder, 8B, 12B, 13B, (Av. 22) 14B, 18B, 22B, etc. mid March, (03 months) (06 months) ' to Kutubdia Sunderban, Dublarchar, 20-23 4 6 From mid From May September to July Baroder, Gulirder, (Av. 21) Jalchirerder, 8B, 12B, 13B, mid March (03 months) 14B, 18B, 22B, etc. (06 months) , , - Cox's Bazar Baroder, Gulirder, 20-24 4 6 From mid From May to August to mid July Jalchirerder, 8B, 12B, 13B, (Av. 22) 14B, 18B, 22B, etc. March (03 months) months) , , (07 Khepupara Kuakata, Asherchar, 6B, 8B, 18-22 4 6 From mid From mid October to mid April to mid 12B. (Av. 20) March July (05 months) (03 months) _ Dublarchar Up to 13 m depth around the 18-22 4 6 From mid From April to August Dubla Islands (Av. 20) October to mid March (05 months) (05 months)

*The word 'Biew/Bam'(abbreviated as 'B') is a local measurement of depth in the sea and it approximately equals to 2.0 m. On the basis of the approximate depth of the area, they named the spot. The locations of the spots are shown in Fig. 1.

References

Akerman, S. 1986. Trials with set-bag-nets (mesh size selectivity study). An unpublished consultant report of the BOBP (Bay of Bengal Programme). 20 pp. BFRI (Bangladesh Fisheries Research Institute).1994. Environmental impacts of the shrimp seed collection from natural source. Bangladesh Fisheries Research Institute, Mymensingh. (in Bengali). 39 pp. BOBP (Bay of Bengal Programme). 1993. Socioeconomic conditions of the estuarine set-bag-net fisherfolk in Bangladesh. BOBP/W/90. 32 pp BOBP (Bay of Bengal Program). 1994. Biosocioeconomic assessment of the effect of the estuarine set-bag-net on the marine fisheries of Bangladesh. BOBP/WP/94. 28 pp. DOF (Directorate of Fisheries). 1999. Preliminary report on the Coastal Marine Strengthening Project. Marine Fisheries Survey, Management & Development Project, Department of Fisheries, Chittagong (in Bengali). DOF (Department of Fisheries). 2001. Departmental report on coastal fish and fislierfolk under the Coastal Marine Fisheries Management Strengthening Project. Marine Fisheries Survey, Management & Development Project, Department of Fisheries, Chittagong Islam, M.S., Khan, M.G., Quayum, S.A., Sada, M.N. and Chowdhury, Z.A. 1991. The estuarine set- bag-net fishery. Marine Fisheries Survey, Management & Development Project, Department of Fisheries, Chittagong. 19- 49 pp. Mazid, M.A. and Rahman, M.J. 2005. Studies on the impacts of marine set-bag-net (MSBN) on the marine fisheries resources of Bangladesh. Final Report, Bangladesh Fisheries Research Institute, Marine Fisheries & Technology Station, Cox's Bazar. 88 pp. 364 Structure & operation of MSBN

MFTS (Marine Fisheries & Technology Station). 2004. Studies on the impacts of marine set-bag-net (MSBN) on the marine fisheries resources of Bangladesh. Third Quarterly Report, Bangladesh Fisheries Research Institute, Marine Fisheries & Technology Station, Cox's Bazar. 17 pp.

Quayum, S.A., Khan, M.G., Islam, M.S., Sada, M.N. and Chowdhury, Z.A. 1991. The marine set bag-net fishery. Marine Fisheries Survey, Management & Development Project, Department of Fisheries, Chittagong. 65- 78 pp.

Rahman, M.J., Mazid, M.A., Zaher, M. and Haroon, A.K.Y. 2007. Catch compositions of marine set-bag-net(MSBN) in Bangladesh waters. Bangladesh J. ZooL, 35(1): 115-129.