Mohammad Arshad-ul-alam eissn

Transcription

1 International Journal of Integrative sciences, Innovation and Technology (A Peer Review E-3 Journal of Science Innovation Technology) Section A Basic Sciences; Section B Applied and Technological Sciences; Section C Allied Sciences Available online at Research Article FISHING INTENSITY OF THE HALDA RIVER, CHITTAGONG, BANGLADESH. MOHAMMAD ARSHAD-UL-ALAM Department of Zoology, Bandarban Government College, Bandarban Hill District - arshadul001967@yahoo.com ABSTRACT Fishing intensity of the Halda River was investigated for two years period from January 2007 to December The study examined the variation of number of fishing efforts among 34 gear types, 8 gear categories and three studied sections. Variations among months and between years were also studied. The total number of daily fishing efforts showed two peaks, the highest in October ( gear/ha/day with 24 types of gears during 2007 and gear/ha/day with 26 types of gears during 2008) and the 2 nd one in April ( gear/ha/day with 20 types of gears during 2007 and gear/ha/day with 21 types of gears during 2008). The mean value of daily fishing efforts was found ±1407 gear/ha/day during 2007 and ± gear/ha/day during 2008.The net fence had the highest number of efforts (0.1375± and ± gear/ha/day during 2007 and 2008 respectively) among 8 gear categories followed by cast net (0.1096± and ± gear/ha/day). Analysis of variance showed strong significant difference among number of efforts of different gear types (P<0.01) and gear categories (P<0.01). Most of the fishing gear showed significant difference in number of efforts between sections and months. KEY WORDS: Halda River, Fishing intensity, Number of fishing efforts, Fishing gear. INTRODUCTION Enumeration of fishing efforts is the prime importance for estimating catch per unit efforts (CPUE), which is a useful index of the abundance and exploitation of fishery resources. The variable yield of fishery is related directly to the alternations in fishing gears, mesh sizes and fishing efforts. In a multi-species fishery different fishing gears used to catch a large variety of these different species. The uses of diverse fishing gears make problem while grouping them into categories, thus estimation of fishing efforts may be affected. To estimate the CPUE and effects of different fishing gears on fishery, intensity of the gears must be monitored separately with precision, with special attention to mesh sizes and mode of operation. There is a decline in wild stock of fish due to mostly open access of fishing. A few management initiatives were taken to limit these open access nature of fishery, to keep potential stock of wild pure genetic race, and to conserve species diversity. Open water fishery should be protected by regulating open access nature of fishing. A large variety of detrimental fishing gears and methods are used for fishing which are responsible for declining aquatic biodiversity of resourceful wild stock. Tidal river Halda of Chittagong, Bangladesh is a natural breeding ground of Indian major carps (IMC) (Catla catla, Labeo rohita, Cirrhinus mrigala and Labeo calbasu) and unique around the globe for collection of fertilized eggs of IMC. Naturally spawned fertilized eggs of IMC are collected by small mesh mosquito nets which are hatched in mud pits in the riverbank by local people traditionally (Ahmed 1948, Bardach et al. 1972, Tsai et al. 1981, Azadi 2004, Arshad-ul- Alam 2011 Azadi and Arshad-ul-Alam 2011). Although country is immensely benefited from this river but very little attention has been paid over this river. Arshad-Ul-Alam (2011) studied on Ichthyodiversity, fishing gears, fishing intensity, catch per unit of efforts (CPUE), catch per unit of area (CPUA), catch composition, and spawn fishery of the Halda River. Although some works on fishing gears of different floodplains of Bangladesh have been done (Alam et al. 1997, Rahman et al. 1999, Ahmed et al. 2003, Ahmed et al. 2005, Ahmed 2008) but no significant works was found on the intensity of riverine fishing gears of Bangladesh. So, in the present study an attempt was made to study the intensity of different fishing gears of the River Halda. 10

2 MATERIALS AND METHODS Study area The tidal River Halda is one of the tributaries of the Karnaphuli River system. It originates from Khagrachari Hill District of Bangladesh and meets with the River Karnaphuli at 15 km North of Chittagong Metropolitan City. It is 88 kilometer in length and 35 to 210 meters in width at the confluence of the river. The present study area was 39 kilometers in length which covered an area of 351 hectares of the river Halda. Total study area was divided into three sampling sections. Three way ANOVA was tested to find the variation of number of fishing efforts among different gears, sections, months and between years. Coefficient of variation (CV) among months for each gear type and category, CV among gear types and among gear categories for each month were also tested. Presentation of data Existing 34 kinds (Arshad-Ul-Alam 2011) of fishing gears of the River Halda were grouped into eight categories based on fishing methods for presentation of data. IMC egg collecting gears and prawn post larvae (PL) collecting gears are not included. Symbols used f g : Number of daily fishing efforts for particular gear type or category in terms of gear/hectare/day. f g : Sum of daily fishing efforts of all gears in terms of gear/hectare/day. Abbreviations used SM: Small mesh, MM: Medium mesh, LM: Large mesh Count of fishing efforts The fishing gears used in the river Halda were counted during every fortnightly survey from January 2007 to December All types of gears found in the study area were counted separately for each location. Numbers of fishing efforts were counted for 24 hours of the day. Active day time gears were counted directly from 06:00 o clock to 18:00 o clock. Four journeys were made by engine boat (sampan) in each survey of the section to observe diurnal change in fishing pattern. Night time gears were confirmed by the questionnaire and by some night visit in the site. All types of gears counted separately during the survey. The fixed gears were checked in each journey. Maximum number of gears observed in all four surveys of the day noted in separate column for number of gears for the day. Cast nets and push nets were noted in total of all four journeys because of their ephemeral nature of operation. Gears of same kinds with different mesh size enumerated separately. As fishing activities depends largely on tidal situation and lunar cycle, survey program was set keeping that in mind. Survey form and questionnaire for fishing effort count and catch monitoring were developed using Flood Action Plan (FAP) -17 (Fisheries study, Department of fisheries, Bangladesh) survey forms. Definitions Net fence and enclosure net: Long rectangular net of different sizes (18 270m) made of mosquito screen or other knotless nylon material of higher mesh sizes (small mesh enclosure net) or multifilament material of mm mesh sizes (large mesh enclosure net) used extensively with or without brush shelter, encircling a portion of intertidal slope of riverbank as a trap for fish as water recedes during ebb tide. Four types of gears namely: SM enclosure net, LM enclosure net, intertidal brush shelter and deep water brush shelter are grouped under this gear category. SM enclosure net is the most popular fishing gear and unique for tidal rivers which is recently banned by Bangladesh government due to its destructive nature. RESULTS Fig 1 shows daily number of efforts (gear/ha/day) for different types of fishing gears over the whole study area in the River Halda during 2007 and Table 1 shows the mean number of daily fishing efforts (f g ) for each gear categories in three studied sections and in total study area of the River Halda during 2007 and 2008 with number of fishing months and coefficient of variation (CV) among months for each gear category. Table 2 shows the sum of daily fishing efforts ( f g ) for each month during 2007 and 2008 with active number of gear types and categories, CV among gear types and among gear categories for each month. Statistical analysis 11

3 Fishing intensity by gear categories (Table 1) During 2007 upstream showed high density for net fences (0.1238± gear/ha/day) followed by cast nets (0.1093± gear/ha/day). Among the three sections midstream showed the highest density for net fences (0.1934± gear/ha/day) followed by cast nets (0.1155± gear/ha/day). Downstream had the high density for line and hooks (0.1537± gear/ha/day) followed net fences (0.1092±0537 gear/ha/day During 2008 upstream showed high density for net fences (0.1491± gear/ha/day) followed by line and hooks (0.1448± gear/ha/day) and cast nets (0.1071± gear/ha/day). In midstream net fences showed highest intensity (0.2248± gear/ha/day) amongst three sections followed by cast nets (0.1235± gear/ha/day). Downstream had the high density for gill nets (0.1423± gear/ha/day) followed cast nets ( ±0683 gear/ha/day) Over the total study area the highest mean f g was estimated for net fences (0.1375± and ± gear/ha/day for 2007 and 2008) 12

4 Monthly distribution of fishing intensity (Table 2, Figs 2 and 3) Daily total number of efforts ( f g ) during 2007 (Fig. 2) in section 1 was ranged from to with a mean value of ±1150. In section 2 the f g ranged from to with a mean value of ± In Section 3 the f g ranged from to with a mean value of ± Daily total number of efforts ( f g ) during 2008 (Fig. 3) in section 1 was ranged from 0.20 to with a mean value of ±1999. In section 2 the f g ranged from to with a mean value of ± In Section 3 the f g ranged from to with a mean value of ± Over the total study area the f g ranged between (in June with 12 types of gears under 8 categories) and (in October with 24 types of gears under 8 categories) during 2007 with a mean value of ±1407 (Figs. 2 and 3). During 2008 the f g ranged between (in June with 10 types of gear under 5 categories) to (in October with 26 types of gear under 8 categories) with a mean value of ± (Figs. 2 and 3). 13

5 2008). Variation among fishing efforts in three sections showed strong significant difference during 2007 (F = 6.38, P < 0.01) and insignificant during 2008 (F = 1.71). Strong significant difference was also observed among fishing efforts of different categories of gears (F = 27.43, P < 0.01 for 2007 and F = 23.28, P < 0.01 for 2008). DISCUSSION The intensity of different gears varied in different sites. Seine nets, bag nets, gill nets, scoop nets were observed the highest in downstream. Net fences were observed the highest in midstream. Line and hooks observed highest in downstream during 2007 and in upstream during Amongst the 34 gear types, LM enclosure net, monofilament gill net, large scoop net, drag net, rod and line, hand line, bottom set long line and top set long line and hand picking were very scarce. Brush shelter, SM cast net, LM cast net and triangular lift net were found throughout the study area in more or less equal number of efforts. Top set long line (section 1), large scoop net (section 2), monofilament knotless nylon net (section 3) were rarely seen and found only in one section. SM bag net and drag net absent in section 1, SM gill net absent in section 2, small lift net, rod and line, rod and reel, fixed rod and line, bottom set long line and top set long line were absent in section 3. Coefficient of variation among efforts of different gear types and categories The coefficient of variation (CV) among fishing months showed that there was <100% variation of f g for each gear types (not shown here) and for each gear categories (Table 1). CV among gear categories showed <100% variation mostly for all months while CV among gear types showed >100% variation for each month of the year. Variation of fishing intensity among gears, months, sections and years Three way ANOVA were tested on mean values of daily fishing efforts to determine the variation of fishing intensity among gears (by types and categories), months, sections and between years. ANOVA (among gears, months and sections) showed strong significant difference among fishing efforts of different gear types (F = 23.63, P < 0.01 for 2007 and F = 27.37, P < 0.01 for 2008), and among fishing efforts of different months (F = 2.24, P < 0.01 for 2007 and F = 2.59, P < 0.01 for On the basis of gear categories net fences had the highest number of efforts (0.1375± and ± gears/ha/day for 2007 and 2008 respectively) in the River Halda followed by cast net (0.1096± and ± gears/ha/day) (Table 1). The hook line and gill net had the 3 rd and 4 th position. Present findings showed a different fishing pattern form other floodplain rivers where the most dominant gears were seine nets and gill nets (Kader et al. 1999, Ahmed 2008). It is due to tidal nature of the river and resembles in fishing pattern with tidal rivers where net fences used in higher extent (Thomas and Kurup 2004, Lamberts et al. 2008). degraff and Chinh (1992) reported traps (1.4850± gear/ha/day) and bag nets (Fyke net) (0.0930± gear/ha/day) as most frequently used gears from a floodplain of Vietnum. In the present study rod and reel and small lift net were found in upstream and midstream (because of more curvature and low water current) and completely absent in downstream. Rod reel used to angling Labeo rohita (Rui), Cirrhinus mrigala (Mrigal) and Labeo calbasu (Kalibaush) by recreational people and small lift nets used to 14

6 collect small prawns by female and children. Downstream which is adjacent to Kanaphully river estuary enriched with prawn angling hook (0.1504± and ± gear/ha/day during 2007 and 2008 respectively) and MM gill net (0.0809± and ± gear/ha/day) used for capturing mainly mature Setipinna phasa. Ahmed and Hambery (1999) observed the variation of intensity of different gears in different sites of Kaptai Lake and reported the absence and exclusiveness of some gears in some sites. In the present study monthly mean data of total daily fishing efforts (all gear combined) showed two peak seasons of fishing, one in April and one another in October (Figs 2 and 3). Ahmed (2008) reported highest number of gears in September from Titas flood plain. There were no previous records of fishing intensity in terms of gear/ha/day from the river Halda or from other rivers of Bangladesh. Ali and Morris (1977, 1978) recorded 276 commercial fishing units with an average crew size of 6.0 fishermen (which totals to 1656 fishermen) and fishing efforts 6.32 hours/day for July-August period and 5.81 hours/day for November-December period from Halda and adjacent floodplain. Present study showed that fishing pressure was highest in downstream followed by midstream and upstream. SM enclosure net had the highest fishing efforts over the study area. Highest efforts laid on October followed by April. Fishing intensity increased during 2 nd year (2008) is due to the declaration of sanctuary without any control measures. CONCLUSION Fishing intensity of the River Halda from January 2007 to December 2008 (gear/ha/day) was monitored. Over the total study area the combined fishing efforts ranged between (in June with 12 types of gears under 8 categories) and (in October with 24 types of gears under 8 categories) during 2007 with a mean value of ±1407, while during 2008 the combined fishing efforts ranged between (in June with 10 types of gear under 5 categories) to (in October with 26 types of gear under 8 categories) with a mean value of ± The mean fishing efforts among gear categories over the study area ranged between ± gear/ha/day (scoop net) and ± gear/ha/day (net fence); and between ± gear/ha/day (small subsistence gears) and ± gear/ha/day (net fence) for the year 2007 and 2008 respectively. Analysis of variance showed strong significant difference among efforts of different types of fishing gear categories (P<0.01). Most of the gear showed significant difference between sections and months. Mean data of daily fishing effort for each month showed two peaks, one during April and another one during October. The enclosure net had the highest number of efforts (0.1337± and ± gears/ha/day during 2007 and 2008 respectively) among 34 gear types followed by SM cast net (0.0935± and ± gears/ha/day). ACKNOWLEDGEMENT The author takes this opportunity to express heartfelt gratitude to his esteemed supervisor Dr. Mohammad Ali Azadi, Professor, Department of Zoology, University of Chittagong, for his invaluable help, able guidance and whole hearted cooperation, during the whole course of this investigation. Dr. Arshad-Ul-Alam is grateful to University grants commission, Ministry of Education and Chittagong University, Bangladesh for their kind support. REFERENCES 1. Ahmed, K.K. and J.B. Hambrey Brush Shelter: A Recently Introduced Fishing Method in the Kaptai Reservoir Fisheries in Bangladesh, NAGA, the ICLARM Quarterly, 22(4): Ahmed, M. S Assessment of fishing practice on the exploitation of the Titas flood plain in Brahmanbaria. Bangladesh. Turkish J. Fish. Aquat Sci. 8 (2) : Ahmed, M.S., Hossain, M.M. and Zaman, A Floodplain gears of Bangladesh: A case study of the Titas floodplain, Brahmanbaria. Bangladesh J. Zoology 30(2), Ahmed, N Methods of collection and hatching of carp ova in Chittagong with some suggestion for their improvement. J. Bombey Nat. Hist. Soc. 47(4): Ahmed, N., Rahman, M.M. and Rahman, M.M Fish catch assessment of Maljehee- Kangsa floodplain in Bangladesh. Pakistan Journal of Biological sciences 8(3) Alam, S.S., Ali M.Y. and Chu-fa-Tsai Fishing gear of floodplain fisheries in Bangladesh: A case study of Chanda, BKSB and Halti beels. Open water fisheries of Bangladesh. Chu-fa-Tsai and M.Y. Ali (ed.) University press Ltd. Dhaka Ali, L. and Morris, E.L Results of the economic and catch assessment program (First survey) in the Chandpur, Muhuri, Halda and Ichamati project areas. Development of fisheries in the Chandpur, Muhuri and Karnafuli (Halda and Ichamati) irrigation and flood control project, working document No.4, Directorate of Fisheries Bangladesh with Snell environmental group, Inc. Lansing, Michigan, U.S.A. 8. Ali, L. and Morris, E.L Results of the economic and catch assessment program (Second survey) in the Chandpur, Muhuri, 15

7 Halda and Ichamati project areas. Development of fisheries in the Chandpur, Muhuri and Karnafuli (Halda and Ichamati) irrigation and flood control project, working document No.7, Directorate of Fisheries Bangladesh with Snell environmental group, Inc. Lansing, Michigan, U.S.A. 9. Arshad-ul-Alam, M Fishery of the Halda River with special reference to biology of Setipinna phasa (Hamilton). Ph. D. Research work. Department of Zoology, Chittagong University. 328 pages, contain 65 figures, 111 tables and 26 plates with 232 images. 10. Azadi, M.A Management of spawn fishery of major carps (Labeo rohita, Catla catla and Cirrhinus cirhosus) in the Halda River, Chittagong, Bangladesh. Bangladesh J. Fish. (Special Issue), 27: Azadi, M.A. and Arshad-ul-Alam, M Diversity of Finfish and Shellfish of the River Halda with notes on their conservation. Page In Roskaft, E. and Chivers, D.J. (Eds.), Proceedings of the International Conference on Biodiversity - Present State, Problems and Prospect of its Conservation. Norwegian Center for International Cooperation in Education (SIU), NO 5809, Bergen, Norway. 12. Bardach, J.E., Ryther, J.H. and McLarney W. O Aqualture: The Farming and Husbandry of Freshwater and Marine Organisms Wiley interscience, Sydney, Toronto. 13. de Graaf, G.J., and Chinh, N.D Floodplain fisheries in the southern province of Vietnam. Annual Report, Ministry of Fisheries, 9 pp. 14. Kader, M.M., Hossain, M.M. and Kabir. S Patterns of fish catches in river and open beels. In M.M. Hossain (Ed.) Community based fisheries management and future strategies for inland fisheries in Bangladesh. Proceedings of national workshop on CBFM, DOF, Ford Foundation, Dhaka: Lamberts, D., Fernando C., and Wah S.L.P Introduction to Fishing Methods and Gear of the Delta Region of Myanmar, Agriculture Cluster Myanmar Technical Fact Sheet. No.16, 10 pages, FAO Emergency and Rehabilitation Coordination Unit, Seed Division Compound, Myanmar Agriculture Service, Yangon, Myanmar. 16. Rahman S., Mazid M.A., Kamal M., Hossain M.A. and Hossain M.S Study on fishing gears, species selectivity towards gears and catch composition of BSKB beel, Khulna, Bangladesh. Bangladesh J. Fish. Res., 3(1) Thomas J.V. and Kurup B.M Padal Fishing A unique fishing method in Ashtamundi Estuary of Kerala (south India) NAGA, The WorldFish Center Quarterly Vol. 27 No. 3 & 4 Jul-Dec Tsai, Chau-Fa, Islam, M.N., Karim M.R. and Rahman, K.U.M.S Spawning of major carps in the lower Halda River, Bangladesh, Estuaries 4(2):