Abstract: Ramnabad River is a vital river in the southern Bangladesh in terms of fishing. This survey aimed to assess the fish and fishing gear diversity in the Ramnabad River from March 2013 to February 2014. Fish samples were collected fortnightly from four sampling stations of the Ramnabad River at Patuakhali district in Southern Bangladesh. A total of 64 species of fish under 12 orders and 32 families were recorded during the study period in the Ramnabad River. Perciformes were most leading order constituting 34.38% of the total fish population followed by Siluriformes (21.88%), Cypriniformes (17.19%), Clupeiformes (9.38%), Pleuronectiformes (4.69%), Tetraodontiformes (3.13%), Osteoglossiformes (1.56%), Beloniformes (1.56%), Anguiliformes (1.56%), Pristiformes (1.56%), Rajiformes (1.56%) and Aulopiformes (1.25%). Eight major types of fishing gears were detected to harvest fish in different stations of the Ramnabad River. Major categories of gears include nets, traps and hooks. For fishing purpose, a wide variety of nets such as gill nets, seine nets, lift nets, push nets and cast nets were usually used. The fishing traps were Polo and Bana. For line fishing chip barshi, wheel barshi and longline were used. From this estimation there were indication of low fish species composition and richness in the population of fish in Ramnabad River. For sustainability of these resources, an adequate knowledge of species composition, diversity and relative abundance of its water bodies must be understood. Use of the illegal fishing gear should be prohibited and monitored properly. Therefore, there is need for the conservation and management of the fisheries resources of this water body by relevant agencies. So, the government as well as non-government initiatives also should come forward to consider these cynical impacts.
INTRODUCTION
Bangladesh is blessed with numerous inland water bodies which are very rich in diversity of fish species (Ali et al., 2012; Al Mahmud et al., 2012). About 800 rivers counting tributaries flow through the country constituting a waterway of total length around 24, 140 km where it bears a huge potential for fisheries sector (Banglapedia, 2012; DoF., 2013). It has the third biggest aquatic fish bio-diversity in Asia, after China and India, with about 800 species in fresh, brackish and marine waters (Hussain and Mazid, 2001).
Fish is deliberated as one of the most significant food items from the very beginning of human civilization (Akter et al., 2012; Islam et al., 2012; Ahmed et al., 2012; Hossain et al., 2013). It is one of the major important elements in the aquatic habitat and play a key role in economy of many nations (Okyere and Denis, 2011) as they have been a stable item in the diet of many people (Kouamelan et al., 2003). As animal proteins consumed by 1 billion people worldwide (Marichamy et al., 2011).
Fisheries sector plays a significant role and main source of animal protein, employment opportunities, food security, foreign incomes and socio-economic improvement (Ali et al., 2014a; Siddiq et al., 2013; Azim et al., 2012). This sector contributes 4.39% to GDP and 22.76% to agricultural GDP. Fish supplements to about 60% of our daily animal protein intake. About 10% of the population is dependent directly and indirectly on the fisheries for their living (DoF., 2013). It has already been renowned as a vital income and employment-generating sector in Bangladesh, cheap sources of healthy food for the population of the country (Ali et al., 2014a, b). However, over exploitation, degradation of fish habitats and subsequent declining fish production from natural aquatic resources, inland capture fisheries contribution has declined from 50-35% of total fish production and marine capture fisheries production has remained static over the last ten years (Mazid, 2002).
Generally gears are those equipment’s that are used to catch the fishes. For fishing, different kinds of crafts, gears and traps are used. Different types of fishing method used from primitive times and now fishing methods had been modified. The fishermen selected their fishing gears depending on types of water body, different operation area, depth of water and availability of target species to the caught. In Bangladesh fish and fisheries items of inland water still are caught by using traditional crafts and gears. The amount of catch by unit depends upon its effectiveness and productivity of the fishing grounds (Naidu, 1939). Most of the fishing gears have to break off process after certain period of action for rest and repair work (Ahmed, 1958).
During the last century, associated habitats are a great challenge. In addition, riverine ecosystems have suffered from intense human the conservation of aquatic biodiversity has gained great intervention resulting in habitat loss and degradation and ecological importance over recent years. As a consequence, many fish species have become highly Bangladesh is exclusively endowed with extremely endangered, particularly in rivers where heavy demand is rich and extensive inland and marine water resources, placed on freshwaters (Rahman et al., 2012).
The degradation of natural water bodies resulting from human interferences due to construction of roads, embankments, deforestation, encroachment for agricultural production, indiscriminate use of pesticides and natural causes (siltation, drought, cyclone and intrusion of saline water) has had negative impacts on fish diversity in Bangladesh. On the other hand, the indiscriminant use of different fishing gears, harmful techniques of fishing threatens the biodiversity of the seasonal floodplains. For the implementation of National Biodiversity Strategy and Action Plan it is essential to manage some of the distinct features of which biodiversity are composed (Chowdhury et al., 2011).
Therefore, our main objective in this study was to provide accounts of the fish and gear diversity in the Ramnabad River. In addition, it can identify the existing fish capture techniques and diversified fishing gears. The information from this investigation will serve as a baseline data for carrying out further study on ecology, conservation, sustainability and management of fisheries resources of this water body.
MATERIALS AND METHODS
Study area: The current study was carried out for the identification of the fish and gear diversity in the fishing community of Ramnabad River from March 2013 to February 2014. Ramnabad River is situated in the Patuakhali district, Southern Bangladesh (Fig. 1). There were four landing centers were selected for this experiment.
| Fig. 1: | Study area showing the sampling stations |
| Table 1: | Commonly operated fishing gears in Ramnabad River, Bangladesh |
The names of the sampling stations as landing centers are four union of the kolapara upazila named Dhankhali (Station-1), Lalua (Station-2), Dhaluasar (Station-3) and Lata chapli (Station-4). The stations were selected on the basis of the possibility of getting more fishes and operated fishing gears.
Methodology: Fish samples were periodically collected from the catch of fishermen in the Ramnabad River. A number of fishing gears were used during the catching of fishes by fishermen (Table 1). Samples were also collected from fish-landing centers and fish markets. Samplings were conducted fortnightly from commercial catches landed at different fish landing centers.
Primary data on the concerned species were collected from the fishermen, fish traders, local people and also from the on the spot situation. Relevant data such as local name of the collected fish samples, source, distribution and availability of the species etc. were collected from the study sites. Secondary data were also collected from the District Fisheries Offices, Department of Fisheries (DoF., 2013), Statistical Yearbook of Bangladesh etc. The collected fish samples were identified by evaluating their morphometric and meristic characteristics as well as the color of the specimens referring the books, Fish Base etc. Data were analyzed in relation to composition of species caught in every month (March 2013 to February 2014) with help of key from Rahman (2005) and Inland Fishes of India and Adjacent countries by Talwar and Jhingran (1991), Fischer and Whitehead (1974) and De Bruin et al. (1995) were also used for their identification.
Data analysis: Collected data from different stations were coded and entered into a data base system using Microsoft office Software. The processed data were transferred to a master sheet from which classified tables were prepared revealing the findings of the study. Finally these data were analyzed by MS-Excel and then presented in textual, tabular and graphical forms to understand the present status of the fish and gear diversity in the Ramnabad River.
RESULTS AND DISCUSSION
Fish diversity: A total of 64 species of fish under 12 orders and 32 families were recorded during the study period in the Ramnabad River. Perciformes were most leading order constituting 34.38% of the total fish population followed by Siluriformes (21.88%), Cypriniformes (17.19%), Clupeiformes (9.38%), Pleuronectiformes (4.69%), Tetraodontiformes (3.13%), Osteoglossiformes (1.56%), Beloniformes (1.56%), Anguiliformes (1.56%), Pristiformes (1.56%), Rajiformes (1.56%) and Aulopiformes (1.25%). In Table 2, Fish orders, families, species, English name, local name(s) and their availability status in different stations in Ramnabad River are given.
There were no previous information of fishes and fishing gears in the Ramnabad River was found and thus comparison of the present findings with previous one was not possible.
| Table 2: | Diversity of fishes and fishing gears of ramnabad river at Southern Bangladesh |
The recorded fish species was much lower than some other rivers of Bangladesh (Bhuiyan et al., 2008; Rahman et al., 2012) but presence of similar number of fish species was also reported in Mahananda River (Mohsin and Haque, 2009).
However, all these researchers concluded with gradual loss of biodiversity in their considered rivers. In that sense, this is also true for Ramnabad River. Order Cypriniformes was found to be the most diversified fish group in terms of both number of species and individuals followed by Perciformes and Siluriformes. Similar findings were also reported by Ali et al. (2014b), Galib et al. (2009), Mohsin and Haque (2009), Mohsin et al. (2009) and Imteazzaman and Galib (2013). This is because these three groups are the most dominant groups in freshwater bodies of Bangladesh (Rahman, 1989, 2005).
Fishing gears: A total of 8 major types of fishing gears were detected to harvest fish in different stations of the Ramnabad River (Table 1, 3-5). Major categories of gears include nets, traps and hooks. For fishing purpose, a wide variety of nets such as gill nets, seine nets, lift nets, push nets and cast nets were usually used. The fishing traps were Polo and bana. For line fishing chip barshi, wheel barshi, Tagi and longline were used.
According to previous study in the literature the fishing gears in Chandpur, Muhuri, Halda and Ichamati project area there were 21 different types of gears. There is the degradation or overexploitation of natural resources in the riverine system is a common phenomenon (Ali et al., 2014c). Dewan and Mazid (1994) mentioned the fishing techniques that are currently used amongst the fishermen of Bangladesh have been broadly categorized into netting, angling, trapping, spearing and hand fishing. Beside these many researcher such as Khaled (1985), Rahman et al. (1993), Aosomboon (1994), Dewan and Mazid (1994), Chakraborty et al. (1995), Alam et al. (1997), Das et al. (2003) and Alam et al. (2009) worked on fishing activities in beels and rivers. This has been found similar in the current study.
At present, the earliest effective management is necessary to sustain the biodiversity of the fishes. According to Lakra (2010), conservation of fish diversity is essential to maintain ecological, nutritional and socio-economic equilibrium.
| Table 3: | Main species caught by the different types of gear in the Ramnabad River |
| Table 4: | No. of different types of gears used in the Ramnabad river |
| Table 5: | No. of species caught by different gears used in the Ramnabad river |
Abundance of threatened fish species among the total catch strongly reflecting its potentiality to be an excellent site for natural conservation (IUCN Bangladesh, 2000).
Management steps should be needed for stopping illegal fishing, identifying illegal fishing gears, protecting crucial breeding habitats. Mass awareness should be needed to save the threatened fish fauna of this river; also fishermen and protecting diverse fish resources. There should be a strong implementation of conservation laws and acts to make free from illegal catch and pollution in this river.
ACKNOWLEDGMENTS
We express our gratitude to (i) Shaharior Hossen (Undergraduate student, Patuakhali Science and Technology University, Bangladesh) for collecting samples and local fishers (Patuakhali, Bangladesh) for collecting samples. Special thanks are extended to those people who helped in different capacities in this research.