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Balancing Between Livelihood and Biodiversity Conservation: a Model Study on Gear Selectivity for Harvesting Small Indigenous Fishes in Southern Bangladesh

Mohammad Mahmudul Islam
Department of Coastal and Marine Fisheries, Sylhet Agricultural University, Sylhet, Bangladesh

Naimul Islam
Department of Coastal and Marine Fisheries, Sylhet Agricultural University, Sylhet, Bangladesh

Md. Mostafiz
Department of Coastal and Marine Fisheries, Sylhet Agricultural University, Sylhet, Bangladesh

Atiqur Rahman Sunnya
Department of Coastal and Marine Fisheries, Sylhet Agricultural University, Sylhet, Bangladesh

Hendrik Jan Keus
WorldFish Bangladesh and South Asia Office, Dhaka, Bangladesh

Manjurul Karim
WorldFish Bangladesh and South Asia Office, Dhaka, Bangladesh;

Mohammed Zakir Hossain
WorldFish Bangladesh and South Asia Office, Dhaka, Bangladesh;

Subrata Sarker
Department of Oceanography, Shahjalal University of Science and Technology, Sylhet, Bangladesh

Abstract/ Executive Summary:

This study has determined a suitable mesh size for small indigenous fish species (SIS) harvesting and has also developed a new gill net operation technique taking into consideration of aquatic biodiversity conservation, the daily intake of micro-nutrients and the livelihood of the rural community. A total of 60 household women involved in mola carplet (Amblypharyngodon mola) culturing participated in this study. We e used mola catch data obtained from harvesting operations of two different durations. Mola harvesting was carried out twice a day at two sites for a period of 180 days using three different mesh-size nets. Mesh size, duration and timing (time of the day) of the harvesting operation were found to be important factors determining mola catches. Among the three mesh size nets used for mola fishing, the 0.70 inch mesh size net proved to be the most suitable... This mesh size net exhibits high efficiency in catching mola, the catch rate of small indigenous non-target fish being lower, and thus contributes to the aquatic diversity conservation. This study provides an insight into how employment of specialized fishing gear can help balance SIS fishing as a source of the rural community’s livelihood against biodiversity conservation.

Keywords: Mola carplet; Gear selectivity; Small indigenous species; Conservation; Bangladesh

Location: Barisal district of Bangladesh.

Start Date:

End Date:

Program Area: Conservation and Biodiversity

Commodity: Fish

Objectives:

The main objectives of the present study were: (i) to develop efficient mola fishing gear; (ii) to determine the economically and ecologically viable mesh size; (iii) to assess the role of mola harvesting in the livelihood of the local population.

Methodology:

Study area This study was conducted in two villages of Barisal district of Bangladesh. This area has favorable climatic conditions and indispensable resources (i.e. manpower, small-scale ponds) for fisheries development. In addition, owing to the Aquaculture for Income and Nutrition (AIN) project of WorldFish, farmers in this area received training in fish farming. Gill net preparation In the course of this study, an economically viable and female user-friendly gill net was developed. Details of the schematic representation of this special gill net preparation and operation techniques are shown in Figure 1. Three different mesh size gill nets, i.e. 0.6, 0.7 and 0.8 inch, were used in this study. The nets were 25 feet long by 5 feet wide. Two bamboo poles with a hook on each pole were used on two sides of the pond. The rope was passed through the hook on the bamboo pole in such a way that the rope could be easily moved. Two hooks functioned as smooth handles for the rope to be passed through. The selected net was held in water by a rope. The net is usually set and deployed in water from one of the two bamboo poles. The operator has to tow the rope (the opposite side of the net hung) simultaneously passing it through the hook on the bamboo pole. Then the net is deployed into water by the rope which is attached to the poles on two sides of the pond to keep the net rigid. Unused plastic bottles were used as floating materials of the net and broken pieces of bricks were used as the weight to keep the net straight in water. The bottom and surface of the gill net functioned as a barrier to prevent mola from escaping from the area covered by the net. The net operator has to set the net in the pond and leave it there for a while. To pull the net out of the pond, the operator has to tow the rope (the opposite side of the net hung) simultaneously passing the rope through the hook on the bamboo pole. This allows pulling the net towards the operator. Fish can be harvested from the net by standing on the land, even without getting into the pond. To operate this female user-friendly gill net, no special equipment is required except an operator. Pond selection and carp-mola polyculture system A total of 60 female farmers were selected for this study from two study sites, i.e. 30 farmers from each station. The criteria used for selecting farmers included their access to the pond and their interest in fish culturing. In the study areas, the majority of households have a homestead pond. Based on farmers’ interest in participating in this study, 60 ponds were selected from two study sites with an average size of 11.7 decimals. All selected farmers (86% were women) were beneficiaries of the AIN project of the WorldFish, the purpose of which was to train local farmers in carp-mola polyculture in their ponds. The carp polyculture ponds were stocked with mola brood stock at an average rate of 25 kg per hectare during April 2012. Mola brood stock was collected from three sources: (1) brood ponds established by WorldFish within the neighborhood, (2) farmers’ homestead ponds, and (3) nursery ponds. Brood ponds are ponds where mola fry are stocked and raised for 3–4 months. Ponds with abundant natural mola fish were mostly selected as homestead brood ponds. Nursery ponds were used for holding the mola brood stock collected from brood ponds and open water bodies for up to a week until their distribution among ponds close to the respective nursery. Three Indian major carps (Labeo rohita, Catla catla, and Cirrhinus mrigala), one Chinese carp (Cyprinus carpio) and several other species such as Rajputi (Barbonymus gonionotus), Grass carp (Ctenopharyngodon idella), and Nile tilapia (Oreochromis niloticus) were stocked in the pond (for detailed culture procedure.

Source of Information: Zoology and Ecology, 2018

Article Link (Online Journal): https://doi.org/10.1080/21658005.2018.1429895

Funding Source:

Budget:

Total Budget (Tk.) :

Achievement/Findings:

In the present study, some other nutrient rich small indigenous species such as dhela (Rohtee cotio) and punti (Puntius sophore) were also found caught in the net, which indicates that the modified gill net could be also utilized for harvesting other SIS. However, further research is required to confirm this presumption. As mola is distributed throughout other countries of south and south-east Asia, the gear could be also used in the region to improve the nutritional value and security of food, to derive income and to conserve fish species.

Knowledge Management: Journal