Research

Influence of limnological characteristics on culture-based fisheries

The main focus of this study is on the limnology of CBF-developing reservoirs in Sri Lanka. It will use a number of water quality parameters, sediment quality parameters, reservoir morphometry, and derived indices using GIS tools to understand the spatial and temporal patterns in selected reservoirs. The research is carried out in both in situ and ex situ manners by conducting field visits to each reservoir on a bimonthly basis to collect limnological parameters and by performing lab analysis on the collected samples, respectively. Finally, a model of fish and GFP yields in those selected reservoirs will be developed by correlating the identified patterns to determine the best conditions for CBF development and management in Sri Lankan reservoirs within the present research scope.

2. Giant freshwater prawn and finfish distribution in microhabitats

Giant freshwater prawn fishery in Sri Lanka is a growing process along with finfish culture-based fishery (CBF) in Sri Lankan reservoirs. These reservoirs are stocked with fingerlings of finfish, and post-larvae of giant freshwater prawn (Macrobrachium rosenbergii). After the stocking, fingerlings and post-larvae should have suitable niches and environments for their better survival. The production of the CBF in Sri Lankan reservoirs is directly affected by the survival and growth rate of the cultured organisms. Observing and identifying different microhabitats and their characteristics will help to identify microhabitat suitability for cultured organisms. The characteristics of microhabitats could be separated into physical, chemical, and biological factors. Observation and identification of favorable physical, chemical, and biological conditions in different microhabitats help to understand the microhabitat suitability for cultured organisms and GFP at different life stages in reservoirs. Distribution variation of cultured species in different microhabitats provides information on habitat-species relationships between the cultured species and microhabitats. If the habitat-species relationship could be identified, the fish yield of culture-based fishery can be increased by applying fishing effort meaningfully.

3. Modeling of Reservoir Food Webs

This study focuses on understanding the trophic dynamics of reservoir food webs, which is important for sustainably planning culture-based fisheries. To achieve this, stable isotope analysis and stomach content analysis are used to construct the reservoir food webs. Six reservoirs from the Hambantota, Monaragala, Kurunegala, and Puttalam districts were selected as study sites. The final phase of field visits and data analysis using R software is currently being carried out. Additionally, the quantification and identification of predators of GFP are being conducted through community-based surveys and stable isotope analysis.

4. Giant Freshwater Prawn (Macrobrachium rosenbergii) Product Quality in Relation to Habitats and Postharvest Conditions

The research will address the postharvest product quality, freshness, and remaining shelf life of giant freshwater prawns (GFP) and GFP products with respect to handling and existing postharvest techniques in dry zone reservoir environments. The results will provide a basis for recommendations to enhance quality through the supply chain, thereby attracting more income for rural fisher communities. Additionally, this study will provide a baseline for quality management and branding of GFP in the aquaculture sector in Sri Lanka and beyond.

5. Aquatic Pollution related to Heavy metals, Pesticides & Microplastics in Dry zone Reservoirs

Aquatic pollution due to heavy metals, pesticide residues, and microplastics accumulation in water, sediments, and organisms therein has become a global and emerging threat that can enhance the potential risk for human health. Freshwater prawns and many other fin fish species have a high potential to accumulate heavy metals within the tissues of their body (Bhakta and Munekage, 2015) and also there is a potential for pesticide residue accumulation within those species (Fakhruddin et al., 2011; Sultana et al., 2012).

Not only chemical pollutants such as heavy metals and pesticides but human exposure to microplastics is also quite evident as microplastics have been reported within human food mainly in marine species including fish and crustaceans (Pinheiro, Oliveira and Vieira, 2017).

This study focuses on determining heavy metals and pesticide residues in 6 dry zone irrigational reservoirs including several untouched reservoirs for research purposes. Furthermore, the accumulation of heavy metals & pesticide residues in different tissue types of GFP and other selected food fish will be investigated. Also, microplastic determination in water, sediment, and accumulation in selected biota will be conducted within these dry zone reservoirs.

Filter paper retaining microplastics

Operating AAS

Water Samples

6. Estimation of hydroacoustic fish biomass in reservoirs

7. Hydrological influences on up and downstream migration of foodfish in reservoirs

8. Product quality of chitosan extracted from exoskeleton of Giant Freshwater Prawn

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