Culture‐based fisheries in non‐perennial reservoirs in Sri Lanka: production and relative performance of stocked species

Abstract

In Sri Lanka, there is a great potential for the development of culture-based fisheries because of the availability of around 12 000 non-perennial reservoirs in the dry zone (<187 cm annual rainfall) of the island. These reservoirs fill during the north-east monsoonal period in October to December and almost completely dry up during August to October. As these non-perennial reservoirs are highly productive, hatchery-reared fish fingerlings can be stocked to develop culture-based fisheries during the water retention period of 7-9 months. The present study was conducted in 32 non-perennial reservoirs in five administrative districts in Sri Lanka. These reservoirs were stocked with fingerlings of Indian (catla Catla catla Hamilton and rohu Labeo rohita Hamilton) and Chinese (bighead carp Aristichthys nobilis Richardson) major carps, common carp Cyprinus carpio L., genetically improved farmed tilapia (GIFT) strain of Nile tilapia, Oreochromis niloticus (L.) and post-larvae of giant freshwater prawn, Macrobrachium rosenbergii De Man, at three different species combinations and overall stocking densities (SD) ranging from 218 to 3902 fingerlings ha )1 , during the 2002-2003 culture cycle. Of the 32 reservoirs stocked, reliable data on harvest were obtained from 25 reservoirs. Fish yield ranged from 53 to 1801 kg ha )1 and the yields of nonperennial reservoirs in southern region were significantly (P < 0.05) higher than those in the northern region. Naturally-recruited snakehead species contributed the catches in northern reservoirs. Fish yield was curvilinearly related to reservoir area (P < 0.05), and a negative second order relationship was evident between SD and yield (P < 0.05). Chlorophyll-a and fish yield exhibited a positive second order relationship (P < 0.01). Bighead carp yield impacted positively on the total yield (P < 0.05), whereas snakehead yield impact was negative. Bighead carp, common carp and rohu appear suitable for poly-culture in non-perennial reservoirs. GIFT strain O. niloticus had the lowest specific growth rate among stocked species and freshwater prawn had a low return. K E Y W O R D S : culture-based fisheries, fish yield, genetically improved farmed tilapia, non-perennial reservoirs, species combinations, stocking density.

Production trends, monetary returns and benefit sharing protocols from the extensive aquaculture practice of culture-based fisheries in rural communities in Lao PDR

“…A minor exception in rare instances is the feeding of grass to stocked grass carp. In view of the low capital required to develop CBF and the fact that rural communities are often organised to manage these water bodies, the practice has been widely adopted in some Asian countries with direct community benefits through food fish production Nguyen et al, 2005;Wijenayake et al, 2005;Jayasinghe et al, 2006;Kularatne et al, 2009;Pushpalatha and Chandrasoma, 2010).…”

“…The total number of fingerlings and species breakdown of the seed stock were determined based on experiences in countries such as Sri Lanka and Vietnam Nguyen et al, 2005;Wijenayake et al, 2005;De Silva et al, 2006;Pushpalatha and Chandrasoma, 2010). The predicted total yield from a water body, based on the catchment land use patterns model of Amarasinghe et al (2002) was used.…”

“…Representative water bodies (Table 1) were selected based on experiences in other developing countries that have successfully adopted CBF Wijenayake et al, 2005;De Silva et al, 2006). A preliminary short list was initially developed of the water bodies that were thought to satisfy the criteria suitable for CBF such as size at full supply level, water retention period, mean depth and accessibility, among others.…”

Co-occurring bighead and silver carps show similar food preference but different isotopic niche overlap in different lakes

“…Recent developments in stable isotope analytical methods when combined with computer-based data modeling, are useful to solve this kind of ecological questions related to aquatic food webs. Studying feeding ecology of BC and SC is helpful to control fish yields depending on the trophic conditions of water bodies not only within China, but also worldwide where they play a major role in food security of rural people (Sugunan and Katiha 2004;Wijenayake et al 2005;Rahman et al 2012). Also, it is useful in places where these fish species should be managed in order to control either eutrophication levels of water bodies or protect indigenous species from invasion threats (Yang et al 2006;Ma et al 2010;Tsehaye et al 2013).…”

Performance of GIFT strain of <i>Oreochromis niloticus</i> in culture-based fisheries in non-perennial reservoirs, Sri Lanka

“…The present study, a component of a larger study (see Wijenayake et al 2005), was conducted in 14 non-perennial reservoirs in five administrative districts located in the dry zone of the country (receiving less than 187 mm annual rainfall), with a large number of non-perennial reservoirs. In this study GIFT Nile tilapia was used as one of the stocking materials in combination with Chinese and Indian major carp species and performance of GIFT strain in culture-based fisheries in reservoirs was evaluated on the basis of specific growth rate, survival, species interaction and biological productivity of habitat.…”