Overview Objectives

This project extended the work of an earlier project (FIS/1994/040) to increase inland fish production in perennial and seasonal reservoirs. One aim was to validate models for predicting yield of capture fisheries in perennial reservoirs, and also show how the research findings could be used to improve fisheries management. For culture-based fisheries in seasonal reservoirs, the aim was to develop a best practice model that could be used to popularise such fisheries in the dry zone of Sri Lanka.

Project Background and Objectives

Capture fishery in perennial reservoirs is the backbone of Sri Lanka’s inland fishery. The government and development agencies are now also promoting the use of seasonal reservoirs (known as village tanks) for fish production by local communities, using a stock and recapture strategy referred to as culture-based fishery. Most of the village tanks are located in the dry zone of Sri Lanka; they retain water for six to nine months of the year and are ideally suited for fish production.
Fisheries in reservoirs are increasingly seen as an integral part of whole watershed management, making geographic information systems (GIS) an ideal tool for fisheries management. An earlier project used GIS land-use data to predict yields from capture fisheries. This project validated the GIS-based models and disseminated information about the nature, scope and applicability of the models to relevant stakeholders.
For culture-based fisheries, the initial project found that the lack of availability of suitably sized fingerlings for stocking was a major constraint, and that minor cyprinids (a type of freshwater fish) from perennial reservoirs could provide the feed needed to rear fish fry to the fingerling stage in cages. This project studied how to improve the preparation of this type of feed, the growth and survival of seed stock, and the economic viability of cage culture operations.

Progress Reports (Year 1, 2, 3 etc)

Capture Fisheries
As a follow-up to the national workshop held in May 2001, and based on a major recommendations thereof, the findings on catchment land-use patterns on fish yield in Sri Lankan reservoirs, and the use of relevant models in management were rewritten, in a simplified form, comprehensible to fishery extension workers and was submitted to the National Aquaculture Development Authority for implementation.
The work on the validation of the yield-predictive models based on catchment land-use patterns was completed, using catch data collated by an independent body, the National aquatic Resources Agency. This study confirmed the robustness and the validity of the models, and thereby proved the possibility of such models being used in management of the fishery resources in reservoirs. This validation was published in a peer reviewed journal; Fisheries Management & Ecology, Vol. 9 (2002). In view of the increasing interests in GIS use in fishery studies, and catchment affects on fish yields, the team reviewed all the findings and made a presentation at the “Second International Symposium on GIS in Fisheries”, held in Sussex, UK, in September 2002.
Culture-based fisheries
One hundred and forty non-perennial reservoirs (seasonal tank), in four districts, were randomly selected and the respective management committees (village cultivation committees) were contacted and on the basis of their responses to a questionnaire 16 reservoirs from each district were chosen for the study. The selected reservoirs were visited and person to person interviews were held with the individual committees, and further details on the socio-economic status of the communities, and other relevant data, eg. distance to the closest township, past experience in fish rearing, etc. were collated. This information was augmented with physico-chemical studies and catchment land-use patterns of the water bodies. The data were analysed using an Analytical Hierarchical Technique, which enables socio-economic, GIS and physico-chemical data to be weighted to a common denominator, enabling the development of a scale (preliminary) to determine the suitability of individual water bodies for culture-based fisheries development. The data for the Hambantota District (16 reservoirs) have been completed and those in the other three Districts are in progress. The preliminary results on the developed scale was presented at the “Second International Symposium on GIS In Fisheries”, held in Susses, UK, in September 2002.
The selected reservoirs were stocked in October-November 2002, as planned; two stocking densities and four different species combinations at each density. Since stocking the water quality parameters have been monitored on monthly, in each reservoir.
Cage culture
Fry to fingerling rearing experiments on Oreochromis niloticus and Labeo rohita in cages commenced in three perennial reservoirs, Kiriibban Wewa (Moneragela District; 09 cages), Chandrika Wewa (Rathnapura D.) and Weerawil Wewa ((Hambantota D.; 09 cages). The stock were fed farmer-made feeds using locally available agricultural by-products such as rice bran (RB), cassava flour (CF) and soybean meal, mixed in different proportions with fish powder (FM) prepared from small cyprinids (minor cyprinids; not consumed) caught in the reservoir by the fishers, sun dried and ground. Currently three feed types (4FM:3CF:3RB, 4FM:4CF:1RB and 2FM:5CF:1RB) are been tested for their efficacy. The proximate composition of each of the feed types have been determined, and the results of the first cage trial are in the process of being analysed.
General matters
The Australian Project leader visited Sri Lanka for project monitoring activities in Feb. 2002.
All Research Assistant appointments have been finalised, and accordingly two full time Ras are involved in the work on non-perennial reservoirs.
National aquatic Resources Agency has continued to cooperate effectively on the GIS analysis and cage culture experiments.

Year 3 (01/01/2003-31/12/2003)
Capture fisheries
This component was completed in year 2002, and the recommendations are currently being implemented by the national Aquaculture Development Authority in the management of the fisheries in the large, perennial reservoirs.
Culture-based fisheries
Forty four non-perennial reservoirs were stocked (three species combinations and three stocking densities) over two culture cycles and the growth of the stock, yields and the limnology (physical, biological and geographical properties) of each of the reservoirs were monitored. In addition, the size of each of the non-perennial reservoirs used in the study together with their catchments was determined using GPS and 1:50,000 scale maps. The land use patterns of the latter were determined using satellite imagery and confirmed with random ground-truthing.
Of the 44 reservoirs stocked data could be obtained only from 36; that from the other eight being unreliable. The yield data and the growth data are being analysed and it is believed the study will enable the development of a best-practice model, incorporating water quality features, stocking density, species combination and the socio-economic conditions of the village community, for culture-based fisheries in Sri Lanka. Socio-economic criteria and biological criteria were incorporated into the model using the Analytical Hierarchical Process.
The project activities have brought about cooperation and integration between governmental departments that have jurisdiction over the utilisation of the water bodies, namely the Department of Agrarian Services and National Aquaculture Development Authority. Consequently, the Agrarian Services Statue will be amended to permit fishery activities in non-perennial reservoirs which hitherto had no legal status and hindered further fisheries developments.
Extension booklets on the technical and management aspects on culture-based fisheries were developed and provided to all the stakeholders. In the preparation of the material extensive consultations were held with all stakeholders, and the material is being utilised by the national aquaculture Development Authority in its endeavours to popularise the activity.
A workshop in 2002 on culture-based fisheries brought together governmental officials responsible for management of non-perennial reservoirs, agricultural extension in the command areas, fishery extension officers and aquaculturists and the practitioners. The overwhelming consensus at the workshop was that the project has stimulated the development of a new and useful activity for the community and that culture-based fisheries development should be extended to other regions in the country.

Project Outcomes

Capture fisheries As a follow-up to a national workshop held in May 2001, and based on a major recommendations thereof, the findings on catchment land-use patterns on fish yield in Sri Lankan reservoirs, and the use of relevant models in management were rewritten in simplified form comprehensible to fishery extension workers. The findings were submitted for implementation by the National Aquaculture Development Authority.
Validation of the yield-predictive models based on catchment land-use patterns was completed, using catch data collated by an independent body (the National Aquatic Resources Agency). This study confirmed the robustness and the validity of the models, thereby proving the possibility that such models could used in managing the fishery resources in reservoirs. This validation was published in a peer-reviewed journal; Fisheries Management & Ecology, Vol. 9 (2002). In view of the increasing interest both in use of GIS in fishery studies and in catchment affects on fish yields, the team reviewed all the findings and made a presentation at the Second International Symposium on GIS in Fisheries, held in Sussex, UK, in September 2002.
Recommendations arising from the project were implemented by the National Aquaculture Development Authority. Selected reservoirs were stocked in October-November 2002, as planned, with two stocking densities and four different species combinations at each density. Since stocking, scientists have monitored the water quality parameters each month by testing each reservoir.
Culture fisheries Forty-four non-perennial reservoirs were stocked (three species combinations and three stocking densities) over two culture cycles and the growth of the stock, yields and the limnology (physical, biological and geographical properties) of each of the reservoirs were monitored. In addition the size of each of the non-perennial reservoirs used in the study, together with their catchments, was determined using GPS and 1:50,000 scale maps. The land-use patterns of the latter were determined using satellite imagery and confirmed with random ground-truthing.
Of the 44 reservoirs, reliable stocked data could be obtained only from 36. The yield data and the growth data are being analysed and it is believed the study will enable the development of a best-practice model, incorporating water quality features, stocking density, species combination and the socio-economic conditions of the village community, for culture-based fisheries in Sri Lanka. Socio-economic criteria and biological criteria were incorporated into the model using the Analytical Hierarchical Process.
The project activities brought about cooperation and integration between governmental departments that have jurisdiction over the utilisation of the water bodies, namely the Department of Agrarian Services and National Aquaculture Development Authority. Consequently, the Agrarian Services Statute is being amended to permit fishery activities in non-perennial reservoirs - these had never had legal status, and this was a hindrance to further fisheries developments.
Extension booklets on the technical and management aspects on culture-based fisheries were developed and provided to all the stakeholders. A workshop in 2002 focused on culture-based fisheries. The overwhelming consensus at the workshop was that the project has stimulated the development of a new and useful activity for the community and that culture-based fisheries development should be extended to other regions in the country.

Project ID
FIS/2001/030
Inactive project countries
Commissioned Organisation
Deakin University, Australia
Project Leader
Professor Sena De Silva
Email
sena@deakin.edu.au
Phone
03 5563 3527
Fax
03 5563 3462
Collaborating Institutions
Kelaniya University, Sri Lanka
National Aquaculture Development Authority, Sri Lanka
National Aquatic Resources Agency, Sri Lanka
University of Paradeniya, Sri Lanka
Project Budget
$295,183.00
Start Date
01/01/2001
Finish Date
31/12/2004
Extension Start Date
01/01/2005
Extension Finish Date
30/06/2005
ACIAR Research Program Manager
Mr Barney Smith