Endemic Fish Species Diagnostic in Lake Itasy Catchment Area - Towards a Conservation Strategy

Jean Robertin Rasoloariniaina

The overarching goal of this project is to complete a gap analysis for the distribution and the ecology of the three endemic species: Ptychochromoides itasy, Ratsirakia sp. and Paratilapia polleni; to identify the impacts of the invasive species and to describe the habitat quality and the fish resource use patterns for competent biodiversity conservation and fishery management. To achieve this main goal, the following core aims are identified:

Aim 1: Conduct expeditionary and exploratory research on the aquatic ecosystem and the fish species

Aim 2: Monitor fishery basic indicators and their change over time and space

Aim 3: Assess the economic and social dimensions of fisheries, the fish resources utilisation, the related local governance and the local communities’ knowledge.

Aim 4: Promote awareness on endemic fish fauna conservation as well as on the fisheries sustainable management importance.

Ptychochromoides itasy.

Ptychochromoides itasy.

The Lake Itasy catchment area, situated about 120 km to the west of the capital, Antananarivo is a large wetland network composed by Lake Itasy, a large lake of volcanic origin, and numerous satellite lakes and rivers where local fisheries and fish farms are common. At least three fish species are known to be endemic to this area. Besides, several exotic species were introduced in this area, dating back to the mid-19th century.

The combination of exotic fish species, over exploitation, and habitat loss, are suspected to have eliminated endemic species in many parts of the catchment. Few sites are known to host relict populations. Currently there is very limited data available to aid the conservation of freshwater fish and to assess the threats they face in the catchment. Moreover, no protection is afforded in this region to fish and freshwater ecosystems. This project aims to complete a gap analysis for the distribution and the ecology of the endemic species and will assess the threats in order to establish locally-managed fisheries and fish conservation.

This project will be carried out by a multidisciplinary team. The first research activity will assess the aquatic habitat; will describe and catalogue them to document changes over time and space. Basic data concerning the macroinvertebrate assemblages, the ecology and distribution of the three endemic fish species (Ptychochromoides itasy, Ratsirakia sp. and Paratilapia polleni) as well as the sympatric invasive fish species will be gathered.

To perform a fishery study, we will gather data on catch, fish abundance, and fish diversity in different areas of the Lac Itasy catchment. The technical attributes of the local fisheries (artisanal, small-scale, commercial, industrial, gear/fishing technology, species harvested, and level of exploitation) and the resource use (number of resource users, gear, catch, and habitat) will be assessed for the current year and for the last 10 years.

For the socio-economic assessment, information will be gathered about fish resources, resource use activities and human people. A series of meetings and discussions will be held with resource users, stakeholders, and government officials to begin to develop communication and a consensus on their interests and concerns, and to build awareness about resource protection, management and rehabilitation.

This project is the first step of a long-term project that will protect the three endemic fish species and manage the exotic species and local fisheries. Priority sites for freshwater ecosystem and fish conservation will be identified. The gathered data will be used in the preparation of development and management plans and strategies, for decision-making, for monitoring and evaluation, and the process of documentation.

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