MATERIALS AND METHODS

Study Area:The study was conducted in the Aghanashini River estuary (Lat 14.391^o to 14.585^o N Long 74.304^o to 74.516 ^oE) of Kumta taluk and the Sharavathi River estuary (Lat to 74°6711″–75°30′63″E and 14°7′27″–13°77′08″N) of Honavar taluk in the Uttara Kannada district of central west coast in Karnataka, India (Figure1). The Aghanashini originating in the Sirsi taluk of UK runs its short course of about 70 km through Western Ghats valleys widens into an estuarine expanse in the Kumta taluk where it opens into the Arabian Sea. The Sharavathi River, famed for the Jog Water falls, originates in the Tirthahalli taluk of Shimoga district. The 128 km long river winding through the deep gorges of Western Ghats spreads in to an estuarine expanse, three km at its widest part, in the Honavar taluk of UK. Its river mouth is quite narrow due to a sand bar across.

Figure 1. Locations of Aghanashini and Sharavathi estuaries

Study on fish diversity: Fish catches from both the estuaries were routinely monitored for a year, and fishermen interviewed on month-wise income from catches of commercial fishes. Fishes collected were identifiedusing keys provided by Talwar (1991); Day (1967, 1971) and Munro (2000). In cases of unidentified fishes the local names given by the fisher-folks have been used.

Salinity measurement: Salinity was measured for one year in both the estuaries using a portable salinity refractometer. Most of rainy season from June to September salinity was very low (less than 1 ppt from mid June to August). Whereas salinity started increasing from the weakening of rainy season by September and reached peak (> 24-34 ppt) during April and May in Aghanashini, in most of Sharavathi estuary it remained less than 1 ppt only during peak summer months also bringing adverse conditions for typical estuarine and marine fishes.

Income estimates from fisheries: Details regarding number of estuarine village-wise number of fishermen were collected from the local gram panchayat offices. Details regarding village-wise numbers of active fishermenwere collected through household surveys covering 5-15 households in every village. These numbers were extrapolated for all the fishing community households to arrive at village-wise number of active fishermen. All the fishermen interviewed were asked about average days spent on fishingmonth-wise, and on average fishing income per fishing day, and the figures arrived at extrapolated for the households of all active fishermen. These ground level data collections helped in arriving at total annual income generated from fisheries from both the estuaries. Tables 1 and 2  provides the details of economic valuation of Aghanashini and Sharavathi estuaries respectively.

Table 1: Aghanashini estuary

Table 2: Sharavathi estuary