Materials and methods

The 121 km long, west flowing Aghanashini River from central Western Ghats of South-west India joins the Arabian Sea forming an estuary of about 48 sq.km (Lat 14.3910 to 14.5850 N Long 74.3040 to 74.5160 E) in the Kumta taluk of Uttara Kannada district (Figure 1). The study period (June 2011-May 2012) was divided into three quarters, monsoon (June-September), post-monsoon (October-January) and pre-monsoon (February-May). As a preliminary step pre-monsoon high tide salinity was measured, at two km intervals, and the estuary was divided into three zones: ‘high’ (>20ppt) ‘medium’(10-20 ppt) and ‘low’ (>10 ppt). Catches by fishermen were monitored for one year. Monthly monitoring of environmental parameters salinity, DO, pH, air and water temperature during high tides, was carried out in three stations Aghanashini, Kodkani and Divgi, representing high, medium and low salinity zones respectively. Fish specimens collected from five consecutive cast-net hauls from each zone, month-wise, by fishermen were identified using taxonomic keys8- 12. Similarity of fish assemblages on temporal scale from salinity zones were measured using Bray-Curtis index13. Fish distribution related to environmental variables was obtained using Canonical Correspondence Analysis14.

Figure 1: Aghanashini estuary with sampling stations

 

Citation : Mahima Bhat,  Nayak V. N.,  Subash Chandran M. D. and  Ramachandra T. V., 2014. Fish distribution dynamics in the Aghanashini estuary of Uttara  Kannada, west coast of India, Current Science,  106 (12):1739-1744

* Corresponding Author :
	Dr. T.V. Ramachandra Energy & Wetlands Research Group, Centre for Ecological Sciences, Indian Institute of Science, Bangalore – 560 012, INDIA.		Tel : 91-80-23600985 / 22932506 / 22933099, Fax : 91-80-23601428 / 23600085 / 23600683 [CES-TVR] E-mail : cestvr@ces.iisc.ernet.in, energy@ces.iisc.ernet.in, Web : http://wgbis.ces.iisc.ernet.in/energy