C. V. Asha , R. I. Cleetus , P. S. Suson , S. Bijoy Nandan

Department of Marine Biology, Microbiology & Biochemistry, School of Marine Sciences, Cochin University of Science and Technology, Fine Arts Avenue, Kochi-682016, Kerala, India
Author    Correspondence author
International Journal of Marine Science, 2015, Vol. 5, No. 23   doi: 10.5376/ijms.2015.05.0023
Received: 03 Jan., 2015    Accepted: 10 Mar., 2015    Published: 30 Mar., 2015

This is an open access article published under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

Asha et al., 2015, Environmental factors structuring the fish assemblage distribution and production potential in Vembanad estuarine system, India, International Journal of Marine Science, Vol.5, No.23 1-13 (doi: 10.5376/ijms.2015.05.0023)

Vembanad wetland system, a Ramsar site on the West coast of India is the largest estuarine system, renowned for its rich fishery diversity and endemicity. In 1976, to regulate salinity intrusion into the Vembanad estuarine system, the Thannermukkom barrage was constructed across the estuary dividing it into fresh water dominated southern and a northern region dominated with brackish water, which has grossly altered the eco-biology of the region. In this context, the influence of environmental factors on fish assemblage structure has been poorly recognised in Vembanad estuarine system mainly for effectively implementing proper management and conservation measures. Information on fish assemblage in relation to environmental parameters collected from February 2012 to January 2013 is reported in this contribution. Estimates of annual average fishery production indicated a catch of 4774.46 t in the estuary, in which 10.1% and 89.9% was contributed by southern and northern zones respectively. Seventy four species of finfishes, eleven species of shell fishes were identified for the study period.Multidimensional scaling and canonical correspondence analysis significantly demarcated the spatio – temporal variation of fish species distribution and observed a strong correspondence between fish assemblage and environmental variables. Depth, temperature, pH and salinity were the most important parameters explaining the variation in fish assemblage composition and abundance in Vembanad estuarine system. The aging Thaneermukkom barrage and its faulty operation reduced the tidal flushing altering the circulation and mixing process, especially in the southern part of estuary. This influenced the hydrological characteristics leading to a decline in estuarine fishery and its production potential.

Environmental factors; Fish assemblage; Ramsar site; Vembanad wetland system