Indian Journal of Geo-Marine Sciences Vol. 46(6), June 2015, pp. Marine ichthyofaunal biodiversity in the trawling grounds off Mangalore coast Jitendra Kumar * , S. Benakappa, A.P. Dineshbabu 1 , H.N. Anjanayappa, S.R. Somashekara, Kumar Naik A.S. & Mahesh, V. Department of Fisheries Resources and Management, College of Fisheries, Karnataka Veterinary, Animal and Fisheries Sciences University, Mangaluru-575002, India 1 Central Marine Fisheries Research Institute (CMFRI), Mangaluru, India [ * Email: jitenderanduat@gmail.com] Received 22 October 2013; revised 15 May 2015 Present investigation was taken to assess the status of ichthyofaunal diversity off Mangalore coast. The data for the present study was collected from the multiday trawlers operating from Mangalore fishing harbour over a period from September-2012 to April-2013 and sampling was done once in fortnight. A total 97 species belonging to 72 genera, 50 families and 15 orders were recorded during the study period. The value of Shannon-Wienner index (H') was recorded ranged from 1.404 to 1.648. There is less variability among H'. Diversity and evenness are highly correlated (0.90) and showed variation with each other. Average value of Simpson index was found to be 0.038 and the value of Simpson index increased with decrease in diversity. In the present study the Margalef richness index showed a high positive correlation with H', N 1 and N 2, and J' and negative with Simpson index (λ), Evenness index (N 21 and N 21' ). The value of H' showed positive correlation with all diversity indices except λ. K-dominance plot clearly demonstrated the diversity pattern during the study period. When the data of 8 month (September-2012 to April-2013) were plotted together, the curve which lied on the lower side during October-2012 extended further and rose slowly due to the presence of more number of species. K-dominance curve showed that density of fish species was high in the month of October-2012 and proved the number of species (richness) more in the month of October-2012 compared to other months. Bray-Curtis similarity (hierarchical clustering) from the overall cluster analysis, it was observed that the maximum similarity (89.65%) was observed between March-2013 and April-2013. [Key Words: Ichthyofaunal biodiversity, diversity, trawling, Mangalore] Introduction The most unique feature of earth is the existence of life, and the most extraordinary feature of life is its diversity 1 . India is one of the 17 mega biodiversity countries of the world. With only 2.5% of the land area, India accounts for 7.8% of the recorded species of the world 2 . Marine fish stocks in many parts of the world have been exploited beyond recovery 3 and trawling is one of the most efficient methods of catching fish world over and is also the most important human intervention causing physical disturbance to the world’s continental shelves, and consequently, the physical destruction of ecosystems 4 . Trawling is targeted at specific groups of organisms, and trawl net being a non-selective gear, catches everything available in its towing path. In general non-targeted, non-commercial species in the by-catch will be thrown overboard, a practice called discarding 5 . The state of Karnataka has a coastline 320 km and constitutes nearly 15% of the coastline with numerous river mouths, lagoons, bays, creeks and a few islands. Mangalore fishing harbour is one of the important landing centres of Karnataka coast, contributing more than 40 per cent of the total catch of Karnataka. There are about 96 fish landing centers in the state. Mangalore and Malpe in South Karnataka and Karwar in the north are major landing centers. The main types of fishing are by purse-seine, trawl and gill net. Number of trawlers operating along Karnataka are 2847 of which 1050 trawlers are operated from Mangalore fishing harbour 6 .