The data on species-wise marine fish landings at Kerala andKarnataka during 1970-2005 were used to examine diversities of fished taxa through alpha, beta, and gamma diversities which are the fundamental descriptive variables of ecology and conservation biology.In Kerala, fishing zone K5 (Kochi) and K3 (Kollam-neendakara) and in Karnataka, fishing zone KN4 (Gangolli-Coondapur-northern Udupi district)followed by KN11 (Mangalore) had high alpha diversity values. These zones are major trawling zones. The beta diversity values and the species turnover rates were also high for these zones. The high beta values indicate uniqueness in species diversity when compared to other zones. The gamma diversity was 818 for Kerala and 524 for Karnataka. Beta diversity index showed a positive relationship with alpha index, indicating dependence of beta on alpha values. While the arthropod diversity was similar in Kerala and Karnataka, the chordate and mollusc diversity was higherin Kerala. The results from the present study indicate that similar studies have to be carried out from other ecosystems along the Indian coast, so that it becomes benchmark information for studying the anthropogenic impacts on biodiversity.

Alpha, beta, gamma diversity, fished marine taxa, southwest coast of India