Marine Policy 30 (2006) 237–248 Mechanization and technical interactions in multi-species Indian fisheries: implications for economic and biological sustainability Mahadev G. Bhat à , Ramachandra Bhatta a Environmental Studies Department, Florida International University, Miami, FL 33199, USA b Fisheries Economics Department, College of Fisheries, University of Agricultural Sciences, Mangalore 575002, India Received 19 February 2004; received in revised form 14 January 2005; accepted 15 January 2005 Abstract Joint capture of multiple species by multiple fleets results in technical and economic interactions between fleets. This paper develops a bioeconomic model that incorporates interrelationships between fleets for a representative fishery in India. The study analyzes the impacts of overcapitalization on bio-economic sustainability. Results show that a continuation of the current fishing intensity would deplete most commercially important species in the near future. However, an optimal effort re-allocation between fleets would increase fishery profits substantially, although some species would remain unsustainable. The study demonstrates how the newly emerging, large bodies of fishery data can be used for management decisions in developing countries. r 2005 Elsevier Ltd. All rights reserved. Keywords: Multi-species fisheries; Multi-gear; Technical interactions; Sustainability; India 1. Introduction Most fisheries around the world today possess three types of pluralism: the capture of multiple species (resources), the co-existence of multiple fleets (technol- ogy), and the coexistence of small-scale and large-scale fisheries in a given fishing ground (user groups). The fisheries literature has long recognized that interactions occur within and between these three fishery compo- nents [1–5]. For instance, biological interactions such as predator–prey or competition relationships may exist between multiple species [2,6]. Due to these relation- ships, excessive harvesting of one or more species may cause unsustainable changes in the stocks of related species. Economic and technical interactions occur when multiple fleets (e.g., trawlers and purse seines) compete for the same stock of one or more species. A failure to consider biological and technical interactions in fishery management may give rise to the problems of by-catch, stock unsustainability, and economic inefficiency [7]. Finally, social interactions take place between user groups. It is common in most fisheries for both small- and large-scale fishers to co-exist and to compete for resource stocks and space [8]. Small-scale fishers with limited access to credit and, in turn, limited access to advanced fishing technology are normally competed out by the more mechanized cost-efficient fishing fleets. Fishery management regimes in many, if not most, tropical developing countries have paid little attention to biological, technical and social interactions. Biologi- cal interactions are often poorly understood. Technical and social interactions are sometimes ignored for political and social reasons. For whatever reason, the net effect of failing to consider these interactions is for multi-species fisheries to be exploited at a sub-optimal level [9,10]. Such fisheries generally experience an increase in number of users as well as number of user conflicts. Multi-species and multi-fleet fisheries have compli- cated fisheries management particularly in India. The ARTICLE IN PRESS www.elsevier.com/locate/marpol 0308-597X/$ - see front matter r 2005 Elsevier Ltd. All rights reserved. doi:10.1016/j.marpol.2005.01.001 à Corresponding author. Tel.: 305 348 1210; fax: 305 348 6137. E-mail addresses: bhatm@fiu.edu (M.G. Bhat), rcbhat@sanchar- net.in (R. Bhatta).