Diet of demersal fish species in relation to aquaculture development in Scottish sea lochs Eleni Mente a,b, ⁎ , Graham J. Pierce b , Nicky J. Spencer b , Joanna C. Martin d , Ioannis T. Karapanagiotidis a , M. Begoña Santos c , Jianjun Wang b , Christos Neofitou a a School of Agricultural Sciences, Department of Ichthyology and Aquatic Environment, Fytoko Street, GR-38446 N. Ionia Magnisias, Greece b School of Biological Sciences (Zoology), University of Aberdeen, Tillydrone Avenue, Aberdeen, AB24 2TZ, UK c Instituto Español de Oceanografía, Centro Oceanográfico de Vigo, P.O. Box 1552, 36200, Vigo, Spain d FRS Marine Laboratory, PO Box 101, 375 Victoria Road Aberdeen AB11 9DB, UK Received 14 August 2007; received in revised form 3 February 2008; accepted 4 February 2008 Abstract The diets of demersal fish, principally haddock (Melanogrammus aeglefinus), whiting (Merlangius merlangus) and several flatfish species, sampled from four Scottish sea lochs (Hourn, Kishorn, Duich and Nevis) which support aquaculture sites, were examined in order to determine whether the impact of aquaculture on benthic biodiversity would affect the diets of demersal fish. Loch Kishorn had the highest maximum planned aquaculture production, loch Nevis follows and lochs Hourn and Duich have the lowest planned production. Samples were collected from locations less than and more than 2000 m from fish farm cages. Fish close to the fish farm cages were on average of greater individual weight than those further away from fish farms. Haddock ate predominantly Malacostracan crustacea, Ophiurid echinoderms and Polychaete annelids; whiting ate predominantly Malacostracan crustacea and teleost fish and flatfish ate Malacostracan crustacea, Polychaete annelids and Ophiurid echinoderms. A small number of saithe sampled had eaten mainly fish farm pellets. Dietary variation in each species was analysed in relation to loch, proximity to aquaculture facilities and fish size. Diet of whiting varied with body size. Dietary differences were observed between the lochs and between sites close to and far from farms in two lochs although these differences cannot be specifically attributed to aquaculture development. Controlling for differences between individual lochs, proximity to aquaculture facilities did not consistently affect diet composition. © 2008 Elsevier B.V. All rights reserved. Keywords: Aquaculture; Diets; Sea lochs; Demersal fish 1. Introduction During the last 20 years, aquaculture has assumed an important role in the Scottish economy as well as for the generation of jobs and development of many rural areas (Scottish Executive, 2000). The salmon farming industry is now a major source of employ- ment, particularly in many of the more remote areas in Scotland (Scottish Executive, 2000, 2006). The Scottish salmon aquaculture industry began in 1968 by domestication of the natural river stock (Heen et al., 1993). Commercial production started in the mid-1970s and 500 tonnes of salmon where produced from 14 different sites in 1979 (Shearer, 1992). Since the early 1980s, the total annual production of Atlantic salmon increased steadily from 600 tonnes in 1980 to 126,686 tonnes in 1999 (Scottish Executive, 2000). The West Coast of Scotland, along with the Western Isles, Orkney and the Shetland Isle are the principal locations for the Scottish salmon industry. Indeed, the West Coast has become the most productive salmon region in the UK, with an estimated 42,634 tonnes of farmed salmon produced in 2000. This reflects the requirement for relatively clean and sheltered areas in which to locate marine fish farms. Multi-nationals, two-thirds of which are owned by foreign companies and around 50% by Norwegians, currently dominate the salmon industry in Scotland (ICES, 2002; Scottish Executive, 2006). In contrast shellfish farms are usually run by small local companies (Scottish Executive, 2000, 2006). Available online at www.sciencedirect.com Aquaculture 277 (2008) 263 – 274 www.elsevier.com/locate/aqua-online ⁎ Corresponding author. School of Biological Sciences (Zoology), University of Aberdeen, Tillydrone Avenue, AB24 2TZ Aberdeen, UK. Tel.: +44 1224 272459; fax: +44 1224 272396. E-mail address: e.mente@abdn.ac.uk (E. Mente). 0044-8486/$ - see front matter © 2008 Elsevier B.V. All rights reserved. doi:10.1016/j.aquaculture.2008.02.022