SHORT COMMUNICATION A preliminary study on the utilization of hazelnut meal as a substitute for fish meal in diets of European sea bass (Dicentrarchus labrax L.) Ylmaz Emre 1,2 , Hˇseyin Sevgili 1 & Murat S ¸anl 2 1 Mediterranean Fisheries Research Production and Training Institute, Kepez Unit, Kepez, Antalya,Turkey 2 Mediterranean Fisheries Research Production and Training Institute, Beymelek Unit, Demre, Antalya,Turkey Correspondence: H Sevgili, Mediterranean Fisheries Research Production and Training Institute, Kepez Unit 07001, PO Box 190, Antalya,Turkey. E-mail: husevgili@akdenizsuurunleri.gov.tr Introduction Fish meal (FM) is the main protein source of ¢sh feeds, particularly for high-value carnivorous spe- cies.The annual world FM production averages about 7.05 million metric tonnes. Of the 11-year average global production of FM,31.5% was used in ¢sh feeds in 2002.This percentage is, however, expected to in- crease to 65% in 2010, when the aquaculture sector’s annual growth is taken into consideration. Intensi¢- cation of the ¢sh production method requiring nutri- tionally complete diets is also the cause for increased demand for FM. Moreover, El-Nino ì events occurring every 5^7 years on average reduce global FM sup- plies. As a result, availability and prices of FM have become problematic (Hardy 2006). Hence, reduction of the reliance of ¢sh diets on FM and evaluation of every single protein source as an alternative are ex- tremely important for aquaculture to continue as a sustainable activity (Glencross, Booth & Allan 2007). The top hazelnut ( Corylus avellana L.) producer in the world is Turkey, constituting about two-thirds of the world production. It is followed by Italy, Spain and the United States (Klc° & Alkan 2006). Even though the hazelnut is used mainly in chocolate manufacture, its oil fraction has attracted consider- able attention because of health-related features. The crude oil and protein contents of hazelnut are about 56^68% and 17.4^22% respectively (Úzdemir & Aknc 2004; K˛ksal, Artik, S ¸ im ¸ sek & Gˇne ¸ s 2006). Hazelnut meal (HM) obtained after oil extrac- tion is rich in protein ( ca. 40%). The current amount of HM production is unknown, but it is estimated to increase as a result of oil production. In addition, it is available at a substantially low price as compared with FM in Turkey. So far, its nutritional value has been investigated in terrestrial animals such as rumi- nants (Sar c° ic° ek 1999; Karsli, Tasal & Nursoy 2006) and poultry (Úzen & Erener 1992; Erener, Úzer & Ocak 2003). However, there is only one study indicat- ing its use in rainbow trout diets as a source of pro- tein in lieu of soybean meal (SBM) (Bilgin,Tˇrker & Ergˇn 2007). Therefore, our aim was to evaluate the e¡ect of partial replacement of FM with various levels of HM (0%,7.5%,15%, 22.5% and 30%) in the diets on the growth performance of European sea bass, a commercially important carnivorous species cultured in the Mediterranean region. This work was conducted at the Beymelek Unit of Mediterranean Fisheries Research Production and Training Institute. The ¢sh used in the experiment were obtained from the institute’s hatchery. Before the start of the experiment, ¢sh were acclimatized to experimental conditions for 2 weeks. At the start of the trial, European sea bass with an initial individual weight of19.16  0.26 g were randomly distributed at the rate of 40 ¢sh per 500L square experimental tank. Each of ¢ve experimental diets was fed to tripli- cate groups of ¢sh for10 weeks. Fish were fed by hand twice a day at 2% body weight and feed quantity was adjusted according to biweekly total batch weighing. Over the course of the study, a10 L min 1 £ow rate of Aquaculture Research, 2008, 39, 324^328 doi: 10.1111/j.1365-2109.2007.01881.x r 2008 The Authors 324 Journal Compilation r 2008 Blackwell Publishing Ltd