Aquafeed imprint on bogue (Boops boops) populations and the value of fatty acids as indicators of aquaculture-ecosystem interaction: Are we using them properly? Besay Ramírez a,b , Daniel Montero a, ⁎, Marisol Izquierdo a , Ricardo Haroun b a Grupo de Investigación en Acuicultura, Universidad de Las Palmas de Gran Canaria and Instituto Canario de Ciencias Marinas, P.O. Box 56, 35200 Telde, Las Palmas, Canary Islands, Spain b BIOGES, Marine Sciences Faculty, Campus Tafira, Universidad de Las Palmas de Gran Canaria, 35017 Las Palmas de G.C., Canary Islands, Spain abstract article info Article history: Received 4 April 2012 Received in revised form 13 April 2013 Accepted 7 August 2013 Available online 16 August 2013 Keywords: Aquaculture-ecosystem interaction Wasted aquafeeds Fatty acid indicator Bioindicator of aquaculture-environment interaction Escapes of farmed fish into the ecosystem have recently received a marked interest from scientists for their com- petition with wild populations or the risk of genetic contamination. Fatty acid profiles have been proposed as bio- indicators due to the inclusion of terrestrial oils in aquafeed ingredients. This study evaluated 1) the effect of wasted food on the fatty acid content of a farm-associated fish and 2) the suitability of fatty acid profiles as a bioindicator of aquaculture-ecosystem interactions, using the bogue (Boops boops) as a model. This species is an opportunistic fish usually associated with–or even found in–sea farms, and with a high natural occurrence along the Mediterranean and Atlantic coasts. The results showed that fish farms had a direct effect on the condi- tion index, muscle and whole lipid content of bogue inside or around the sea cage, and this effect disappeared completely at 3 km from the cages. Despite the fact that aquafeeds also affected the bogue fatty acid profiles by increasing linoleic and oleic acids and reducing DHA, these profiles were very similar to those of bogue sam- pled close to a sewage outfall, denoting that these fatty acids are not exclusively influenced by aquaculture and therefore should not be considered as good biomarkers for escapees. However, bogues influenced by aquaculture were higher in linolenic acid than those found further than 3 km from the farm or close to the sewage, suggesting this fatty acid as a better indicator of aquaculture influence. © 2013 Elsevier B.V. All rights reserved. 1. Introduction Aquaculture constitutes the fastest growing food production sector and the main contributor of marine food to satisfying the demand of the unceasingly increasing human population (Tacon and Metian, 2008). Nevertheless, this rapid growth can only be maintained if it is sustainable from a social, economic and, particularly, environmental point of view. Thus, the fast development of aquaculture production in coastal areas, particularly when sea-based, has stimulated research into its interactions with the environment (Black, 2001; Hargrave, 200; Naylor et al., 2000). Aquaculture activity may affect marine biodi- versity in terms of genetic variability, species–species interaction or ecosystem alteration (CBD, 2004). The most direct, and the most stud- ied, effect of aquaculture on the environment is that which stems from wasted food and, secondly, faecal discharges, which may modify the characteristics of the sediment under the fish cages (Mente et al., 2006; Molina Dominguez et al., 2001). Besides, the presence of sea cages may alter the surrounding ichthyological community (Carss, 1990; Dempster et al., 2005; Machias et al., 2004; Tuya et al., 2006). Nevertheless, other types of impacts may be linked to the addition of anti-fouling treatments, transfer of parasites or exotic species, discharge of toxic therapeutic products or fish escapes (Fernández-Jover et al., 2010). Escapes of fish from sea-cage aquaculture have been reported for many aquaculture species including Atlantic salmon (Salmo salar), At- lantic cod (Gadus morhua), rainbow trout (Oncorhynchus mykiss), Arctic charr (Salvelinus alpinus), halibut (Hippoglossus hippoglossus), gilthead sea bream (Sparus aurata), European sea bass (Dicentrarchus labrax), meagre (Argyrosomus regius) or kingfish (Seriola lalandi)(Gillanders and Joyce, 2005; Moe et al., 2009; Naylor et al., 2005; Soto et al., 2001). The escapes can be attributed to many factors but are mainly re- lated to farming equipment and its operation. Massive fish escapes (of more than 10,000 fish) are very rare and represent only 19% of the es- cape incidents reported in salmon or cod, but they account for 91% of the total number of escaped fish (Jensen et al., 2010). When escaped fish belong to an exotic species, the environmental impact is less pre- dictable and this type of incident is considered to be one of the major threats posed by aquaculture activities to ecosystems from both a bio- logical and an economic perspective (Soto et al., 2001). If the escapes Aquaculture 414–415 (2013) 294–302 Abbreviations: ALA, alpha-linolenic acid; ARA, arachidonic acid; CI, Fulton's K condition index; DHA, docosahexaenoic acid; EPA, eicosapentaenoic acid; HSI, hepatosomatic index; HUFA, highly unsaturated fatty acid; LA, linoleic acid; OA, Oleic acid. ⁎ Corresponding author at: Grupo de Investigación en acuicultura, Universidad de Las Palmas de Gran Canaria, P.O. Box 56, 35200 Telde, Las Palmas. Canary Islands, Spain. Tel.: +34 928 132 900; fax: +34 928 132 908. E-mail address: dmontero@dbio.ulpgc.es (D. Montero). 0044-8486/$ – see front matter © 2013 Elsevier B.V. All rights reserved. http://dx.doi.org/10.1016/j.aquaculture.2013.08.010 Contents lists available at ScienceDirect Aquaculture journal homepage: www.elsevier.com/locate/aqua-online